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View Diary: Sunday Train: Unleashing the Political Power of Bio-Coal (128 comments)

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  •  What's the per-acre potential? (5+ / 0-)

    For example, land to run a 1000 megawatt power plant (or plants) on biocoal 50% of the hours in a year?

    •  Why would we need to run ... (17+ / 0-)

      ... a plant on biocoal for 50% of the hours of the year? A firming power supply is drawn on for something much more like 5% of the hours of the year ~ even a 1:4 stored output to thermal or Direct Carbon Fuel Cell power source ratio would be the biocoal running 20% of the hours of the year. A 1:2 ratio would be 10% of the hours of the year.

      This conference paper from 2001 cites biomass yields for Sycamore Coppice on a 3 year coppice cycle as 7.5-15 oven dry tons per hectare per year, so 3-6 ODT per acre ~ call it 4 ODT.

      engineer poet performed his analysis on the basis of 0.72b tons of waste biomass and 1b tons of biomass production, and arrived at:

      There are several uses for fuel gas, but one of the best is making electricity.  Hot combustible gas is more or less what an SOFC runs on.  GE and Delphi have been developing small SOFC's for automotive applications, and both recently beat the $300/kW price barrier.  Efficiency is 49% and headed upward.  If we assume that:
      • 1.72 billion tons per year of biomass is carbonized.
      • This biomass has 15.8 million BTU/dry ton of energy (27.1 quads total energy).
      • 53.5% of the energy is yielded as charcoal (30% by weight).
      • 88% of the remainder is yielded as chemical energy in hot gas (11.1 quads gas + 1.51 quads reaction heat + recycled heat).
      • The gas can be converted to electricity at 50% efficiency.

      The electric yield from the processing of the gas would be 5.55 quads, or 1620 billion kilowatt-hours.  This is more than twice the US electric generation from natural gas (~750 billion kWh), and more than 1/2 of the total US electric generation from all fossil fuels.  In short, all non-renewable natural gas generation could be replaced by energy from the carbonization stage, and a large chunk of the coal-fired generation as well.

      ... which is without taking the biocoal into account.
      An annual supply of 515 million short tons of charcoal fed to DCFC's would produce roughly 3400 billion kilowatt-hours of energy.  This is more than the total US generation from fossil fuels, and about 84% of the total electric energy consumed in the USA in 2005; together with the generation from the gas, it could conceivably replace every kilowatt-hour we now use, from the trivial amounts made by solar to the entire contribution of coal, with about 25% extra to play with.
      Now, if under a Pedal to the Metal approach, we retire the least efficient, most polluting Coal Power Plants and only retain the most efficient in use, then as they go out of service life, Direct Carbon Fuel Cells would be the technology for new investment. But the thermal coal power plants would be more like 35% efficiency, for 1,500 billion kilowatt hours of electricity, so the total from 1.72b tons of biomass would be closer to 3,100 billion kilowatt hours.

      So that gives a ratio of 1,800 Kilowatt Hours per ton of biomass, or 7,200 Kilowatt hours per acre for Sycamore coppice.

      1000 Megawatts over 1,752 hours (20% load) is therefore about 250,000 acres of output of Sycamore coppice (unless there is a mistake in my math ~ its more dangerous to do this in a comment than in a diary where arithmetic mistakes can be fixed ^_^). To bracket that for comparison, we have about 80m acres under cultivation in corn in the United States.

      Note that other biomass feedstocks could have yields of up to 10tons/acre, but the most productive biomass fields also tend to be the most productive food crop fields.

      The use of biomass in the role described in the diary is much less aggressive than engineer-poet's analysis, which is more along the lines of "how far could biomass go". Given that Wind and Solar power are more economical, but are "use it or lose it" power sources rather than scheduled power sources, my approach is rather how much do we need, rather than what is the maximum we might conceivably produce.

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      by BruceMcF on Sun Sep 29, 2013 at 08:08:08 PM PDT

      [ Parent ]

      •  Could put out very considerable amount of energy (2+ / 0-)
        Recommended by:
        Her Masters Voice, KenBee

        250,000 acres of land not used for other agriculture could be found in several areas of the Northeast or Appalachia.

        Issue with biomass (or coal) plants with low operating hours is that conveyors, ash handling, transport infrastructure, etc. will require fairly high operating hours to keep going financially, even if long-ago paid for.  

        Not even considering increased damage due to cycling, it's hard to imagine a structure that would permit a coal (or biocoal) plant to sustain operations over time at less than 25% of the hours in a year.

        Natural gas, or a liquid/gas fuel produced from surplus wind/solar, consumed in a combustion turbine would handle these peak needs better. Thermal storage for air conditioning and heating could help meet such needs and is greatly under-used.

        •  Is that the real operating costs ... (0+ / 0-)

          ... or the real operating costs plus the service on the debt?

          The EPA cost estimates for a Dual Unit Advanced PC are $31.18 fixed O&M cost/KW capacity/year, $4.47/MWh.

          On a 90% average cycle, that is 7.884MWh per KW capacity, which is $3.94/MWh fixed O&M, so a total debt free cost of $8.31/MWh for "baseload" power.

          On a 20% average cycle, that is 1.752MWh per KW capacity, which is $17.80/MWh, so a total debt free cost of $22.27 for "peak/store-for-peak" power.

          This last July, in most hubs wholesale prices for electricity ranged from $32-$100/MWh.

          The EIA figures for Dual Unit Advanced PC with Carbon Capture and Sequestration is $66.43/kw-year for annual fixed O&M and $9.51/MWh Variable O&M, which on a 90% cycle is $8.43/MWh or a debt-free cost of $17.94/MWh for lower value "baseload" power.

          Support Lesbian Creative Works with Yuri anime and manga from ALC Publishing

          by BruceMcF on Mon Sep 30, 2013 at 08:48:51 PM PDT

          [ Parent ]

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