Originally Posted by some_guy282
Correct. Both are net energy losers (it takes more energy to make them than you get out of them), and neither is scalable. There isn't enough farm land in the country to produce enough ethanol or bio diesel to run our fleet of cars. Professor David Pimentel of Cornell calculated that
I don't have a really high regard for Pimentel's methodology. Every year he gets a bunch of beginning grad students and higher-up undergrads together for a seminar to mine coefficients of whatever from the literature to calculate why something or other isn't feasible and he gets them all published in Science but doesn't really ever advance much.
David Tilman has a more
proactive approach to biofuel based on actual data collection and experimentation, generating something that is both useful and productive, if lacking large lobbyist support:
There are biofuel crops that can be grown with much less energy and chemicals than the food crops we currently use for biofuels. And they can be grown on our less fertile land, especially land that has been degraded by farming. This would decrease competition between food and biofuel. The United States has about 60 million acres of such land -- in the Conservation Reserve Program, road edge rights-of-way and abandoned farmlands.
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Whether converted into electricity, ethanol or synthetic gasoline, the high-diversity hay from infertile land produced as much or more new usable energy per acre as corn for ethanol on fertile land. And it could be harvested year after year.
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Across the full process of growing high-diversity prairie hay, converting it into an energy source and using that energy, we found a net removal and storage of about a ton and a half of atmospheric carbon dioxide per acre. The net effect is that ethanol or synthetic gasoline produced from this grass on degraded land can provide energy that actually reduces atmospheric levels of carbon dioxide.
When one of these carbon-negative biofuels is mixed with gasoline, the resulting blend releases less carbon dioxide than traditional gasoline.
Biofuels, if used properly, can help us balance our need for food, energy and a habitable and sustainable environment. To help this happen, though, we need a national biofuels policy that favors our best options. We must determine the carbon impacts of each method of making these fuels, then mandate fuel blending that achieves a prescribed greenhouse gas reduction. We have the knowledge and technology to start solving these problems.