Biofuels produced from algae, rather than from crops, have entered the spotlight lately, and several companies now say that they are close to overcoming the technical hurdles to making algae-derived biofuels competitive on a commercial scale. However, experts caution that significant obstacles still need to be dealt with to make algae competitive with energy from fossil fuels.For several years, entrepreneurs, investors, and even oil companies have been quietly looking to turn the photosynthetic powers of the once lowly and obscure but now coveted green slime, algae, into energy. Industry giants such as Dow Chemical Co., Exx-onMobil Corp., BP p.l.c., and Chevron Corp. have recently made major investments in companies seeking to develop renewable fuels from algae, pushing this group of prolific organisms to center stage.With thousands of strains of algae to choose fromseach possessing varying ratios of oils, proteins, and starch in their cellssexperts are exploring a wide range of possibilities for harnessing energy from these microbes. For example, the algae can be indigenous strains or genetically engineered organisms. And companies can choose from a diverse range of growing techniques, from inexpensive open ponds to carefully controlled enclosed tanks, to coax algae into secreting the desired product, which might be ethanol, biodiesel, or pump-ready gasoline.Algae thrive in the presence of sunlight, CO 2 , and water. They multiply quickly and can be harvested year-round. Unlike conventional biofuel feedstocks such as corn, soy, palm, and canola, algae do not require vast and often valuable tracts of land and ample fresh-
