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Water use for UK hydrogen energy systems

How will low-carbon technologies, such as green hydrogen, and the changing climate impact water demand needed to scale the energy transition?


The production of almost all types of energy relies on the water required for the extraction of raw materials, steam generation, hydrogen production, carbon capture and storage, cultivation of crops for biofuels, and cooling for thermal processes. However, some renewable power systems, such as wind and solar PV, require very little water.

In our UK Energy Transition Outlook 2024, we forecast that as we move towards 2040 and beyond, the energy split in the UK will shift so that electricity will deliver around 50% of the final energy demand. Renewable wind and solar generation will account for nearly a third of total primary energy supply. The shift to new low-carbon technologies will change the demand for water and it will remain a key challenge for future low-carbon energy systems.


Producing green hydrogen

Hydrogen is likely to be an important part of the energy mix in the future. Although it is the most abundant element on earth, it is normally combined with other elements, such as oxygen or carbon. Hydrogen therefore needs to be extracted from either water (using low-carbon electricity) or by reforming fossil-fuel hydrocarbons in the presence of steam. For hydrogen to be a low-carbon fuel, the electricity for electrolysis needs to be low-carbon, and carbon capture and storage (CCS) needs to be part of reforming fossil fuels.  


Primary Water

Primary water is defined as water that is consumed during a process. For example, green hydrogen is produced by breaking down water molecules into hydrogen and oxygen and this water is lost to the environment. Blue hydrogen also involves the breaking down of water molecules in the presence of hydrocarbons to produce hydrogen and carbon dioxide. The chemical reactions around hydrogen production using primary water are shown in the infographic (see Figure 2). The actual quantities of water required will be slightly greater than the theoretical values as shown in Figure 1 – this is due to losses during water purification and inherent inefficiencies in blue and green industrial process plant. 

Note that when hydrogen is burned, it combines with oxygen in the air to form water which released back into the environment.

Figure 1: Water demand for hydrogen production by technology


Secondary Water

Secondary water is defined as the water required for cooling – this water is returned to the environment (often a river) although it may be returned at a higher temperature or at a slightly different location. Other secondary water uses might include steam or water injection in the gas turbine, or air inlet cooling.


The importance of water

The role of water in the energy transition is shown in Figure 2. Primary water is largely required for hydrogen production and its use will rise 5-fold by 2050. Secondary water is required in all forms of energy generation; growing and using biomass; and carbon capture processes. Although secondary water is returned to the environment (for example, cooling water taken from rivers or the sea and returned to them), the quantities required are five to ten times greater than primary water and, most importantly, the power generators and CCS plant cannot run without it. One of the most water-intensive processes is BECCS (bioenergy with CCS), though on the positive side this creates net negative carbon emissions. Also, post-combustion CCS plant installed on coal- and gas-fired power plant decreases the efficiency of electricity production.

Figure 2: Water in the energy transition


Impact of climate change on water supplies

Whilst demand for water is projected to increase, supply will be impacted by climate change in both quantity and security. The frequency and intensity of natural disasters and extreme weather events will:


  • Influence when, where and how much precipitation falls.

  • Affect aquifers as the ground more effectively accepts water during prolonged steady rain rather than short intense periods, which can increase the risk of flooding and reduce the amount of water that is stored.

  • Increase temperatures which will cause more evaporation and reduce available surface water sources, such as rivers, lakes, and reservoirs.

  • Increase atmospheric water vapour resulting in more frequent, intense rainfall and more frequent floods which can damage water quality.

  • Warm the oceans leading to rising sea levels – this can cause saltwater to contaminate coastal freshwater supplies, such as aquifers.

  • Increase the loss of freshwater glaciers supplying waterways.

  • Decrease snowfall which can reduce the supply of water following the winter.


Water supply and demand in the UK

Climate change is expected to significantly impact water resources in the UK, particularly changing precipitation patterns, increasing the risk of flooding, water quality and impacting ecology of aquatic ecosystems and freshwater habitats.


But climate change could also affect the availability of water resources for domestic and industrial use, energy production, and agricultural use. Changes in precipitation patterns, combined with increased evaporation due to higher temperatures, can alter the timing and quantity of water available for extraction from rivers, lakes, and groundwater sources. This can pose challenges for water resource management and may require the development of adaptive strategies to ensure water security in the face of changing climate conditions.


It’s worth highlighting five key points about UK water supply and demand:


  1. Water is crucial to almost every aspect of energy supply, from fossil fuel extraction and processing, biofuels cultivation and electricity generation.

  2. Reliable access to usable water sources is a worldwide concern and will affect the feasibility of both hydrogen projects and projects in the wider energy sector. Availability of suitable water resources is already having an impact on energy production and reliability, affecting a wide variety of locations and technologies.

  3. The availability of water resources to supply new hydrogen production will ultimately be contingent on the selected location and scale of production. The identification and evaluation of suitable water supply sources should be a key consideration when deciding the location and design parameters of a hydrogen production plant. Climate change is already having an impact on water supply, security, and demand — this is likely to get worse in the future.

  4. As the share of renewable power in the energy supply increases, replacing gas-fired power, the demand for cooling water at gas-fired power stations will correspondingly decrease. Despite this, water demand will remain above current day figures, as primary water demand for hydrogen production and secondary water demand for nuclear power cooling increase over time. The fuels or technologies used to achieve the energy transition, if not properly managed, may increase water stress or be limited by it.

  5. Water usage for energy production in the UK is projected to reduce until 2025, after which it will increase out to 2050. This is attributed to an increase of primary water demand for hydrogen production and secondary water demand for nuclear power cooling and carbon capture technology.


Overall, climate change poses significant challenges for water management and requires proactive measures to mitigate its impacts, including the development of resilient infrastructure, sustainable water use practices, and adaptation strategies to cope with changing hydrological conditions.


The UK already faces several water infrastructure challenges, including aging infrastructure, leakage, water quality, flood risk management, water scarcity in certain regions, resilience to climate change, and increasing population demands. Addressing these water infrastructure challenges requires coordinated efforts from government agencies, water utilities, stakeholders, and the public.


Investing in modernizing and upgrading water infrastructure, improving water efficiency and conservation measures, enhancing flood risk management, and promoting sustainable water management practices are essential for ensuring a reliable, safe, and resilient water supply for the UK's population and ecosystems, and the scaling of the energy transition.

Written by Sarah Kimpton, Vice President, Energy Transition & Innovation Development, DNV

Sarah is the Vice President, Energy Transition & Innovation Development for DNV’s Energy Systems business in the UK & Ireland. Sarah has over 30 years’ experience working as a consultant to the natural gas industry, focusing on the impacts of gas quality on network operation, customers, and measurement systems. Together with colleagues at DNV, Sarah works closely with the gas networks to demonstrate whether it is safe and possible to replace natural gas with low-carbon hydrogen. Sarah is a Chemist and holds a BSc and PhD from University College London



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