Will a transition to a hydrogen economy affect water security?

The need for clean energy alternatives to reduce the impact of climate change encourages us to look at hydrogen as a potential new energy carrier. Hydrogen is now viewed by governments and energy companies as a viable alternative to the traditional fossil fuel-based energy industries. Terms such as 'hydrogen economy' or 'hydrogen society' encourage us to believe that we can completely move away from fossil fuels and rely solely on hydrogen. Growing worries over future water resources, however, show that relying solely on hydrogen may, in certain cases, overburden our water resources.

Here, I examine the current energy use of various states and calculate the amount of hydrogen required to meet current energy demands. This amount of hydrogen is then converted into the amount of water required to produce this hydrogen via electrolysis.

Nearly two decades have passed since the US released its Energy Policy Act of 2005. This addressed the hydrogen economy in the US and triggered a hydrogen boom, beginning in the US and spreading around the world. Then the 2008 global financial crisis hit; its fallout created a headache for hydrogen energy as significant funding and effort were redirected to more urgent problems. The hydrogen boom faded away between 2009 and 2010 and many factors are to blame for this. That the available technology was too expensive and not mature enough to be applied commercially was another contributor. Yet, the funding available for research and development of hydrogen technologies allowed the hydrogen economy to slowly mature in the following years.

It took nearly a decade for hydrogen to make a comeback. In that time, Japan, South Korea and China rapidly emerged as the hydrogen leaders. In 2017, Japan and South Korea decided to officially support the hydrogen economy and make it an important part of their energy security strategies. Meanwhile, Australia began to see renewable hydrogen and other renewable fuels as a potential new mass export.

The Chinese government sees hydrogen as a viable strategy for addressing fossil fuel pollution in transportation. It provides many subsidies, tax incentives and grants to develop hydrogen fuel cell vehicles and build hydrogen refuelling and energy storage infrastructure. While big announcements stating that entire countries or cities can run solely on hydrogen may sound like a dream, the hydrogen economy is steadily becoming a reality.

Continuous technology development over the last ten years has allowed the idea of hydrogen-based energy to return stronger than ever. The Paris Agreement and announcements made in 2021 by a number of countries to phase out the use of internal combustion engines in the coming decades further benefited the hydrogen economy.

California and Germany already have a number of hydrogen refuelling stations. Hydrogen fuel cells can also store surplus energy produced from renewable resources, such as solar, wind or hydropower. Hydrogen finds uses in numerous other industries as well. Oil and gas and the food industry rely on hydrogen for crude oil and food processing respectively.

Producing hydrogen from renewable resources involves the electrolysis of water, where an electric charge splits water molecules into hydrogen and oxygen. In an era of increasing water security issues, rapidly progressing climate change and droughts, however, water scarcity has become an urgent problem globally. A growing world population only worsens the water scarcity problem. Many have questioned whether using hydrogen for energy storage and transportation fuel will force industries, such as the energy sector and agriculture, to compete for water resources.

The below numbers are theoretical and indicative. It is unlikely that countries will switch entirely to hydrogen-based energy supply. Although, small states, which do not have enough land for wind and solar deployment, may be fully reliant on hydrogen imports. These include Singapore, Qatar, Luxembourg, Bahrain and Malta. That being the case, these states would not rely on their own water for hydrogen production, but on water from exporting states.

Once hydrogen is combusted with oxygen to release energy, it becomes water. This in return, opens up a unique opportunity, where countries with water scarcity could not only import energy, but also address their water shortages through hydrogen.

Simple calculations on these data sets, available on the World Bank website, including the annual energy use per country and total annual freshwater withdrawal, show that providing for the total energy needs of a country with hydrogen should not be burdensome to water resources in most cases. Though these numbers are only indicative of the water security problem, they provide a general idea of how much water would be required to replace the current energy sector within specific countries that switch to a hydrogen-based economy.

Only nine of the 135 countries studied would require an increase in their current freshwater withdrawal of over 10% to completely transition to hydrogen-based energy, whereas 62 countries would need to increase their freshwater withdrawal by less than 1%. There is a visible trend among the countries with a significant increase in water withdrawal to transition to hydrogen. These countries are either desert countries with little annual precipitation, such as Qatar, Israel, Kuwait or Bahrain, or small island states, such as Singapore, Trinidad and Tobago or Malta, which would also struggle due to limited freshwater reservoirs.

Singapore, which relies highly on neighbouring Malaysia for freshwater resources, tops the list. It would have to increase the water it uses to convert to hydrogen-based energy by about 46.4%. On the other hand, Tajikistan, being at the very bottom of the list, would require an increase of only 0.056%. The average value for all 135 countries is 3.3%.

The hydrogen economy also opens up interesting prospects for countries that are already experiencing water shortages, including Singapore and Qatar. It is unlikely that these two states will produce their own hydrogen, they will rely on imported hydrogen. This allows them to capture water produced from the reconversion of hydrogen back into energy, either via combustion or fuel-cell technology, and then reuse this high-purity water locally.

It is clear that the shift to a hydrogen-based economy for most will not negatively impact water security or other water-heavy industries. While hydrogen can gain a significant share of the transportation market, other energy-related sectors will most likely experience a mix of different technologies, which lowers the percentage of water used for hydrogen. In addition, when hydrogen is burned or converted with atmospheric oxygen in the fuel cell, water is formed, which can be captured and reused to produce more hydrogen. With more countries making hydrogen part of their energy agenda, the hydrogen economy could soon arrive in our households, providing clean, efficient and carbon-free solutions for transportation, electricity generation, central heating and even cooking.

The data used for the calculations presented in this article was derived from the World Bank, which drew from the Food and Agriculture Organization's AQUASTAT data. For countries with multiple records, the annual value nearest to the year 2011 was selected to match the energy use (kt of oil equivalent). All the data was recorded in 2011 and is available from the World Bank. Stoichiometric water consumption of nine litres of water per kilogramme of hydrogen was used in the calculations. These calculations do not consider cooling water or other water usage along the hydrogen value chain.