The yields of crops has to increase dramatically for biofuels to make sense. It currently takes around 3 tonnes of wheat to produce 1 tonne bioethanol via fermentation. That is using grain, rather than the whole wheat, from seed to root and is probably only sustainable in fairly limited quantities of bioethanol production.
Why? mostly because if the US would starve. Now these sums are as rough as a badgers’ behind but…
Taking the averages US gasoline consumption for September this year and converting this to tonnes/year with a rule of thumb found in The Economist World Measurement Guide (paper, I know but it was printed in 1980 (page 134)) that 1 barrel/day is 50 tonne/year. If September’s consumption is average then the US will use between 462 million tonne and 472 million tonne/year gasoline. The US Department of Agriculture (USDA) estimates in its March 2006 year book that this year there will be 41m US acres under wheat, producing around 2105m bushels (equivalent to 57m ton grain). Even if we malted, brewed and distilled all of this, we’re talking about 19m tonne ethanol. That’s not quite enough to make a 5% blend with gasoline. Even if we diverted the whole world’s supply of vegetable oil estimated at 106.82 million tonnes in 2005, by the USDA in its march yearbook (Its in spreadsheet 48, if you get that far).
Even if it were a drop-in replacement for gasoline, which it isn’t, we’re going to be way short. While the lack of margarine, would be good news for the butter lobby, this would be offset by the black market in Fried Food that would inevitably spring up.
Which is why people are interested in using the whole of the wheat from the seed to the root. Which is why people are interested in biomass,things like weeds, though whether we’d be better burning them and generating electricity from the steam you could make is something I’ll be looking at later.