Outlook for ethanol

Re “Why ethanol backfires,” Opinion, May 17

Colin A. Carter and Henry I. Miller present a false argument regarding biofuels. Current fluctuations in food prices do not represent an irreconcilable competition between fuel and food.

Biotechnology-based improvements in producing ethanol from corn are already helping to meet the current rapid growth in demand for biofuel -- ethanol yields have increased 20% since 2000. The United States can produce half its transportation fuel needs from agricultural resources, reducing our dependence on imported oil while maintaining an abundant and affordable food supply. U.S. biotechnology companies -- supported by federal grants -- are constructing refineries to produce ethanol from cellulose. Soon, ethanol made from a variety of materials will reach the marketplace.

Biotechnology advances can help meet both the energy and food needs of growing populations throughout the world. Government policies that support increased production of ethanol are based on sound science and economics.

JAMES C. GREENWOOD

President, chief executive

Biotechnology Industry

Organization

Washington

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Carter and Miller do a thorough job of stating the limitations of corn-derived ethanol as a renewable energy source, but they leave out one factor in deciding whether ethanol produced from corn is truly renewable. Corn crops require nitrogen-based fertilizers, virtually all of which are derived from synthetic ammonia. Synthetic ammonia is produced by the reaction of nitrogen gas and hydrogen. Nitrogen gas, which makes up about 80% of air, is abundant and renewable, but hydrogen presents a problem. The current major source of hydrogen is from natural gas, a nonrenewable fuel.

I have seen many statements about the energy yield of corn-derived ethanol outweighing its costs, but it is unclear whether these estimates include the cost of natural gas needed to produce fertilizers. If the energy cost of fertilizers, harvesting, distillation and transportation match or exceed the energy produced by burning the ethanol, then claims that corn-produced ethanol is a renewable energy source are invalid.

HENRY ABRASH

Los Angeles

The writer is a professor emeritus of chemistry at Cal State Northridge.