Reviewed by Lexie CornerNov 15 2024
An international group of researchers from Washington University, the University of Missouri, and Texas A&M University have developed an electro-biodiesel that uses 45 times less land and is 45 times more efficient than biodiesel made from soybeans. The study was published in the journal Joule.
Researchers in the labs of Joshua Yuan in the McKelvey School of Engineering and Susie Dai at the University of Missouri used electrocatalysis of carbon dioxide to turn carbon dioxide into intermediates that are then converted by microbes into lipids, or fatty acids, and ultimately became biodiesel feedstock. The process is much more efficient than photosynthesis and uses less land than soybean-based biodiesel. Image Credit: Kainan Chen
Diesel-powered vehicles produce significant carbon emissions that are challenging to reduce. According to the US Energy Information Administration, diesel fuel accounted for about one-tenth of all energy-related carbon dioxide emissions and one-fourth of all transportation-related carbon dioxide emissions in the United States in 2022.
This novel idea can be applied to the circular economy to manufacture emission-negative fuels, chemicals, materials, and food ingredients at a much higher efficiency than photosynthesis and with fewer carbon emissions than petrochemicals. We have systemically addressed the challenges in electro-biomanufacturing by identifying the metabolic and biochemical limits of diatomic carbon use and have overcome these limits.
Joshua Yuan, Professor and Chair, Department of Energy, Washington University
Joshua Yuan also began collaborating with Dai at Texas A&M University.
To convert carbon dioxide into biocompatible intermediates like acetate and ethanol, the team used electrocatalysis, a chemical process initiated by electron transfers between reactants and catalyst surfaces.
Yuan, who is also the director of the Carbon Utilization Redesign for Biomanufacturing-Empowered Decarbonization (CURB) Engineering Research Center (ERC), funded by the National Science Foundation, explained that these intermediates were later converted by microbes into lipids, or fatty acids, and eventually used as biodiesel feedstock.
The innovative microbial and catalyst process developed by Yuan, Dai, and their teams enabled the production of electro-biodiesel, which converts carbon dioxide into lipids with a solar-to-molecule efficiency of 4.5 %, a significant improvement over traditional biodiesel.
Yuan noted that natural photosynthesis in land plants typically operates at efficiencies below 1 %, meaning less than 1 % of solar energy is converted into plant biomass through the transformation of CO2 into various chemicals required for plant growth.
The amount of energy diverted to the biodiesel precursor, lipid, is even lower as lipid has high energy intensity. On the contrary, the electro-biodiesel process can convert 4.5% of solar energy to lipids when a solar panel is used to produce electricity to drive electrocatalysis, which is much higher than the natural photosynthetic process.
Joshua Yuan, Professor and Chair, Department of Energy, Washington University
The scientists used an engineered strain of Rhodococcus jostii (RHA1), a bacterium known for its high lipid content, to create a novel catalyst made of zinc and copper. This catalyst generates diatomic carbon intermediates, which can be transformed into lipids to initiate electrocatalysis. Additionally, the engineered strain enhanced the metabolic capability of ethanol, which may have supported the conversion of acetate into fatty acids.
After developing the new process, the team examined its potential effects on climate change and found promising results. The electro-biodiesel method could potentially lead to negative emissions, as it uses renewable resources for electrocatalysis. This process might reduce carbon dioxide levels by 1.57 g for every gram of electro-biodiesel produced from biomass, ethylene, and other byproducts.
In contrast, traditional biodiesel production generates 2.5 to 9.9 g of carbon dioxide per gram of lipids, while petroleum-based diesel production results in 0.52 g of carbon dioxide per gram.
This research proves the concept for a broad platform for highly efficient conversion of renewable energy into chemicals, fuels, and materials to address the fundamental limits of human civilization. This process could relieve the biodiesel feedstock shortage and transform broad, renewable fuel, chemical, and material manufacturing by achieving independence from fossil fuel in the sectors that are fossil-fuel dependent, such as long-range heavy-duty vehicles and aircraft.
Joshua Yuan, Professor and Chair, Department of Energy, Washington University
Journal Reference:
Chen, K., et al. (2024) Electro-biodiesel empowered by co-design of microorganism and electrocatalysis. Joule. doi.org/10.1016/j.joule.2024.10.001.