Quenching the world's thirst: The impact of water desalination technology

Authored by HDI

Water scarcity is one of the world’s most critical challenges, growing increasingly urgent due to climate change and rising population numbers. Implementing innovative desalination solutions and sustainable practices can alleviate the pressure on people and the environment

Only 3 per cent of the planet’s water is fresh water, most of which is difficult to access. According to the UN, agriculture accounts for 72 per cent of global water withdrawals, while municipalities and the industrial sector use the remaining 28 per cent. Factors such as rising temperatures, pollution, sea level rise, urbanisation, and population growth contribute to the deteriorating quantity and quality of water resources.

Experts warn that by 2030, 1.8 billion people could face “absolute water scarcity,” with global freshwater demand exceeding supply by 40 per cent. Absolute water scarcity occurs when water demand surpasses available supply to the point where basic human needs cannot be met. Regions like the Middle East and North Africa are particularly vulnerable due to their arid climates and limited alternative water sources. Even parts of Europe are not immune to regular water scarcity events. The shortages increasingly affect businesses worldwide – in addition to people and wildlife.

As water scarcity reaches critical levels, desalination technologies are becoming increasingly important. Desalination, the process of removing salt and impurities from seawater, holds the potential to provide a sustainable source of fresh water to regions in need. 

Desalination: High demand in the Middle East

According to the World Bank, conventional methods to manage water demand, such as improving agricultural productivity and enhancing industrial and municipal efficiency, are progressing too slowly to meet the widening supply-demand gap. Even with innovations like treated wastewater reuse, only half of the gap would be addressed. Desalination, though generally expensive and complex, is a promising solution requiring strategically sound implementation. It’s ideally used in areas where other solutions are not viable and where it can supply high-quality potable water for large cities, for example.

Currently, water desalination is particularly crucial in arid regions, providing about 70 per cent of domestic water needs in the Middle East and North Africa, with Saudi Arabia leading as the largest producer of desalinated water. The Saudi Water Authority recently received multiple awards from the Guinness Book of World Records, recognising the world’s largest desalination plant at Ras Al-Khair, with a daily production capacity of nearly 3 million cubic metres. In Israel, large-scale desalination accounts for 85 per cent of all potable water supplied by municipal and regional utilities.

However, despite its importance in addressing acute water shortages in arid regions, desalination currently supplies less than 1 per cent of the world’s water.

Desalination technology advancements

The dominant desalination technologies are multi-stage flash (MSF) distillation and reverse osmosis (RO), with RO being used in 84 per cent of desalination plants and accounting for 69 per cent of global desalinated water production. Reverse osmosis water desalination works by pushing seawater through semi-permeable membranes under high pressure. These membranes allow water molecules to pass while blocking salts and other impurities. RO is the dominant desalination technology due to its higher efficiency, lower energy consumption compared to other methods, and advancements in membrane technology that significantly reduce costs. However, the still relatively high cost of desalination compared to other water purification methods remains a significant barrier to its widespread adoption. 

Nevertheless, its scalability and effectiveness currently make RO the preferred choice for desalination plants worldwide. Industry leaders and researchers have developed membranes with higher permeability and greater durability, allowing increased water flux while using less energy. For instance, polyamide reverse osmosis (PA-RO) membranes achieve high water permeability and salt rejection, making them essential for efficient desalination processes​​​. Additionally, enhanced energy recovery technologies, such as those developed by Energy Recovery Systems, capture and reuse energy from the high-pressure brine stream. This approach significantly lowers overall energy requirements and makes the process more cost-effective​.

Another breakthrough is the development of an advanced solar-powered desalination system by researchers at MIT. This innovative system uses multiple layers of evaporators and condensers to improve the efficiency of water desalination. In addition, by harnessing solar energy, the system passively separates salt from water, preventing salt accumulation and ensuring continuous operation. The system mimics natural ocean convection processes to enhance water circulation, which increases the desalination rate and maintains high salt rejection. This design allows the system to produce freshwater more cheaply than conventional methods.

Energy and environmental considerations

Despite technological advancements, desalination remains more energy-intensive than other water purification methods. Reverse osmosis (RO), the most common desalination process, typically consumes about 3 to 4 kilowatt-hours (kWh) of energy per cubic meter of produced fresh water, compared to only 0.2 to 0.4 kWh for traditional water treatment processes​​​​.

Other desalination methods consume even more energy, which translates to higher costs and environmental impacts, as most of the energy currently comes from fossil fuels. Although renewable energy integration is increasing, it still accounts for only a small fraction of desalination energy use. To address these challenges, innovative projects like NEOM, a futuristic city in Saudi Arabia, are leading the way. NEOM is constructing a cutting-edge desalination plant and waste-to-minerals facility powered entirely by renewable energy. This plant aims for more than 60 per cent water recovery and enhanced efficiencies, potentially transforming brine management and reducing environmental impact. 

Another challenge is the environmental impact of brine production. Brine, a byproduct of desalination, is high in salt and pollutants. However, some research suggests that economic opportunities may be found in brine by extracting valuable elements such as uranium, lithium, magnesium, and boron. For instance, the SEA4VALUE project, an EU initiative, focuses on recovering critical raw materials from brine using advanced separation technologies. Globally, the extraction of these elements could generate significant revenue. This transformation of waste into valuable resources not only offsets desalination costs but also promotes sustainable practices and resource efficiency. In the long run, that will have to be the way forward.