Commentary 1/26/09 Why Biofuels are a Dumb Idea

After 30 years of listening to bad decisions, it is wonderful to hear the news every morning: the prison at Guantanamo closing, torture of prisoners ended, the (illegal) military commissions suspended, car mileage required to rise, the EPA probably going to allow California and 16 other states to regulate carbon dioxide as a pollutant. How about ending subsidies for corn-based ethanol – even if it means buying out some of the new ethanol plants. Supporting ethanol from corn was a total political boondoggle in the first place, a green (!) way of getting rid of some of the overwhelming American corn crop (rather than forcing farmers to farm more decently), thus helping farmers by raising the price of corn.

A simple argument against biofuels comes from the potential power density of vegetation. At 0.5 watts per square meter, the power density of vegetation is an order of magnitude (10 times) less than that for wind or flowing water (which itself is not a lot in regions of low relief), three orders of magnitude (1000 times) less than the radiation flux (sunshine mostly) in sunny locations. Power density is a measure of the land required to produce a certain amount of power. The various land uses have different effects on the land. Dams (the cheapest) destroy rivers, turning them into lakes and changing their chemistries and populations of fish and invertebrates, with effects that propagate downstream into estuaries and the sea. By storing silt, dams on rivers erode sea beaches. Devices that make electricity directly from sunlight (solar cells) can be installed on existing buildings, in back yards, over parking lots. Cells on roofs will provide most of the electricity people use and do not further interfere with the landscape. Biomass must be grown: it displace crops or timber, or if grown as algae in plastic tubes, displaces everything. How it is grown and harvested determines how destructive it is. Obtaining 20% of U.S. electricity from wind would require less than 1% of the land, 5% of that in turbines, roads and associated infrastructure, the rest usable as farmland or grazing land. One percent of the U.S. would constitute most of North Dakota, the best site, and require new transmission lines to distribute the power (and involve considerable losses of power along those lines). All of U.S. farmland in biofuels would not power the current U.S. car fleet. Ethanol from corn is probably the worst choice, since the same amount, or more energy, goes into the ethanol than it contains, and since corn, as it is now grown, is a very destructive crop, causing tremendous soil erosion and damage to rivers, groundwater and the sea. Wind turbines change the landscape and kill birds, insects and bats (those slow-moving blades are moving very quickly at their tips), but are cheaper than solar cells. Solar cells at 17% efficiency (the current rating) average 30 watts per square meter, or 6 times that of vegetation.

The best way to make energy is to save it. Cars that get 100 miles per gallon are well within current technology. Cars that get 200 miles per gallon would be made of carbon fiber, which, when combined with anticrushing eggshell technology, is several time stronger in crashes than steel. If cars got 150-200 miles per gallon, the world’s car fleets could run on waste agricultural materials (peach pits, peanut hull, apple pomace, used cooking oil, discarded animal fats); and perhaps on perennial grasses, interplanted with food crops on farms, and serving as habitat for useful birds and insects and for erosion control. Crops could be rotated with the grasses as with legume hays and the mash from the conversion spread as a manure on farmland—though it might be better to feed the grasses to cattle and bacterially process the cow manure, using the generated methane to make electricity.