Making useful products from carbon dioxide

Carbon dioxide is a waste product from the burning of fossil fuels, but it is increasingly being recognised as a potential resource of useful carbon. Finding an energy efficient way to 'reduce' carbon dioxide to a less oxidised form could enable the carbon to be re-used as part of the circular economy. Re-using this carbon as a source of fuel or chemical feedstock would prevent the need for further extraction and use of fossil fuels.

In microbial electrochemical systems, microbes can be used in two ways to convert carbon dioxide to useful carbon products. First, they can be used to recover energy from wastewater (in the anode chamber) to provide electrons for the reduction of carbon dioxide to simple compounds such as methanol, in the cathode chamber. Catalysts can be used to faciliate this process, although yields tend to be quite low. Microbes can also be used in the cathode chamber where they have the ability to donate electrons from the cathode to reduce carbon dioxide, thus increasing the efficiency of the process and giving higher yields. Research has demonstrated the ability of microbes to reduce carbon dioxide to simple organic acids, such as formic acid. The METEORR project aims to develop microbial electrochemical systems which generate more complex compounds from carbon dioxide, such as hexanoic and octanoic acid (longer chain fatty acids), and even petroleum hydrocarbons. These compounds are liquid at room temperature which makes product recovery relatively easy. We aim to demonstrate the feasibility of this approach for the synthesis of products more appropriate for practical use, either directly as biofuels or as feedstocks for production of biofuels, for example longer chain fatty acids for biodiesel production or ultimately hydrocarbons.