Issue Date: July 17, 2006
The interesting article on the increasing importance of ethanol as a motor fuel in blends including "E85" lends some support to what some would see as a prophetic statement by Henry Ford, who never surrendered his loyalty to rural America, where he was raised (C&EN, March 6, page 50). Ford promoted the use of corn alcohol in motor cars as a means of bringing business to struggling farmers in the 1920s. He described it as "the fuel of the future," a view shared by the head of research at General Motors at the time.
J. C. Jones
Bioalcohol-producing plants like corn or switch grass convert, at best, 0.03% of peak incident solar energy into alcohol fuel energy, considering daily and seasonal variations, crop turnover times, photosynthesis efficiencies, and foliage intercept fractions. With 5,400 kW per acre of peak sunshine, 1 acre can thus generate 1.6 kW of biofuel on a continuing basis, equivalent to 9 barrels of oil per year. Therefore, to replace 5 billion bbl of oil consumed yearly in the U.S. requires 555 million acres of arable land or one-fourth of the entire U.S. Only countries with vast arable lands, like Brazil and the U.S., could support such cultivations.
Worse, however, is that 80% of the 1.6 kW of produced biofuel is needed for fabricating and operating farm machinery, manufacturing fertilizers, and extracting alcohol. This extra 1.3 kW per acre can be provided by coal- or uranium-derived electricity. In an only-biomass, no-oil, no-uranium, no-coal economy, however, the needed land would be 2,775 million acres, more than the entire 2,240 million acres of U.S. territory!
The world's oil reserves are sunshine-produced biomass fuels from decayed plants deposited over a billion years. Even assuming that only 1% of the world's land created these ancient oil reservoirs, energy conservation tells us it should be difficult to generate biomass fuel 1,000 times faster than nature did. The solar flux to Earth has not changed much in a billion years.
Solar panels and wind farms require vast areas of sunny and windy (desert) lands with many energy storage units, distribution stations, and access roads. Because of this, capital and maintenance costs for solar or wind power are four times greater than those for equivalent nuclear power. To substitute for the enormous quantities of oil consumed by our fleets of cars, trucks, trains, ships, and airplanes, and to run our heavy industries, we need nuclear- or coal-derived heat and electricity as a prime energy source to synthesize portable fuels (synfuels) from air and water.
Synfuels such as hydrogen, ammonia, and hydrazine can power internal combustion and fuel-cell engines. Uranium reserves can support an oil-substituting synfuel program for 1,600 years with non-air-polluting fast-fission reactors. The other possible prime energy source is air-polluting, globe-warming combustion of coal, which can last 150 years. To avoid global warming and preserve coal for future use in plastics and drugs, for example, coal should not be burned. This leaves us with uranium power to overcome the out-of-oil crisis of 2030.
Jeff W. Eerkens
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