writes with this quote from Chemical & Engineering News:
"Using today's technologies and knowledge, a scale-up of fledgling algal biofuel production sufficient to meet even 5% of U.S. transportation fuel demand is unsustainable, says a report released last week by the National Research Council. The report examines the efficiency of producing biofuels from microalgae and cyanobacteria with respect to energy, water, and nutrient requirements and finds that the process falls short. The energy from algal biofuel, the report finds, is less than the energy needed to make it. In terms of water, at least 32.5 billion gal would be needed to produce 10 billion gal of algae-based biofuels, the report states. The study also finds that making enough algal biofuels to replace just 5% of U.S. annual transportation fuel needs would require 44–107% of the total nitrogen and 20–51% of the total phosphorus consumed annually in the U.S."