Water and Energy: Balancing the New Energy Era

Nuclear power, green hydrogen, and emerging technologies all require large amounts of water to operate. In a context of increasing water stress, solutions like desalination and wastewater reuse systems can become crucial levers for a fully sustainable energy transition in all aspects.

Amid the energy transition, new technologies such as green hydrogen and nuclear energy are taking centre stage in the fight against the climate crisis. Both aim to drastically reduce CO2 emissions: green hydrogen is produced using electricity from renewable sources and emits no emissions during use, while nuclear power offers continuous, low-emission energy independent of weather conditions. These solutions are seen as key to decarbonizing hard-to-electrify sectors and ensuring grid stability. However, they come with another challenge that’s sometimes overlooked: water. Clean energy can still be thirsty energy.  And in a warming world, with a growing population and major climate changes, the question arises: how much water does it really cost to produce energy?

Water and Energy: An Inseparable Link

Water and energy are deeply interconnected. Energy production requires water, and water supply depends on energy. According to the International Energy Agency (IEA), about 15% of global freshwater withdrawals are used for energy production — a figure that could rise to 20% by 2035. But that’s not all: electricity accounts for between 5% and 30% of the operational costs for water utilities, depending on the context. This interconnection can lead to serious challenges. Extended droughts or extreme heat waves can disrupt thermal or nuclear power plants, which rely on water for cooling, risking blackouts and grid instability. 

This is also why water availability has become one of the key criteria in designing new power plants. Alternative cooling systems, such as air-based technologies, do exist, but their costs remain prohibitively high for now.

Nuclear and Hydrogen: Clean Energy, but at What Water Cost?

Zero-emission technologies like nuclear power and green hydrogen often carry a water footprint that is anything but negligible. Nuclear power plants, for instance, have been among the largest industrial consumers of freshwater for decades. Depending on the cooling system used, they can require anywhere from 6 to 160 litres of water for every kilowatt-hour of electricity generated. While some of this water is returned to its source, evaporation losses and the warming of discharged water raise serious concerns, especially during droughts or near fragile ecosystems.

Green hydrogen also involves significant water use. Its production through electrolysis—a process that separates hydrogen from oxygen using renewable electricity—requires about 9 litres of purified water for every kilogram of hydrogen.  However, to ensure the efficiency and lifespan of electrolysers, the water must be treated and deionized, pushing total usage to between 20 and 25 litres per kilogram.

Adding to the picture are carbon capture and storage (CCS) technologies, designed to reduce emissions from coal or gas power plants. Although valuable from a climate perspective, these systems can increase water consumption by up to 90 percent per megawatt-hour due to the energy-intensive processes of gas compression, cooling, and treatment

Desalination and Reuses: Technologies to Prevent Waste

To make water use in energy—and energy use in water—more sustainable, desalination and reuse technologies present major opportunities. Desalination can provide large volumes of water without impacting aquifers or freshwater reserves. Technologies such as reverse osmosis have significantly reduced energy consumption and, combined with re-mineralization systems, can reliably meet the water needs of emerging energy solutions. Similarly, the treatment of wastewater allows for freshwater savings and reduced withdrawals, creating a virtuous cycle in the protection of water resources. 

Conclusions

The connection between water and energy is a crucial factor to consider in climate and sustainability strategies. It’s not just about developing low-emission energy sources but doing so without putting additional pressure on an already stressed water supply. Likewise, ensuring access to clean water must take into account the overall balance of the energy system.

Ultimately, sustainability isn’t measured only by the tons of CO2 saved, but also by our ability to preserve vital resources for future generations.