Ars Technica: "According to current US legislation, biofuels will play a major role in our transportation future. By 2022, the Energy Independence and Security Act dictates that over 10 percent of our current petroleum consumption be replaced by biofuels, with over half that quantity coming from something other than corn. Although ethanol produced from the cellulose in plant waste and dedicated biofuels crops is already in use, many are looking further ahead at biofuels made from algae, which have some distinct advantages. Yesterday, some researchers at the Department of Energy released a study in which they describe a model that can help us determine just how much biofuel we might be able to squeeze out of algae.
At least for the first run, however, they used some pretty unrealistic starting points to just get a sense of how various assumptions influenced productivity. But the model produced some eye-popping numbers: if we maxed out algal productivity, we'd need to use several times the US' annual irrigation water consumption to do so, but we could replace half of our current petroleum imports."