Desalination and energy: Tackling water shortages in an energy efficient way
Desalination turns seawater into drinking water but has traditionally been expensive and energy hungry. Falling solar costs are changing that. Saudi Arabia's Al Khafji plant - the world's first large-scale solar-powered desalination facility - has cut emissions by around 91% compared with conventional thermal plants and has supplied millions of cubic metres of fresh water since coming online. As solar becomes one of the cheapest sources of electricity in history, pairing it with desalination is emerging as one of the more credible answers to a worsening global water crisis.
Water covers 71% of the Earth's surface, yet the world is running short of it. The United Nations warned in early 2026 that the planet has entered an era of "water bankruptcy", with roughly 4 billion people experiencing severe water scarcity for at least one month each year, and 2.1 billion still lacking access to safely managed drinking water. As climate change lengthens droughts and populations grow, governments are under mounting pressure to secure new sources of fresh water - and turning to the sea is an obvious, if technically demanding, solution.
Untreated seawater is far too saline for human consumption, so it must pass through energy-intensive desalination plants before it reaches a household tap. Historically, that energy has come from fossil fuels. But the falling cost of solar power is making desalination a genuinely more sustainable prospect than it was even a few years ago.
Who relies on desalination today?
The largest producers of desalinated salt water are Middle Eastern countries. Saudi Arabia, for example, operates some of the largest single facilities on the planet, including Ras Al Khair, and desalination now meets around 60% of the Kingdom's urban water supply. Building desalination infrastructure is often the combined effort of industries across continents. The desalination plant at Yanbu on the Red Sea was built by a consortium consisting of Chinese and Korean companies, while much of the cable for the project was provided by British suppliers like us. Desalination can be achieved by a variety of methods including reverse osmosis where water is pumped through a filter or, as at the Yanbu plant, as multi-stage flash distillation in which water is evaporated and then captured.
Globally, the International Desalination Association puts installed capacity at well over 100 million cubic metres of water per day, produced across more than 16,000 plants in over 170 countries. Analysts expect that capacity to grow by around a quarter between 2025 and 2029 alone, as water-stressed countries from Morocco to India accelerate investment.
The cost problem: why desalination has always been expensive
Desalination is not a cheap fix. A large plant capable of serving around 300,000 people typically costs in the region of $100 million to build, and roughly half of that ongoing expenditure goes on energy. Producing a million gallons of desalinated water can require around 15,000 kilowatt-hours of electricity, several times more than treating an equivalent volume of freshwater.
There are environmental concerns - the energy required for desalination means that it is not a climate-friendly answer to the water crisis; Saudi Arabia’s desalination capacity is largely thanks to the country’s surplus of oil. Furthermore, the actual pipes that collect seawater can be damaging to marine ecosystems, as can the offshore dumping of waste salt from the desalination process.
There have also been expensive failures. The Yuma desalination plant on the US-Mexico border cost over $250 million to build and has never run at full capacity. In Victoria, Australia, a AUD $5.7 billion facility was mothballed almost as soon as it was finished, after the drought that justified its construction ended before it opened. Both are reminders that desalination infrastructure has to be matched carefully to genuine long-term demand, not built in a rush during a crisis.
Solar power is changing the economics
The picture is shifting because the cost of solar generation has fallen dramatically. The International Energy Agency has repeatedly described well-financed utility-scale solar as offering some of the cheapest electricity ever produced - in many markets now undercutting new coal and gas generation entirely. That shift is exactly what's needed to make desalination viable without relying on fossil fuels.
Saudi Arabia has led the way in proving the concept. The Al Khafji Solar Saline Water Reverse Osmosis Plant, in the country's north-east, was the world's first large-scale desalination facility designed to run primarily on solar power. Backed by a 10 MW solar PV array spread across roughly 90 hectares, the plant supplies up to 60,000–90,000 cubic metres of potable water per day - enough for around 150,000 people - and has delivered several million cubic metres of fresh water since opening. Because it generates surplus power during daylight hours to offset overnight demand, it operates as a near zero-carbon facility, cutting emissions by an estimated 91% compared with conventional thermal desalination.
Smaller-scale projects tell a similar story. In Chile's Lluta Valley, the Padre Francisco Napolitano agricultural school built its own renewable-powered desalination plant for a modest US $210,000 - a fraction of the cost of comparable fossil-fuel-powered facilities, and, according to Fundación Chile, notably simple to build and operate.
What's next: membranes, materials and the next generation of plants
Beyond the power source, researchers are also working on the desalination process itself. Most reverse osmosis plants still rely on polymer-based membranes, which are costly to manufacture and become less efficient over time. Graphene oxide membranes have been researched as a potential replacement for over a decade, and recent research continues to push the technology forward - including new "self-heating" graphene oxide composite membranes that use sunlight to drive the filtration process, delivering a 190% increase in water flow while rejecting more than 99.9% of salt in early trials. Commercial-scale deployment is still some way off, but the direction - combining solar energy with next-generation filtration materials - is clear.
The bottom line
There are also promising new technologies, such as a graphene oxide sieve recently developed by a UK-based team of researchers, which could replace the current filtering processes with more efficient methods. Generally, desalination plants employing filtration methods use polymer-based membranes which are costly to produce and are energy heavy to run. Though this new filtering method is still undergoing testing and investigations into cost effective production, the goal is to be able to desalinate with minimal energy input.
It will still be some time until solar energy can compete with fossil fuels when it comes to desalination, but as the water crisis intensifies and solar power becomes cheaper, we should expect to see more of the type of projects that are currently being trialled in Saudi Arabia and Chile. And while there are numerous problems associated with getting our drinking water from the sea, as new technologies reduce environmental and monetary costs, desalination may end up being the best, as well as the most obvious, solution to our pending water crisis.
Eland Cables supplies the cable and infrastructure behind desalination and renewable energy projects worldwide, from solar farms to seawater treatment facilities. Explore our case studies or get in touch to discuss cabling for your next infrastructure project.
Frequently asked questions about desalination
How much energy does desalination use?
A large desalination plant serving around 300,000 people can cost roughly $100 million to build, with about half of ongoing costs going toward energy. Producing a million gallons of desalinated water can require around 15,000 kilowatt-hours of electricity.
What is the world's first solar-powered desalination plant?
The Al Khafji Solar Saline Water Reverse Osmosis Plant in Saudi Arabia, which began operating in 2017–2018, is widely recognised as the world's first large-scale desalination facility to run primarily on solar power.
Which countries rely most on desalination?
Saudi Arabia, Israel and the UAE are among the world's largest users of desalinated water, together with other Gulf states. The Middle East and North Africa region accounts for over half of global installed desalination capacity.
Is desalination bad for the environment?
Conventional, fossil-fuel-powered desalination is energy-intensive and produces waste brine that can harm marine ecosystems if not managed carefully. Solar-powered desalination significantly reduces the carbon footprint, though brine disposal remains a challenge industry-wide.
