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Any EROI calculation depends on what you call the product. If you call the product of coal production coal, you get one EROI, if you call it electricity from a thermal power plant, you get another.

The thermodynamic losses from conversion of a biomass feedstock in a sealed, semi-pressurized container into biocoal and medium-BTU gas is very low.

Now, you may have a chemical process in which you can directly use warm medium-BTU gas, and another chemical process in which you can directly use charcoal, and for that situation, the EROI would be quite high, dominated by the energy investment into the production of the biomass feedstock, and given the flexibility to choose biomass feedstocks that require no artificial fertilizer or forced drying, the EROI of the production of those end-products would be quite high.

OTOH, you may be interested in electricity production, in which case the medium-BTU gases could be converted by already existing fuel cells at 50% efficiency and the biocoal into electricity at anywhere from 30% to 80% efficiency, but in any case a substantially lower EROI when electricity is the end-product than when biocoal and medium-BTU gas are the end-product.


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Mon Jul 29th, 2013 at 06:27:15 PM EST
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