The Kopernikus P2X project, funded under the German federal programme with the reference 03SFK2J0-2, focused on the industrial scalability of low‑temperature CO₂‑to‑CO gas‑to‑gas electrolyzers. The core objective was to enlarge the active electrode area beyond 3 000 cm² while maintaining the required operating parameters for a commercially viable process. The project was carried out by Siemens Energy Global GmbH & Co. KG in close cooperation with the ifeu Institute, which performed the life‑cycle assessment, and with Evonik as an additional technology partner. The results of the life‑cycle analysis and the techno‑economic assessment are documented in the Roadmap 3.0 and Roadmap 4.0 reports, available for download from the Kopernikus project website.

During the project timeline the electrolyzer was successfully scaled from a 300 cm² cell (C300) to a 5 000 cm² cell (C5000). The large‑area cell operated stably for more than 1 000 hours at a current density of 200 mA cm⁻² and a temperature of 60 °C, delivering a product gas with a CO concentration of at least 30 vol %. The anode CO₂ evolution was kept below 10 %, and the cell voltage remained close to the target value of approximately 4 V. These performance figures meet the target parameters defined in the project’s technical specification table and demonstrate that the cell design and operating mode are suitable for large‑scale deployment. Long‑term operation at higher current densities is still under investigation, as degradation effects become more pronounced beyond the 1 000‑hour benchmark.

The project milestones were largely met according to the schedule. Milestone 1 (M12) defined the cell design and operating mode, selecting the 1/2MEA + gap horizontal configuration after simulation studies. Milestone 5 (M20) saw the construction of the large electrolyzer and its test stand. Milestone 7 (M24) achieved the commissioning of the ≥3 000 cm² cell, and milestone 12 (M39) demonstrated 500 hours of continuous operation at the target current density, with stable CO output. Parallel to the technical work, the techno‑economic analysis subtask (2.3) delivered intermediate and final results to the Roadmap 3.0 and Roadmap 4.0 contributions, respectively, in accordance with the agreed data transfer schedule.

The collaboration network extended beyond Siemens Energy and ifeu to include Covestro, which contributed to the cell design and testing, and HIERN, which developed advanced analytical methods such as a scale‑crossing digital twin for electrode material characterization. The project also linked to the Kopernikus partner projects Rheticus I and II, which operate 10‑stack assemblies of 300 cm² cells and integrate the electrolyzer with a fermentation process. Although a full demonstration plant is not yet feasible due to high capital costs and risk, the project has laid the groundwork for future scaling, including potential increases in cell height and the exploration of bipolar membranes and pressurized operation. The outcomes provide a solid technical foundation for the direct electrochemical conversion of CO₂ at moderate temperatures, supporting the broader goal of coupling renewable electricity to the chemical sector and advancing the power‑to‑X concept.