Techno-Economic Analysis of Low-Temperature Electrolysis' Waste-Heat Utilization

Low temperature electrolysis will be an indispensable system integration asset in future low-carbon energy systems but is known for its inefficiency and associated waste-heat production. Low temperature electrolysis’ waste-heat could be used in e.g. 4th or 5th generation district heating systems. However, its economical feasibility is uncertain due to spatial, temporal and temperature imbalances between waste-heat supply and heat demand. Therefore, this study proposes a model that addresses these hurdles and is able to calculate, under varying circumstances, the distance between low temperature electrolyzers and district heating systems at which waste-heat utilization is still profitable. The model contains a detailed description of the waste- heat extraction system, an electrochemical and thermodynamic model of an alkaline water electrolyzer, and an optimal dispatch strategy of the electrolyzer based on electricity and hydrogen prices. Results show that the economically feasible distance between electrolyzers and district heating system increases with the electrolyzer’s capacity and stack temperature. The model can be used to strategically site electrolyzers by private owners or system operators.