Converting CO₂ Directly Into Fuel And Chemicals

TU Berlin launches two research projects on the direct electrochemical conversion of CO_₂ – bypassing the need to produce hydrogen first

In the future, carbon dioxide could be used as a raw material rather than simply being avoided or captured. Researchers at Technische Universität Berlin are developing processes that use electricity to convert CO_₂ directly into chemical feedstocks and building blocks for synthetic fuels. Over the next three years, two new research projects will tackle different challenges: While JEThylen is advancing the direct electrochemical conversion of CO_₂ into ethylene as a feedstock for synthetic jet fuel, INNOCELL is developing more efficient and scalable electrolyzer cells for CO_₂ conversion. The Electrochemical Catalysis, Energy and Materials Sciences Group at TU Berlin is receiving a total of approximately €2.6M in funding for both projects.

In many processes used to produce synthetic fuels, water is first split into green hydrogen and oxygen using renewable electricity generated from solar, wind, and hydropower. The hydrogen is then combined with CO_₂ to produce feedstocks and intermediates for the chemical and fuel industries. Researchers at TU Berlin are taking a different approach: In direct CO_₂ electrolysis, carbon dioxide reacts directly with water in an electrochemical cell. This process can produce chemical precursors for fuels directly – without the need to first produce and store hydrogen as a separate energy carrier. "Our central experiments for this are already underway in the lab," says Professor Dr. Peter Strasser, head of the Electrochemical Catalysis, Energy and Materials Sciences Group. "The goal now is to improve the efficiency and durability of the electrolyzers and scale them up."

Ethylene as a feedstock for synthetic jet fuel
The JEThylen project is investigating the direct electrochemical conversion of CO_₂ into ethylene. Ethylene is an important raw material in the chemical industry and can serve as a feedstock for the production of synthetic jet fuel. In a subsequent process, it is first converted into longer-chain hydrocarbons, which are then further processed. The advantage of this method is that the direct electrochemical reaction of carbon dioxide and the subsequent chemical processing of ethylene result in a comparatively short process chain at relatively low temperatures. This improves energy efficiency.

Siemens Energy is coordinating the project as consortium lead. Other partner institutions include TU Berlin, the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB), and the aviation think tank Bauhaus Luftfahrt. Together, they aim to make direct CO_₂ electrolysis to produce ethylene more efficient, more durable, and suitable for larger-scale facilities. To achieve this, the cell voltage is to be reduced from the current level of about 4.5 volts to approximately 2.5 volts. "Through these and other measures, we aim to increase energy efficiency from its current level of about 27% to 50%. At the same time, we are aiming for stable operation for at least 1,000 hours," says Strasser. The project also represents a significant step forward in terms of scale: While comparable laboratory setups have typically operated with electrode areas of around 10 square centimeters, the new facility is designed to accommodate cells with electrode areas of several hundred square centimeters. Building on this, the researchers will develop concepts for industrial-scale applications with electrode areas of up to 0.5 square meters – equivalent to 5,000 square centimeters. JEThylen is funded by the Federal Ministry of Research, Technology, and Space (BMFTR) as part of the DISCO₂ funding program (Disruptive Approaches to the Industrial Use of CO₂). The project runs from March 2026 to February 2029, with TU Berlin receiving approximately €1M in funding.

New cells for CO_₂ electrolysis
The second project, INNOCELL, addresses a different challenge: How can electrolytic cells be designed to operate efficiently and reliably, even on a larger scale? The project builds on a cell design for gas diffusion electrodes developed and patented at TU Berlin. These electrodes allow gaseous CO_₂ to be supplied directly to the catalyst, enabling high current densities. The project uses water-repellent, electrically insulating polymer substrates. They help prevent the gas diffusion electrodes from becoming flooded with electrolyte as easily. This "flooding" problem causes the pores in the gas diffusion electrodes to become clogged, thereby severely hindering the process. The water-repellent polymer substrates allow the cells to operate reliably even at high current densities. A specially designed current collector provides the necessary electrical connection.

Beyond ethylene: Producing carbon monoxide and other hydrocarbons
The cells are tested at temperatures of 60 to 80 degrees Celsius and pressures of up to 30 bar – conditions relevant to industrial CO_₂ electrolysis. The project aims to achieve current densities of at least 500 milliamps per square centimeter, an energy efficiency of at least 45%, and an operating life of at least 1,000 hours. The cells are not designed exclusively for ethylene production: INNOCELL is also investigating the production of carbon monoxide (CO). CO is an important intermediate product in the chemical industry and a component of synthesis gas, which is used to produce methanol and other synthetic fuels, among other products. "Which application we ultimately pursue on a larger scale will depend on the performance metrics achieved during the project," explains Peter Strasser.

The project runs from 2026 to 2029 as part of the VIP+ program of the Federal Ministry of Education and Research. The program supports the evaluation and further development of research findings with potential economic or societal applications to assess their feasibility. The funding amount for TU Berlin is €1.6M.