Energy question of the week: Can we secure our fuel supply with the help of algal blooms?
Every hot summer, gigantic carpets of blue algae spread across the Baltic, much to the disapointment of seaside visitors looking for a quick dip in the cool water. Cyanobacteria inhabit the yellow-green plumes and can lead to poisoning if ingested. However, these same microorganisms can also produce flammable hydrocarbon chains known as alkanes and alkenes. Might they be suited to diesel and petrol production?
Several research groups are in fact studying cyanobacteria with a view to using them as a fuel source. Obtaining their nutrients from sewage treatment plants, carbon dioxide and sunlight, they employ photosynthesis to produce fatty acids, which in turn produce alkanes and alkenes. Biofuels can then be obtained from these hydrocarbons. 'Blue algae', the original designation for cyanobacteria, is actually misleading, since they are not members of the algae family; in fact, they are bacteria.
Fuel made by bacteria is still at a very early stage of development
The production of fuels from cyanobacteria is still at a very early stage indeed, and is not an economically viable proposition at present. Nevertheless, great strides are being made in research, as illustrated by a recent result at the US corporation LS9, based in San Francisco. Researchers there have managed to identify the precise genes responsible for alkane metabolism in various species of cyanobacteria. They successfully incorporated these into the genetic materials of E. coli bacteria (Escherichia coli), the workhorses of microbiology, which then produced flammable hydrocarbons.
These laboratory-based E coli cultures do not yet produce significant quantities of fuel. Nevertheless, the decoding and transfer of alkane genes could provide a future basis for producing fuels in tower bioreactors. Effluent from sewage treatment plants could be used as a nutrient for these bacterial cultures. Now, researchers are working on ways to accelerate the metabolism of these 'fuel bacteria', and to increase the yield of useable hydrocarbon chains.
Even 'real' algae offer potential benefits as a fuel
"These approaches aimed at obtaining biofuels are very interesting, but are still far removed from any technological application," says Marina Braun-Unkhoff from the DLR Institute of Combustion Technology in Stuttgart. "However, we should not underestimate the potential for aquatic biomass from the sea to become a future source of fuel. Naturally, its usage will have to satisfy sustainability criteria; for example, water consumption and land usage," says Braun-Unkhoff. With that in mind, DLR is planning a more detailed investigation of the scope for obtaining biofuels from algae. As with other earlier forms of biofuel, the Stuttgart-based combustion experts will then be able to characterise algae-based fuels more accurately, and test their suitability for engines and power plants.
Paper on the alkane genes: 'Microbial Biosynthesis of Alkanes', Andreas Schirmer et al.; Science, Vol. 329, p. 559
The DLR Energy question of the week in 'The future of energy' Year of Science
The Federal Ministry of Education and Research (BMBF) has given the Year of Science 2010 the motto 'The future of energy'. For this reason the science journalist Jan Oliver Löfken will this year answer a question on the subject of energy in his blog each week. Do you have a question about how our energy supply might look in the future? Or do you want to know, for example, how a wave power plant works and how it can efficiently generate electricity? Then send us your question by email. Science journalist Jan Oliver Löfken will investigate the answers and publish them each week in this blog.