Vehicles powered by diesel are a significant source of carbon emissions, posing a considerable challenge on the path to decarbonization. In 2022, diesel fuel was responsible for roughly 25% of carbon dioxide emissions from transportation in the U.S. and about 10% of overall energy-related emissions, according to the U.S. Energy Information Administration. To tackle this problem, researchers have developed a groundbreaking method to convert carbon dioxide into a cleaner, more sustainable fuel—electro-biodiesel.

Joshua Yuan, from the Department of Energy, Environmental, and Chemical Engineering at Washington University, and Susie Dai, a professor at the University of Missouri, have pioneered a process that uses electrocatalysis to convert carbon dioxide into electro-biodiesel. This new method is 45 times more efficient and requires 45 times less land compared to traditional soybean-based biodiesel production, offering a more sustainable alternative.

“This novel idea can be applied to the circular economy to manufacture emission-negative fuels, chemicals, materials, and even food ingredients, all at a much higher efficiency than natural photosynthesis and with fewer carbon emissions than petrochemicals,” explained Yuan, who began this work with Dai at Texas A&M University. Together, they have developed a system that addresses key challenges in electro-biomanufacturing, overcoming the biochemical limits of diatomic carbon use.

The process relies on electrocatalysis, where chemical reactions are driven by electron transfers on catalyst surfaces, to convert carbon dioxide into useful intermediates such as acetate and ethanol. These intermediates are then converted into lipids, or fatty acids, by microbes, ultimately creating biodiesel feedstock.

Yuan and his team’s electro-biodiesel process has reached an impressive 4.5% solar-to-molecule efficiency, which is much higher than the efficiency of natural photosynthesis in land plants, which typically converts less than 1% of sunlight energy into biomass. The electro-biodiesel method uses solar panels to power electrocatalysis, converting up to 4.5% of solar energy into lipids, a substance with high energy intensity.

The key to this high efficiency lies in the team’s innovation in catalyst design. They created a new zinc- and copper-based catalyst that produces diatomic carbon intermediates. These intermediates can then be converted into lipids using an engineered strain of the Rhodococcus jostiii bacterium, which is known for its high lipid content. This strain also enhances the metabolic potential of ethanol, which helps to convert acetate into fatty acids.

In addition to the efficiency of the electro-biodiesel process, its environmental impact is significant. By utilizing renewable energy sources for electrocatalysis, the process could potentially achieve negative carbon emissions. In fact, the electro-biodiesel process can reduce carbon dioxide emissions by 1.57 grams per gram of electro-biodiesel produced. This is in stark contrast to conventional diesel production, which generates 0.52 grams of carbon dioxide per gram of fuel, and traditional biodiesel methods, which produce anywhere from 2.5 to 9.9 grams of CO2 per gram of lipids produced.

“This research demonstrates the concept for a broad platform that can efficiently convert renewable energy into chemicals, fuels, and materials,” said Yuan. “It has the potential to address fundamental challenges in human civilization, such as reducing our dependence on fossil fuels for sectors like long-range heavy-duty vehicles and aviation.”

The electro-biodiesel process is not just a more efficient and cleaner way to produce biodiesel—it’s also a solution to the ongoing biodiesel feedstock shortage. As global demand for sustainable fuel increases, this new process could help bridge the gap, providing a renewable alternative to fossil fuels in critical industries like transportation and energy. By achieving independence from traditional feedstocks like soybeans, it could transform the future of biodiesel production and help accelerate the global transition to clean energy.

“This breakthrough could change the way we think about energy and materials manufacturing,” Yuan added. “It could relieve fossil fuel dependence across many sectors and help us build a more sustainable future for the planet.”

By Impact Lab