A team of researchers from the McKelvey School of Engineering at Washington University in St. Louis and the University of Missouri has developed an innovative technique to convert carbon dioxide (CO2) into biodiesel. This method, led by Joshua Yuan and Susie Dai, uses electrocatalysis, making it significantly more efficient than traditional soybean-based biodiesel production.
The necessity for cleaner alternatives to diesel is pressing. Diesel vehicles are responsible for approximately one-fourth of all transportation-related CO2 emissions and about 10% of total energy-related emissions in the United States, according to the U.S. Energy Information Administration. The new approach aims to help reduce these environmental impacts.
Published on October 31 in the journal *Joule*, the research indicates that their electro-biodiesel method is 45 times more efficient and requires 45 times less land than conventional biodiesel production from soybeans. Yuan, who is a professor and chair of the Department of Energy, Environmental & Chemical Engineering, remarked upon the potential for this approach to support a circular economy, generating fuels and materials with lower emissions than traditional petrochemical processes.
The electrocatalytic process involves using catalysts to facilitate chemical reactions that convert CO2 into useful intermediates like acetate and ethanol. These intermediates are subsequently transformed into lipids—fatty acids that can serve as biodiesel feedstock—by specially engineered microbes.
This innovative process demonstrates a solar-to-molecule efficiency of 4.5% in converting CO2 into lipids, a significant improvement over the less than 1% efficiency associated with natural photosynthesis, according to the researchers. The high energy intensity of lipids adds to the standard challenges in biodiesel production.
To facilitate electrocatalysis, the research team developed a novel zinc- and copper-based catalyst that produces diatomic carbon intermediates, which can be converted into lipids using a modified strain of the bacterium Rhodococcus jostii (RHA1). This strain is known for its high lipid production capabilities and enhances the metabolic conversion of acetate to fatty acids.
By utilizing renewable resources for this electrocatalysis, the team found promising results for climate mitigation. Their electro-biodiesel process could reduce CO2 emissions by 1.57 grams for every gram of electro-biodiesel produced, representing a notable environmental advantage over conventional diesel production methods.
This research clarifies a pathway toward producing renewable fuels, chemicals, and materials that could reduce reliance on fossil fuels, especially in industries that are typically dependent on them. Yuan emphasized that this work presents a significant opportunity to tackle the biodiesel feedstock shortage and contribute to sustainable energy solutions for heavy-duty vehicles and aircraft.