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SOLAR FREAKIN ROADWAYS! We've all seen it plugged. And we've all either cheered it on or smacked our head in the ridiculousness of the proposal. Some of us, myself included, doing both.

It's a utopian vision. There's vastly more road surface in the world receiving solar energy than would be needed to power all of human society. So we just replace our roads with solar freakin roadways, and the climate problem is solved without using any more land. No need to get every house retrofitted for a custom-designed solar panel array installed by hand with its own transformer and all sorts of overhead, you just pave out your solar roads en masse whenever a new road is needed or an old road needs to be repaved, and viola, climate crisis solved and human impact on the planet vastly minimized. And think of all the side benefits. Optionally batteries in the road storing excess between day and night! LEDs providing customizable traffic messages and illumination! Heaters melting inches of snow away in minutes! Piezoelectricity capturing even more power! The proposal is incredible.

The proposal is also, as it stands, ridiculous. The goal of this article is to remedy that.

How realistic is the current proposal?

Let's start with addressing some of the arguments that have been made against the concept that aren't actually valid.

1. "Glass is slippery" - which is why you don't use smooth window glass, you use "traction glass" / "anti-slip glass", which is textured and can be made as rough as gravel. The texturing has a small but not problematic impact on light transmission, and can in some cases help with self-cleaning. In very high traction anti-slip glass the surface texture often ruins optical clarity by distorting the image, but solar cells don't care about image distortion, just transmission.
2. "Glass breaks" - it is amazingly difficult to break a thick pane of resistant glass lying atop a hard surface. Glass has a very high compressive modulus. Its weakness is in flexure, which is why you have joints between panels and don't make the panels too large. Some large buildings even have glass support exterior loads, in much more difficult circumstances than a road.
3. "Broken glass will scatter the road with dangerous shards" - Glass is not a single product with a single set of properties. Laminated glass retains the shards in roughly their original positions after breakage (which is why it's used in, for example, car windshields).
4. "Glass scratches" - which is the purpose of anti-scratch coatings, to raise the hardness above that of quartz and thus prevent scratches from all common materials (sand, steel, glass, etc)
5. "Cars shade the roads" - Go to Google Maps and zoom in on random roads around the country, you'll see that the impact is quite minimal, to the point of near irrelevance on most roads.
6. "Some roads go through forests or other shady spots" - which is why you don't begin with those roads.
7. "It's more efficient per unit area to angle panels" - There's no shortage of "unit area" in roads, so all that matters is economics (covered below). It's also more efficient per unit area to put panels on heliostats than on fixed roof slopes, but you don't see that stopping people.
8. "It makes more sense to put panels beside the road" - not if your goal is minimizing human impact (aka, surface area). Additionally, one of the benefits of a solar road is that you get "two things" (a road and a solar farm) by building only one thing (a solar road). Building a second solar farm next to a road is an additional step which loses this benefit.  
9. "You don't know how this will work out in the real world" - which is why one builds pilot projects, which is what people are seeking. That's the whole point of a pilot project.

And of course let's cover the unspoken reasons for solar roadways:

1. "Hardware costs are less than overhead." We've reached the point where installation and other overhead costs are now greater than panel costs. With current trends, we can expect that in the future, installation costs will be vastly greater than materials costs. Hence it's perfectly fine if by building a solar roadway your materials costs rise and your efficiency declines, so long as you reduce the more critical installation costs.
2. "Home roofs are really pretty bad if your goal is to reduce the installation costs." They're at altitude, on top of a not-nearly-as-solid-as-the-ground structure, require custom design for each home and a lot of other corporate overhead, very difficult to automate, require an transformer for each home, and so on down the line. By contrast, it's hard to envision any way to get lower installation costs than laying down bulk panels from an automated truck in a straight line. And while there is some overhead (permitting, right of way, etc), it's the same overhead required for any road, and per unit area, it's orders of magnitude less than for houses.

But there are some quite legitimate arguments against the "Solar Freakin Roadways!" proposal.

1. "Starting with high traffic roads in cold climates versus, say, sidewalks, driveways, access roads, etc in temperate climates, is not exactly starting with the low-hanging fruit" - No question there.
2. "The 'melting snow' concept just doesn't add up, it'd cost a dollar per square foot to melt a couple inches of snow at 100% efficiency, when it only costs five cents a square foot to plow it" - Absolutely correct.
3. "Capturing piezoelectricity means having your panels give to some extent, which means you're just stealing power from the inefficient, polluting cars driving on it, which effectively must continually drive upwards to counter the give." - By and large, correct.
4. "All of the electronics they plan to put in there would make the panels too expensive even with mass production, and would require panel replacement whenever they fail." - Probably true.
5. "Bright LEDs in particular are very expensive, and its far more efficient to just have light bounce off road paint than to capture it with PV cells then turn it back to light, thus losing over 90% of the energy." - Yep. Not to mention that you can still let whatever wavelengths through the paint that you don't need to reflect rather than absorbing them.
6. "They really hand-waved most of the math and economics, didn't they?" - Yes. Yes they did.

So - where does that leave us?

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An alternative propsal: Realistic Solar Roadways

First off, we need to accept that we must tackle the low-hanging fruit first. There's no shortage of new road construction, you don't need to start with something designed for highways in Idaho. Your best examples would be, for example, sidewalks or access roads in warm, sunny climates that get little traffic. We will analyze below the complex case, but the first actual projects would be much simpler tasks.

Secondly, we need to toss piezoelectric generation. Our goal is to minimize fossil fuel consumption and pollution, not to increase it.

Third, we need to throw away the concept of melting inches of snow and ice. It's just doesn't add up, financially. Instead, I propose an alternative solution. Instead of having drainage channels built into the cells to in-cell drains as the "Solar Freakin Roadways!" team proposes, I propose to handle drainage on the surface (as with a regular road), and instead use airflow that can leak out from over the cells through small (0,7mm) holes at regular (22mm) intervals, creating a very weak "air hockey table" effect over the road. This would be an amount of pressure effectively irrelevant to tire traction (a tiny fraction of a psi, versus the dozens of PSI a car exerts), not even nearly enough to slide a 20 gram air hockey puck, but enough to keep 3 milligram snowflakes from settling. As anyone who's driven in snow before knows, snow doesn't settle when it has to overcome air blowing against it, it flows to the side - even driving at low speeds is enough to keep snow off your car. But when you stop and there's no longer a cross-current, it begins to accumulate. Panel heating would only be used sporadically to remove thin layers of ice should any form. The ability to pump air through the panels would also provide additional solar cell cooling, which raises efficiency. The small hole size (and potentially a hydrophobic interior coating) would prevent water and dirt ingress. More on the calculations behind this proposal in a moment.

Fourth, we need to greatly simplify the panels. Storing energy in little batteries in hard-to-access areas is just a bad idea, and should be tossed - leave it to grid operators to handle that in a much more efficient manner (pumped hydro, peaking plants, flow batteries, whatever). The per-panel control electronics need to go too. The panels need to be simple, passive structures to minimize costs. All more complex activities, such as fans, transformers, and so forth should be done in periodic roadside utility stations with convenient access for maintenance.

Fifth, we must consider real-world constraints. We need to throw away the hex panels and go with simple rectangles. Hex panels are cute, but in the real world we deal with straight lines instead of zigzags - everything from conduits to shipping containers. Our panels should be 50 centimers by 60 centimeters (roughly 1 1/2 by 2 feet), bundled in stacks of four on a standard 1016 x 1219 mm pallet, 18 panels high, to be shipped 20 pallets per standard iso container. Our panel laying truck should receive pallets as-is, forklifted straight into its bed, and feed directly from them. If our goal is to minimize costs, we can't be having tons of wasted space or involving lots of manual labor at any step.

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Now, let's diagram what we're needing here. First, your basic panel:

The cells are wired in series which connects in parallel to a primary lateral conduit, which also allows for airflow between the panels. All current here is DC. For the sake of this design, we will assume that the operating panel voltage is 600V, achieved by running 1200 cells together per panel in series (for the purposes of illustration, we're showing them as boards pre-wired to 40V). 600V is much higher than is used in home rooftop installs, but typical for PV usage with centralized transformers (some installs are now upwards of 1kV). Between the panels, the lateral conduits are kept roughly pressuretight by rubber seals, and the electrical wiring in them connects by snap connectors.

Due to our high voltage, we can use very fine wire, even as low as 40 gauge (0.08mm) if so desired, between the cells without encountering significant loss; our only constraints are on how rugged we want the wires. For our calculations, let us assume 30 gauge uninsulated copper wire (0.255mm, 0.338 ohms/m) between the cells and 20 gauge insulated copper (0.812mm, 0.0331 ohms/m) in the lateral conduits. Waste heat is current squared times resistance. With perhaps 125 centimeters wiring between our cells and an assumed peak cell efficiency of 10% with 90%++ of the panel covered in cells (27 watts, aka 5.4 watts per bank), running at 600V (aka, 0.045A) our resistance works out to a heat loss of 0.00034W in the cell wiring, aka, a mere 0.006% of the generated power.

(++ Ideally we'd like more than 90% cell coverage, but let's be pessimistic)

For the lateral conduits, if we assume that our road has four lanes paved plus enough shoulder space to count as a fifth, and an average lane width of 4m, then we have a road that's 20 meters wide made of 40 panels (1080W per row of panels), meaning an average of 20 meters run length for a full circuit. If we repeat our above calculations for the 600V in the lateral conduits at 20 gauge, we get 2.14W of waste heat, aka 0.018% loss. Hence even with these very thin wires, our total losses are less than two tenths of a percent at this stage.

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All lateral channels connect both power and air to a primary conduit on the side of the road, which handles air flow, two-wire DC transmission, 3-phase insulated AC transmission, and includes a fiber-optic line (a small extra cost that can be rolled into the manufacture to provide net connectivity not just to your utility stations, but to the general public):

The DC lines only run to the next station in each case, which are spaced 250 meters apart; we assume 4/0 gauge insulated aluminum wire (11.7mm / 0.0000272 ohms/km) for this. With an average run length of 125 meters in each direction (250 meters total) at 600V and a peak power of 450kW per segment, we get 3.825kW waste heat, or 0.85% loss. So far our losses are under 1%.

Each of our utility stations then turns this maximum 450kW per segment into AC for distribution. The ideal voltage is difficult to decide, as it depends greatly on your use case (urban with immediate distribution or very long distance transmission out in the middle of nowhere). We'll assume a suburban-to-rural case with an ideal transmission voltage of 20kV and average transmission length of 15km on 20mm insulated aluminum wire. Beyond this length, power should be stepped up to higher voltages for long-distance transmission. Our sample 4-lane + shoulder road generates a peak of 1.8MW/km, so with an average AC transmission length of 15km we need to transmit 27MW, which at 20kV is 1350A, or 450A per phase. The AC resistance on our wire at 10km is 1.29 ohms, yielding a loss of 260kW or about 1%. This brings our net total to 2% loss. One can play with these numbers to customize them to a particular situation; doubling the average transmission distance doubles conductor diameter, while doubling the voltage halves it but doubles the required insulation thickness.

Lets use bulk industrial manufacturer prices from Alibaba.com. Our net total of wiring per kilometer of road is approximately 360 kilometers of uninsulated copper 30 gauge (about $5k), 70 kilometers of insulated (600V) copper 20 gauge (about $5k), 2 kilometers of insulated (600V) aluminum 4/0 gauge (about $5k), and 3 kilometers of insulated (20kV) aluminum 20mm wire per kilometer of road (about $15k), yielding a total of about $30k per kilometer. One could save money by going with aluminum wiring in the panels and conduits instead of copper.

Adding a fiberoptic bundle in the primary conduit will add perhaps $10k per kilometer. Fiberoptic lines are not particularly expensive, most of the cost of laying fiber is the act of laying it.

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Next, our utility stations (whether above the surface or buried) perform a number of different functions, which I will briefly go into:

First off, we have our primary task: the 450kW, 600V DC to 20kV AC transformer. Such a transformer is a box roughly about 1 cubic meter; in bulk this should be about $6k per unit.

Next we have our fan unit, for cell heating/cooling, road dust removal, and snow accumulation prevention. Given a road + shoulder surface area of 250m * 20m = 5000 m² per box, and the desire to have air coming out of holes comprising 0.1% of the panel's area and moving at 5 meters per second, this yields a flow area over a panel of 0.005m² and a flow rate over the current segment of road of 25 m³/s. A bulk-purchased industrial blower of this sort is an approximately $2k box comprising about 2 cubic meters and requires about 25 kilowatts to run at full capacity (only about 5.6% of the peak output of the road, and only needed either during snowfall/blowing snow or when cell cooling calculations suggest it would be a net benefit). A 50kW blower-integrated electric (or otherwise) heating element sufficient to remove thin ice coatings on the road (not to melt inches of snow) would add perhaps $1k to the blower's cost. Heat within the system must be maintained at temperature sufficiently below that which would be hazardous for the system components, such as wire insulation and solar cells. Operating the heater, assuming 500 joules per gram of ice melted (versus the minimum 334 required by physics) would take about 700kWh per millimeter of ice per station (1 1/2 hours of peak road output per millimeter of ice, plus a bit extra to make up for blower consumption; about $300 per kilometer at residential power rates). The blower and heater could be omitted for the utility stations for roads in non-snowy climes, or even abandoned altogether in snowy climes in favor of plowing. If a blower is present, a cooling unit could be optionally included to increase cell efficiency if determined to be economically beneficial overall; however, just blowing outdoor air through the panels will usually provide some degree of cooling, especially on bright summer days when the panels heat up the most relative to their environment.

More about cooling: solar cells are sensitive to temperature, losing about 1% efficiency for every degree celcius they rise. If by blowing a small amount of outdoor or chilled air through the cells one could lower the operating cell temperature by 10 degrees (C) or so, they could gain a (roughly) 10% efficiency boost, well more than the energy needed to run the blower. Whether such flow rates could achieve such cooling is a complex problem to model and will not be attempted in this article; I wish only to point out that the possibility exists.

Continuing onward: The utility box includes a weather/monitoring station to assess current conditions - snowfall, rainfall, temperature, wind, icing, vehicle counting, whatever is determined to be useful for either the road itself, traffic planners, meteorologists, drivers, etc; in bulk, as part of a utility station, this hardware would probably run about $500. The station also has a small central control computer controller, probably nothing more than a $100 unit (its job isn't very complex).

Each utility station has a fiberoptic access point to provide itself net access and to provide net access to local consumers. In addition, the station provides a connection point for local consumers to get electricity (aka, to connect a line to local step-down transformers). All of this, plus the housing shed, etc probably adds another $10k or so to the total cost. If one wishes to bury the substations (so that only a cooling air intake and possibly feeds to local power distribution are visible and noise would be minimized), excavation costs must be added. This, however, should not be a large percentage of the total cost, as one can hire a backhoe and operator for under $100 an hour and it shouldn't take more than couple ours of digging (plus, of course, overhead). It would likely however increase the cost of the station's housing as well. Having them underground would probably increase the costs by about $5k per station. Let's just say that our total net cost is probably in the ballpark of $22.5k per station, or $90k per kilometer of solar road.

This is for a 4-lane road with utility stations spaced every 250 meters. We could reduce the size of these utility stations and their hardware by spacing them more frequently, which would also reduce the diameter of our DC conductors. A 2-lane or smaller road would have smaller station hardware requirements, while a larger road would have larger requirements.

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Now, let's take a closer look at our panels, in comparison to our sample road (4 lanes, shoulder, surface area of 20k m² per kilometer).

The base layer on which everything is built is simple 3mm aluminum sheeting, which is about $10 per square meter, which works out to $200k per kilometer. This has the side effect of reflecting any non-absorbed light back for a second pass at the cells, which should provide a small but relevant boost to their efficiency. It will also help draw away heat from the cells and lose it to the ground, which further increases their efficiency.

Next comes the most important and expensive layer - the solar cells. These are wafers, not panels, so they're cheaper than panel prices - about $0.25 per nominal watt in bulk.  At 15% nominal efficiency this works out to around $40 per square meter. Assuming 90% coverage the total cost here is $720k per kilometer.

Glass is the second most expensive element. We'll assume 1.5cm thick float glass, laminated on one side, anti-slip on the other, with an anti-scratch coating on the anti-slip side (note that the drainage channels, air holes, interlocks, etc will need to be cut before the anti-scratch coating is applied, but we'll cover that in manufacturing later). The base anti-slip laminated glass cost here is approximately $8 per square meter, hardly more than the price of regular laminated glass. So scratch-resistance seems to be the price-dominating factor. High-end anti-scratch glass, like the gorilla glass that's used in cell phones, costs about $60 per square meter, but we don't need anything that extreme; low end anti-scratch glass of this thickness is around $16 per square meter and it should suffice, so let's just say $18 per square meter all together after accounting for anti-slip surfacing. Our total here is $360k per kilometer.

Our ends will have to be sealed with a synthetic rubber to keep the panels watertight and to provide a pressuretight seal where the air channels meet. Let's say $30k per kilometer.

Our cells will fit together with rubber-coated aluminum pins that slots into the glass. Let's say $30k per kilometer.

Our electrical snap connectors for the power cables will probably add another $30k per kilometer.

The primary conduit on the side of the road needs to be rather large and sturdy, probably about $10 per meter. So $10k per kilometer  

Our total thusfar is approximately $1,5m per kilometer. Next we must add manufacturing costs and any shipping/taxes required during manufacture. While it's tempting to dismiss them as insignificant, they're not, and there's reason in particular here to suspect that they'll be a significant portion of total costs - for example, the need to waterjet cut holes, channels to the holes on the underside of the glass, drainage channels on the exterior, interconnects between panels, etc. In mass production it'd be custom hardware designed to put the same pattern into each piece at the same time, not an expensive one-off cutting process, but it will still not be "cheap". The utility stations also need some assembly, although it'll be a lower portion of their total costs. I'm tempted to say that overall these manufacturing and other associated costs could more than double the overall cost per kilometer, despite the fact that we're using some moderately pricey components (solar cells, scratch-resistant glass, etc). So let's say our total suddenly jumps up to $3.2m per kilometer, with the largest component being the glass cutting, and the second largest being the solar cell wiring.

The tacky asphault surface on which all of this is laid will be accounted for in the roadbuilding process.

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Now it's time to look at how we lay the road:

Just like regular roads are laid down by machines custom-designed for it in order to minimize costs, so should our solar road. Pallets straight out of the shipping container are delivered to the site, their bundling plastic is removed, and then they're loaded up in rows onto the paver truck. On the back of the paver is a ramp, which is maintained at the same height as the panels it's feeding from (this means that its angle declines with time, but is always steep enough for the smooth aluminum underside of the panels to slide down it). The paver does a final smoothing pass on the pre-laid road undersurface while tiny wheels at the back of the ramp keep it aligned with any adjacent panels (if any exist) that it might be connecting to. The end of the ramp is staggered so that the panels slide into place one after the next, allowing their pins to slot into place, and a wheel presses them together. Panels are pushed onto the ramp by adjustable high traction rollers, driven by the driveshaft to ensure a proper feed rate. One worker drives the paver, while one walks beside it at all times to make sure that everything is slotting into place correctly and take care of any problems that may arise. On one side of the road, the primary conduit is laid down at the same time, also pinned into place as its unreeled; a small blade digs a channel for it to slot into in the road undersurface, and buries it under at a reasonble depth after it latches into place. On the other side of the road, a seal is applied to the air channels to seal them off. On both sides it may be desirable to create additional structures - curbs, drainage gravel, etc, depending on the situation, as per with a conventional road. While the paver is laying down the road, a loader drives back and forth to fetch additional pallets of panels to load into the paver. An additional team follows the truck afterwards, installing the utility stations.

It's hard to say what the cost of a roadlaying process that does not yet exist will be; however, the overall process and hardware complexity looks similar to that of building traditional roads; it is, in short, a regular road with an alternative, more expensive top layer. Hence we should use traditional road costs per kilometer in our calculations (perhaps $3m per kilometer for such a road). Note that these traditional roadlaying costs also include surfacing materials that we're not using, as we're using the panels instead. We'll just eat those costs, saying that they're equivalent to whatever extra overhead exists for the utility stations.

The panels, as mentioned, come from the manufacturer on standard pallets. If we assume our panels stack 3 centimeters high each, then we can stack panels 18 high (half a meter) in four columns per pallet. Assuming an average panel density of 1500 kilograms per cubic meter then our pallets weigh 972 kilograms, under the 1000 kilogram max for standard pallets. At 20 pallets per container, our total load is 20 tonnes, below the 22 tonne standard maximum. The 1440 panels per shipping container pave an area of 432 square meters, meaning that we require 46 containers per kilometer of road. At a cost of around $10k per container (international shipping plus taxes), this works out to a panel shipping cost of about $460k per kilometer of road. To this we should add perhaps a third of that for domestic shipping, bringing us up to around $650k per kilometer of road. Let's add in another $150k for international and domestic shipping of the utility stations.

Our net figures, thus, are around $7m per kilometer of solar road, versus $3m per kilometer of conventional road, for a net surcharge of $4m (again, remember, the operating assumption is that it's built where a road was needed anyway, that first $3m would have had to be spent anyway).

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Now, what about the generation figures?

As per above, we calculated a maximum generation per kilometer of around 1.8 MW. There's a couple percent losses in the road wiring, plus the transformer losses, plus the occasional blower or heater losses, plus whatever might be on the road that hasn't washed off / been blown off, plus glass transmission losses, plus shading, plus angle losses, plus clouds, plus night, and on and on. All of these things together make up the capacity factor. A typical capacity factor for rooftop installation is about 15%. While we do gain on some fronts, such as using higher voltages and more efficient, centralized transformers, we'll still end up with a significantly lower capacity factor, probably in the ballpark of around 9%. This means that we yield an average output of 162 kW, or an annual net of 1.4 GWh. At a net market rate of 10 cents per kilowatt hour (I think one could debate rates for this ranging from 5 to 30 cents, let's go with 10), that's an electricity sale value of 1.4 million per year, yielding a simple payback period of only 2.9 years.

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What are our failure modes?

We should analyze what significance various system hardware failures would have, as one can always be assured of failures somewhere.

A short in a panel can eliminate the generation of power from that panel and to some degree other panels connected with it, turning it to heat. However, the low gauge of wire limits the potential loss from this mechanism; too much current flow means that the shorting circuit will melt through. Fuses could be added to handle this more cleanly.

There is no realistic fire risk from the road or lateral conduit, as there is little flammable material. The thick laminated glass and thick lateral conduit walls make the risk of electric shock low in the case of breakage, and the aluminum panel underside grounds the road. The primary hazard would be if the primary conduit was dug up and damaged, as there is a medium voltage (20kV) high capacity AC line in there.  However, such buried lines exist all over the place and are not a hazard unique to solar roads.

A breakage of the primary conduit will take out all generation from a 250m segment due to the loss of its DC line. As for the AC, unlike when a regular transmission line is broken, it does not automatically imply that customers go without power, as generation is conducted on both sides of the breakage. Whether any outages occur depend on the local consumption versus local generation.

Any hardware failures in a utility box will be automatically reported, using their fiber connection. The most serious failure would be the failure of the station transformer, which would cut off all generation for that 250m segment of road. Fire is possible, although not particularly likely, and should be handled in the same way as any other fire in medium-voltage electrical equipment.

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Now, what's the significance of all of this?

One can, and should, dispute the various numbers above. They're very rough, and there's no way to know for sure how everything would play out in the real world without a more detailed investigation and then a pilot project. But the fact that with what I felt were at least fair assumptions, we get a very reasonable price and payback period for a solar road.

Why do the numbers perform so well against a rooftop install? Two main reasons:

* The overhead is so much smaller than a rooftop install; everything here is done in bulk, from purchases to installation. And as time goes on, overhead will increasingly be the dominant factor in rooftop installs. That's not to say that roads don't have their own overhead - they do, and it's significant. But nothing compared to the sort of per-house, custom, hand-installation overhead you get with rooftop solar.
* The solar cell wafers are only a fraction of the cost of a solar panel; the rest is itself overhead - associated hardware, assembly, shipping, distribution, taxes, marketing, profit, etc. The fact that the solar road has a less efficient use of wafer and other materials per watt, and higher shipping costs due to the increased mass, indeed increases part of the costs per watt. However, it's not all of the costs per watt.

Why do the numbers perform well even versus a PV solar farm (something that has to use up land that otherwise would have been left wild)?

* A large part of the cost of any project (solar farms included) is overhead - permitting, right of way, environmental studies, contract negotiations, preparing the land, drainage, and on and on. It's a large part of the chunk of the cost of building any large project. But the key here is that a road would have had to have been built anyway where we're building the solar road - hence, these overhead costs are already paid for us. The only real difference is what sort of top layer we choose for our road, one that makes power or one that doesn't.
* The solar farm has some advantages over us, in that they can use cheaper panels and mount them at a more optimal angle or on heliostats (although this comes at the cost of mounting hardware, significant costs in the case of heliostats, and leaves them more vulnerable to weather, which increases maintenance). They're also less prone (but not immune) to dust, debris, and shading. However they're also usually built out in the middle of nowhere to get cheap land and avoid bothering people, meaning you have to build a high power transmission line to move all of the generated power, and, yes, you need to build an access road. It's ironic, but in some cases with small/remote solar farms, the surface area of the access road can be greater than that of the panels, and by making the access road a solar road and piggybacking onto its construction costs, you could actually get more power from the road than from the farm itself! A 30km, 4m-wide solar access road would have a nameplate yield of 120MW and a 9% capacity factor, equivalent to a 60MW PV farm with an 18% capacity factor.

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So in summary?

Solar Freakin Roadways!? No.
Reasonable solar roadways? Yes.

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Comment Preferences

  •  Just wanted to add... (14+ / 0-)

    that I welcome corrections and feedback! And I want to reiterate, without further study and then pilot work, one can't know how well things would work out in the world. This was just to show that the basic concept is in theory quite workable.

    That is, if you don't do all of the ridiculous stuff that the "Solar Freakin Roadways!" team wants to do.

    The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

    by Rei on Fri Jul 04, 2014 at 02:15:09 PM PDT

    •  Rei - a tip and REC for an informative diary (6+ / 0-)

      "let's talk about that" uid 92953

      by VClib on Fri Jul 04, 2014 at 03:38:39 PM PDT

      [ Parent ]

    •  Toss piezo because of 'give'? Really? (0+ / 0-)

      Asphalt gives dramatically more than glass would, with or without piezo generation. Hell, concrete is almost certainly firmer than glass would be even with added piezoelectic generation.

      Before I decided to toss piezo generation because it makes the surface less firm, but still dramatically firmer than the existing alternatives, I would want to know what the impact of the more rigid surface would have on stopping characteristics, as well as on tire wear, and its actual effect on fuel efficiency, to within say an order of magnitude, among other factors.

      My intuition says that if you design a surface with as little give as you possibly can, then it will have a measurable effect on both static and kinetic friction, to the measurable detriment of stopping distance.

  •  The reason nothing will be done is that roadways (14+ / 0-)

    are probably the single largest source of graft in America. Everybody involved at every level makes piles of taxpayer money on roads.

    Dozens of far more efficient and durable solutions have been developed over the years, but none of them provide the ongoing and ever-increasing profits that our current systems does.

    "Those who can make you believe absurdities can make you commit atrocities." - Voltaire

    by Greyhound on Fri Jul 04, 2014 at 02:27:34 PM PDT

  •  This lame idea has been debunked already (2+ / 0-)
    Recommended by:
    Choco8, Theoleman

    The crappiness of the solar road idea has been debunked many times over (like here and here--there are dozens more).  

    Once you account for maintenance, I'm sure that it would be vastly cheaper to put solar panels on every roof in America than to create an equivalent area of solar roads.  Let's do the rooftops first before we start throwing our money down a pit.

    The next Noah will work a short shift. - Charles Bowden

    by Scott in NAZ on Fri Jul 04, 2014 at 02:28:42 PM PDT

    •  Which would be great links... (9+ / 0-)

      had the very point of my diary not been to address all of that. So if you think there's something I missed, please state it. If you have a problem with my numbers, call them out.

      Did you even read my diary?

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Fri Jul 04, 2014 at 02:42:59 PM PDT

      [ Parent ]

      •  I skimmed (2+ / 0-)
        Recommended by:
        Choco8, LakeSuperior

        I think you're wrong about everything.  Until someone has a working model, it's all just silly speculation anyway, and I don't have time to waste on speculation.

        Also, if this was such a great idea, I'd expect to see prominent physicists and engineers jumping out in support.  Where are they?  Meanwhile, a 3-second google search reveals dozens of engineers pointing out fatal flaws in the idea.

        I'd encourage you to stop selling snake oil.  Since research money is limited, the more money that goes into solar roadways, the less there is for research on viable ideas.

        The next Noah will work a short shift. - Charles Bowden

        by Scott in NAZ on Fri Jul 04, 2014 at 02:47:31 PM PDT

        [ Parent ]

        •  Illogical. (7+ / 0-)

          "Until comeone has a working model" - so your proposal as to how projects should work is, someone should build a large-scale profitable version as the first step?  No, the first step is you propose a design and do the calculations for it. Which is what I did above.

          If you see a flaw in them, point it out. If you think there are specifics wrong, cite them. Don't just say "you're wrong but I'm not going to tell you why." I gave specifics. If you want to counter, give specifics.

          Also, if this was such a great idea, I'd expect to see prominent physicists and engineers jumping out in support.  Where are they?
          Given that I just proposed this a few minutes ago right here, how do you expect to have prominent physicists and engineers jumpting out in support?
          Meanwhile, a 3-second google search reveals dozens of engineers pointing out fatal flaws in the idea.
          Really? This link even shows up in Google searches

          How could you have "skimmed this" and missed that I myself am heavily criticizing the Solar Freakin Roadways concept as well?

          The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

          by Rei on Fri Jul 04, 2014 at 02:54:15 PM PDT

          [ Parent ]

          •  Corr: (2+ / 0-)
            Recommended by:
            Lujane, slowbutsure

            There should be a question mark after "This link even shows up in Google searches?".

            The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

            by Rei on Fri Jul 04, 2014 at 02:57:14 PM PDT

            [ Parent ]

            •  Kudos! What a thorough investigation! (1+ / 0-)
              Recommended by:
              Egalitare

              As someone who covers renewables for the industry, I have never seen such thoughtful investigation of this concept and I had initially thought what a silly idea because of the dust and dirt from traffic.

              You made me rethink it - at least your sensible solar roadways.

              I am not sure if you covered it, (skimmed for the gist in parts) but one advantage that I considered is that you could, with one extra step, run the electric power along the ground under them, instead of though wires on wooden poles that always get damaged in storms.

              Thanks Democrats! My Obamacare is permanent coverage no one can take away - and saving $3,000 is nice too

              by sotiredofusernames on Sat Jul 05, 2014 at 09:39:42 PM PDT

              [ Parent ]

              •  In the discussed design... (0+ / 0-)

                there's a buried medium voltage (20kV) AC line and a smaller 600V DC line and a fiberoptics bundle on one side of the road. It's sized for moderate length (average distance from generation to consumer = 15km) transmission. One could used different-sized conduits for different situations, although buried HV would be impractical in this particular situation; if you want to send it long distances you should step up to a long-distance transmission line.

                The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                by Rei on Sun Jul 06, 2014 at 02:59:44 AM PDT

                [ Parent ]

          •  That's basically what you have done. (2+ / 0-)
            Recommended by:
            Choco8, wader

            You have made claims and provided zero evidence to support them.

            1. Glass can be made to provide as much traction as concrete or asphalt. - Citation needed.

            2. Glass can be made strong enough to withstand the rigors of road traffic. - Citation needed

            4. Glass can be made to resist scratching from sand being ground against the surface. - Citation needed

            5.  The impact of cars shading of roads is irrelevant in most places.  - How about some numbers?

            You haven't given us any numbers on the efficiency lost by laying the panels flat, or covering them with scratch resistant, shatterproof traction glass, and you've just glossed over the cost of building the asphalt base for these roads assuming a solar road will only be built when a new road needs to be built anyway. You haven't told us the life-expectancy of these panels or the underlying roads, or if it is even feasible to repair them or whether they'd need to be replaced.

            Don't expect people who are critical of this idea to come to the table with more evidence than you have provided.

            •  Yeay, specifics! (11+ / 0-)
              1. Glass can be made to provide as much traction as concrete or asphalt. - Citation needed.
              Just pulling up the very first product I find, we see their glass has a coefficient of friction of around 0.6 when wet and 0.75 when dry. Looking up concrete, we see an average of 0.6 when wet and 0.72 when dry. Aka, the same. And that's just the very first anti-slip glass product that came up on a google search, not necessarily the best.
              2. Glass can be made strong enough to withstand the rigors of road traffic. - Citation needed
              Holding up traffic? I'll do even better than that! (2) (3) Also noted in the above, "Glass has a very high compressive strength and theoretically very high tensile strength ... Compression strength (ultimate): 1000 N/mm^2" (aka, MPa). That's for basic soda lime float glass, not any form of toughened glass. Now, some varients of glass are less - I find listings online ranging as low as a couple hundred MPa. But typical concrete is about 30 MPa, rarely higher than 60-MPA. And as I'm sure you know, traffic is overwhelmingly compressive stress, not tensile, which is why concrete selection for roads and parking lots is aways focused on the compressive strength of the mix. Okay, okay, but what about bending, what about elasticity? Well guess what, glass solidly beats concrete there, too.

              If the theoretical foundation isn't enough for you, then you should support a pilot project to settle the issue.

              4. Glass can be made to resist scratching from sand being ground against the surface. - Citation needed
              Link Link (one example). I find it rather sad that you want to talk about scratching but seem totally unaware of how hardness of materials works.
              5.  The impact of cars shading of roads is irrelevant in most places.  - How about some numbers?
              Source: Your own eyes, looking at satellite images. Seriously, go do it, right now. Pick random points in the country and zoom in and look at what roads you find.

              Anything else I can help with?

              The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

              by Rei on Sat Jul 05, 2014 at 08:23:15 AM PDT

              [ Parent ]

              •  Yeah, there are a few more things. (1+ / 0-)
                Recommended by:
                wader

                First off, your textured glass seems to have some difficulty with light transmission.  The raised bits are clearly reflective.  Can you tell me what the loss in efficiency is through that textured glass?

                The fact that glass is strong enough to use  in load-bearing is irrelevant.  Windshield glass provides structural support for a car's roof, yet that doesn't prevent it from scratching.  Do you have any real world examples of glass tiles being used in road construction or being tested for that purpose?

                Using a link to the Wikiedia Mohs scale of hardness, along with a personal swipe at me, is reminiscent of the Solar Freaking Roadway folks.  If you want to distance yourself from those guys, you should refrain from such tactics.  I am aware Gorilla Glass exists.  I am also aware that it two images.  Would you say either of those roads would be good candidates for solar roadways?  Would you say the shading factor on either of these roads is "irrelevant"?

                You still haven't addressed the life expectancy of these roads.  My search of asphalt roads came up with an average life expectancy of 8 years.  Do you think your roadways would be economically feasible with such a life expectancy?

                •  Sure. :) (8+ / 0-)
                  First off, your textured glass seems to have some difficulty with light transmission.
                  As per the link about the first anti-slip glass that came up on Google, on the same page they cite that it  "Obscures view while maintaining a high level of light transmittance". I covered this in my article where I wrote:
                  The texturing has a small but not problematic impact on light transmission, and can in some cases help with self-cleaning. In very high traction anti-slip glass the surface texture often ruins optical clarity by distorting the image, but solar cells don't care about image distortion, just transmission.
                  One shouldn't confuse transmittance with distortion. For example, you may have noticed that you can't see well (if at all) through many commercial plastic greenhouses. Yet that actually increases plant growth by scattering the light more evenly around the greenhouse.

                  What is the transmittance of the textured glass in the link? You just need to click the product specifications link at the bottom, and scroll to page 9, where you'll see that their products range from 88-93% of visible light transmission. That's essentially the same as non-textured glass of the same thickness.

                  The fact that glass is strong enough to use  in load-bearing is irrelevant.  Windshield glass provides structural support for a car's roof, yet that doesn't prevent it from scratching.
                  That is an entirely different topic. Compressive strength and young's modulus are two properties unrelated to hardness. I gave you links trying to explain the concept of mineral hardness to you, but I'm not sure if you actually read them.

                  Minerals have a hardness value, traditionally measured in the 1-10 Mohs' scale, where 1 is talc and 10 is diamond. Basic soda lime glass has a hardness of around 5. This is softer than both quartz and steel, meaning that common materials can scratch it. Various processes can increase the hardness of glass. The most advanced processes are used for glass for cell phone screens, which can be in excess of 9 on the Mohs' scale for high-end phones. However, having a Mohs' hardness of 7 resists quartz (same strength) and renders it immune to steel, while anything higher than 7 renders it immune to quartz.

                  It doesn't matter whether it's a road, a window, a pair of sunglasses, a cell phone screen, whatever; hardness is a universal property. Softer materials don't scratch harder materials. You're not going to scratch a diamond with a knife. Have a diamond wedding ring? Try to scratch it with a knife to your heart's content. It'll never work.  Scratch resistant glass raises the hardness of glass above that of all common materials (the hardest one commonly encountered being quartz, aka, sand). It significantly raises the price (which you'll see in my above calculations), but there's no "magic" to it, it's just elevated hardness.

                  Note that hardness should not be confused with compressive strength, which should not be confused with elasticity, which should not be confused with fracture properties, and so forth. Hardness is only about scratching. I once heard a minerologist complaining about how he once met a frustrated amateur diamond prospector in a known diamond area complaining about how he couldn't find any diamonds. The guy had appearently kept encountering these greasy-looking translucent rocks (aka, what raw diamonds look like), some of very good size, but they never turned out to be diamonds. The minerologist asked the guy what he was doing to test them. The guy informed them that he was taking them, putting them on an anvil, and hitting them with a sledgehammer, but they'd break so he knew they weren't diamonds. The prospector then had to break the news to the guy that he'd likely destroyed tens of thousands of dollars worth of diamonds  ;)  

                  Using a link to the Wikiedia Mohs scale of hardness, along with a personal swipe at me, is reminiscent of the Solar Freaking Roadway folks.
                  Well, I'm confused as to what part of this you're not understanding. What part of scratch resistance do you not understand? Because that's how scratch resistance works. Soft materials don't scratch hard materials. I give you a link on how it works and you don't read it. So what exactly is it that you want? Do I need to have a minerologist send you an email or something?

                  Perhaps I'm just more used to this concept because I do some mineral prospecting, so I'm always doing scratch tests for identification.

                  am also aware that it two images.  Would you say either of those roads would be good candidates for solar roadways?  Would you say the shading factor on either of these roads is "irrelevant"?
                  Your first link doesn't work.  No, I wouldn't begin with the second road. The US builds over 30,000 lane miles of public road per year (not counting driveways, parking lots, access roads, private roads, etc) intercepting 180 gigawatts (times capacity factor, more like an average of 15 gigawatts recoverable) of sunlight.  There is no shortage of road to choose from; one can afford to be choosy.
                  You still haven't addressed the life expectancy of these roads.  My search of asphalt roads came up with an average life expectancy of 8 years.  Do you think your roadways would be economically feasible with such a life expectancy?
                  Asphalt has such a short lifespan because - we're back to the Mohs scale here - of 1-2 on the Mohs scale. That means that virtually everything can scratch it, even a fingernail can scratch softer asphalt; consequently, it wears away relatively rapidly. Concrete has a complex Mohs hardness, as it's a composite between soft (Mohs 3-4) cement and hard (Mohs 7) sand. Generally it acts as a Mohs 7 surface. Concrete roads have a lifespan of usually 30-50 years. Moreover, it doesn't fail from being worn away; rather, it's from carbonation or chlorine impregnation of the cement, removing the passivation layer from the steel reinforcement, allowing it to rust (cement is a water-permeable hydrate), causing it to expand nearly an order of magnitude in size and spalling chunks off of the surface.

                  The solar roadway proposal above involves a surface harder than Mohs 7 - even more resistant to surface wear than concrete - and with no structural steel involved to rust.

                  The theoretical basis suggests an extremely long lifespan. If you want to know more than the theoretical basis, however, if you want to see the real-world then you're going to need to support a pilot project.

                  The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                  by Rei on Sat Jul 05, 2014 at 12:48:07 PM PDT

                  [ Parent ]

                  •  I was also skeptical of the science behind earlier (0+ / 0-)

                    "So, please stay where you are. Don't move and don't panic. Don't take off your shoes! Jobs is on the way."

                    by wader on Sat Jul 05, 2014 at 06:26:29 PM PDT

                    [ Parent ]

                    •  Whoops, only posted a partial comment! (0+ / 0-)

                      My gist was to offer that I, like you (and many others) have found the science behind prior solar road claims to be rather wanting, so I appreciate all the effort you've placed into this diary.

                      I suppose my general feeling is that, regardless of potential long-term savings and additional benefits if tests and more extensive trials of your ideas show promise, the politics continues to run against logic, rational thinking and planning which actually embraces change to find better, public solutions.

                      Doesn't mean we should stop working and writing about these types of proposals, because there may be unforeseen opportunities which open up and could take advantage of these ideas, one day.

                      "So, please stay where you are. Don't move and don't panic. Don't take off your shoes! Jobs is on the way."

                      by wader on Sat Jul 05, 2014 at 06:41:50 PM PDT

                      [ Parent ]

                  •  I'm supposed to believe... (0+ / 0-)

                    you are pushing something different than Solar Freaking Roadways and you come at me with asphalt is softer than fingernails?  Roads are not made of asphalt, they are made of an asphalt concretion with asphalt as a binder.  Most of what we call asphalt is crushed rock and sand.  Do you not understand that, or did you just think no one else would?  And asphalt is such a weak surface that you made it the underlayment for your solar freaking roadways.  Whatever your theoretical basis says, reality says they last about 8 years.  Anyway, it doesn't matter.  Scratch-resistant glass is just that, scratch resistant.  If it were scratch-proof, they would call it that.  Reputable companies don't make bold, indefensible claims because they want to stay in business.

                    As for your coefficients of friction, I assume you understand that coefficients of friction are calculated based on the interaction between two surfaces.  The numbers you came up with for concrete,and by the way your link is broken there, are calculate between rubber and concrete. The numbers for your glass tiles is between the tiles and something called a "neolite heel assembly".  I tried to find, for comparison, a neolite heel assembly vs. road concrete but was unsuccessful.  Anyway, as I'm sure your aware, the coefficient of static friction isn't particularly relevant here.  What we need to know is the coefficient of kinetic friction.  I'd also be curious to know what the frictional heating would do to both the coefficient of friction and the material strength.

                    •  Which is, of course, irrelevant. (0+ / 0-)
                      made of an asphalt concretion with asphalt as a binder.
                      If you wear away the binding, you wear away the road. In asphalt, as far as the surface goes, not only do the tires wear off the binder, but the loosened particles in turn grind further against the binder and weaker aggregates, loosing more material and dust - this is known as the "sandpaper effect".
                      There is a significant average increase of 38.5% in the skid number during the first six months immediately after placement of the wearing surface. This is most likely due to increased aggregate exposure as a result of asphalt film weathering.
                      (Link)

                      Eventually this requires repaving of the surface layer. Also, the asphalt underneath fail with time simply due to oxidation, UV, and frost damage due to the presence of voids:

                      As soon as the freshly laid hot asphalt pavement mix begins to cool, so also begins the aging process which will eventually rob the pavement of its life. When oxygen and water, which constantly bathe the pavement, start to combine with the asphaltic binder of the pavement, a chemical change takes place. At first, this process is necessary for the pavement to become hard and firm. Later, if this process is not arrested, a complete deterioration of the asphaltic binder will take place and reduce the pavement to a layer of loose stone. The asphalt binder is essentially what differentiates a gravel road from a paved road.

                      The destruction rate of an asphalt pavement varies:
                      Heat & Sunlight will accelerate the deterioration process; salt will act as a catalyst. Water which penetrates the surface can get into the base course to cause trouble, and at the same time start oxidizing the asphaltic binder inside the pavement.

                      most asphalt failures arise from water seeping down into the gravel base and weakening the foundation's shear strength. Once this happens, it is not long before surface cracks (alligator or fatigue cracking) appear due to the weight and flexing of the pavement. If the base is wet and soft the asphalt is going to flex more than if the base was dry and solid. As the asphalt ages it loses some of the black oil that keeps it flexible. When it turns grey in color it is more rigid and more prone to cracking, which in turn allows more water to seep in.  
                      (Link)

                      But anyway, this is all tangential. The simple facts are, and I think you know, asphalt roads last for about a decade (more in rural areas, less in urban), while concrete roads usually last 30-50 years.

                      And asphalt is such a weak surface that you made it the underlayment for your solar freaking roadways.  
                      How exactly do you think traffic is going to wear away something beneath the surface panels? Do you think cars are boring through the ground or something? Of course it's immune to surface wear. It's also not directly exposed to surface oxygen and encounters no UV light. And as for binding strength, which declines over time, none is  needed; it's mainly just proposed to provide a layer that the panels can be pressed evenly down into before it sets, having each panel have an even base on which to sit.
                      If it were scratch-proof, they would call it that.
                      Yes, if your tires were made of freaking rubies, you'd scratch the road up. So clearly that's a show stopper!
                      What we need to know is the coefficient of kinetic friction
                      You know what, I'm not even going to waste the time. You can clearly see that it's a comparable high traction surface, and this was just a random product pulled off the top of a Google search, let alone something specifically chosen for tires.  Unless there's someone else who thinks that's an issue, I'm just going to classify this as you grasping at straws.

                      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                      by Rei on Sun Jul 06, 2014 at 03:49:35 AM PDT

                      [ Parent ]

                      •  You are clearly being dishonest here. (0+ / 0-)

                        Your claim about hardness involved scratch-resistance, not durability.  You can't scratch glass with something softer, and asphalt is softer than your fingernail, wasn't that your argument?  And it's not the tires that scratch the road, it's the stuff that's ground between the tires and the road, like asphalt.  If it is only rubies that will scratch Gorilla Glass, maybe it's all those rubies people carry around in their pockets which scratch their Gorilla Glass cellphone screens.  I'm guessing it's sand.

                        And again, it was you that place your solar freaking roadway on top of a bid of asphalt, which you now tell me has a limited lifespan because of its material strength.  I'm guessing you are counting on your gorilla glass to add longevity to the asphalt underlayment.  Not sure how it is going to protect it from oxidation or frost damage.

                        I'm sure you are confident that as you are standing on a glass surface in your neolite-heeled shoes, should someone push you, the friction between your shoes and the road will adequately prevent your moving.  I am more concerned about whether cars can stop on it.  Perhaps the reason you've had difficulty finding those numbers is they do not make roadways out of glass.  I suspect there are reasons for that.

                        •  Glass (2+ / 0-)
                          Recommended by:
                          petral, wagdog
                          You can't scratch glass with something softer, and asphalt is softer than your fingernail, wasn't that your argument?
                          This is a fact, you can't scratch softer things with harder things. Hey, I've got a copper (Mohs 3) brush here, would you like me to post a video to youtube for you of me trying my heart out to scratch my windows (Mohs 5) with it?
                          And it's not the tires that scratch the road, it's the stuff that's ground between the tires and the road, like asphalt
                          Your wording is unlear here where you say "like asphalt". The stuff that scratches asphalt is not asphalt itself, it's sand, loose aggregate, etc. Which then loosens more aggregate, which further helps wear the top surface. Meanwhile, oxidation and frost attack the asphalt from underneath. Hence it lasts a lot longer than concrete which is resistant to all of these forms of damage. Scratch-resistant glass is even harder than concrete, is totally water impermeable (assuming the rest of your structure is made so likewise), and immune to oxidation. It doesn't even have concrete's wear mechanisms (carbonation / chloride attack leading to rust and then spalling).

                          Do you have a theoretical wear mechanism? No? Well, that doesn't mean that there isn't some wear mechanism, there almost certainly is. But you know how you find them? By doing pilot projects.

                          If it is only rubies that will scratch Gorilla Glass, maybe it's all those rubies people carry around in their pockets which scratch their Gorilla Glass cellphone screens
                          I really don't know what you're talking about. My Xperia 2 has gorilla glass on both sides, and it's usually sticking out of my back pocket when I'm out working on my land, where the surface is predomantly basalt and I'm often sitting down, sliding around, etc. There's not the slightest evidence of a scratch on it. If you're finding a way to scratch gorilla glass, I really want to know how. Here's a video of people trying (unsuccessfully) to scratch their Galaxy 3 with knives, keys, etc.

                          Note that there have been several generation of gorilla glass, and they've had significant improvements with each generation. I believe the one my phone has is gorilla glass 3. Also note that gorilla glass serves two purposes, only one of which is needed here (scratch resistance). The other is high strength (wide variety of properties) in a small, light package from an expensive ion-exchange toughening process - important for cell phones, but for a road, your glass thickness and weight are not that important.

                          Perhaps the reason you've had difficulty finding those numbers is they do not make roadways out of glass.  I suspect there are reasons for that.
                          First off, there was no reason to. Look at the numbers above, the solar surface - of which the glass is the second most expensive materials cost and the dominant machining cost - more than doubles the cost of the road. Without solar cells underneath, why on earth would people do that?

                          Secondly, the Romans had both asphalt and concrete, yet didn't build roads out of either asphalt or concrete. The process of trying new things and seeing how well they work is called invention, and is the story of our species. To see how things work in the real world, one conducts a pilot project. So if you don't think there's enough real world data, then you should be supporting a pilot project.

                          Third, I've not once had trouble finding any numbers - I'm simply not doing it any more with you. I've spent way too much time gathering numbers for you that you could have easily gotten yourself before complaining, and which any reasonable person would consider  more than enough to show you that glass can easily and near-losslessly be made into a high-traction surface, something that is already done in a widespread manner today. If you think you have reason to think that there's some major unresolveable disparity in anti-slip glass static and kinetic friction versus concrete, show me.

                          The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                          by Rei on Sun Jul 06, 2014 at 10:44:06 AM PDT

                          [ Parent ]

              •  dude, how much does glass block cost? (1+ / 0-)
                Recommended by:
                wader

                then add in the cost of making glass block out of
                Gorilla glass.

                http://www.homedepot.com/...

                thats' about $12/SF.  add in the gorilla glass coating and you
                are at $24/sf without even blinking.

                Now, buy in quantity, say for 80%, so it's $3/sf.

                Now what's a 4" thick square foot of concrete?

                You buy for about $1/Cubic foot, in a 4" thick pad it's
                going to be 30 cents/square foot.  

                Glass is a commodity, Concrete is a commodity, you
                aren't going to get Glass down 10X.
                but you are claiming you can get Glass performance up by 10X.  Maybe but, not cheaply.

                •  Manufacturers don't shop at Home Depot. (1+ / 0-)
                  Recommended by:
                  wagdog

                  They buy shipping crates full of pallets of materials straight out of factories where it costs a small fraction as much. Nor do manufacturers of glass products make them out of decorative "8 pack decora glass blocks".

                  Please go back and read starting at "Glass is the second most expensive element". If you want a link to a manufacturer that sells scratch-resistant glass in bulk, here's an example - scratch resistant laminated float glass, $20 a square meter for 1/2 inch thick.

                  Yes, I did do research on prices before I wrote this.

                  The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                  by Rei on Sun Jul 06, 2014 at 03:56:48 AM PDT

                  [ Parent ]

                  •  $20/SQM is $2.20/SF (0+ / 0-)

                    and that's for Half inch material.

                    You want a lot thicker material

                    i said glass block in quantity would be $3/SF for 4 inch
                    material and I was being generous.

                    I grew up in Chicago, we had glass sidewalks,
                    wonderful stuff, helped light the underground.

                    thick stuff, cast in panels,

                    Never used on roadways.

                    •  Which is exactly what I budgeted. (0+ / 0-)

                      And no, you don't "want a lot thicker material". Glass has superb compressive strength (an order of magnitude better than concrete). It sucks at dealing with tensile stress++ (also like concrete, though glass is has several times the Young's modulus as unreinforced concrete - and yes, it can be reinforced like concrete if desired, though that's not relevant to this application). Your example of glass sidewalks where there's a hollow cavity beneath them and weight above is an example of tensile stress. A glass panel lying flat on a hard surface with an object sitting on it (aka, a road with a car on it) is an example of compressive stress. Glass has an ultimate compressive strength of several hundred to a thousand MPa. Mass-produced concrete is usually only a few dozen MPa.

                      (++ - actually, in theory glass is great at dealing with tensile stress too... unfortunately, in practice, glass has tiny fractures which expand uncontrolled under tensile stress, leading to a break; when the glass is in compression, this prevents fracture expansion, so its compressive strength matches theory but its tensile strength is far weaker. It's also how toughened glass (like gorilla glass) works - toughened glass is given an innate internal compression by swapping out sodium ions with larger potassium ions, so it compresses itself and prevents fracture expansion)

                      Never used on roadways.
                      Search for "First off, there was no reason to" in the comments.

                      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                      by Rei on Mon Jul 07, 2014 at 02:57:35 AM PDT

                      [ Parent ]

                      •  no my example is bending stress. (0+ / 0-)

                        which glass doesn't perform well in.

                        tell you what instead of you arguing with me,

                        Why don't you get a couple hundred
                        glass block and just try and set up a test strip on a
                        road somewhere,  and get some experience.

                        won't cost you much,  build a 10o feet of roadway using
                        glass block on some road. that gets heavy traffic.

          •  it's not easy to fix a bad idea (0+ / 0-)

            tell me why your idea is better then

            this?

            http://cache.boston.com/...

            or

            http://www.fhwa.dot.gov/...

            or

            http://wordlesstech.com/...

            or

            http://www.salem-news.com/...

            or

            http://0.tqn.com/...

            Tell me what's wrong with those ideas?

            •  Before commenting, please read the diary. (0+ / 0-)

              This is the second time in the road that you've written ~20 line posts complaining about something that was covered in the diary. This particular one was #8 in the very first section of the diary, so you really have no excuse for having not seen it.

              The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

              by Rei on Sun Jul 06, 2014 at 04:00:26 AM PDT

              [ Parent ]

              •  Every big road has shoulders (0+ / 0-)

                which is part of the road design.

                That's more then enough.

                And dense roads with lots of buildings, will have
                crappy view factors.

                The reason solar panels mostly go on rooftops
                vs the yard, is the view factor improves and
                the impact on people declines.

                It's not like we build 300 foot towers to run these,
                we just have a simple system.

                we get roofers to install these.

                •  Every big road absolutely does not have (0+ / 0-)

                  shoulders big enough for any relevant amount of solar panels (which need their own "shoulders"). Plus the whole point of shoulders is to provide the ability to pull off / drive off without hitting anything and to provide an unobstructed view, if you insist on putting panels there, then you're going to have to make the cleared area even larger (if you don't believe me, ask a civil engineer). And you're proposing to build something in the new area, rather than just clear it and level it, which means more overhead, versus just switching out what top later you're using for something you already have to pave.

                  And dense roads with lots of buildings, will have
                   crappy view factors.
                  As this was covered in the diary, I'm just going to say, "Read before you comment".
                  The reason solar panels mostly go on rooftops
                   vs the yard, is the view factor improves and
                   the impact on people declines.
                  And this changes anything about roads versus rooftops how?
                  we get roofers to install these.
                  With overhead greater than materials costs, and on a trend to have overhead become vastly greater than materials costs. Which is a problem and why roads are a solution.

                  The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                  by Rei on Mon Jul 07, 2014 at 03:03:57 AM PDT

                  [ Parent ]

        •  Solar Roadways (0+ / 0-)

          There's already a working model in the driveway of Solar Roadways in Sandpoint, ID. The owners are Julie and Scott Brusaw, and they've already had some funding from the FHA, and their hexagonal panels look pretty impressive to me!

  •  Rooftop Solar First (2+ / 0-)
    Recommended by:
    Scott in NAZ, wilderness voice

    Putting solar panels under roads is just dumb, horribly inefficient, and astronomically expensive. There is no way ANY kind of glass is going to stay clean and scratch-free enough to even deliver a fraction of the panel's output.

    Putting them on roofs is cheap and efficient. You can even angle them! Nobody drives on your roof - bonus!

    It's too bad the people behind this have kind of cratered their credibility with all the claims that are not backed up by facts and or research, like the ridiculous snow-melting BS.

    •  In what way are you addressing... (3+ / 0-)
      Recommended by:
      mookins, Lujane, slowbutsure

      ... anything that I actually wrote in this diary? Given that I went into in detail the reason that this logic about rooftop vs. roadway economics?

      "The people behind this"? Did you even read the last sentence of the intro to this diary? Or the conclusion of my diary? Did you read anything I wrote before commenting?

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Fri Jul 04, 2014 at 02:45:21 PM PDT

      [ Parent ]

      •  Sigh... I really should proofread before I submit. (2+ / 0-)
        Recommended by:
        Lujane, slowbutsure

        "Given that I went into detail about about rooftop vs. roadway economics?" - forgot to delete part of an old sentence in there.

        The fact that you mentioned "This snow melting BS" points out how little you skimmed. I recommend you and Scott start at this line:

        "But there are some quite legitimate arguments against the "Solar Freakin Roadways!" proposal."

        The snow melting proposal was #2 (of 6) that I criticized about the Solar Freaking Roadways concept.

        The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

        by Rei on Fri Jul 04, 2014 at 03:04:57 PM PDT

        [ Parent ]

        •  You are mistaken (0+ / 0-)

          When I referred to the snow melting BS, I was talking about the claims made by the couple behind the project, not you.

          I have read quite a bit about this, and think it's probably suitable for small scale light load projects in the southwest, but that's about it.

          •  I don't think their proposal is worth even that. (4+ / 0-)

            See my six criticisms of it, only one of which has to do with snow. The electronics are way too expensive, the concept of embedding battery storage in roads is idiotic, the concept of turning light to electricity then turning it back to light (LEDs) rather than just reflecting it with paint is idiotic, the concept of capturing power from piezoelectricity (aka, robbing polluting cars of energy) is idiotic, and so forth.

            As I noted, however, I fully agree that it's best to start in more ideal locations.

            The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

            by Rei on Fri Jul 04, 2014 at 03:44:50 PM PDT

            [ Parent ]

            •  LEDs have one big advantage (0+ / 0-)

              Visibility in bad weather. The painted lines can be very hard to see when it's pouring rain, especially the white ones. And that's when you most desperately need that information. Having LEDs available just for that would be great for safety. They don't even need to be on all the time, just when conditions warrant it. You could put a rain/light/humidity sensor on the control stations.

              The problems that exist in the world today cannot be solved by the level of thinking that created them. - Albert Einstein.

              by Cvstos on Sat Jul 05, 2014 at 06:00:12 PM PDT

              [ Parent ]

      •  Lots of speculative claims like this: (4+ / 0-)
        It's ironic, but in some cases with small/remote solar farms, the surface area of the access road can be greater than that of the panels, and by making the access road a solar road and piggybacking onto its construction costs, you could actually get more power from the road than from the farm itself
        Sure...in some cases. In a whole lot of other cases, that simply isn't an issue. I just don't buy the idea that Solar Roadways could compete in any way, shape, or fashion to rooftop and solar farms.

        Here's a solar farm in Vermont. In an old hay field behind a subdivision. Short access road.

        When the developers of the Solar Roadways have actually proven their project to actually work on a small scale ( beyond having a tiny soft tired tractor gently roll over their  display panel set), I'll be all ears.

        Until then, I think the best use of solar panels ( and the possibly finite supply of rare earth metals that goes into them) is best used where it's efficient - in the OPEN.

        •  Cool picture Choco8. (1+ / 0-)
          Recommended by:
          Choco8

          Humor Alert! No statement from this UID is intended to be true, including this one. Intended for recreational purposes only. Unauthorized interpretations may lead to unexpected results. This waiver void where prohibited. Artistic License - 420420

          by HoundDog on Fri Jul 04, 2014 at 03:21:06 PM PDT

          [ Parent ]

          •  Here's an article about the farm (2+ / 0-)
            Recommended by:
            HoundDog, slowbutsure
            The solar farm, located on South Burlington’s Dubois Drive, harvests around 2.2 MW of power — enough for 450 Vermont homes, according to the developer — from some 9,000 panels. The panels are grouped in rectangles of 24 that perch on poles mounted in rows throughout what was once a hayfield.
            25 acres powering 450 homes. Pretty damn impressive.
            •  And the 25 acres of tress that used to be there... (3+ / 0-)
              Recommended by:
              lurker123, Odysseus, US Blues

              would have sequestered 6 tones of CO2 per year, at the rate of 500 pounds of carbon per temperate forest acre per year.

              Is there a reason you find it preferable to bulldoze wilderness land rather than reuse existing space? Do you find that to be the preferable option?

              The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

              by Rei on Fri Jul 04, 2014 at 03:41:52 PM PDT

              [ Parent ]

              •  Holy Toledo (2+ / 0-)

                What part of "it was an old hay field" do you not get?

                It wasn't wilderness. It wasn't forested.

                I don't know how I can make that any more clear.

                •  Check post times. (0+ / 0-)

                  I was writing replies while your "Speaking of skimming" post was posted. I am not instantly made aware of everything you write.

                  The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                  by Rei on Fri Jul 04, 2014 at 04:17:05 PM PDT

                  [ Parent ]

                •  In places like Vermont (0+ / 0-)

                  Old hay fields turn into forest pretty fast if you do nothing.

                  "Victory means exit strategy, and it's important for the president to explain to us what the exit strategy is." - George W Bush

                  by jfern on Sat Jul 05, 2014 at 05:21:23 PM PDT

                  [ Parent ]

            •  Do they get buried in snow? (0+ / 0-)

              I have zero technical knowledge about solar panels (though we did just have a system installed on our barn roof to off set all of our use, home and barns). But I do know something about snow in VT having lived three for 8 loooooong years! It seems these would be buried from November through April.

        •  Or, I could point to others, for example... (3+ / 0-)
          Recommended by:
          Odysseus, US Blues, tb mare

          this one. Just because there exists some farms that are not far away from the consumption doesn't mean that this is a universal property. Oh, and by the way, see how orders-of-magnitude larger the plant I linked to is? The one I linked to is about 60MW. What's yours, a couple hundred kilowatts? If that?

          And really, do you really think that example above is a good thing? Congratulations, they ripped out a forest to power a couple dozen houses, let's all cheer!

          When the developers of the Solar Roadways have actually proven their project to actually work on a small scale
          For the last time, I'm criticizing the developers of the Solar Freaking Roadways project and their ill-thought-out proposals. I'm proposing a completely different alternative. Please do not bundle me in with them
          and the possibly finite supply of rare earth metals that goes into them
          1. Why did you post a link to an article about magnets? Do you think solar cells are made of magnets or something?
          2. The solar cells that do use rare metals, such as indium, do not use metals that are only found in small places. Indium is found everywhere, just in tiny quantities, and can be recovered from dozens of different types of mining processes. And the amount of indium used in such cells is miniscule.
          3. Silicon solar cells, the most common kind, do not use rare metals. Silicon is one of the most common materials on Earth, and it's usually doped with phosphorus and boron, neither of which are rare.
          4. If you really believed that, then you'd be protesting rooftop solar and only supporting solar farms with heliostats. Do you do that?

          The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

          by Rei on Fri Jul 04, 2014 at 03:25:49 PM PDT

          [ Parent ]

          •  Speaking of skimming (1+ / 0-)
            Recommended by:
            wilderness voice

            Me:  

            Here's a solar farm in Vermont. In an old hay field behind a subdivision
            You:  
            Congratulations, they ripped out a forest to power a couple dozen houses, let's all cheer!
            25 acres. 2.2 MW. 450 homes. Old hayfield.
            •  Irrelevant. (3+ / 0-)
              Recommended by:
              RMForbes, Odysseus, tb mare

              You can see that that used to be forest at one point. And it's no longer serving agricultural purposes. It's using up land that could be sequestering carbon and providing habitat for wildlife.

              The reason why rooftop - and yes, roadtop - solar is desireable is that it's land that people have to use anywaay.

              The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

              by Rei on Fri Jul 04, 2014 at 03:47:36 PM PDT

              [ Parent ]

              •  LOL! Oh good GOD. (2+ / 0-)
                Recommended by:
                Gooserock, wilderness voice
                You can see that that used to be forest at one point.
                I think I am done here.
                •  Oh please. (2+ / 0-)
                  Recommended by:
                  sviscusi, tb mare

                  Are you trying to tell me that that perfectly straight line of trees surrounding the field is natural?  That was a forest that was cleared to make a hay field. Now it's no longer producing hay. So it could be allowed to become a forest again, thus restoring habitat and sequestering CO2 - if we didn't need that land for a solar farm.

                  Solar farms use up land. Land is habitat, land is sequestration. You really think using up land that could otherwise be left as wilderness is a good thing?

                  The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

                  by Rei on Fri Jul 04, 2014 at 04:20:12 PM PDT

                  [ Parent ]

        •  Let's do a little math, shall we? (0+ / 0-)

          Even with your "very short access road" example (something not typical).

          Those look like they're heliostat-mounted, so we'll credit them with 3x the capacity factor of a solar road. Let's say that those house lots are about 20 meters across cross to get a sense of scale, so it looks like they've bulldozed a forest maybe 500 meters squared - 25000 square meters. The panels sem to be spaced to capture perhaps 20% of the sun's energy, so 5000 square meters of panels. Giving them the 3x capacity factor bonuss, that equates to 25000 square meters of solar road. It appears that the neighborhood road in the map is about 8 meters wide and the access road about 4 meters wide and about 250 meters long. So that means that this access road plus a mere 3 km of neighborhood road equals the whole output of that solar farm.

          Backing up for a second, if we're placing homes every 20 meters on the road on both sides, then 3km of road serves 300 homes. Thes homes average consuming about 400kW of power. But at 9% capacity factor over 25000 square meters of solar road is 2.25 MW. The roads that equal that solar farm power 5.6 times more homes than lie adjacent to it.

          But if you prefer bulldozed forests, by all means, choose the solar farm option.

          The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

          by Rei on Fri Jul 04, 2014 at 03:38:48 PM PDT

          [ Parent ]

          •  For the last time (1+ / 0-)
            Recommended by:
            wilderness voice

            This solar farm was installed in an old hay field.

            "Hay" is what we feed cows and such here in Vermont, in case you are a city slicker who isn't familiar with the practice. Long ago, forests may have indeed been chopped down to make way for the Villainous Hayfields and the Solar Farms of Doom that followed!

            Hay. It's not a tree. No bulldozers were required.

            •  Again, check post times. (3+ / 0-)
              Recommended by:
              Odysseus, US Blues, tb mare

              I was writing my replies when you posted yours above. But thank you for your highly informative lecture on what hay is. It's not like I own land in the countryside or anything, so it's good you let me know, I had thought that hay was a type of duck sauce.

              Are you really saying that once people chop down a forest, the best option is to leave it chopped down forever? If the land is no longer being used for hay, then there's no reason we have to leave it unforested. Unless you want to put something there. Like a solar farm. That would be totally unnecessary if the neighborhood that it's powering was even fractionally covered by a solar roadway.

              The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

              by Rei on Fri Jul 04, 2014 at 04:26:05 PM PDT

              [ Parent ]

          •  lot more then 3X (0+ / 0-)

            don't use 3X for horizontal planar cells compared to heliostat
            cells.

            Do the math instead.

            Select your latitude,  then figure your best case is going to
            be the Sin of the latitude for 4 hours/day.

            Heliostats will start with no sin losses, and will then
            track for 8-12 hours/days. I'd say 10 as a ballpark.

            Essntially up north flat horizontal panels are very inefficient,
            and they are okay down at the equator.

            •  Not nearly so. (0+ / 0-)

              Here's a graph of flat versus ideal fixed generation for London, a very high latitude location. Note that flat intercepts 85% as much as fixed - it's not at all that big of a difference. The reality is actually a bit worse than the graph suggests, as lower angles also lose more to reflectance, but it's in no way some sort of radical difference.

              In the southern US, heliostats boost generation over an ideal south-facing fixed installation by 12-25% for single axis and 30-45% for dual axis. I've seen higher figures, 30% for single axis for high latitude (Germany).

              I think I'm being more than generous in the difference here.

              The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

              by Rei on Sun Jul 06, 2014 at 04:12:04 AM PDT

              [ Parent ]

            •  you are using roof numbers not road numbers (0+ / 0-)

              roofs stick up over terrain, while roads don't.

              it's going to be worse.

              a helio stat at ground level has a mean height of say 9 feet
              almost 1 story.  that helps a lot

  •  Great article. Sounds like they should hire you (7+ / 0-)

    as a consultant to help refine their ideas.

    The most serious problem in American politics today is that people with wrong ideas are uncompromising, and people with good ideas are submissive and unwilling to fight. Change that, and we might have a real democracy again.

    by Eric Stetson on Fri Jul 04, 2014 at 02:47:33 PM PDT

  •  Expertise and imagination here, great combo! (6+ / 0-)
    Recommended by:
    Rei, HoundDog, scottsvine, eOz, tb mare, slowbutsure
  •  Very interesting and obviously highly-educated (1+ / 0-)
    Recommended by:
    slowbutsure

    diary/diarist, thanks.

    I have a couple of questions:

    1 - Can you offer a "realistic" solution to cleaning off the inevitable dirt, grease, rubber and general schmutz that will accumulate and occlude light - and how much would said annual janitorial maintenance costs be?

    2 - You mentioned using aluminum wiring to save on costs. I thought aluminum wire oxidized relatively quickly once current went through it, and since aluminum oxides are quite resistant to current, thus soon would become a fire hazard or at minimum would represent a significant loss in efficiencies to heat/resistance (hot wires themselves as well are a source of resistance). The mobile home industry had a huge scandal years ago over aluminum wiring, including not a few lives lost from house fires, resulting in a ban on aluminum wiring. What am I missing here?

    In theory there is no difference between theory and practice. In practice there is.
    Yogi Berra

    •  Re (3+ / 0-)
      Recommended by:
      eOz, tb mare, slowbutsure

      1. One of the two main reasons that I credited solar roadways with such a low capacity factor (9% in sunny locations) is the assumption that they're dirty (the other primary reason being the suboptimal angle to the sun). There's some things about the road that could help with cleaning, like the fact that I included budget for waterjet cutting an "air hockey table" type surface which could blow away loose dust, but that's tangential.

      One could have regular road cleaning crews, but it's probably not important, at least according to the economic figures above.  It's okay to have a low capacity factor so long as you can lay the panels cheaply per unit area; solar installs are no longer dominated by wafer costs. And since you already need a road in the area, you already have to pay for all of the overhead, it's just a different top layer.

      As for how much it would affect light? We can look at albedo figures to see how much dust and grime roads typically accumulate over time. Concrete roads typically equalize at about 2/3rds of their initial albedo after a few months. So versus a perfect clean surface (note: it should be pointed out that unless you regularly wash your rooftop panels, they're hardly a perfectly clean surface either, although certainly less prone to grime than a road!), one would expect about two thirds as much generation versus said perfectly clean surface. Now, it seems highly likely that one could design a surface texture that could minimize the impact of grime somewhat - but I'm not assuming that. My assumed 9% capacity factor is half that of a typical fixed rooftop install in a sunny location.

      2. Aluminum wiring is trickier than copper, and there's all sorts of reasons it fails (it's not prone to oxidizing away like, say, steel, but its oxide is an excellent resistor, so poor connections can develop resistance). Aluminum is prone to metal fatigue from bending, it's prone to creep if not poorly terminated, and so forth. Due to all of these things, it proved to be very problematic in homes, which were wired by hand; it's unforgiving of improper usage. But aluminum wiring is still widely used, from motor windings to home feeder lines. There's also copper-coated aluminum wiring on the market. Still, copper is usually the best choice for small wires.

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Fri Jul 04, 2014 at 04:15:14 PM PDT

      [ Parent ]

    •  I lived in a townhouse with aluminum wiring. (0+ / 0-)

      We were very careful about the connections...  SO went through the entire house and redid any that looked wonky.

      ...Son, those Elephants always look out for themselves. If you happen to get a crumb or two from their policies, it's a complete coincidence. -Malharden's Dad

      by slowbutsure on Sat Jul 05, 2014 at 01:59:18 PM PDT

      [ Parent ]

  •  Hi Rei, you've done a lot of interesting analysis (3+ / 0-)
    Recommended by:
    Choco8, AoT, slowbutsure

    here and brought up a lot of my concerns about the solar roadways ideas that have troubled me. One critic brought up the issue of how long any would last against snow plows.

    I appreciate the energy, creativity, and time you've put into this idea so want to honor your analysis with some specific reactions in the spirit of collective creativity.

    I liked the way your analysis logically boils the challenge down to competition with solar farms as the best test case.

    Also, I like the idea of applying cost-reduction to what you are calling here the overhead cost.

    I've recently reported on some cases of solar farms in West Texas, achieving grid parity because of the completion of the major transmission line upgrade that delivers the power to East Texas.

    I've do have links in my archives pointing out the paradox that by virtue of their amazingly low land cost, amount of sun received, number of cloudless days it should be a solar farm paradise, yet until this recent spurt of big megawatt projects I was reporting on, (the articles have Texas in their titles) hardly any solar was being built there.

    Part of the problem was the lack of an upgraded high voltage power line.

    Also Texas apparently has no state Renewable Energy Standard so few extra tax incentive.

    The cost per watt came in a little bit higher than the current cost of natural gas but the utility still signed a 20 year contract with one of the last solar farms because they guaranteed the fixed price for 20 years while natural gas prices will both volatile and expected to rise.

    So this is a historic moment where a major solar farm compete advantageously with natural gas in Texas.

    If we could get the cost analysis of that project we would have a benchmark test case a road cost would have to compete against.

    If we could prove it made more sense to put that last solar farm there on a nearby road instead, we could then move from there and claim land cost advantage, and point to areas which do not have modernized transmission lines where this "modified solar roadway" concept may have some advantage.

    But here are some disadvantages or extra costs the MSR, Modified Solar Road, concept would face in this specific test case.

    1. As you point out, the solar farm panels are positioned at optimum angles of about 30% while the road panels are disadvantageously flat.

    2. The roadway panels are going to need substantial extra cost to modify them to hold up while trucks drive on them, if  that is even possible from an engineering point of view.

    So you start with the same exact low cost panels the solar farm would have, in the standard framing which is already cheap because of standardization and economies of scale, and now what do we do? Encase each one in some super-hard glass, or high tech ceramic which can withstand all the extra weight and traffic. What is our base estimate of how much this adds to the cost of existing panels, which have come down in price 75% in the last 4 years due to economies of scale.

    A solar roadway is going to five up that economy of scale by going back or zero installed base. What order of magnitude of extra cost will these new super-ceramic-cellar-panels have after this super encasement? 500% 1,000%? Could we even imagine it would only be 100% more than existing panels?

    The producers would need whole new factories. And, as you point out, new frames of different size, will give up existing economies of scale and add extra cost as well.

    3. The above is just to make them, your proposal claims the rational for the cost-cutting to over-head, is the mass-production of installation that is more difficult to achieve on roof tops, (although Eton Musk, chairmen of First Solar, recently described their several year effort to achieve exactly those kind of reductions to installation cost, enabling their rooftop installations teams to complete 2 per day now.)

    But, what overhead reduction advantage would roadway installations have over mass-production massed process innovation costs applied to solar farms?  

    I like the idea of your "installation truck" picture, (my favorite part of your analysis) but wondered why we couldn't apply that same idea to the solar farms and still expect solar farm installation cost per frame to be substantially less per unit than roadway installations.

    Just one of the extra costs of the roadway installations is going to be the incredibly higher specs for a level grade beneath them. The slight change in angles of even a micro-fraction of an millimeter will cause relative joint motions, and wear. Whereas, the angles of the solar farm panels can be "close enough" by inches, the exact line up positioning of the roadway panels may have to be micro fractions of a millimeter, and the electrical connections of each joint point is going to be subjected to enormous stress forces and multiple ton trucks pass over every couple of inches.

    4. Maintenance cost per panel has got to be higher.

    5. An issue with current designs of rooftop panels is that if one panel in an array get less sunlight than the others in the array if brings down the efficiency of the whole array. A tree shadow for example. Every car that drives over a panel will induce this inefficiency for that whole section of the array during that time.

    I better post this sometimes I loose long comments and I can never type them over.

    My approximate feeling about this is that if you an I were solar entrepreneurs hoping to pitch a project to a big Texas utility, and were going to locate in West Texas where desert land, is literally dirt cheap, and we had a side by side choice, we'd decide to buy a couple hundreds of acres of desert we owned for cheap, rather start whatever complicated political process might be involved trying to "lease," or buy, or form some kind of special arrangement with the Texas Department of Transportation to disrupt traffic during installation (any alternate access roads during constructions, and traffic cops are an extra cost.)

    Do you agree with this much so far at least?  I'd give an approximate estimate that this solar farm test case will beat the solar roadway farm by 1000% or more, and also involve 10% of the politics, zoning approvals etc.

    But, I admitted two disadvantages at the beginning, what about more urban locations where land is not as cheap, or places that do not have upgraded transmission lines?

    One would have to get into places with some expensive land for standard solar farms before could make up the many extra costs of the MSR.

    As one data point, in the last week the article I did on the community solar farms in Wyoming, and Colorado, the company is paying the local town $1,000 per year for the 20 acres of land that is slightly contaminated with toxic chemicals. The company specializes in building their small and mid scale solar farms on "scap" land no ones for other reasons.

    These cases should also beat the MSR test case, wouldn't they

    Then what about urban locations?  

    Wouldn't you suspect that roof tops, the sides, of buildings, and the tops of parking lots, and even the sides, of overpasses, roads, bridges, warehouses any anyplace a standard panel would fit, would be cost advantageous to do first?

    After that, then, the next "traunch" of projects would be in a radius out from the cities until the per mile extra cost of poor transmission lines exceeds the extra total of the five kind of costs outlined above.

    Even still I very much appreciate your post and analysis as have not yet until now found a way to articulate these concerns, without piggybacking on your excellent analytic framework.

    You did such an excellent job of organizing these concepts that your helped me organize my own thoughts, which previously without the helpful focus of your post here, I've never had the energy to try to jump into as it seemed too complicated a set of thoughts to try to communicate.

    So I appreciate your thoughtful and creative analysis even though I may appear to be critical, all of my comments are building up off of your analytic framework.

    So I consider your post to be great success and have become one of your followers.

    My hope is that maybe I will inspire you to take a more careful look at any data we can find on the cost economics of these solar farms, as they are breaking out all over.

    And, I especially like and appreciate this idea you communicate as the "long-hanging" fruit.

    Each potential solar project needs to be analyzed with an approach like yours and then ranked like a parieto chart on those with the highest return on investment.

    Wise investors will examine each project on a case by case basis and should chose the best first.

    However, all you need to is find one special case where your MSR is advantageous because special circumstances. Framed like this it not difficult to imagine some possible "best of all possible cases" for the MSR where we could create the conditions under which they could win.

    I predict the first case may be something like one of the following:

    1: Disneyland, or EPCOT Center or  some entertainment park which has a brand orientation towards being a technology leader or futuristic perspective. With your creativity, I believe you could already write up a winning proposal to Disneyworld, and Disneyland, to install a solar "flight" path, from their parking lots into the park, where those electric cart people transports drive to take people from the parking lots to the park.  

    The biggest part of the appeal to a company like Disney, or Universal Studios, etc, would be brand enhancement, as in "Hello and Welcome to Epcot Center, where your experience of exciting new future possibilities, and creative thinkin starts in the parking lot before you even get inside.

    Here's where the Hexagon people should also focus as a possible first demonstration case. Then their hexagon shape is part of the "sex appeal' of the product even if it cost more. The first ones are all going to be custom made anyway.

    2. Elite Golf Clubs or Spas, who are again going for more than just power production so do not care if their 20 by 100 feet launch area for their premier solar Golf Carts (which also have a panel on their roof) is the most cost efficient.

    They get bragging rights that they are the first golf course in the world where their entire fleet of Golf carts are solar powered. (only in the fine print do you learn that the majority of the power is coming from a standard panel array  mounted in the roof of the cart storage shed and parking lot.

    3. Maybe NASCAR which already has one of the largest solar arrays for a stadium adds to the "solar sex appeal" of the whole complex by having a few solar pit stops.

    4. Remote heliports, or airstrips which one may want to turn into an intelligent surface anyway.

    These are just a few examples, one would want to look at aircraft carriers, or any other place it might be advantageous to have an "intelligent surface and figure if one is already going to be putting intelligent sensors, and LEDs into customize surface panels anyway, adding solar cells doesn't increase the cost much and adds a free bonus.

    Well these are just a few ideas to help kick off a discussion. Thanks REI.  I look forward to see how you/we can develop these creative ideas.

    HD

    Humor Alert! No statement from this UID is intended to be true, including this one. Intended for recreational purposes only. Unauthorized interpretations may lead to unexpected results. This waiver void where prohibited. Artistic License - 420420

    by HoundDog on Fri Jul 04, 2014 at 04:57:08 PM PDT

    •  Good post, HoundDog. :) (3+ / 0-)
      Recommended by:
      HoundDog, Odysseus, slowbutsure
      So you start with the same exact low cost panels the solar farm would have, in the standard framing which is already cheap because of standardization and economies of scale, and now what do we do? Encase each one in some super-hard glass, or high tech ceramic which can withstand all the extra weight and traffic. What is our base estimate of how much this adds to the cost of existing panels, which have come down in price 75% in the last 4 years due to economies of scale.
      I recommend searching for "Glass is the second most expensive element" for my comments on the glass. The glass costs about half of what the solar wafers costs. Of course, one shouldn't assume that the cost of wafers equals the cost of solar panels, the wafers are much cheaper than the panels per watt - there's a lot of overhead in making and distributing any kind of panel.  

      I'm in full agreement, there's no question that road panels would be more expensive per watt (and would require their own factories, so there's capital cost issues as well). But as you note, panel prices have been plunging like a stone in general. This now means that overhead/installation becomes an increasingly dominant factor in overall costs. Hence the focus on reducing that. The nice thing about a solar roadway is that, since you need a road anyway, almost all of the overhead is already done for you - right of way, environmental permiting, grading, drainage, etc. You're just putting a different top layer on the road, using a process no more complex than that of any other road top layer. You reduce it down to little more than materials costs. And since materials costs keep on declining...

      What order of magnitude of extra cost will these new super-ceramic-cellar-panels have after this super encasement? 500% 1,000%?
      Nowhere near that. The proposed glass is, as pointed out, about half the cost of the wafers. You can get raw scratch-resistant laminated 5/8" float glass for $16 a square meter in bulk from China (search alibaba.com or any other source for industrial supply rates).  And glass and wafers are just a portion of the total panel costs. So the impact of the more expensive glass isn't actually that radical of a difference.

      The more concerning factor than the raw glass cost, and one I couldn't work out precisely without seeking quotes, is machining. The geometry I call for here calls for a fair bit of maching of the glass to cut interconnects, air channels, vent holes, etc. A simpler geometry could significantly reduce that. It'd be pretty costly if each piece of glass as designed had to be cut by a general purpose water jet cutter, but if you have a custom cutter which nozzles to cut out the whole pattern in one step, the cost should be dramatically lower.

      A lesser issue is that the thicker glass also raises your shipping costs. On the other hand, the in-bulk, miles-and-miles-at-a-time-in-a-row process lends itself to reduced shipping costs. I estimated the shipping above (I actually have a bit of smaller scale international shipping experience, having sent two ISO containers from the US to Iceland), and it doesn't appear to be problematic.

      (although Eton Musk, chairmen of First Solar, recently described their several year effort to achieve exactly those kind of reductions to installation cost, enabling their rooftop installations teams to complete 2 per day now.)
      I would personally be shocked if there would ever be a process that makes rooftop solar installs on houses of different shapes in different environments, at altitude, disjoint from each other, each with their own inverter and grid connection, etc, will ever compare to rolling along and laying down panels off the back of a truck  ;)  I commend Musk for his efforts, and hope he achieves great success in them, but the task at hand is just such an inherently high overhead / high labor process.
      But, what overhead reduction advantage would roadway installations have over mass-production massed process innovation costs applied to solar farms?
      Greatly reduced, although not eliminated. Paving out a road or parking lot is still simpler than putting panels on mounts. Of course, if you're doing panels on mounts in great enough bulk, the difference becomes a lot less, you can get that too to be pretty automated, and the higher efficiency almost always justifies using mounts in solar farms. The downside with the farms (apart from the land use issue) are 1) that they require more than just the farm, they need transmission lines, access roads, etc (although that varies greatly from farm to farm) and 2) they have to pay all of their own overhead, from environmental study to grading, while a solar roadway - by virtue of piggybacking onto an existing roadway project - does not. The solar roadway adds some extra overhead, such as handling grid interconnects and the like, but only a fraction of the total.
      I like the idea of your "installation truck" picture, (my favorite part of your analysis) but wondered why we couldn't apply that same idea to the solar farms and still expect solar farm installation cost per frame to be substantially less per unit than roadway installations.
      The way they're built isn't that bad, at least the case that I've seen, they have a truck that drives in poles to mount the frames on, then the  pre-manufactured frames get shipped in on trucks and connected manually to the mounts.  They then install the panels by hand (you can't exactly drive on the frames  ;)  ), but they've optimized the process pretty well to do it quickly. So yeah, it's not as simple as continous road paving, but it's not too bad.
      Just one of the extra costs of the roadway installations is going to be the incredibly higher specs for a level grade beneath them. The slight change in angles of even a micro-fraction of an millimeter will cause relative joint motions, and wear.
      In my example I accounted for this with rubberized pin connectors to allow for flex, but one could account for this in dozens of different manners. Expansion joints in concrete road surface slabs is certainly nothing new.  :) I see no reason you can't have  expansion joints between road panels. I also don't think a little wear on the glass would be that problematic anyway.
      Whereas, the angles of the solar farm panels can be "close enough" by inches, the exact line up positioning of the roadway panels may have to be micro fractions of a millimeter,
      Why do you say that? Concrete slabs aren't connected within millimeters.
      4. Maintenance cost per panel has got to be higher.
      Than asphalt? Absolutely, by a large margin. Than solar farms? Likely. Than rooftop? Probably not.
      5. An issue with current designs of rooftop panels is that if one panel in an array get less sunlight than the others in the array if brings down the efficiency of the whole array. A tree shadow for example.
      Actually, that's an excellent point and one I should have covered above! You may have noticed that I had the panels connected in series within (many small cells, to get up to the high operating voltage), and parallel between the panels. A small amount of shading on a single panel can zero it out or significantly reduce it, even if the whole panel isn't in shade. But shading on one panel won't zero out other panels.
      My approximate feeling about this is that if you an I were solar entrepreneurs hoping to pitch a project to a big Texas utility, and were going to locate in West Texas where desert land, is literally dirt cheap, and we had a side by side choice, we'd decide to buy a couple hundreds of acres of desert we owned for cheap, rather start whatever complicated political process might be involved trying to "lease," or buy, or form some kind of special arrangement with the Texas Department of Transportation to disrupt traffic during installation (any alternate access roads during constructions, and traffic cops are an extra cost.)

      Do you agree with this much so far at least?

      I fully agree with you, from a "now" standpoint. Solar roadways have a long way to go before the concept has proven itself enough that any investor would realistically even consider choosing it. These things take a long, long time to become accepted.

      However, if there were pilot roadways out there that had shown economical advantages, and there was public interest in local generation and land reuse / saving natural environments, and departments of transportation (and people building private roads, access roads, etc) had begun doing small scale projects and were getting used to them. I think the situation would be different.

      Basically, do I think something like this is just around the corner? No, not at all. But I would like to see more work on the concept, because I think - conceptually - it could be both economically viable and environmentally beneficial.

      As one data point, in the last week the article I did on the community solar farms in Wyoming, and Colorado, the company is paying the local town $1,000 per year for the 20 acres of land that is slightly contaminated with toxic chemicals. The company specializes in building their small and mid scale solar farms on "scap" land no ones for other reasons.
      Personally I'd prefer to see the land cleaned up then left a toxic mess and built apon, but that's just me  ;)  Even on a toxic wasteland, however, there's still overhead for any new project.

       It's not expensive to just get a truck and workteam out somewhere to something. You can hire a guy with an excavator and all of the fuel, maintenance, etc costs for $60 or so an hour for a little excavator, $150 an hour for a 32 tonne excavator (I'm actually doing this right now on my land  ;)  ).  And I can buy fill shipped to me for $8 a cubic meter. But when you're doing a major construction project, that's just a fraction of it - the prep, planning, permitting, etc are huge costs.

      Wouldn't you suspect that roof tops, the sides, of buildings, and the tops of parking lots, and even the sides, of overpasses, roads, bridges, warehouses any anyplace a standard panel would fit, would be cost advantageous to do first?
      Actually, I wouldn't, due to the overhead. At least once the process is refined by pilot projects.
      You did such an excellent job of organizing these concepts that your helped me organize my own thoughts, which previously without the helpful focus of your post here, I've never had the energy to try to jump into as it seemed too complicated a set of thoughts to try to communicate.
      And I appreciate the comments and criticisms!  :)

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Fri Jul 04, 2014 at 06:58:22 PM PDT

      [ Parent ]

      •  I can't believe I just lost a long comment from my (1+ / 0-)
        Recommended by:
        slowbutsure

        jumpy keyboard.

        I missed the rubber flexjoints.

        Your well thought out response cause me to realize a limiting traditional assumption in my original thinking.

        I had assumed that you would be be using solar panels manufactured in a factory, and assembled on the roadway, being the actual surface driven on, but only now do I realize this does not have to be the case.

        Two ideas:

        1) If you used spring joints, or V like copper connectors with an outward force that the panels squeezed together at a spot of an inch wide or so you could have an eighth or third of an inch leeway between panels.

        2) If one didn't pour the molten glass until the last step then the panels could be as far apart as convenient, and no alignment precision needed at all.

        You could design a different kind of connector that might be a wire "unrolled" across hundreds of feet of connectors and snapped on, or spot welded onto each connector.

        BTW i like your parallel and in series array connections and accept that as a solution to the efficiency drop problem with shadows.

        If one had the solar panels dropped on the existing road surface from you truck and then connected, the a second truck could follow pouring a lane wide final top surface.

        This might solve nearly all of the problem of extra stress on the panels and their joints from lack of precision alignment I was thinking might be the primary cause of panel damage, and maintenance issues.

         

        Humor Alert! No statement from this UID is intended to be true, including this one. Intended for recreational purposes only. Unauthorized interpretations may lead to unexpected results. This waiver void where prohibited. Artistic License - 420420

        by HoundDog on Fri Jul 04, 2014 at 08:35:17 PM PDT

        [ Parent ]

        •  Aw, hate it when that happens! (1+ / 0-)
          Recommended by:
          slowbutsure

          That  molten glass concept is... interesting. I never thought of it before. If I get bored, maybe I'll do the heat conduction calculations to see whether it'd fry the cells through the glass that they come with  ;)

          I don't know how it would affect transmission, but I suspect it probably wouldn't be too bad. If you're pouring on top of laminated glass, the whole thing will be laminated, so that's not a problem.  Assuming it doesn't burn up the lamination.

          Scratch resistance may or may not be a problem, I don't know the process used for that. I imagine anti-slip texturing wouldn't ne a problem.

          One unfortunate aspect would be that you can't let air through like in my design (couldn't water-cut, at least), so the cells will basically be in a greenhouse, which would lower their efficiency, and you'd lose the ability to do things like blow away snow or melt thin layers of ice. And I'm not sure how easy repairs would be if you had a continous surface..

          Still, a very interesting idea!

          The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

          by Rei on Sat Jul 05, 2014 at 07:37:23 AM PDT

          [ Parent ]

  •  Your opening paragraph seems pessimistic (3+ / 0-)
    Recommended by:
    Rei, tb mare, slowbutsure

    Being unfamiliar with the"utopian vision" of the "solar freaking roadways" advocates, I initially thought you were dismissive of the entire concept. But your excellent analysis shows that there is real potential in the use of road surface for energy generation. If leadership in those regions without snow or excessive cloud cover were to demonstrate cost effective energy generation, others would follow.

    Having read through the comments, the issues raised seem to argue that roadway solar is more or less effective or efficient than rooftop solar.  I don't understand why we need to choose one over the other, why not both?

    I hope that our progressive leaders begin to put this into effect asap.

    'Tis with our judgments as our watches, none go just alike, yet each believes his own. - Alexander Pope

    by liberaldad2 on Fri Jul 04, 2014 at 05:25:36 PM PDT

    •  I agree - it's silly to even have the (2+ / 0-)
      Recommended by:
      tb mare, slowbutsure

      "What's better, Coke or Pepsi?" argument. Folks can neither promote nor prevent "lesser" methods from existing side-by-side with "greater" methods, whether they approve of it or not. The diversity just will happen anyway for a whole series of reasons - some having to do with economies of scale, some having to do with available resources, some just hard-headed preference. Just as all technologies begin with wide diversities in style, performance and technical details and then gradually mature with just a few stand-out successes (e.g., literally scores of automobile companies have disappeared in the last hundred years and then there's the PC and Mac - you don't see Commodores much anymore) - the same consolidation will eventually materialize in a mature solar industry....and Solar City has no guarantees of being in the winner's circle!

  •  I think the point of "Solar Freakin Roadways" (3+ / 0-)
    Recommended by:
    Odysseus, laurak, slowbutsure

    to take isn't that it is The Solution, but that it is a potential solution to several significant, but very unsexy, problems that we habitually ignore.

    It is not an overstatement to say that civilization rests on our physical infrastructure, yet we take it for granted and allow it to degrade to the point of crisis.

    Modularization and manufacture of standard components makes a lot more sense than that haphazard, non-system of transportation/power/water/sewage/communications that we have now. Rebuilding what we've lost will already cost more than we can pay*, so isn't it a better idea to start spending that money we have to spend, smarter?

    BTW, we already have roads that don't freeze. You don't have to melt ice, you never let ice form.

    "Those who can make you believe absurdities can make you commit atrocities." - Voltaire

    by Greyhound on Fri Jul 04, 2014 at 05:29:12 PM PDT

  •  Build the thing already (1+ / 0-)
    Recommended by:
    slowbutsure

    lets get moving.

  •  Correction: $10 per meter = $10k per kilometer. (2+ / 0-)
    Recommended by:
    Rei, slowbutsure

    Not $100k.

    The primary conduit on the side of the road needs to be rather large and sturdy, probably about $10 per meter. So $100k per kilometer

    The Dutch kids' chorus Kinderen voor Kinderen wishes all the world's children freedom from hunger, ignorance, and war. ♥ ♥ ♥ Forget Neo — The One is Minori Urakawa

    by lotlizard on Sat Jul 05, 2014 at 02:04:55 AM PDT

    •  Whoops, nice catch, thanks - will fix. (1+ / 0-)
      Recommended by:
      slowbutsure

      Works out to basically a rounding error, but still good to correct.  :)

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Sat Jul 05, 2014 at 06:56:44 AM PDT

      [ Parent ]

  •  Thanks for the comprehensive look (3+ / 0-)
    Recommended by:
    Rei, slowbutsure, Egalitare

    at this. I haven't had time to look at all the specifics, but I would just like to note that something like this would be great for a bike path or mixed use path, although I loathe them because of their danger. The amount of wear would be drastically decreased and the price would likely be decreased as well.

    No War but Class War

    by AoT on Sat Jul 05, 2014 at 08:54:14 AM PDT

    •  Indeed! (3+ / 0-)
      Recommended by:
      AoT, tb mare, slowbutsure

      I think that while it's important to do road pilot projects for proof of concept and data gathering, the first attempts for scale should be on things like sidewalks and paths, then driveways, access roads, and other low-traffic environments. One shouldn't try to commercialize the high-hanging fruit first! That should however be the long-term goal, since it represents the greatest surface area.

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Sat Jul 05, 2014 at 12:50:11 PM PDT

      [ Parent ]

  •  Well, if I'm following this (5+ / 0-)
    Our net figures, thus, are around $7m per kilometer of solar road, versus $3m per kilometer of conventional road, for a net surcharge of $4m

    If this is really true
    electricity sale value of 1.4 million per year, yielding a simple payback period of only 2.9 years.
    then even if you cost estimates are off by between a factor or 2-3 the ROI is still incredible (like 10%).

    And I've never understood this concern about snow.  I haven't encountered snow on a road in many years... (heh) Just how many miles of road that never has snow on it exists in the US?  Lots and lots and lots.

  •  Wonderful diary and (mostly) comments. (1+ / 0-)
    Recommended by:
    Rei

    I am not much of a shiny object person, but I just want a solar roadway.  I just do!

    ...Son, those Elephants always look out for themselves. If you happen to get a crumb or two from their policies, it's a complete coincidence. -Malharden's Dad

    by slowbutsure on Sat Jul 05, 2014 at 02:15:30 PM PDT

  •  Thank you (5+ / 0-)

    for one of the most intellectually engaging diaries I have read in a very long time.  I am particularly appreciative of your intellectually demanding, but highly collegial, responses to comments.  The effect was to raise the level of conversation and prevent appropriate skepticism from deteriorating into cynical rejection.  I regard this as a model for honest efforts at persuasion.

    That said, I have no training in engineering, so I'll have to leave the actual merits of the proposal to those who do.  

  •  Elegant Engineering! (0+ / 0-)

    Now, if our corrupt and brain-dead politicians (i.e., most of them) could ever grasp the significance of what you propose, we could start ameliorating the fossil fuel consumption problem.

    We need leaders to see the possibilities.  In today's political environment, unfortunately:  Fat Chance!

    Just a soul on a roll...

    by CAOgdin on Sat Jul 05, 2014 at 03:42:33 PM PDT

    •   (0+ / 0-)

      Eh, the only person you really need to convince is Elon Musk.  If it's workable, he could fund development and incentivize various suitable pilot locations to try it out via profit-sharing.  If it was then shown to be viable in practice, other locations would clamor to take part as well.  And then finally, long after the idea was obviously the right thing to do, the politicians would line up to lead the parade.  ;)

  •  All of our great engineering accomplishments --... (4+ / 0-)
    Recommended by:
    koseighty, BeninSC, Egalitare, Rei

    All of our great engineering accomplishments -- rural electrification, the CA Water Project, landing a man on the moon, etc. -- have been met with skepticism; skepticism is easier and less work than generating ideas and solutions (an ongoing frustration of mine). Having said that, I've got a question: I'm a building contractor and live in Minnesota. I've installed a lot of concrete and asphalt drive surfaces. A key quality of both those materials is that they are very accommodating of variations in the substrate. And I think you're going to need that; we grade, compact and install within, I suppose, an inch or so, but it's definitely not perfect, and neither are the base or wear courses. Concrete you can get pretty flat, but it's expensive and still not perfect. I think your panel connection mechanism is going to need to accommodate some amount of deviation. And then there's frost heave.... The technology and cost modeling make a compelling argument but we know wherein the devil lurks....

  •  I think you miss the point (0+ / 0-)

    While yes in modern solar systems the install costs are
    now dominating over panel costs, they can get the costs
    of install down fast.

    Wether it's BIPV, or solar shingles,  the goal for
    DOE Sunshot is $1/watt.  The germans are at
    $3/watt right now,  and as more buildings come
    on line with installed racks and conduits in place, it will
    really start changing.

    You use power in buildings, you don't use power on roads,
    really, so, why collect power there?  Sure, you can
    collect power in New Mexico but then you pay
    a fortune moving it to NYC.

    far better to work out methods to collect power
    on the side of the Empire State building, or WTC
    and use it right at point of sale.

    People install solar panels on roofs because it's out of the way.  That's going to keep expanding game hits 100%.

    http://ei.marketwatch.com/...

    the pic above is about all the power you need on a road,
    to run a light,  so, why do more?

  •  The issue of cars blocking sunlight is easily (0+ / 0-)

    dealt with. Just install solar panels on the tops of all cars, and whatever light they "steal" from the road they give back to themselves, saving net energy.

    Btw, has there been any investigation into whether EVs could be charged by roads (whether solar or not), in a safe, reliable and cost-effective manner?

    "Reagan's dead, and he was a lousy president" -- Keith Olbermann 4/22/09

    by kovie on Sat Jul 05, 2014 at 05:25:23 PM PDT

  •  if you really really want a two fer (0+ / 0-)

    while you're laying all these miles of electrically interconnected roadways, add an internet backbone line.
    then all we need to do is add wifi transmission, and we'll have free internet around our highways.
    costs should be pretty minimal compared to laying new cable elsewhere.

    •  I didn't add "backbones" (0+ / 0-)

      ... but in the proposal I did include a fiber bundle. And I didn't credit the road with any economic advantages for doing so, which I really should have.

      Fiber is cheap. Laying it is what costs money. Laying it here adds no incremental costs. Not even for the access points, since the utility stations need the access points on their own.

      Clever idea on your part, having the utility stations act as wifi access points. Hmm, is 250m too far apart for wifi access points?

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Sun Jul 06, 2014 at 04:15:12 AM PDT

      [ Parent ]

  •  ...hotlisted...amazing! thank you!... (0+ / 0-)

    Ignorance is bliss only for the ignorant. The rest of us must suffer the consequences. -7.38; -3.44

    by paradise50 on Sat Jul 05, 2014 at 05:53:01 PM PDT

  •  One possible critical flaw (plus one other thing) (1+ / 0-)
    Recommended by:
    Rei

    Wet, lake-effect snow. Heavy, heavy snowflakes. More like mini snowballs, really. They'll power right through the air shield, land, and freeze into ice.

    Also, while I agree that most of the electronics can be done without for now (eventually they'll get cheap enough to justify including), LEDs are still quite viable when used in concert with paint. The reason being, in dense fog or a heavy downpour, painted lines are hard to see no matter what the surface they're on. Even with jet black, fresh asphalt and new white lines, a heavy downpour can render the paint effectively invisible. LEDs can still be seen in that. You don't need to have them on 24/7 - just when conditions warrant it. You don't even need sensors on all the panels, just rain/humidity/light sensors on the control boxes which can turn all the units they're connected to on at once.

    Second, I agree with you on the fact that this is a PILOT PROJECT. Of COURSE not everything is accounted for yet! But there's potential here, and relatively cheap potential, too. That's why you build and test PROTOTYPES! And if they fail, it's NOT the end of the world! You find out WHY they failed, see if it can be fixed, and if so, FIX IT, and then TRY AGAIN! Sheesh!

    It's not like we're saying give them a trillion dollars right now and put it all in as is! We're saying toss them some research money to explore the idea! Even if it doesn't work out 100%, there could be lessons in there that are still worth the money!

    The problems that exist in the world today cannot be solved by the level of thinking that created them. - Albert Einstein.

    by Cvstos on Sat Jul 05, 2014 at 06:19:29 PM PDT

  •  A road is not the place to try this. (0+ / 0-)

    Parking lots would be ideal. Think of all those shopping center and mall parking lots covered in panels. Even with cars parked over some significant part of the surface, assuming the system does work which I still have doubts about, you get some use out of all that wasted space.

    •  Fully agree for the beginning. See my comments.. (0+ / 0-)

      about low hanging versus high hanging fruit.  :)  While I spent most of the article analyzing the difficult case to show its potential, and think pilot projects are important on actual roads for data gathering, I mentioned that people should begin commercialization on the low hanging fruit - sidewalks and such, then driveways, parking lots and access roads, and so forth, working up to eventually large high-traffic roads as the end-game.

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Sun Jul 06, 2014 at 04:18:22 AM PDT

      [ Parent ]

  •  I stopped wasting my time when you began babbling (0+ / 0-)

    about "expensive batteries" that aren't part of the proposal you're ineptly challenging.

    But then, I've seen your schtick before and don't tell to fall for the same crap more than twice.

    The UN should give Iraq a restraining order against the US.

    by JesseCW on Sat Jul 05, 2014 at 06:53:27 PM PDT

    •  Thank you for your polite and thoughtful (1+ / 0-)
      Recommended by:
      wagdog

      input. If only fewer commentors would stick to the facts and focus on personal attacks like this, the world would be a better place!

      The Solar Roadways team does talk about the concept of putting batteries in their system. They say that they did not put it in their prototype. Now, if you think that what I wrote is a misrepresentation, you could simply write, "I think you misrepresented their view".  But given that you write personal attacks against me pretty much everywhere you see me on DK  (I guess it's kind of flattering to have my own personal stalker), regardless of the content of the post you're replying to, even when I'm agreeing with you, I guess I shouldn't expect that.

      The day I'll consider justice blind is the day that a rape defendant's claim of "She consented to the sex" is treated by the same legal standards as a robbery defendant's claim of "He consented to give me the money": as an affirmative defense.

      by Rei on Sun Jul 06, 2014 at 04:32:49 AM PDT

      [ Parent ]

  •  why wouldn't we just put more conventional panels (0+ / 0-)

    over the roadway, like at the height of an overpass? Sure, this requires some structure, but the idea is that you are not stealing new real estate. You could also really cherry-pick the best places to start. Also you might be able to completely eliminate the need for blocking diodes (maybe...) since there will be no traffic shadowing the cells.
    As an engineer who has worked some with solar cells and structures, I am skeptical of the "on the road" concept, but appreciate the investigation of this possibility nonetheless.

  •  Rei, you've done a terrific job with this (3+ / 0-)
    Recommended by:
    Egalitare, Rei, wagdog

    article.  Daily Kos needs more facts and analysis like this and fewer spit ball fights by people who can't be bothered to read and especially, understand what was written before commenting.  Too bad we can't have commenters gain a ranking by fellow readers as contributing helpfully to a discussion and use that ranking to show or hide comments according to ranking.  That would be kind of like the "recommend" list, but applied to comments as well.  We have the hide rate system but that's a negative filter, not a positive one that would reward people as they made useful and contributing comments that added information or a perspective to a diary.  Life's too short to wade through many comments that are clearly based solely on ignorance and refusal to read before spouting off.  We get enough of that from the Reich wing commenters on far too many sites.

    Republicans claim "tax cuts pay for themselves" but unemployment insurance, food stamps, student loans, road repair, disaster aid, must be offset with spending cuts. Who benefits most from tax cuts? The Ultra-rich. Who loses? You.

    by monkeybrainpolitics on Sat Jul 05, 2014 at 09:30:27 PM PDT

  •  VG diary (0+ / 0-)

    While I am not convinced that your realistic solar roadways proposal would work as described, I commend you for attempting to create a solid practical and economic basis for it.  If nothing else, you have made much clearer what the pros and cons of solar roadways are.

    Meanwhile, given the experience of Germany, etc., it looks like rooftop solar is becoming more and more practical over time.  Human dwellings generally need power, and using their roofs to generate some of that power greatly reduces the need for large, centralized, polluting power stations.  And further perfecting rooftop solar does not exclude developing solar roadways.  It's just that rooftop solar is farther along, and will probably become a standard design element in new construction before long.

  •  Value added service (2+ / 0-)
    Recommended by:
    DonMahoney, Rei

    Fascinating article, in so far as I could grasp the technical aspects, which isn't to say, very far.

    But I had a "kill two birds" idea for piggy-backing on an additional component to those roadside service areas/buildings.  

    The USPS is proposing creating groupings of mail delivery boxes for neighborhoods instead of delivering door to door and to individual, roadside mailboxes.  

    Everyone has wondered where these would be located, how land would be acquired, parking/drive up facilitated, cost, etc.  If we are going to acquire land for one project, why not both consolidated in one location?

    No cost analysis or building specs.  I'm no techie.  Just an idea.

  •  tippenwrecked (1+ / 0-)
    Recommended by:
    Rei

    for writing a very thought-provoking diary.

    "As soon as the land of any country has all become private property, the landlords, like all other men, love to reap where they never sowed, and demand a rent even for its natural produce." - Adam Smith: The Wealth of Nations

    by ozsea1 on Sun Jul 06, 2014 at 02:21:31 AM PDT

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