Hydrogen's Potential in Desalination: Providing Clean Water for Communities

The world is facing a severe water crisis. According to the United Nations, over 2 billion people live in countries experiencing high water stress, a number expected to rise due to climate change, population growth, and urbanisation. Finding sustainable and efficient solutions to water scarcity is one of the most pressing challenges of our time.

Desalination, the process of removing salt and other minerals from seawater or brackish water, has long been considered a viable solution to provide clean water for communities worldwide. However, traditional desalination methods often rely on energy-intensive and polluting technologies, contributing to greenhouse gas emissions and environmental degradation. The growing demand for desalination has raised concerns about these methods' long-term sustainability and ecological impact.

Contrary to the idea that hydrogen is directly used as a power source for desalination, its actual role is more nuanced and is closely tied to the production process. Large-scale hydrogen projects, like those in NEOM (Saudi Arabia), Namibia, and Chile, incorporate desalination to produce the pure water necessary for hydrogen electrolysis.

An integrated water purification system is essential when building significant hydrogen projects because electrolysers require highly pure water to produce hydrogen efficiently.

Reverse osmosis (RO) is often the preferred method for water purification in these setups, as it effectively removes impurities and salt. In such cases, RO serves a dual purpose: supplying purified water for hydrogen production and desalinating water for surrounding communities, efficiently using resources.

Today, two primary desalination methods are used: thermal and membrane desalination. Each method employs different techniques to remove salt and impurities from seawater or brackish water.

Thermal Desalination

• Multi-Stage Flash (MSF) Distillation: Multi-Stage Flash (MSF) Distillation: This process involves heating seawater and passing it through multiple stages with progressively lower pressures, causing the water to 'flash' into steam. The steam is then condensed to produce fresh water. MSF accounts for around 26% of desalinated water production worldwide, but it is energy-intensive, typically requiring 23–27 kWh/m³ of distilled water. Many MSF plants use waste heat from power plants in a cogeneration setup to reduce energy costs. Despite this efficiency improvement, MSF remains more expensive and less environmentally friendly than newer desalination technologies like reverse osmosis.​
• Multi-Effect Distillation (MED): Multi-Effect Distillation (MED): Similar to MSF, MED involves heating seawater in multiple stages or 'effects,' where the vapour produced in one stage is used to heat the next, allowing efficient reuse of thermal energy. MED operates at lower temperatures (typically below 70°C), reducing issues with scaling and corrosion. It is more energy-efficient than MSF, with a significantly lower electrical consumption of less than 1.0 kWh/m³. However, it still requires substantial thermal energy, often supplied by steam from power plants or industrial processes.
• Vapor Compression Distillation (VCD): Vapor Compression Distillation (VCD): This process involves using either mechanical or thermal energy to compress and heat the vapour, which is then condensed into freshwater. There are two main types: Mechanical Vapor Recompression (MVR), which uses a mechanically driven compressor and is more energy-efficient, and Thermal Compression, which utilises steam ejectors. VCD is particularly suitable for smaller-scale applications such as resorts, industries, and drilling sites due to its simple construction, reliability, and higher energy efficiency than MSF and MED.

Membrane Desalination

Membrane desalination uses semi-permeable membranes to separate salt and impurities from water. The most widely used membrane desalination methods are:

• Reverse Osmosis (RO): Reverse Osmosis (RO): The most widely used desalination technology, RO, involves forcing seawater through a semi-permeable membrane under high pressure, allowing freshwater to pass through while retaining salt and impurities. While RO is more energy-efficient than thermal desalination methods, it still requires significant electricity, typically around 3.5 to 4.5 kWh per cubic meter of water. Despite being energy-intensive, it remains more efficient than methods like Multi-Stage Flash (MSF) and Multi-Effect Distillation (MED)​.
• Electrodialysis (ED): This desalination process uses an electric field to move salt ions through ion exchange membranes, effectively separating them from the water. ED is particularly suited for brackish water desalination, especially for water with a salt concentration between 2,000 and 15,000 ppm. However, increased energy requirements make seawater with higher salt content less efficient. ED offers tunability and lower operational pressure than reverse osmosis (RO), making it a viable option for specific industrial applications.

Traditional desalination methods rely on massive amounts of energy. This high energy consumption is due to high-pressure pumps, pre-treatment and post-treatment processes, and maintenance operations.

The production of energy required for desalination is often linked to greenhouse gas emissions, which contribute to climate change. According to the International Energy Agency (IEA), the energy sector is responsible for over 60% of global GHG emissions, with the power sector being the most significant contributor.

The environmental impact of traditional desalination methods extends beyond energy consumption and GHG emissions. Some of the hidden costs include:

- Brine discharge harming marine life and ecosystems

- Chemical usage contaminating water and harming aquatic life

- Intakes and outfalls disrupting natural habitats

Large-scale hydrogen projects offer an opportunity to integrate desalination processes effectively. By using the same water purification facilities for both hydrogen production and desalination, resources can be optimised, and costs can be reduced.

A Synergetic Solution for Clean Water

Hydrogen production and desalination integration offer a sustainable solution for clean water production. Leveraging this synergetic relationship can optimise resources, reduce costs, and provide a more efficient and sustainable way to produce clean water for communities worldwide.

Here’s how this works:

Hydrogen production through electrolysis requires highly purified water. Reverse Osmosis (RO) systems installed in hydrogen projects handle this purification process, ensuring the electrolysers operate efficiently. The same RO system can be scaled to serve a broader purpose, providing desalinated water for communities and addressing water scarcity.

The integration of hydrogen into desalination processes offers several significant advantages:

1. Decarbonisation: Integrating green hydrogen production with desalination can significantly reduce environmental impact. These combined systems can operate with minimal greenhouse gas emissions by using renewable energy sources for hydrogen production and desalinating water for hydrogen electrolysis.

2. Energy Storage and Flexibility: Hydrogen is an excellent energy storage medium, allowing surplus renewable energy to be stored and used when needed.

3. Reduced Environmental Impact: Integrating hydrogen into desalination processes can mitigate some environmental issues associated with conventional desalination.

Several projects worldwide demonstrate how hydrogen can power desalination plants, making the process more sustainable, efficient, and accessible.

One of the most ambitious and advanced hydrogen-powered desalination projects is in NEOM, a futuristic megacity under development in Saudi Arabia. NEOM aims to be entirely powered by renewable energy, and green hydrogen is a cornerstone of its energy strategy.

Namibia is developing one of the world’s most extensive green hydrogen projects. These initiatives are centred around a significant $9.4 billion project, which aims to generate about 2 million tonnes of green ammonia annually by the decade's end.

The project will utilise a desalination plant to provide fresh water for the electrolysers, a crucial component in the production of green hydrogen. This desalination plant not only supports the hydrogen project but also has the potential to provide fresh water for local communities, addressing a critical resource need in the region.

This project will employ around 7 GW of renewable energy and 3 GW of electrolyser capacity, potentially cutting 5-6 million tonnes of CO2 emissions each year. This is substantial given that Namibia’s total emissions in 2021 were 4.01 million tonnes.

The project is expected to create 15,000 jobs during construction and 3,000 permanent positions, with a commitment to hire 90% of these roles locally. Namibia aims to become a leader in the green hydrogen market and an exporter of green hydrogen to enhance energy security and sustainable energy transition​ Global African Hydrogen Summit 2024

The most notable project in Namibia is the $10 billion Hyphen Hydrogen Energy initiative, a joint venture between Enertrag and Nicholas Holdings. This gigawatt-scale project has recently received significant support from the German government. It aims to produce 350,000 tonnes of green hydrogen and 2 million tonnes of green ammonia annually before the end of the decade, with full-scale operation expected by 2029​ Mining Weekly

Chile’s green hydrogen projects also incorporate desalination, using RO systems to purify seawater for electrolysis. The Green Hydrogen Action Plan aims to reduce costs by 2030 and position Chile as a competitive producer and exporter by 2040.

Over 50 projects are in different phases, mainly in the Antofagasta and Magallanes regions. This plan includes establishing the industry's development, promoting scientific research, and providing financial incentives. Government of Chile

Additionally, the World Bank approved a $150 million loan to promote investment in green hydrogen projects in Chile, supporting green growth and the country's commitment to carbon neutrality by 2050. This project aims to benefit local communities and create green jobs while decarbonising industries​ World Bank

Western Australia is another example of how hydrogen-powered desalination is gaining traction as a sustainable solution for water-scarce regions. In collaboration with various stakeholders, the Australian government invests in hydrogen infrastructure to support desalination projects.

In the Netherlands, the Port of Rotterdam is leading a green hydrogen desalination initiative as part of its broader goal to become a sustainable energy hub. This project integrates green hydrogen production with desalination to create a self-sufficient water and energy system.

While hydrogen-powered desalination presents an exciting opportunity to tackle water scarcity sustainably, it faces several challenges:

1. High Energy Requirements: Solutions include advancements in electrolyser technology and integration with renewable energy sources.

2. Water-Energy Nexus: Approaches involve using non-traditional water sources for electrolysis and developing advanced energy storage technologies.

3. Durability and Maintenance of Infrastructure: Solutions include researching advanced materials and coatings and implementing predictive maintenance and monitoring technologies.

1. High Initial Investment Costs: Potential solutions include government incentives and subsidies, public-private partnerships, carbon credits and green financing options.

2. Cost of Hydrogen Production: Economies of scale and technological innovations are expected to help lower hydrogen production costs over time.

1. Ecological Impact of Brine Disposal: Solutions include brine valorisation and advanced discharge techniques.

2. Regulatory and Policy Hurdles: Establishing global standards and supportive policy frameworks can help overcome these challenges.

Hydrogen-powered desalination presents a promising solution to the global water scarcity crisis. By addressing the environmental and energy-related concerns associated with traditional desalination methods, hydrogen has the potential to transform how we produce clean water for communities worldwide.

The path forward requires a multifaceted approach involving technological innovation, policy support, financial investment, and community engagement. While obstacles remain, the potential benefits of hydrogen-powered desalination—providing clean, sustainable water for communities worldwide—make it a goal worth pursuing.

Whether you're looking to implement a small-scale hydrogen desalination project or integrate hydrogen technology into existing large-scale operations, Hydrogenera's team of experts can guide you through the process.

Contact Hydrogenera today to learn how hydrogen technology can revolutionise your approach to clean water production and contribute to a more sustainable future.