Water-conscious green hydrogen production and conversion for harnessing long-term storage in remote renewable microgrids

Water plays a pivotal role in the production of green hydrogen, requiring meticulous management. Approximately 10 L of water are needed to produce one kilogram of hydrogen through electrolysis. Furthermore, roughly 10-20 L per kilogram are required for process cooling. A share of this water consumption is blowdown, which can be recirculated, while water is also generated as a byproduct of energy conversion in fuel cell. Although green hydrogen production via renewable-supplied electrolysis is a crucial focus for sustainable energy systems, its water implications are often overlooked. Understanding and addressing the water-hydrogen nexus as the global energy transition progresses is pivotal for successful green hydrogen deployment. This paper highlights the role of water in green hydrogen production to bridge this gap. Accordingly, it presents a systematic model of water generation, withdrawal, and blowdown cycles in the power-to-gas and gas-to-power processes within a green hydrogen chain system for long-term storage. The primary water intake of the system is saline water treated with a storage-integrated desalination unit. This water-conscious subsystem for seasonal storage based on green hydrogen is then incorporated into the planning process of a hybrid remote and renewable microgrid. The proposed model uses actual environmental data from Qeshm Island in south Iran as a case study. The simulation results and comparisons with previous research show that the proposed model is effective for managing real- world green hydrogen systems, especially in water-scarce regions. Also, the developed model is versatile enough to be used within any other energy system based on green hydrogen.