I'm never quite sure what to say when people start talking about ethanol. Is it a useful alternative fuel that we should be putting to greater use? Or a boondoggle - taxpayer money wasted on subsidies to farmers for a fuel that will never save us from oil? So I was happy to see a Q & A on ethanol in the Sunday New York Times Automobile section.

In "Solution or Distraction? An Ethanol Reality Check," reporter Jim Motavalli presents an ethanol FAQ that addresses some of the basics: Ethanol is a biofuel produced mainly, at least in the U.S., from corn. It is generally sold in a blend with 15 percent gasoline, called E85. As a biofuel, it has much lower greenhouse gas emissions than fossil fuels. But it is less efficient, cannot be used in many older cars, and, according to some experts, requires so much fossil fuel to produce that it actually does nothing to reduce emissions or our dependence on oil.

In a now-famous scientific paper, published last year, researchers found that "the corn-to-ethanol process powered by fossil fuels consumes 29 percent more energy than it produces." Using switchgrass instead of corn (ethanol can be made from a variety of crops) further ups the energy required to produce ethanol, to 50 percent more than the ethanol will generate. But not everyone agrees with this study: another study found that we could slash our fossil fuel usage by a third by relying on ethanol.

A review of existing studies on ethanol, published this past February, found that while corn-based ethanol was not efficient enough to make a difference, other forms of ethanol have "a clear advantage over gasoline." Agricultural residue and wood chips are two potentially useful raw materials for ethanol, according to the paper - as is switchgrass, the same crop that the 2005 study said was far too inefficient.

What are we to conclude? I have no idea. The NRDC has a useful series of web pages on ethanol, and they maintain that continued research is a good investment. But it seems the jury is still out on this biofuel. Which is fine for the moment, since according to the Times story there are only 600 gas stations in the whole country selling E85.

Image credit: Department of Energy