Alternative Cellulosic Biomass By the Numbers

The Wall Street Journal editorial page today sided with a the group of senators who are asking EPA Administrator Stephen Johnson to eliminate federal mandates for biofuel production. The Center for American Progress has a fact-check on “Biofuels Done Right” demonstrating why the Journal and the senators are wrong to place blame for the global food crisis on biofuels. But the Journal contends that “there’s no getting around the fact that biofuels require vegetation to make fuel,” going on to mock next-generation cellulosic ethanol: “Perhaps some future technology will efficiently extract energy from useless corn stalks and fallen trees.”

But the facts are again not on their side. While cellulosic ethanol is not a silver bullet for solving the country’s need for sustainable transportation fuel, there is a sufficient supply of biofuel feedstocks that do not compete with food crops. David Tilman, of the University of Minnesota, explained at a briefing on capitol hill last month that there are good alternative feedstock sources (pdf) that are not dedicated biofuels crops grown on fertile land:

Biofuels from Residual Agricultural and Forestry Biomass: corn stover (the “useless corn stalks” the Journal refers to), straw, slash, bark, manure, and municipal waste. Ethanol derived from these materials has life cycle carbon emissions that are lower than gasoline, and none are in competition with food crops.

Biofuels Grown on Degraded Land Set Aside from Agriculture. Ethanol derived from these materials also has life cycle carbon emissions that are lower than gasoline, and none are in competition with food crops.

Tilman went on to offer these estimates for how much biofuel feedstock we could derive from waste products and vegetation grown on degraded land:

80 to 100 million tons per year: Dedicated perennial energy crops grown on the least productive or least sensitive abandoned lands.

100 to 150 million tons per year: Sustainable supplies of corn and wheat residues.

70 to 140 million tons per year globally: Forestry slash, thinnings, urban waste wood, mill residues, etc.

20 to 40 millions tons per year: Reclaimed paper and board waste.

This comes to a total of 270 to 430 million tons of biomass per year without competing with food for fertile land, which Tilman calculates would yield 20 to 32 billion gallons per year of ethanol, which can meet or exceed current 2007 Energy Bill goals for Advanced Fuels, and with ethanol that provides greenhouse gas reductions of at least 50 percent.

Tags: biofuels

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