Integration of commercial alkaline water electrolysers with renewable energies: Limitations and improvements

• The analysis is based on a commercial 1 Nm3 h−1 alkaline water electrolyser.
• A year energy balance of the electrolyser conventional integration with PV and wind RES is shown.
• Limitations such as lower operating limit and No. of electrolyser stops are analysed.
• Two strategies for improved electrolyser integration with RES are proposed.
• 62.1–63.1% reduction in the number of stops and 6.3–7.6% increased efficiency was achieved.

Hydrogen can be stored, transported and used in a large number of applications in which fossil fuels are currently used. From a sustainable point of view, the synergy existing between hydrogen and renewable energy sources shows great potential. In this respect, hydrogen can be produced from water electrolysis using the electricity generated by renewable systems. This paper studies the integration of a 1 Nm3 h−1 alkaline water electrolyser with photovoltaic solar energy (PVE) and wind energy (WE) in a stand-alone system. In particular, a one year energy balance of the conventional integration of the electrolyser with PVE and WE is carried out. To do so, actual weather data are used for irradiance, ambient temperature and wind speed, in addition to the technical specifications and characteristics of a 6.8 kWp PV generator and a 6 kW wind turbine. This energy evaluation reveals the main limitations of commercial electrolysers, such as the lower operating limit and the number of stops permitted by manufacturers. Two strategies are therefore proposed to improve the integration of conventional electrolysers, namely to allow the electrolyser to operate for a period of 10 min under the lower operating limit and to integrate a battery bank. Both strategies achieve successful results, with a reduction in the number of stops by up to 62.1% for the PVE integration and 63.1% for the WE, which should increase the electrolyser service life, and an increase in energy efficiency by up to 6.3% for the PVE integration and 7.6% for the WE.