Bruce E. Dale often plays the role of devil's advocate not only against the rosy picture of biofuels painted by start-ups and trade associations but also against the gloom-and-doom message of some environmental groups. That's because he's devoted to developing meaningful methods to compare the economic, national security, and environmental value of the various renewable transportation fuels now vying to extend and eventually replace petroleum-derived fuels.

Dale is a chemical engineering professor at Michigan State University and a lead scientist in the Great Lakes Bioenergy Research Center. He is well-known for conducting life-cycle analyses of biobased fuels and chemicals.

Any biofuels conversation with Dale eventually turns toward the importance of making realistic comparisons. "To properly compare fuels, we need appropriate metrics," Dale says. Energy return on investment, or EROI, is perhaps the key metric for comparing different fuel types, he believes.

"You must 'invest' energy to produce energy, whether it is drilling for oil or growing corn," he explains. An EROI of 5:1 is a reasonable benchmark value, Dale says. "Below this value, all we would have time to do is produce energy. Nothing else would be possible—no recreation, arts, or education. Those activities require that we have lots of surplus energy."

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