Craig is right about the price being bound by what the market is able to pay, and what they're willing to pay, but let's not forget about the cost of the alternatives. Maybe petroleum derived energy is too expensive, but unless it becomes more expensive than the alternatives, why would anyone "give up their car?"

Yes, you can run trucks and cars on vegetable oil. But can you provide a buh-jillion (that's a whole bunch) gallons of vegetable oil a day for $3.00 a gallon? I submit that if there were a demand for a buh-jillion gallons of vegetable oil a day, then vegetable oil would cost a site more than $2 or $3 a gallon, and what would that do to the cost of french fries?

I don't know if y'all have such things on that side of the pond, but here in the States many of the large cities have "ozone alert days." The environmentalists insist that this is caused by all of the internal combustion engines. They say the problem is too many emissions. I say that if they want to see an emission problem, let 5 million people commute into Manhattan every day, on horseback. They'll be stepping in emissions.

But don't be so short sided as to fall for the myth that electric cars are zero-emission vehicles. They aren't. Just because gasoline engines don't defecate in the street doesn't mean that they're zero-emission, and just because electric cars don't have tail pipes doesn't mean that they're zero-emission either. A bad brush in one of those electric motors can start producing plenty of ozone (with every arc), and even if they never have a mechanical or electrical fault, they're still going to emit tons of lead-acid, or some similar heavy metal toxic soup, over the course of their lifetime. Where are people going to dispose of all those batteries?

As for fuel cells, I'm not sure about catalyst consumtion, but at least the normal daily exhaust is plain old potable water. Now there's an idea worth chasing down. Energy use that produces (or at least restores) a commodity instead of consuming one. What are the economic implications of that?