There are a lot of questions, though, about whether this would have to be subsidized given the current prices of oil and coal. The energy needed to grow fuel crops is also a factor.

But if ten percent of North American energy needs could be met through fuel crops, that would be a substantial contribution. The problem is that we may not be able to replace the energy presently supplied by oil if oil supplies tighten sharply enough.

A lot may depend on newly discovered (or existing but untapped) offshore oil in the North Pacific and Gulf of Mexico.