Green hydrogen from wind energy: mitigation of operating point fluctuations

Today, hydrogen production is mainly based on fossil fuels and it is therefore associated with a great amount of CO2 emissions. Hydrogen production from renewable sources through electrolysis can increase the sustainability in both energy and industrial sectors. North Europe, for example, has a great potential for offshore wind farms that can be employed to produce hydrogen to be used in other sectors such as mobility or industry. However, direct coupling of electrolysers with renewable energies could cause frequent shutdowns and high production fluctuations. The problem is even more accentuated in stand-alone or weakly-connected systems if stable hydrogen production is required (e.g. when it feeds a chemical plants). In this study, the integration of a battery in a hydrogen production system consisting of a wind turbine and an alkaline electrolyser is investigated. The battery provides a short-term storage to mitigate fluctuations. Annual simulations are performed with different battery and electrolyser sizes in Matlab. The electrolyser and battery operating conditions are set by a power management strategy as function of the battery state of charge and a moving average of wind power. Results are compared from both energy and economic points of view.