The EU project ECO2Fuel has presented new results on the co-electrolysis of CO2 and water at low temperatures. In CO2 electrolysis, carbon dioxide is chemically converted into other substances using electric current, such as carbon monoxide, ethylene, or other hydrocarbons. The system typically requires water and catalysts in addition to CO2; thus, basic materials for chemicals or synthetic fuels are produced. According to project information, a cell with an anion exchange membrane (AEM) achieved a Faraday efficiency of 69 to 70 percent for carbon-containing products. However, this is by no means the energy efficiency of the system. Rather, the value describes what proportion of the electricity used or the electrons transferred actually flows into carbon products.
When the project includes the simultaneously produced hydrogen, the total Faraday yield is reportedly close to 100 percent. This means that the electricity is almost entirely found in measurable reaction products, with few by-products. The energy efficiency is not mentioned in the source.
The work focuses on the membrane electrode assembly (MEA), the core component of the electrolyser. The tested configuration combines copper oxide (CuOx) at the cathode, where CO2 is reduced, with a nickel-iron-based (NiFe) catalyst at the anode for oxygen evolution. The AEM is responsible for ion transport and aims to limit unwanted substance permeation.
According to project information, the system remained operational in long-term tests for more than 800 hours at 300 mA/cm2. The cell voltage ranged from about 2.1 to 2.25 volts depending on the test conditions. In the product mixture, gaseous products predominated over liquid ones. This indicates that further process steps remain important for the production of liquid e-fuels.
For the consortium, the results are particularly relevant with regard to scaling. They are intended to reduce the technical risk when transitioning from single cells to stack configurations. According to the participants, a 50 kW system is also being developed in the project. ECO2Fuel is an EU project under the Horizon 2020 program. In the long term, a low-temperature system for direct electrochemical CO2 conversion on a megawatt scale is to be developed.