Freshwater supply for hydrogen production: An underestimated challenge.

This paper presents a thorough critical literature review aimed at understanding the challenges associated with freshwater supply associated with rapidly growing global hydrogen economies. The review has been prompted by the fact that the hydrogen production projected for 2030 will create at least an additional demand of 2.1 billion cubic meters for freshwater, which needs to be addressed to support sustainable development of emerging hydrogen economies. The key solutions explored by this study include seawater and wastewater treatment methods for large-scale freshwater generation, along with the newly introduced technique of direct seawater-fed electrolysis. Prior research indicates that desalination technologies, including reverse osmosis and membrane distillation, also offer promising avenues for large-scale freshwater production at costs comparable to other desalination techniques. Additionally, low-temperature desalination methods such as membrane distillation could play a significant role in freshwater production for electrolysis, underscoring the importance of exploring waste recovery opportunities within the system (e.g., fuel cell heat recovery). This review also identifies research gaps that need to be addressed to overcome freshwater supply challenges and enhance the sustainability and techno-economic viability of large-scale hydrogen energy systems. • The projected hydrogen demand by 2030 will create approximately 21 billion cubic meters of freshwater demand. • The target cost projections of ∼2–3 $/kg-H 2 have often neglected the cost of freshwater supply. • Seawater and wastewater resources can be utilised to support hydrogen production at large scales. • Direct seawater electrolysis and desalination technologies can support green hydrogen production. • Utilising fuel cells and electrolysers waste heat for desalination can reduce the energy cost of hydrogen production by ∼5%. [ABSTRACT FROM AUTHOR]