It’s been a trying time here at Daily Kos since the election. Nowadays it seems that all everybody wants to do is call each other “snowflakes” and re-litigate the primary. Why can’t Daily Kos go back to how it once was? Back to that time where we all came here for one common, unifying purpose.
Rock crushers.
In the interests of unity, let’s go into a quick review of rock crusher related news!
Solar power is booming as prices on solar cells continue to fall. A feat that would have been almost unthinkable a decade ago, India recently completed the world’s largest solar power plant. With 648MW (nameplate) of photovoltaic generation capacity and completed at a cost of $679M, commercial scale solar power has effectively reached the price point of $1/W installed. By comparison, a typical fossil fuel plant — of which construction costs are overwhelmed by fueling and operations costs during its lifetime — usually costs about the same price to build. The new plant doesn’t even require crews to clean the panels; an included robotic system does it for them.
But photovoltaic panels don’t grow on trees. Most are based around silicon semiconductors, which require a highly pure silicon produced from silicon dioxide. And some of that may pass through rock crushers!!!
A NEW DAWN OF ROCK CRUSHERS IS UPON US! PRAISE BE UNTO ROCK CRUSHERS!
Ahem. Sorry.
To produce solar-grade polysilicon, traditionally a purification process involving the vaporization of silicon tetrachloride has been used. This process gained a bad reputation in China, where a number of plants were built without any recycling for excess silicon tetrachloride — instead dumping their waste on the surrounding land and acidifying the soil to the point that plants could not grow. While this was never the case in the rest of the world, and even China has heavily cracked down on the behavior, the industry has continued to search for new refinement processes to be cheaper and cleaner.
Just a dozen or so kilometers from my land, Silicor is planning to make their first full scale plant testing a new process that involves no vaporization of any chemicals at all. Rather, they form a molten alloy of silicon and aluminum (from the smelter across the bay) and let it cool; the silicon cools first and forms a layer on the surface, leaving most of the impurities behind in the aluminum. The impurities have little effect on the “waste” aluminum’s properties, but some of the silicon is left behind, which is actually a desirable alloying agent in aluminum — making it not waste but a separate product to sell. Any remaining aluminum (and residual impurities) on the silicon are dissolved with hydrochloric acid, yielding polyaluminum chloride — a chemical in high demand for water purification. When completed, the new plant is expected to produce about 3% of the world’s supply of solar-grade polysilicon.
Any new industry being built in a location is always controversial (an old-style silicon smelter on Reykjanes recently caused chemical irritation for nearby residents when “burning in” their furnace for the first time). But I’m cautiously supportive here. Everything in the world comes at a cost, but many costs are worth paying.
Why just crush rocks on Earth when you can crush them in outer freaking space? A new boom is underway among companies looking to mine asteroids, either to provide supplies for spacecraft without having to launch them from Earth (water, oxygen, fuel, radiation shielding, etc) or to export valuable minerals back to Earth, taking advantage of the fact that many asteroids contain precious metal resources richer than the richest mines on Earth, with no overburden.
This glorious rock-crushing future is however hindered by one major factor: launch costs. As Daniel Faber of Deep Space Industries explains:
"Launch is the biggest thing slowing us down right now," he said. "We can do an exploration campaign for $3.5 million. But the launch is going to cost us 10 [million dollars]. And that's a boot in the teeth for an exploration company."
Nobody gets more attention in terms of reducing launch costs than SpaceX, but an on-pad explosion last fall became a huge roadblock to a company whose launch schedule was already backed up. SpaceX has since been simultaneously been rushing to complete a new launch pad, repair the damaged one, and complete rockets for both east and west coast launches while conducting their accident investigation. Their first new launch is targeted at December 16th.
But what about the cause? The report is expected "soon", but enough details have leaked out thusfar to try to piece together the cause. The explosion initiated in one of the COPVs — “composite overwrapped pressure vessels” — located in the liquid oxygen tank used to store helium pressurant at high pressures. A COPV involves a thin-walled aluminum vessel wrapped in carbon fiber to provide the strength to prevent it from exploding. Unfortunately , liquid oxygen and organics (such as carbon fiber composites) tend not to get along; whatever organics liquid oxygen doesn’t immediately react with, it usually will react with when given a strong enough shock or at high enough pressures. And liquid oxygen can seep into the overlay on the vessels. This is, however, not normally a problem; as the COPV gets pressurized and the aluminum pushes tighter up against the overlay, the liquid is squeezed out. Apparently, this did not happen in this case. Due to very low temperatures and high pressures, solid oxygen formed in the overlay, which does not squeeze out; as the pressure continued to increase, it eventually reached its detonation point, destroying the COPV and thus the rocket.
The fortunate part is that this should be addressable just by changing the propellant and pressurant fueling procedures. But it does stress the dangers involved in working with liquid oxygen and composites — an issue that will become dramatically more critical when dealing with the vastly larger, all-composite Interplanetary Transport System.
Not all rock crushers are created equal!!! Don’t buy an inferior rock crusher!
NOTE:
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