EU Harmonised Testing Procedure: Determination of Water Electrolyser Energy Performance

The objective of this pre-normative research (PNR) document is to present a testing procedure for establishing the energy performance of water (steam) electrolyser systems (WE systems), whether grid-connected or off-grid and individual water electrolysers (WEs)/high-temperature electrolysers (HTEs) for the generation of hydrogen by water/steam electrolysis. The WE systems use electricity mostly from variable renewable energy sources. HTE may additionally utilise (waste) heat from energy conversion and other industrial processes. By applying this procedure, the determination of the specific energy consumption per unit of hydrogen output under standard ambient temperature and pressure (SATP) conditions allows for an adequate comparison of different WE systems. Also, the energy performance potential of WEs or WE systems employing low-temperature water electrolysis (LTWE) technologies compared to HTE employing high-temperature steam electrolysis (HTSEL) technologies may be established under actual hydrogen output conditions by applying this procedure. The test method is to evaluate the specific energy consumption during steady-state operation at specified conditions including rated input power, pressure and temperature of hydrogen recommended by the manufacturer of the WE or WE system. The energy efficiency and the electrical efficiency based on higher and lower heating value of hydrogen can be derived from respectively the specific energy consumption and the specific electric energy consumption as additional energy performance indicators (EPIs). In a plant setting, the specific energy consumption of an individual water electrolyser including HTE under hydrogen output conditions may also be determined using this testing procedure. This procedure is intended to be used as a general characterisation method for evaluating the energy performance of WEs including HTEs and systems by the research community and industry alike.