Ethanol Subsidies: Not Gone, Just Hidden a Little Better | Mother Jones

Ethanol production is limited to sugars and simple starches. The same compounds we use as food. We can not readily produce alcohol from vegetation high in celluloses. In order to use vegetation high in cellulosic compounds we have to put in a lot of energy to break them down to simpler carbohydrates that yeast can use or genetically modify bacteria or yeast to use cellulose directly.

Or we could use methanogenic bacteria that have been around for hundreds of millions of years that break these compounds from non-food crops down into CO2 and methane. This process is common place and is typically referred to as composting amount other terms. Or we can pyrolyze these compounds to produce a mixture of gaseous and liquid fuels similar to natural gas and petroleum. The big difference between these fuels and fossil fuels is that the pyrolysis or composting fuels are carbon neutral.

Production of ethanol converts sugar in to ethanol at 2/3 the carbon content, but only the sugar. Methanogenesis converts 1/2 of all carbohydrates, fats and oils and proteins to methane. Pyrolysis converts almost every carbon to a fuel compound.

Grass in NY can yield about 8 tons/acre-year of dry matter which can yield about 96,000 scf of methane. As an estimate of the available acreage I am citing a report from Nature:

A recent US government scenario says that over a billion tons of biomass could be made available within a few decades—enough for 60-billion gallons of ethanol. Under this scenario, 60-million acres would be planted with biofuel perennials like poplar and switchgrass. This study is more ambitious than one by the Rocky Mountain Institute, a think tank in Golden Colorado—and more conservative than one by the NRDC.

That is 60 million acres in the US at 96,000 scf of methane from methanogenisis gives 5.8 trillion scf of methane a year. And a byproduct is a good slow release fertilizer to supplement traditional inorganic fertilizers made from petroleum products. Pyrolysis is produces more fuel on a weight basis, but requires energy input to heat the biomass up to over 500 degrees C. If this could be done through a combination of solar (concentrated and PV) and wind, the energy input would be a moot point. Production of the biomass and the conversion to fuel products would be best done on a local, municipal or regional level creating thousands of jobs around the country that can not be off shored.

These are the types of programs we should be subsidizing. Not the ones that compete with food crops.