Researchers at the Imperial College London and the University of Turku in Finland have discovered a way to make engine-ready propane using E. coli, an abundantly available bacteria found in the intestinal tract of humans and cattle. E. coli in hamburger meat has sickened many when the burger was not cooked thoroughly — now that same bacteria may supply the answer to a clean burning fuel to supplant our dwindling fossil fuel supply.
The researchers used enzymes to redirect fatty acids into a different biological path creating propane instead of cell membranes. The goal is to one day insert this system into photosynthetic bacteria and directly convert sunlight into a chemical fuel.
Dr. Patrik Jones of the Life Sciences Department at Imperial College said of the groups findings:
“Although this research is at a very early stage, our proof of concept study provides a method for renewable production of a fuel that previously was only accessible from fossil reserves. Although we have only produced tiny amounts so far, the fuel we have produced is ready to be used in an engine straight away. This opens up possibilities for future sustainable production of renewable fuels that at first could complement, and thereafter replace fossil fuels like diesel, petrol, natural gas and jet fuel.”
The choice of propane was because it is easily released from a cell as a gas and economically transformed into a liquid, making it easy to transport and store with very little expenditure of energy.
Jones noted that fossil fuels are finite and that with the constantly growing demand for energy, it is imperative that an alternative be found and that low-cost and economic sustainability are key. He acknowledged that we are able to make bio-diesel from algae, but that process is not commercially realistic due to the costs involved in harvesting and processing the algae into fuel. His group chose propane because of the ease of separating it from natural processes with minimal expenditures of energy. It’s also compatible with existing infrastructure eliminating the need to build from the ground up.
Science 2.0 explains how the process works:
“To interrupt the process, the researchers discovered a new variant of an enzyme called thioesterase which specifically targets fatty acids and releases them from the natural process. They then used a second bacterial enzyme, called CAR, to convert butyric acid into butyraldehyde. Finally, they added a recently discovered enzyme called aldehyde-deformylating oxygenase (ADO), which is known to naturally create hydrocarbons, to form propane. “
Previous attempts had proven disappointing, but the researcher at Imperial College and Turku found that when they stimulated ADO with electrons, they were able to enhance its catalytic properties and release the propane.
The process is still at least 5-10 years away from being able to produce the amounts of propane necessary for a commercial venture. The amounts that the researchers have produced so far are 1,000 times less than what would be needed for a commercial product, but it is a step in the right direction. Jones said that his group does not yet fully understand how the process works but that he has hopes that it will be able to meet our energy needs in the near future.