Algae/biodiesel
 

Here is an article on algae to biodiesel in progress

http://www.inhabitat.com/2007/10/22/...-by-livefuels/

Others are working on it, too. I posted one link (now expired) in https://www.ford-trucks.com/forums/5...kton-oil.html; they were supposed to have an operational plant by the end of 2007, according to: http://ipsnews.net/news.asp?idnews=34239

Unlike regular crops, this could, at least in theory, produce enough fuel to replace fossil fuels, though I still think that photovoltaic cells can yield more energy from the same amount of land.

May be true, but I don't think that the demand for diesel will be going away any time soon.