Growing algae for fuel and feed
Algae grown in sewage and flue gases can be transformed to biogas, bioethanol, biodiesel, fertiliser or fish and animal feed.
Researcher Francesco Gentili has been conducting a unique project in which he has cultivated strains of micro-algae (phytoplankton) in the laboratory. The strains that grew fastest were then tested in a greenhouse prototype cultivation system.
It was found that the algae grew well on a combination of nutrients from untreated sewage and carbon dioxide from a thermo-power plant. The algae absorb carbon dioxide from flue gases and can remove up to 90 per cent of the nitrogen and phosphorus in the sewage. They are also able to fix heavy metals.
The selected micro-algae were found to have a substantially lower ash concentration than marine algae (seaweed), for example, which is important if dried algae are used directly as biofuel. There are also plans to use yeast, which is capable of converting the carbohydrates in the biomass into ethanol.
A sizeable pilot unit with four cultivation basins and a laboratory has recently been built close to the power plant in Umeå. The idea is to encourage the development of algae cultivation, and researchers from several universities and companies are now involved in the project.