Hydrogen from algae — fuel of the future?

Bielefeld, May 18 :

The green energy of the future: A German-Australian research team has succeeded in breeding algae, which produce hydrogen in previously unheard-of quantities. Amid rising oil prices and dwindling energy reserves, a genetically altered alga is now nourishing visions of an environment-friendly supply of energy.

Researchers from the University of Bielefeld in Germany and the University of Queensland in Brisbane, Australia, have genetically changed the single-cell green alga ‘Chlamydomonas reinhardtii’ in such a way that it produces an especially large amount of hydrogen.

This gas can then be burned to produce energy. In contrast to the use of fossil-based fuels such as petroleum, coal or natural gas, no carbon dioxide is produced, but instead only water. It has been known for a long time that certain algae can produce hydrogen during the photosynthetic process, explains Bielefeld biologist Olaf Kruse. But the catch was efficiency, as one litre of alga produces only about 100 ml of hydrogen.

“Then it’s over, because the cells die off.” But the genetically altered variant boosts this up to half a litre of hydrogen. By Kruse’s estimates, it can, in the long run, produce five times the volume made by the wild form of alga. Economic feasibility with regard to algae sets in only when the energy efficiency - the conversion of sunlight into hydrogen - reaches 7-10 per cent. But alga in its natural form achieves at most a meagre 0.1 per cent. The new ‘turbo-alga’ has now come up to 1.6-2.0 per cent.

“We have not reached our goal yet,” says Kruse, “We want to reach it in five yea-rs.” At the end of the develo-pment process could be a biological fuel cell in which the alga produces the necessary hydrogen directly at the site of consumption. A motorist would then, instead of a stop at the petrol pump, need only to have an alga power plant on board.

Kruse has been working on such a ‘turbo-alga’ together with Ben Hankamer of the Institute of Molecular Bioscience at the University of Queensland since the year 2001. From a pool of 20,000 random mutations, the scientists have selected 20 algae, ultimately coming up with a genetically altered mutation called ‘Stm6’.

Meanwhile, at the Technical University in Karlsruhe, a prototype of a bio-reactor containing 500-1,000 litres of algae cultures is being developed. The reactor is to be used to prove the economic feasibility of the system in the next five years.

“What is of decisive importance is finding a way of producing energy for which we won’t need to import any resources,” Kruse says. On the basis of calculations, a reactor shaped like a cube measuring three metres per side and filled with algae could supply a two-person household with their energy needs. Decentralised reactors with a million litres of alga cultures could in the future supply entire districts of 1,000 households.

“Hydrogen is absolutely the energy of the future,” Kruse stresses, “A precondition however is that certain things must be improved.

In the next 20 years, we must have built up a carbon dioxide-free alternative source of energy.”