Climate Change: Scientists use algae to absorb carbon dioxide

Sep 29, 2007 - IPS/GIN

The possibility that algae could be used to capture carbon dioxide from the air is changing the negative reputation of these organisms, which are often seen as a plague caused by excessive fertilizer runoff. Until very recently, the proliferation of algae was interpreted as an undesirable consequence of the overuse of agro-chemicals, which has caused skin irritation in humans and the death of aquatic fauna from lack of oxygen.

But algae's potential for absorbing one of the principal greenhouse gases could be crucial for averting environmental catastrophes. Like terrestrial plants, the algae consume carbon during photosynthesis. "We took algae from the ocean we put it in plastic containers in greenhouses, where we fed it with carbon dioxide produced by conventional electric generators," said Laurenz Thomsen, a bio-geologist from Jacobs University in the northern German city of Bremen. "Exposed to solar light, the algae transform the carbon dioxide into biomass that can later be used as biodiesel, whose combustion doesn't emit greenhouse gases," he added. The Greenhouse Gas Mitigation Project is coordinated by Thomsen, with cooperation from the Bremen polytechnic university, the Alfred Wegener Institute for Marine Research and several companies, including the European electricity supplier E.ON. Thomsen has dubbed the small greenhouse "Algenreactor." It is set up at Jacobs University, where the algae transform carbon dioxide into organic fuel. The project is operating at the experimental phase, producing just a half-liter of biofuel.

"The diesel that we refine here is absolutely organic. It satisfies the European standards. I'm confident that we will be able to move on to an industrial phase in the coming months," he added. Fritz Henken-Mellier, director of the Farge thermoelectric plant just outside Bremen, agreed with that prediction. Some of the carbon dioxide emissions from this coal-fired generator were captured by the Greenhouse Gas Mitigation Project. "Surely we need to build a much bigger greenhouse, covering hundreds of square meters, so that the capture of carbon dioxide and the production of biofuel correspond to the scope of a commercial energy plant," he said in an interview for this report. Henken-Mellier calculated that "the capture of just 10 percent of the gases emitted by the Farge plant means a reduction of 600 tons daily of carbon dioxide." According to Thomsen, the area of a greenhouse capable of absorbing the carbon dioxide from a 350-megawatt electrical plant and transforming it into biofuel would have to be 25 square kilometers and would cost some $480 million.

The sum is small compared to the cost of conventional crops to produce biofuel and reduce toxic gases at a scale similar to that of the "algae-based reactor." An equivalent planting of rapeseed, for example, could cost as much as 25 times more. But Thomsen's project doesn't convince everyone. "Those calculations are very ingenuous," said Karl-Herrman Steinberg, director of one of Europe's leading algae producers, located in the northern German city of Kloetze. "The costs of growing algae, the elimination of the water and distillation of the combustible oil are very high for this to be profitable on an industrial scale," Steinberg said. Thomsen admits that the location of the greenhouses should be decided based on available sunshine. In northern Germany, with relatively few hours of sunlight, the model would not work. "The greenhouses would have to be built in the south and southeast of Europe," he said.

"We are already negotiating with German and foreign firms, from Brazil and India, which manage large algae crops," he added. The Greenhouse Gas Mitigation Project is not the only project of its kind. During the first global oil crisis, in the 1970s, U.S. scientists came up with a similar process for transforming algae into biofuel. But the attempt was abandoned in 1996, when low oil prices obliterated the incentives to study organic fuels. Now, with the current energy and environmental crisis, the U.S. company GreenFuel in Massachusetts is planning a greenhouse to cover at least 1 square kilometer for 2009. Isaac Berzin of GreenFuel said that to capture the carbon dioxide released by a 1,000 gigawatt generator would require an algae greenhouse between 8 and 16 square kilometers that could produce more than 150 million liters of biodiesel and 190 million liters of ethanol.