Algae biofuel report covers sustainability, improvement potential

By Luke Geiver | October 24, 2012

A new report from the National Research Council has found that algae-based biofuel production could place unsustainable demands on energy, water and nutrients if total production capacity reached roughly 39 billion liters, or five percent of the country’s transportation fuel needs. “However, these concerns are not a definitive barrier for future production, and innovations that would require research and development could help realize algal biofuels full potential,” the report said.

The report, “Sustainable Development of Algal Biofuels in the United States,” was supported in part from a grant between the National Academy of Sciences and the U.S. DOE. A 15-member committee met four times over the course of 2011 to assemble the report. The members were from academia and other research and analysis firms. The committee used published papers, government and industry reports and performed interviews with private company representatives, other academic experts and government agency program managers.

The group focused on the supply chain, including the species used to the methods for cultivating and processing algae into fuel. The report didn’t cover the topic of economics however, focusing instead on overall sustainability. The report noted five areas that were “concerns of high importance,” including: water usage and requirements; nutrient supply; land area requirements; energy return on investment; and greenhouse gas emissions over the life cycle of algae-based biofuels.

For the concerns on water, the committee noted the high amount of water that would be needed for open-pond systems and for photobioreactors, the committee pointed to the potential for evaporation loss caused by temperature maintenance in the closed systems. On nutrients, the committee recognized the potential negative effect nutrient transport could have on energy return or overall greenhouse gas (GHG) emissions, and for land use, it found that climate and a suitable geographic slope would be required.

The report emphasized that for adequate energy return on investment, cultivation and conversion processes must be more efficient for the energy out to be greater than the energy in. And, on GHG emissions, the committee offered the belief that because emissions estimations can span a wide range, factors such as the CO2 source and the disposition of coproducts need to be addressed.

To address the areas of concern, the committee offered several areas where research and development could help algae biofuel producers overcome those concerns. The committee suggested improvements in strain selection, improvements in the energy return on investments, the use of wastewater for cultivating algae, recycling the nutrients used during the cultivation process and continuing to engineer solutions to enhance collection.

The report found that to produce 39 billion liters of algae based biofuel, roughly six to 15 million metric tons of nitrogen and nearly 1 to 2 million metric tons of phosphorus would be needed if the nutrients are not recycled. Utilizing wastewater or recycling nutrients could reduce the amount of nitrogen and phosphorus, however.

The full 274-page report, and the NRC are part of the National Academies, a non-profit organization that compiles research and produces reports including expert analysis, and, several former members of the National Academies have been nominated or have received the Nobel Prize.