I'm just getting around to reading an optimistic report from USDA about how much more energy we are getting from converting corn to ethanol.
The report surveyed corn growers for the year 2005 and ethanol plants in 2008 and happily reports that energy yields are improving.
Never mind that the mere thought of using food resources to feed cars rather than farm animals or people makes no sense from the standpoint of sustainability. Early estimates of energy efficiency made it clear that it took almost as much—or, in fact, as much—energy to convert corn to ethanol as could be obtained from the ethanol, and that the size of the energy yield depended on who was doing the estimating.
This latest report says that "the net energy balance of corn ethanol has increased from 1.76 BTUs to 2.3 BTUs of required energy" since 2004. If true,
Ethanol has made the transition from an energy sink, to a moderate net energy gain in the 1990s, to a substantial net energy gain in the present. And there are still prospects for improvement. Ethanol yields have increased by about 10 percent in the last 20 years, so proportionately less corn is required. In addition to refinements in ethanol technology, corn yields have increased by 39 percent over the last 20 years, requiring less land to produce ethanol.
I still think this is not a good idea. A rational energy policy must develop sustainable sources, and corn is not one of them.