Published: August 27, 2008 10:35 am            

Algae as a renewable energy? Start thinking green

Originally published in the August 22, 2008, print edition.

Grow energy in your farm pond?

Maybe that won’t happen in Minnesota farm ponds but growing algae for ethanol could be one of the new feedstocks for the ever-growing renewable energy industry.

“I think algae certainly has potential to be a player in our biomass world of agri-energy,” said Richard Hemmingsen, director of the University of Minnesota’s Initiative for Renewable Energy and the Environment.

At the U of M Extension tent at Farmfest, he cited a couple of key reasons why algae has promise: 1) It’s not a food crop; and 2) It’s very productive — several times more than any of our current biomass sources because you continuously harvest algae as opposed to once a year for crop sources of biomass.

So where do you grow this “algae crop”? Farm ponds could potentially be a source, especially in warmer climates with a particular medium (feedstock) to nourish their growth. A closed-loop system is being developed at the U of M.

“We’re particularly intrigued with the usage of wastewater from municipal wastewater treatment facilities as a nutrient source. Algae are tiny, microscopic plants with an appetite for carbon dioxide so they can absorb significant amounts of carbon,” Hemmingsen said. This leads to the possible location of “algae factories” adjacent to facilities that are large emitters of carbon dioxide, like a coal-fired power plant which would also have heat. Algae grow faster in warm water.

He indicated some commercial applications of an algae “biomass” business are under development in Minnesota. A firm called SarTec in Anoka is evaluating algae as a feedstock for biofuels production utilizing their patented “Mcgyan” biodiesel process.

He doubts southern catfish ponds could be good algae producers because the rapidly growing algae may simply become “too thick” in the pond and interfere with the growth of the catfish.

At the U of M project, closed-loop photo bio-reactors are being developed, and the research team is screening different strains of algae to identify which are the fastest growing and which have the highest oil yield. “But that is also a particular challenge,” Hemmingsen said. “Because they mutate very quickly, if you identify a particular strain it could easily get contaminated with other algae strains.”

Looking at the prospect of biodiesel from algae, particular high-oil algae strains could have a bright future. Net British thermal units per ton of algae, or BTUs per gallon of oil, are logical measuring tools for determining the productivity of a given strain of algae. “In addition to oil, there’s also a lot of biomass in the cell wall material of algae which can be converted to bioenergy,” he said.

China and other Asian nations are already into algae energy research. In fact the key researcher with the U of M project is Roger Ruan, who is originally from China and is well acquainted with some of the algae work going on in China.

Hemmingsen’s thoughts on when algae might indeed become important in biomass energy? “I’ll give an economist’s answer — it depends. Funding of research, who will get the big breakthrough discoveries, even the role of the Department of Defense are factors. The Defense Department has a huge proposal for soliciting algae research because their goal is JP8 fuel (the base military fuel) from algae or other “non-food sources within three to five years.”

So stay tuned. That “green stuff” that sometimes discolors Minnesota lakes and ponds could indeed be part of the greening of America’s renewable fuel future.

        

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