Harmful algal bloom as seen from the research docks of The Ohio State University’s Stone Laboratory on Gibraltar Island in Lake Erie in 2013. Photo: Jeff Reutter/Ohio State University

Biotechnologists from Aarhus University have demonstrated how the rare properties of an atypical light-dependent enzyme can be used with a photo-bio-catalytic continuous flow system in order to generate drop-in biofuels, converted from waste oils and fats.

The light-dependent enzyme is found in microalgae. The special properties of the enzyme are such that, with light as the only source of energy, the enzyme is capable of decarboxylating fatty acids into alkanes, and thereby synthesize biofuel. The generation process is described by the researchers as “carbon neutral.”

According to lead researcher Bekir Engin Eser: “The project covers all stages of the process, from selection of the best mutant of the enzyme to development of the flow system itself, which, via photobiocatalysis, will convert organic waste oils and fats into different biofuels in a continuous flow.”

The type of biofuel created is a “drop-in” biofuel. These have the same functionality as fossil fuels and are compatible with the existing oil industry infrastructure. The sustainable biofuel extracted can be used directly in existing energy generation systems, including petrol and diesel vehicles.

Production is via a single, continuous flow system whereby waste oil is added through an enzymatic photobiocatalysis, containing the algae enzymes (where the decarboxylation of fatty acids takes place, converting them into hydrocarbons). At the other end of the process, the biofuel appears. The process still requires some refining, in terms of producing alkanes (acyclic saturated hydrocarbons) of different lengths. The longer-term aim is to have a more controlled process whereby the length of the alkanes can be standardized.

The process, which works on a micro-scale, will need to be scaled up. This will be dependent on the level of interest from the energy industry.

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