From 1978 to 1996, NREL embarked on a great search and cataloging of algae. "It's fun to think it's all coming back," said Nagle. "We're now working with industry partners and other universities, collaborating and really moving this forward."
NREL's contributions include using sunlight to drive growth, and using growing cells to convert solar energy to chemical energy by converting carbon dioxide to organic molecules, along with a comprehensive analysis of the different biomass components.
"We take these champion strains and put them into virtual environments, particular locations in the United States that lend themselves really well to algae cultivation," Laurens said. "We're working with partners in Florida, California, Arizona, Ohio, and Hawaii to quantify how the rain and temperature mix affect growth and composition of the biomass produced."
NREL is analyzing how to get the most out of the harvested biomass. A pretreatment with dilute acid yields fatty acids that can be used for diesel-like biofuels and carbohydrates that can be fermented to ethanol. That still leaves proteins that can be used for other kinds of fuel. Working with Sandia National Laboratories, NREL researchers are subjecting proteins from algae to a fermentation process to boost the production of short-chain alcohols such as butanol.
"We've been able to examine the fine variables and recommend the best tradeoffs in production of biomass, taking the biomass chemical composition into account. Like, 'this scenario won't yield as much biomass, but you would get much higher oil content,'" Laurens said. "Ultimately, it will come down to how many total gallons of biofuel we can make per acre of algal ponds per year. This is no different than our measure of corn productivity in terms of bushels per acre per year." Researchers ultimately place all the pieces together and advise on the process' economic viability through a techno-economic analysis.
In large-scale outdoor cultivation — for example, in large open ponds such as those in Columbus, New Mexico, or Phoenix, Arizona—a tweak here, an extra boost of nitrate there, more sunlight here, a little less nitrogen or a little higher temperature there, and a champion strain can produce oils and carbohydrates in a familiar setting. Wastewater facilities can be a prime setting for closing the loop — from the anaerobic digestion of the non-fuel components of the biomass, which generates the energy and the methane, to the nutrients that can be recycled to feed another generation of algae.
Industry Is Intrigued, and Wiser, About Algae
Nagle remembers the heady times in the 1980s when oil companies invested a lot of money in algae research. "It's like we put a message in a bottle and sent it out to sea," he said. "Now it's coming back, and that's pretty exciting."
A chlorella strain of algae grows in NREL's bioreactor. Photo by Dennis Schroeder, NREL
After the first romance with algae, irrational exuberance ebbed, and oil companies became wiser and smarter, say Laurens and Nagle. These companies are investing dollars in algae research again, and funding from the Energy Department's Bioenergy Technologies Office has become more consistent.
Companies such as Exxon are looking for proof that algae can be important players in the biofuels landscape of the future. "They're investigating all the pathways," Laurens said.
Cost is falling steadily, and "you're not going to run out of algae" as production increases, Nagle said.
NREL will remain a key player, "a good neutral third party in the game, doing our own great research but also keeping our finger on the pulse of industry," Laurens said. "It allows us to gauge who is where. And we see that that there's a lot going on, that they're starting to take this very seriously. We're seeing companies that are serious, that have significant plans for the commercialization of algae."