Optimizing temperature, pressure, and waste heat utilization in PEM electrolyzers: a model-based approach to enhance integrated energy system efficiency

Citation
38th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2025
Contribution to Conference
38th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2025  
Publisher Link
https://ecos2025.org/wp-content/uploads/2025/06/Program-at-a-glance_ECOS_2025.pdf
“Green” hydrogen is regarded as a crucial energy carrier for defossilizing global energy systems. However, its production via electrolyzers remains energy-intensive and costly, hindering widespread adoption. Two promising strategies address these challenges: waste heat recovery from electrolysis and optimization of the interplay of electrolyzer operating parameters (i.e., current density, temperature, pressure). This paper combines these approaches to assess the potential energy and cost savings from optimized waste heat utilization and its influence on optimal operating parameter selection. To achieve this, a polymer electrolyte membrane electrolysis process model is integrated into a superordinate energy system model to investigate the interplay between waste heat recovery and parameter optimization. Two operational modes – prioritizing hydrogen production efficiency versus system-wide efficiency – are compared to a reference case without waste heat recovery. The results reveal that waste heat utilization achieves cost savings of 0.8 to 2.9% and energy savings of 0.6 to 1.9%, while parameter optimization yields cost savings of 5.9 to 6.4% and energy savings of 3.4 to 3.7%. The highest savings (7.7 to 9.2% cost, 4.6 to 5.3% energy) are achieved by combining these strategies through a holistically designed operational approach, balancing efficient hydrogen production with optimized heat provision. This requires accepting marginal electrolyzer efficiency losses to gain systemic benefits through improved heat integration by mainly increasing pressure and adapting load points (i.e., current density). Operational flexibility – enabling dynamic adjustments to align hydrogen production with intermittent PV availability and electricity prices – proves essential. To preserve this flexibility, electrolyzers should supplement rather than fully meet heat demand.
DDC Class
624: Civil Engineering, Environmental Engineering