A new study from Duke University (by way of Green Car Congress) indicates that we're probably better off from an environmental perspective by leaving fields fallow and not trying to grow corn ethanol at all. The researchers, after analyzing 142 soil studies and extrapolating forward, found that the greenhouse gases reduced by running cars on corn ethanol are largely offset by the carbon released in the corn farming and harvesting. Corn farming releases 30 percent to 50 percent of the carbon in soil, according to Gervasio Piñeiro, the lead researcher. When consumed in cars, corn ethanol produces 20 percent fewer greenhouse gas emissions than gas at the tailpipe. Corn ethanol, though, only has about 70 percent of the energy content of regular gas, so you have to burn more. Corn ethanol, thus, is really carbon neutral. A better way to reduce carbon in the atmosphere would be to plant fields and leave them. The growing plants would absorb carbon dioxide. In a head to head contest between corn ethanol and doing nothing over a 50 year period, doing nothing would be better for the environment for the first 48 years, the study stated. It's also a lot cheaper. By contrast, cellulosic ethanol preserves about 30 percent to 50 percent of the carbon in soil. Unlike corn, cellulosic plants are dug up every year. They get planted and clipped, sort of like trees. Cellulosic ethanol, however, remains in the experimental stage. Amyris, one of the early companies, says it will have fuel in two years. Large volumes of cellulosic ethanol, however, are further off. And just to take a walk down memory lane, let's salute Cornell's David Pimentel.  Back in the early part of the decade, he criticized corn ethanol. He was heavily criticized in many quarters for this.