Once touted as a climate-friendly renewable alternative to foreign oil, the corn-based liquid ethanol has been exposed as an environmental and economic mistake. Lured by federal subsidies, Midwestern farmers have devoted millions of acres to corn that might otherwise have been devoted to soil conservation or feed-grain production.

Meanwhile, a “dead zone” fed by fertilizer runoff spreads at the mouth of the Mississippi, and production costs throughout the grain-dependent U.S. food industry rise. And on Friday, the Environmental Protection Agency delivered yet another policy defeat for ethanol — which is to say, a victory for common sense.

We refer to the EPA’s proposed cut in the amount of ethanol that the nation’s refiners must add to the fuel supply in 2014, from 18.15 billion gallons of ethanol called for in current law to a new target of 15 billion to 15.52 billion gallons. The downward revision of roughly 3 billion gallons is the first such reduction since Congress enacted the Renewable Fuel Standard in 2007. At the time, gasoline consumption was high and rising, and it seemed reasonable to put the country on course to blend 36 billion gallons of ethanol into motor fuel by 2022, as the RFS statute did.

Changes in motorists’ habits, along with advances in fuel economy, have rendered that objective utterly unrealistic.

What’s really needed is a repeal of the ethanol mandate. More efficient fuel-conservation measures, such as a gas-tax increase, would let broad incentives, not politics, determine the best way to move cars and trucks while meeting energy security and environmental goals.

The Washington Post (Nov. 19)