What is the significant water requirement for producing green hydrogen?

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The Production of Green Hydrogen is Highly Water-Intensive

Producing one kilogram of green hydrogen necessitates approximately nine kilograms of ultrapure water. This significant water requirement presents a considerable challenge, particularly in regions facing water scarcity. The process highlights a critical trade-off, as optimal locations for solar-powered electrolysis, often arid and sun-rich, may also be areas with limited water resources.
Water Consumption in Green Hydrogen Production

The process of generating green hydrogen is notably water-dependent. For every kilogram of hydrogen produced, an estimated nine kilograms of ultrapure water are consumed. This factor is crucial when considering the scalability and sustainability of large-scale green hydrogen facilities.
Implications for Water-Scarce Regions

The substantial water needs for green hydrogen production raise concerns for areas already experiencing water stress. Locating electrolysis plants in such environments, even if they are ideal for renewable energy generation, requires careful consideration of the environmental and logistical implications. Strategies such as desalination or extensive water transportation can add significant costs and complexity to the overall process.
System Integration and Water Infrastructure

The review emphasizes that the economics of green hydrogen must account for water infrastructure. The concept of "hybrid system optimisation," which involves intelligently integrating various energy sources and storage solutions, is presented as a key challenge. Ignoring the water component in these economic calculations, as some back-of-the-envelope assessments may do, overlooks a fundamental operational requirement.
Green Hydrogen as a Premium Molecule

Given the technical hurdles, including water intensity, dependence on rare metals like iridium and platinum for certain electrolyzer types (PEM), and the complexities of system integration, green hydrogen is likely to remain a premium product. Its application may be best suited for sectors where its unique properties are essential, such as in the production of steel and ammonia, or for long-duration shipping, rather than for widespread use in heating or passenger vehicles.

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What is the significant water requirement for producing green hydrogen?

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