From algae to green aviation fuel

 In a joint project with Uppsala University and Industridoktorn, RISE has investigated how cyanobacteria can produce the hydrocarbon isoprene using carbon dioxide, water and sunlight. In turn, isoprene can be converted into hydrocarbons similar to the aviation fuels used today.

Within the two-year project, funded by the Swedish Energy Agency, the aim has been to work towards a future industrial process by improving the concept. The project has covered several of the steps in the chain from carbon dioxide to finished product.

Although isoprene can be produced by cyanobacteria, the amount formed is still very low. It has therefore been important in the project to investigate which cultivation conditions can affect productivity. At RISE, large-scale cultivation trials have been carried out to see which cultivation conditions can increase productivity. To accelerate the light-driven reaction, where isoprene is linked to longer carbon chains, different catalysts have been investigated. At RISE, a photochemical reactor for the polymerisation of isoprene has been built to carry out tests on a slightly larger scale.

Opens door to future process that utilises carbon dioxide

William Siljebo, a researcher at RISE, has been involved in building and testing the photochemical reactor.

- I think we have succeeded well with the scale-up of the photochemical reactor. We have had a good and close collaboration with PhD students at Uppsala University for the design of the reactor and managed to run the process continuously. The results we see from this study improve the possibilities to replace fossil sources for aviation fuel", says William.

Within the framework of the project, studies have also shown that cyanobacteria grow well even in flue gases. This opens the door to a future process that utilises carbon dioxide from industrial emissions. The project was recently completed but the technology and the photobiological and photochemical steps will continue to be developed in the EU project ALFAFUELS. The new project will start in early 2024 and will be coordinated by RISE. Here, larger scale testing will take place to reach the ultimate goal of an established industrial process.