Green Hydrogen is produced through the electrolysis of water with 100% or near 100% renewable energy. Around 9 litres of water are needed to produce 1 kg of green hydrogen, with 8 kg of oxygen as a by-product. On this basis the IEA recently calculated that if all current hydrogen production (circa 90 million tonnes per annum) were produced through electrolysis (using water and renewable electricity), the water requirements would be 790 million cubic meters. While that’s a lot of fresh water, it’s only a tiny proportion of global water use (less than .01%). However, this also significantly underestimates the challenge.
Worldwide, we use more than 4 trillion cubic meters of freshwater each year. Agriculture accounts for 70%, industry 19% and households 10%. 2 billion people lack access to safe drinking water and 40 per cent of the world’s population are affected by water scarcity. In addition, humanity’s demand for water keeps growing, with pressure on freshwater projected to increase by more than 40 per cent by 2050. The UN’s 2023 Water Conference in New York recently noted that climate change will “hit hardest through water”, impacting forced migration, conflict, poverty and food security.
While it is not the total amount of water used which will be a challenge for our industry, some of the best opportunities for producing renewable energy (in particular solar energy) are in water-stressed environments. Desalination is often considered a solution. However, this increases the energy use, and raises additional challenges regarding saline wastewater disposal. Compared to alternative ways of producing energy, it may not be a huge challenge, but it nevertheless needs to be taken seriously.
Water demand can be much higher than the 9 litres per kilo cited above. The engineering firm GHD have identified a number of commonly overlooked water supply and disposal factors:
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Raw water feed requiring treatment to meet high purity electrolyser requirements – with around 20-40% of the water sent to waste during the treatment process, depending on the quality of the imported raw water.
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Cooling load for electrolysers – which can require an additional 30 to 40 kg of water per kg of hydrogen in evaporative cooled systems;
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Other cooling loads– such as the multi-stage compressors with intercooling to compress the produced hydrogen to a suitable pressure for storage or use;
GHD concludes that these additional loads can require as much as 60 to 95 kg of water per kg of green hydrogen. Even at this level, total water consumption will still be relatively small compared to total consumption (still less than .01% of global freshwater use). But it will be a significant constraint in some cases. The future of the green hydrogen industry depends on developing a sustainable approach to sourcing and disposing of water, reducing water demand, and avoiding negative impacts on water-stressed ecosystems and communities.
This issue highlights a key weakness in the conventional approach to hydrogen standards and certification. Almost all of the standards that have been proposed to date focus solely on measuring greenhouse gas emissions and do not take social and environmental impacts like water use into account. This is obviously insufficient.
GH2’s Green Hydrogen Standard (GHS) provides certainty and transparency to producers, consumers and other stakeholders that green hydrogen production conforms to the highest standards on emissions, environmental social and governance performance and alignment with the sustainable development goals.
Specifically, under requirement 5B of the GHS, accreditation and certification requires a publicly accessible evaluation of the project’s utilisation of water and the project’s approach to wastewater treatment and water pollution. The project operator must demonstrate that it has identified and implemented measures for efficiency in its consumption of water, particularly in risks associated with water access and water stress. These measures should integrate the principles of cleaner production into product design and production processes with the objective of optimising water consumption and minimising water pollution. Project operators are encouraged to consider opportunities to generate co-benefits for local communities through provision of drinking water, water for irrigation, and /or water treatment.
While the Standard provides a robust framework, we recognise that more work is needed to address the most challenging aspects of water management. The GHS Committee that oversees the implementation and elaboration of the standard recently established a water working group. The group met this week, and agreed to undertake further work focused on:
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More clearly defining water scarcity and water stress
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Wastewater management from desalination facilities;
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Wastewater management from production facilities;
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Groundwater extraction; and
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Oversizing water treatment facilities to support community development.
Water is at the core of sustainable development. The green hydrogen industry needs to tackle these issues as a high priority. The challenges are not insurmountable. But they require a collaborative approach that leverages support from government, industry and civil society.
