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Around 47 total liters of water need to be withdrawn to produce 1 kilogram of hydrogen

Producing 1 kilogram of green hydrogen typically requires between 23 and 33 liters of treated water. This breaks down into about 9 to 10 liters used for electrolysis, and 14 to 23 liters needed for cooling.1 However, before the treated water can be used in production, a larger volume of raw water must be withdrawn and purified. Not all raw water meets the necessary quality standards for production, and a portion is discarded. As a result, hydrogen producers generally need to withdraw significantly more water than is ultimately used in the production process.2

The efficiency of converting raw water into treated water depends on several factors, such as the quality of the source water. For electrolysis, typically only 35% to 66% of raw water is suitable after treatment, while for cooling, this range is 40% to 85%. These figures vary heavily depending on the source of water. Seawater requires more extensive treatment and a lower percentage of the withdrawn water is ultimately usable.3 However, surface or tap water generally requires significantly less treatment and a much higher percentage of the withdrawn water is ultimately used in production.4

Despite these variations, we can estimate the overall water withdrawal needed to produce one kilogram of green hydrogen by averaging the treated water percentages:

  • Electrolysis: On average, 50% of withdrawn water is usable.
  • Cooling: On average, 62.5% of withdrawn water is usable.

Based on these averages, the water withdrawal required per kilogram of hydrogen is approximately:

  • Electrolysis: 19 liters of raw water
  • Cooling: 28 liters of raw water
  • Total: 47 liters of raw water per kilogram of hydrogen

These estimates provide a useful guideline for understanding the water demands of green hydrogen production.

Sources:​

Footnotes​

  1. IRENA and Bluerisk. (2023). Water for hydrogen production. International Renewable Energy Agency, Bluerisk. Pg. 26 https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2023/Dec/IRENA_Bluerisk_Water_for_hydrogen_production_2023.pdf ↩

  2. Australian Hydrogen Council. (2022, November). Water for Hydrogen. https://h2council.com.au/wp-content/uploads/2023/02/221114-Arup-Technical-paper-Water-for-Hydrogen-report-FINAL.pdf ↩

  3. Ibid. ↩

  4. Ibid. ↩