Converting Algae Into Fuel

Algae might keep jet airplanes and cars running someday.

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By Marlene Cimons, National Science Foundation

The algae that keep salmon and shrimp a bright pink might keep jet airplanes and automobiles running someday.

It’s no secret that government, scientists and industry are devoting considerable resources and talent to developing renewable, cost-efficient and environmentally-friendly energy sources, the path to energy independence and to reducing the harmful effects of burning fossil fuels.

One solution could come from the fatty acids produced by certain species of salt water algae.

“All photosynthetic plants take water, sunlight and carbon dioxide and make either sugar or fatty acids,” said Dr. William L. Roberts, a professor in the department of mechanical and aerospace engineering at North Carolina State University. “We want the ones that produce a lot of fatty acids.”

He and his colleagues, four biologists and three engineers, are working on ways to produce and extract these fats from Dunaliella, a microscopic species of algae, and convert them into fuel on a large scale, much larger than is possible today. Their research is funded by $1.99 million over four years from the National Science Foundation as part of the American Recovery and Reinvestment Act of 2009.

The North Carolina State University project is one of several teams in the nation studying the potential of algae as an energy source, and with great promise. This year the Department of Energy has awarded more than $100 million for bio-fuels research, an investment that includes a recently announced $24 million to specifically address the challenges in the commercialization of algae-based fuels.

“This is going to be one of the most important and dominant industries of the future because we will run out of fossil fuel,” Roberts said.

Algae have the potential to provide 100 times more feedstock per acre as conventional crops, he said. “If you look at (conventional) crop oils, there’s a range on the order of 100 gallons per acre per year--that would be a good year,” he said. “The promise of these algae is thousands of gallons per acre per year.”

Furthermore, the cultures can be grown in a wide variety of locations, meaning that fuel can be produced on site, rather than having to be shipped or hauled elsewhere after it has been harvested.

To be sure, using these bio-fuels will release carbon dioxide into the atmosphere, but most importantly, “we’re not putting new carbon dioxide into the air,” as we are now doing with fossil fuels, he said.

“We wanted to find a feedstock that wasn’t a food source, and make a fuel that would seamlessly fit into the existing infrastructure without modification,” he added.  “You wouldn’t have to change how you distribute it, store it or burn it.”

The algae under study are not the kind “you find on your pond or your pool,” he said. “These aren’t plants floating on the surface that you often see. These are microscopic. You’re not going to filter them out with a net.”

This species, unlike most other species of algae, has a cell membrane, rather than a cell wall, which makes it easier to extract the needed fats.  The scientists are using synthetic biology to interrupt the algae’s usual cycle, which turns its fatty acids into triglycerides, to obtain the fatty acids before the process is completed--and before the fatty acids can become toxic to the organism. The fats are secreted through the membrane, leaving the organism unharmed.

“The idea is that we will sit there and milk these things,” Roberts said. “The concentration never gets too high to be toxic. These fatty acids won’t dissolve in water; they will float to the top and we will be able to skim them off.”

One of the hurdles the researchers face is finding ways to increase the manufacturing scale.  “We need to produce many billion gallons of aviation fuel a year, and right now we are making a liter at a time. “ Roberts said. “Thirty billion gallons is a huge quantity. But that’s the goal: to make a cost-competitive, fit-for-purpose fuel from marine algae that needs to be scale-able.”