Last week’s column explored the options for powering vehicles when supplies of imported petroleum and products start to decline. At present it appears that biofuels, natural gas, and electricity are the only alternatives that will be available in large deliverable, quantities in the next ten or 20 years. While biofuels are already in widespread use, it is becoming obvious that turning food crops into fuel is bad policy. Fuels from non-edible plants may provide a significant share of our fuel someday, but that day is still someway off. Many think it will be years and certainly well into the time of oil depletion, before cellulosic ethanol becomes commercially viable on a large scale. Not only does the technology and economics still need to be worked out, but also massive amounts of infrastructure would have to be built.