Actually, the ultimate alternative is oil-laden algae. From these algae we can easily refine diesel fuel, heating oil, and even kerosene. And the “waste” from the processing can be refined into ethanol. I think with improving technologies to clean up diesel exhaust expect within 10-15 years the majority of the world’s new-production motor vehicles to have diesel engines, with an increasing mix of fuel-cell powered vehicles further down the road.
Good point RayChuang. They have a working exhibit of this at the Museum of Science in Boston. LOVE IT.