Water stress a major factor for hindering green hydrogen production; treatment of water subject to increased costs, hence lower feasibility.
Here’s an article posted in Mongabay.
According to the article,
Green hydrogen production is a promising clean energy solution, but concerns remain about its water requirements and availability. Here are the key points to consider:
- Water Requirement: Green hydrogen production requires water, with an annual water requirement relative to Earth’s water resources1.
- Water Consumption: Green hydrogen systems consume less water than fossil fuel-based hydrogen or some types of hydrogen, but efficient process management is essential
Here are some key technological advancements being explored globally to reduce the water requirements for green hydrogen production
Our specialty focus areas include 
- Using seawater or brackish water directly in electrolysis without extensive treatment: Some initial experiments and studies are exploring the potential of using seawater or other saline water sources directly in the electrolysis process to produce green hydrogen. This could help avoid the energy-intensive and costly process of desalinating or demineralizing freshwater.
- Developing advanced electrolysis technologies like solid oxide electrolyzers: Solid oxide electrolyzers are highlighted as a promising technology that can achieve higher efficiencies of around 40 kWh of electricity input per kg of hydrogen produced, compared to 52-55 kWh for conventional alkaline or PEM electrolyzers. Higher efficiency means lower water requirements per unit of hydrogen.
- Improving electrode and catalyst materials in electrolyzers: Researchers are working on reducing the use of precious metal catalysts like platinum and iridium in PEM electrolyzers, and enhancing nickel-based catalysts in alkaline systems. This can help lower the overall cost and energy requirements of electrolysis.
- Scaling up electrolyzer unit sizes: The industry is moving towards developing much larger electrolyzer units, up to 1 GW of capacity, which can achieve greater economies of scale and drive down the capital costs per unit of hydrogen produced. This indirectly helps reduce the water requirements per kg of hydrogen.
- Utilizing waste heat from external sources in electrolysis: Solid oxide electrolyzers can leverage waste heat to reduce the primary energy input, thereby improving overall efficiency and lowering water needs.
Interestingly, we have some other posts related to this content:
Green Hydrogen Production Water Challenges: AECOM article highlights water demand for green hydrogen production, advocating strategies like desalination and treated wastewater, requiring additional investment and energy consumption.
