Artificial photosynthesis to boost biofuel generation

The project will investigate ways to harness the excess light energy that reaches phototrophic organisms (certain algae and plants) but cannot be used due to bottlenecks in natural photosynthesis.

‘A simple analogy is a power plant unconnected to the distribution grid,’ said project partner Prof Anne Jones of Arizona State University. ‘Unconnected, excess energy goes to waste and this is what currently happens in photosynthetic organisms when they are overwhelmed with light.’

Part of the project will aim to couple the photosynthetic apparatus in one bacterial species to the fuel-producing metabolism of a second species then funnel energy directly into fuel production. This is what the UK side of the project will focus on, as Prof Lee Cronin, from Glasgow University, told The Engineer.

‘We have to do engineering at the cellular level to get these bugs to talk to each other — plug them into each other to get energy transfer. Then we have to engineer their relative organisation next to each other and upscale it into a flow system and a bioreactor,’ he said.

Cronin explained that certain bacteria naturally grow ‘conductive nanowires’ called pili that exchange genetic information with other bacteria. They could exploit this mechanism to transfer energy or augment it with artificial nanotubes — although the real challenge will be in upscaling, he said.

‘It will probably look like a film that will be pointed up at the sun. You would have the phototroph on the top getting all the sun and the pili going down to the heterotroph, which will do the fuel production, and that will drip out through a kind of capillary network, or a sponge, and into a bunch of vessels that will be at the bottom of the reactor,’ Cronin said, adding that they aim to produce biodiesel.

The team also hopes to transfer the knowledge it gains from algae and bacteria into plants, which will allow photosynthesis to produce sugars more efficiently — thereby improving yields. It could even lead to a blueprint to make a fully artificial leaf capable of removing carbon dioxide from the atmosphere.

Indeed, Cronin has previously done some work with a group at the Massachusetts Institute of Technology (MIT) that last week announced it had created the first artificial leaf using a silicon chip coated with a special catalyst.

The funding has been awarded by the UK Biotechnology and Biological Sciences Research Council (BBSRC) and the US National Science Foundation (NSF). The British part of the team also includes Travis Bayer at Imperial College London and Thomas Bibby from Southampton University.