Scaling and heating will drive low-temperature CO2 electrolysers to operate at higher temperatures

Low-temperature carbon dioxide electrolysis (CO2E) provides a one-step means of converting CO2 into carbon-based fuels using electrical inputs at temperatures below 100 °C. Over the past decade, an abundance of work has been carried out at ambient temperature, and high CO2E rates and product selectivities have been achieved. With scaling of CO2E technologies underway, greater discourse surrounding heat management and the viable operating temperatures of larger systems is important. In this Perspective we argue that, owing to the energy inefficiency of electrolysers, heat generation in CO2E stacks will favour operating temperatures of between 40 and 70 °C, far from the ambient temperatures used so far. Such elevated temperatures put further pressure on catalyst and membrane stability and on the stack design. On the other hand, elevated temperatures could alleviate challenges in salt precipitation, water management and high cell voltages, aiding the technology. We reflect on these aspects and discuss the opportunities for waste heat valorization to increase the economic feasibility of the process.