Hugh Pickens writes "Algae has long been known as a promising source of biodiesel, however algae also produce a small amount of hydrogen during photosynthesis. The MIT Technology Review reports that now researchers have created a mutant algae that makes better use of sunlight to increase the amount of hydrogen that the algae produce. In a commercial bioreactor, the top layers of algae absorb most of the sunlight but can only use a fraction of it. Anastasios Melis and his team at the University of California have manipulated the genes that control the amount of chlorophyll in the algae's chloroplasts reducing the chlorophyll so that the algae absorb less sunlight. This lets more light penetrate into the deeper algae layers so that more cells use the sunlight to make hydrogen. Although the process is still at least five years from being used for hydrogen generation, Melis estimates that if 50% of capacity of the photosynthesis of the algae could be directed toward hydrogen production, an acre could produce 40 kilograms of hydrogen per day bringing the cost of producing hydrogen to $2.80 a kilogram. At this price, hydrogen could compete with gasoline, since a kilogram of hydrogen is equivalent in energy to a gallon of gasoline."