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Bioreactors filled with algae in a German lab
Researchers are working on developing efficient algae farming methodsImage: picture-alliance / dpa

Natural power

April 7, 2010

With global fossil-fuel reserves slowly running out, a search for replacement energy sources is underway. Some scientists believe that a hi-tech method of farming algae could provide a solution.


Algae are extremely simple plants - but could represent a revolution in energy production.

They're mostly found in water and are best known for their most complex variety: seaweed. Algae can be found in unicellular and multi-cellular forms, and their photosynthesis functions are similar to those of other plants.

Many researchers believe that large microalgae farms could turn sunlight and carbon dioxide into bio-ethanol - a replacement for conventional fuel - or bio-kerosene, which could be utilized by the aviation industry. They also emphasize that this energy production method would not take up any space on dry land.

A disputed theory

As good as this concept may sound, some are skeptical about its viability. One such skeptic is Ulrich Steiner - a specialist in new strategies for algae-based energy production at the chemical and pharmaceutical company Bayer in the German city of Leverkusen.

"I think this is totally unrealistic," said Steiner at a recent conference in Frankfurt. "The problem is that we have a very limited source of energy - namely sunlight that reaches the earth's surface. And the other problem is that photosynthesis is already an inefficient process to begin with."

Steiner says that even in the sunniest places on earth, more energy would have to be put into producing algae-based fuels than would be gained from the process. And, according to him, this is true of many of the steps involved in this method, including pumping, extraction and drying. He believes that this would create "a negative energy balance, which would make absolutely no sense."

Optimistic scenarios

Microalgae in synthetic tubes
Microalgae can be grown in controlled conditions to produce optimal resultsImage: DW-TV

Steiner's argument triggered a heated discussion at the conference. Supporters of the idea claim that although microalgae research is still in its early stages, it holds a lot of potential. Most of the scientists favor the method of farming algae in so-called photo-bioreactors, since a closed system allows them to control the conditions under which the algae grow.

"A great deal depends on our ability to create efficient, cost-effective photo-bioreactors that lead to energy gains," said Olaf Kruse, an algae biotechnology professor at Bielefeld University.

"Biologists can try to create more efficient strains of algae, and we've already had some success in this area," he added.

Together with a colleague from Australia, Kruse leads a new international research syndicate. Its goal is to advance the production of biofuels with the help of microalgae. In an article for the scientific journal Nature Biotechnology, the two scientists suggested various uses for algae - in large bio-refineries that would also produce other substances apart from ethanol and biodiesel.

According to Kruse, these additional substances could be top-quality products that would be useful in the pharmaceutical and cosmetic industries, but they could just as well serve as simple animal-feed products.

"I think that a combination of bio-energy with materials that have multiple uses makes it realistic to look at the bio-energetic utilization of microalgae in the future," said Kruse.

While scientists see the matter differently, there is one point that most seem to agree on: even if algae-based energy production does function well, it will still be a long time before significant amounts of this energy can be generated through this process.

Author: Volker Mrasek (ew)
Editor: Kate Bowen

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