Algae industry faces sustainability hurdles — NAS report

Source: Amanda Peterka, E&E reporter • Posted: Thursday, October 25, 2012

Producing enough algae to displace 5 percent of U.S. transportation fuel will place “unsustainable” demands on resources under current technology and practices, according to a report released today by the National Research Council.

The industry’s heavy demands for water, nutrients and energy are not, though, insurmountable barriers to large-scale production of biofuels derived from algae, the report says, as improvements in technology can help mitigate some of the impacts. It recommends further research in areas such as improving algal strains and recycling resources used in production.

“The committee does not consider any one of these sustainability concerns a definitive barrier to sustainable development of algal biofuels because mitigation strategies for each of those concerns have been proposed and are being developed,” the report concludes. “However, all of the key sustainable concerns have to be addressed to some extent and in an integrative manner.”

The 274-page report by the research arm of the National Academy of Sciences represents one of the most sweeping looks to date at the nascent algal biofuels industry.

The Department of Energy’s Office of Energy Efficiency and Renewable Energy requested the study, and it was carried out by a 15-expert research committee chaired by Jennie Hunter-Cevera, an independent consultant and former president and CEO of the University of Maryland Biotechnology Institute.

Key among the study’s findings are estimates of what resources would be needed to scale up algae technology.

Producing algal biofuel equivalent to 1 liter of gasoline would require anywhere from 3.15 liters to 3,650 liters of water, depending on what method is used to produce the fuel, the study found. To reach 39 billion liters of algal biofuels, or 5 percent of the nation’s current transportation fuel demands, would require at least 123 billion liters of water.

Reaching that 5 percent level would also require 15 million metric tons of nitrogen and up to 2 million tons of phosphorus a year, if nutrients are not recycled.

To make algal biofuel production sustainable, water and nutrients would have to be harvested and recycled, the committee said. Algae facilities would also have to be located near water supplies, but more study is needed on finding suitable sites.

“Although the use of inland saline water, marine water or wastewater has been suggested as a mitigation strategy for reducing freshwater use,” the report says, “information on the depth and accessible volume of saline aquifers is lacking, and the actual land area close to wastewater sources suitable for algae cultivation has not been assessed.”

Other concerns with scaling up production include finding enough land to hold algae ponds and measuring the amount of greenhouse gases emitted during production, the committee said.

While there are several possible ways to make algae-based fuels, the report focused on the most common, which involve growing strains of algae in ponds or closed tanks, extracting the oil from the algae and processing the oil into fuel.

Improvements in technology, such as enhancing the traits in algae that increase the amount of fuel that can be obtained relative to resource use, “have the potential to greatly improve the energy balance and enhance the overall sustainability of algal biofuels,” the committee said.

Committee members are also recommending a research agenda for DOE that includes measuring the sustainability of the algal biofuels supply chain, analyzing environmental effects, and weighing costs and benefits. The study released today does not address the economics of the industry.