That's the subject of the second annual Algae Biomass Summit starting today in Seattle. The conference will explore the great question of whether microscopic plants could cut out the geologic middleman of time and pressure and just deliver fuel directly. The number of companies pursuing this idea is exceeded in magnitude only by the number of different strains of algae and the ways to genetically manipulate it.

Solazyme in San Francisco grows its puny plants in the dark and Fort Collins, Colo.–based Solix partners with breweries to keep costs down. GreenFuel Technologies in Cambridge, Mass., meantime, plans to build the first "commercial scale" algae farm near Jerez in southern Spain—in an effort to turn carbon dioxide spewed by a cement plant into renewable fuel.

The question is whether GreenFuel can actually pull it off. The company ran into problems in 2007 when  it tried to harvest all the algae it had grown at a coal-fired power plant outside Phoenix, Arizona. And it takes a lot of a of water and land (GreenFuel's plant will ultimately cover 247 acres) to grow the stuff and a load of energy to separate the algae from the water.
The solution: algae that thrives in waste water or even seawater,  which is where much of it grows naturally (and can bloom out of control to cause dead zones). Less pond scum and more sea slime--and then algae fuel might even take flight.