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 (NRC). 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.
NRC conducted the study at the request of the Department of Energy, which for nearly 20 years had a robust program to develop biofuels from algae. The program ended in 1996 when DOE concluded algal biofuels were unlikely to be cost-competitive with petroleum, the report says. “Fast-forward to 2012 and with advances in genetics and engineering we are back to the future in considering if algae can be an economic and sustainable alternative,” the report says.
Despite the shortcomings of current technology for algal biofuels, the report does not consider sustainability to be an insurmountable barrier and notes that better mitigation strategies might be developed. More R&D is needed before “the promise of sustainable development of algal biofuels has any chance of being realized,” NRC reports.