Green energy from sun and water
They are commonly called “blue-green algae”, but the proper name is cyanobacteria. These living fuel machines can convert sun and water to energy through photosynthesis. The product can be used as fuel, but first the process needs to be optimised.
‘Cyanobacteria can cope with a lot and are extremely hardy. They exist all over the earth, on land and in cold and warm water. They grow rapidly and can be altered’, says Karin Stensjö, a researcher at the Department of Chemistry at Ångström Laboratory.
This is green energy – literally. In the lab there are several vessels full of a greenish, cloudy liquid. The bacteria are growing here. A gas chromograph measures exactly how much hydrogen is emitted from each strain of bacteria. They are genetically engineered bacteria created in the lab by Karin Stensjö and her research colleagues.
Each strain of bacteria entails several years of research. To be able to extract energy, an uptake mechanism in the cells has had to be shut down, for example. It’s a matter of controlling the production of hydrogen, to be able to extract as much energy as possible.
‘We test which processes in the cells can be turned off completely and which ones we can turn on. We base this on the cell’s own capacity but optimise it by altering the genetic code and tweaking the system’, explains Karin Stensjö.
‘For instance, it’s about getting sufficient energy without stressing the cells. They have to be as robust as possible to cope with the variations in sunlight, water, and the supply of nourishment.’
These green fuel machines can also produce carbon-based fuel, for example using classic genetic engineering and synthetic biology to introduce biosynthesis paths from plants.
The advantage is that carbon-based fuel is easier to feed into the systems in place today
for biodiesel and ethanol, for instance. But here too there’s more work needed before large-scale production can be a reality.
‘One challenge is that we want to be able to produce the fuel directly, without biomass as an intermediate step. This is important, because each extra step requires energy and reduces the amount of energy we can produce.’
The consortium for Artificial Photosynthesis (CAP) was established in 1994 and since 2006 has been housed at Ångström Laboratory in Uppsala. In recent years the research field has attracted more and more interest, and now some sixty researchers are working within CAP in different countries.
‘Solar fuel research is an extremely dynamic field. In collaboration with other research teams and companies in Europe, we’re exploring how bacteria might be grown in photobio reactors.’
In the longer term it might be possible to grow them on a large scale in the oceans, in order not to take valuable land away from agriculture.
‘There’s great potential in using cyanobacteria as a sustainable source of biofuel, but this research takes time. We’re working with living organisms that don’t always behave as we wish. But I relish this complexity’, says Karin Stensjö.
Annica Hulth