By Barbara Kessler

The virtues of growing corn for fuel have been so widely lauded, everyone knows the formula: Convert vast corn fields to ethanol production, burn cleaner fuel, save the atmosphere and kick foreign oil. And yet this magic formula has lately been showing its flaws.

First, there was the nagging problem of all that fish habitat-destroying fertilizer being dumped on those super-size corn fields. Then came concerns that growing corn (or soybeans or sugar cane) for fuel was displacing farmland needed for food. Now, the ultimate question – Does it work to reduce greenhouse gas emissions? – has been raised, and the answer isn’t what we wanted to hear.

Bio fuel crops actually increase carbon emissions, according to two studies published Thursday in the journal Science. The gist: Clearing grassland and forests to grow crops releases more carbon into the air than is saved by burning biofuels instead of gasoline. In fact, it could take more than 150 years of growing biofuel crops to get to net zero carbon emissions. Furthermore, the whole shift toward growing crops for fuel instead is pushing food production into developing nations, where rain forests and other carbon sink areas are being cleared for soy bean farms — and increasing greenhouse gas emissions.

The ethanol industry has maintained that ethanol production saves about 20 percent in greenhouse emissions. But the scientists’ model in one of the new studies showed that it could take hundreds of years before realizing any carbon emissions savings because of these global land-use changes.

“It’s a little frightening to think that something this well intentioned might be very damaging,” study co-author Jason Hill, an economist and ecologist at the University of Minnesota, told the LA Times.

Growing something other than corn may not work either, according to the researchers who warned that converting any “productive land” to biofuel production would produce more greenhouse gases than it would save. A collaboration of scientists from Princeton and Georgetown Universities and various agricultural think tanks did one study; the other was sponsored by the University of Minnesota and the Nature Conservancy.

The scientists urged policy makers to look at trash, crop waste and prairie grasses as better potential sources for fuel.

For more on this study, see the abstract at Science magazine or the University of Minnesota news report.