A New Bloom for Algae

Green fuel: Algae, pictured here in a tank, is being studied by researchers at the National Renewable Energy Lab for its potential to make biofuels.
NREL, Warren Gratz

Energy

A DOE roadmap marks a return to research on a source of fuel that was once thought too costly.

Friday, July 2, 2010
By Kevin Bullis

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This week the U.S. Department of Energy released a new roadmap for the development of algal biofuels. DOE researchers had dismissed this type of biofuel as too costly to be commercially successful in the mid-1990s following a nearly two-decade-long research project.

The new roadmap was accompanied by the announcement of $24 million in new DOE funding for algal biofuels research. That money is in addition to $140 million in algae funding from last year's Recovery Act.

"Biotechnology has come a long way" since the earlier project, says Valerie Sarisky-Reed of the Office of Energy Efficiency and Renewable Energy, one of the lead authors of the roadmap. "With a dedicated research and development program, we can bring the economics to a suitable place within a 10-year time frame," she says. "We chose to invest in it again because we felt we were within striking distance."

The DOE originally considered algae as a means of making biofuels because some types of algae naturally produce large amounts of oil. The prolific organisms, if grown in ponds or closed bioreactors, could be used to produce more fuel per acre than other biofuels approaches, such as biochemically or thermochemically converting cellulosic biomass into fuel.

But the DOE program, which concluded in 1996, found that growing algae, and then harvesting and processing the oils, would only be cost-effective at high petroleum prices--between $59 and $186 a barrel. About that time, oil prices were less than $20 a barrel. Current estimates of the required price of petroleum for algae to be competitive range widely, from $10 to $100 a barrel, Sarisky-Reed says. Some estimates are even higher. Conventional approaches are only competitive when oil prices are as high as $400 a barrel, says David Berry, a partner at Flagship Ventures, based in Cambridge, MA.

The roadmap lays out a wide-ranging plan to bring the cost of algal biofuel production down. It identifies a broad set of challenges and research goals rather than selecting the most promising approaches. Sarisky-Reed says more research is needed to know whether it's better, for example, to grow algae in an open pond and then harvest the oil, or to grow algae that's been genetically engineered to continuously secrete fuels inside closed bioreactors.

The roadmap also details the reasons algal biofuels have proved challenging. For example, growing algae in open ponds is likely the lowest capital cost option, but pilot projects have shown that highly productive strains in these open ponds are quickly crowded out by less productive wild strains from the environment. Sealing algae in bioreactors can help protect them, but can also cause algae to overheat.