As part of the EU-funded PEACE ^[1] project, an innovative, efficient alkaline electrolyser is being developed that will significantly reduce the costs of hydrogen production thanks to a two-stage pressurisation concept. A key aspect is operation at up to 90 bar, which both increases the efficiency of the overall system and simplifies downstream process steps by eliminating compressor stages. Higher pressure reduces the change in gas volume during load fluctuations, which has a positive effect on dynamic operation, but also increases the solubility of the gases, making gas purity more critical. ^[2]

To analyse this dynamic operation, the TEMPEST ^[3] simulation framework was parameterised and expanded for high-pressure operation. TEMPEST allows the investigation of the steady-state and transient behaviour of process engineering systems with electrochemical reactors. The focus here is on developing operating strategies and analysing scaling approaches. Critical parameter distributions within the cells (temperature, current density, flow rate, composition) are resolved in detail.

This work describes the application of TEMPEST to the high-pressure alkaline electrolyser of the PEACE project. Various operating strategies are evaluated with regard to their suitability for ensuring high gas purity and uniform temperature distribution. The simulation studies are carried out in close synergy with experimental investigations, which provide both parameterisation and validation data. This results in simulation-based findings that enable targeted experiments and also analyse operating conditions that go beyond the experimentally accessible range.

[1] https://www.h2peace.eu/

[2] A. Roy et al., Comparison of electrical energy efficiency of atmospheric and high-pressure electrolysers, doi.org/10.1016/j.ijhydene.2006.01.018

[3] M.Tomberg et al., Transient Modelling of Solid Oxide Cell Modules and 50 kW Experimental Validation. Stuttgart (2019), ECS Trans. 91