Text|Wang Fangyu.
Edit|Su Jianxun.
Under the guidance of the dual carbon goal, China's hydrogen energy industry has ushered in vigorous development. At present, China is the world's largest hydrogen producer, with hydrogen production reaching 37.81 million tons in 2022. According to the China Hydrogen Energy Alliance**, from 2026 to 2035, the output value of China's hydrogen energy industry will reach 5 trillion yuan, and the prospects for the hydrogen energy industry chain are very broad.
But at the same time, the issue of water use related to hydrogen production is also increasingly discussed and concerned. Especially with the rapid development of the hydrogen industry, its water consumption will surge in the future. How much water is consumed in the development of hydrogen energy, and how to balance the development of hydrogen energy with its impact on water resources and potential risks?
On December 10, the Global Report on Water for Hydrogen Production (hereinafter referred to as the "Report") jointly authored by the International Renewable Energy Agency (IRENA) and Weilan Consulting was officially released during COP28, providing a reference for the global hydrogen production industry to achieve sustainable development in terms of water resources. According to reports, this is the world's first report to systematically analyze the problem of water for hydrogen production.
The report statesHydrogen manufacturing is not yet a "big water user", but it could significantly increase local water stress. For example, a 230,000-tonne coal-to-hydrogen plant equipped with carbon capture uses as much water as half a year's worth of water for all London residents.
International Renewable Energy Agency, Global Report on Water Use for Hydrogen Production
At present, the mainstream hydrogen production methods in the market include green hydrogen (hydrogen production through water electrolysis of renewable energy sources such as photovoltaic and wind power), gray hydrogen (hydrogen production from natural gas), brown hydrogen (hydrogen production from gasification of coal as raw material), and blue hydrogen (CCUS link added to gray hydrogen). The report statesOf the four hydrogen production technologies, green hydrogen (proton exchange membrane electrolysis) has the lowest average water intensity, with an average consumption of 17 per kilogram of hydrogen produced5 liters of water, followed by grey, blue and brown hydrogen.
Compared with the water consumption of different hydrogen production methods, green hydrogen is undoubtedly a more water-efficient way to produce hydrogen. The report also uses simulations to show that with advances in green hydrogen manufacturing technology, water consumption for green hydrogen can be reduced by about 2% for every 1% increase in electrolysis efficiency in the future.
On the whole, because hydrogen energy production does not consume much water, it does not account for a significant proportion of water consumption for either the country as a whole or the energy sector as a whole. According to the report, 2.2 billion cubic metres of freshwater is currently pumped from hydrogen production globally each year, accounting for only 0.0 percent of the total water withdrawals from the energy sector6%。
However, if we focus on local areas where hydrogen production capacity is intensive, the water consumption situation becomes more serious. The report found that more than 35% of the world's green and blue hydrogen production capacity (operating and planned) is currently located in areas with high water stress. China, the European Union, the United States and other G20 countries are also facing varying degrees of water stress.
Among them, due to the enrichment of coal resources, China's Yellow River Basin gathers more than eighty percent of the country's coal-to-chemical plants, and therefore undertakes more than 80% of the country's coal-to-hydrogen production capacity, but the water resources in this region account for less than 4% of the country's total, and the contradiction between water supply and demand is prominent. As a result, the report points out that the development of water-intensive coal-to-hydrogen will continue to increase the local water burden, and if CCUS is added to coal-to-hydrogen plants to reduce carbon emissions, it will further significantly increase water demand.
In this regard, the report suggests that green hydrogen with low water consumption would be the best choice if hydrogen energy is to continue to develop hydrogen in the Yellow River Basin. According to the report, if the Yellow River Basin uses SMR+CCUS, alkaline electrolysis or a combination of the two to replace coal-to-hydrogen production, switching from brown hydrogen to green hydrogen could reduce the amount of water extracted by 28% and the water consumption by 20% while the hydrogen production increases by 11%.