We're stuck on oil, and we better start getting out

This long piece by Michael Klare of Tomdispatch.com on how our economy's reliance on oil is only going to increase has this nugget of insight:

With oil demand regularly outpacing supply and disorder spreading in major producing areas, global shortages and resulting high prices are likely to become the norm, not the exception. Ideally, the United States could compensate for any shortfalls in the global availability of petroleum by increasing its reliance on other sources of energy. When producing electricity, for example, it is often possible to switch from coal to natural gas and back again.

But most of our petroleum supplies are used in transportation – mainly to power cars, trucks, buses, and planes – and, for this purpose, oil has no readily available substitutes. Indeed, we have so organized our economy and society around the availability of cheap and abundant petroleum that we are severely ill-equipped to deal with the sort of shortages and supply disruptions that are likely to become the norm in the years ahead.

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That means we should really pump up biodiesel and ethanol which come from soy and corn instead of from oil.

Why isn't Metra using biodiesel instead of petroleum?