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To expand global access to clean water, we need clean nuclear energy.
In the pursuit of a zero-carbon world, clean energy and clean water are united goals. As the world explores ways to shift to clean energy, we must also consider ways to accelerate change to solve the global water and sanitation crisis.
By deploying nuclear energy with speed and at scale, we can make clean energy – and clean, sanitary water – vastly more accessible.
Fueled by nuclear power, desalination provides an opportunity to accelerate these changes, and transform the ways we manage our water resources.
Desalination is the process of removing salt and other impurities from seawater and other “non-potable” water, or water that is unsuitable for human consumption. While desalination is a fairly straightforward concept, it’s an energy-intensive and expensive process.
Typically, desalination is performed by plants that separate “saline” or salty water into two parts: one with a lower concentration of salt (the “treated” water) and one with a much higher salt concentration than the original water, described as the brine concentrate or simply “concentrate.”
Most desalination plants use either thermal technology, which heats water and then captures the condensation, or reverse osmosis, which forces seawater through tiny membrane pores. This process traps salt molecules while permitting smaller water molecules to pass through the membrane. Within these two categories, there are several types of methods with various differences and tradeoffs.
While both methods of desalination produce clean, drinkable water, they require massive quantities of energy and primarily run on carbon-intensive energy sources.
Clean water is non-negotiable – and in an ideal world, so is clean energy. Using nuclear to fuel desalination, we won’t need to compromise with dirty energy sources.
According to the U.S. Department of Energy (DOE), large-scale desalination systems – which can provide tens of million gallons of fresh, desalinated water per day – require tens of megawatts of energy to run. The unparalleled energy density and a24/7 reliability of nuclear power make it uniquely capable of providing such copious amounts of energy, for large-scale desalination.
How can we visualize this quantity of energy; and in the process of desalination, where does all that energy go? For reference, a megawatt equates to about the same amount of electricity consumed by 400 to 900 homes in a year, when this electricity is produced by a conventional generator.
However, there is a key difference between the literal definition of megawatts – literally, 1 million watts – and average megawatts. Average megawatts express the maximum amount of power that a generating plant can produce in an average year; therefore, this average may be less than the actual energy capacity of a plant. Depending on the type of energy generator, average household electricity consumption, sunshine, temperature, and wind, average megawatts can vary dramatically by region.
Large desalination systems require tens of megawatts to separate salts and other dissolved solids from water. Smaller desalination systems still require tens to hundreds of kilowatts – equal to 1,000 watts each – which are used to operate pressurized pumps. In operation, the pressure required to separate solids from water is roughly two times the osmotic pressure, according to the DOE.
In short: desalination requires a lot of energy – and, in turn, significant fundingOne study estimates that the energy required to run these high-pressure pumps accounts for approximately 25-40% of the overall cost of desalinated water.
Researchers are working to reduce the costs of desalination, with an emphasis on the high cost of brine disposal. In 2019, the Massachusetts Institute of Technology announced a process that could turn concentrated brine – the waste product of desalination – into useful chemicals like sodium hydroxide, which can be used to pretreat seawater before it enters a desalination plant.
Other brine management strategies seek to achieve “zero liquid discharge,” in which desalination produces high-quality water with a recovery rate of 95-99%. Any remaining solutes are compressed into solids, which can be further processed to produce useful substances.
Guided by a philosophy that mirrors our approach at Last Energy, some researchers argue that the solution is to reduce manufacturing costs of various components – not to improve the performance of existing desalination technology. As of today, however, most of these strategies are still in development, and the price of new desalination technologies often exceeds their benefits.
In its current form, we don’t necessarily “need” desalination: instead, we need its sustainable, energy-efficient counterpart. If we briefly set aside its economic, environmental, and energetic demands, desalination has the potential to resolve growing challenges with global water supply.
Just within the U.S., the west coast is experiencing one of its worst droughts in at least 1,200 years. As of March 2023, 31.45% of the U.S. and Puerto Rico and 37.65% of the lower 48 states are in drought, according to the U.S. Drought Monitor.
Globally, clean water sources are also drying up fast. The combination of high water demand and inadequate supply has led to dire water shortages in several regions, including the Middle East, North Africa, and Australia.
In 2018, South Africa’s Cape Town started counting down to “Day Zero”: the moment when the city completely runs out of drinking water. These scenarios may seem apocalyptic, but they create an incentive to invest in more sustainable, large-scale desalination systems. Despite the potential to scale, desalination currently supplies only around 1% of the world’s drinking water, according to the International Water Association.
Water is life. Globally, as high-quality water resources become scarce, we need a technology that supplies clean, affordable water at scale, and without the challenges created by current desalination technology.
Today, desalination poses major energy demands as well as a significant environmental impact: one that can overshadow its ability to provide clean, affordable water. In the process of removing salt from saltwater, desalination plants produce carbon emissions and brine: the primary waste product of desalination.
Based on a 2018 study of desalination, global brine production is about 141.5 million cubic meters per day: approximately 50% greater than the total volume of fresh, desalinated water produced globally. This brine can’t simply sit in desalination plants; instead, it’s often dumped into natural bodies of water.
As advances in brine management continue to develop, we can look at how to alleviate the first environmental concern: carbon emissions.
Many researchers discuss the potential of renewably powered desalination; but even then, renewable energy sources like solar and wind are intermittent, meaning their operations are subject to the whims of weather, climate, and seasons.
While some regions intend to replace conventional systems with renewably powered desalination, these energy sources are additionally limited by high operating costs. The feasibility of renewable desalination largely depends on the cost of renewable energy, which is generally higher than the cost of conventional desalination powered by fossil fuels.
“Conventional” nuclear plants – large, complex builds – cannot respond to the issues that plague conventional desalination. But small modular reactors (SMRs) can meet global demands for fresh water, and several nuclear companies are developing reactors with this vision in mind.
Nuclear energy is already being used for desalination, and it’s cost-competitive relative to desalination powered by fossil fuels. It’s also carbon-free and, unlike renewably powered plants, SMRs can be sited virtually anywhere in the world with minimal geographic footprints.
At Last Energy, the PWR-20 reactor design can surmount the obstacles posed by current desalination technology. Using nuclear energy for desalination, water users (A.K.A., everyone) benefit from the following outcomes:
In arid regions like South Africa, the benefits of nuclear desalination are unfolding in real-time. 10 African countries are actively exploring the use of nuclear for desalination and other vital technologies. To meet the immediate demand for water, these regions need a quick, effective solution: nuclear energy.
Compared to renewables, nuclear can supply consistent power to augment power shortfalls, which are increasingly common in the South African energy grid. To ensure reliable access to clean water, countries need and deserve reliable electricity – and as a baseload power, nuclear supplies a year-round solution.
Even with nuclear as its primary energy source, desalination still produces high-salinity brine and demands high amounts of energy to separate salt from water. But given the cost savings of compact reactor designs and the natural abundance of uranium, nuclear grants us time to develop technologies that can manage desalination waste.
Based on current estimates, nuclear plants would more than pay for themselves by their own revenue. To respond to water crises across the globe, we need to build many more SMRs; but once they’re up and running, these plants are relatively cheap to operate.
The newest fleet of SMRs go one step ahead by producing both thermal and electrical energy without emitting greenhouse gases. As zero-carbon energy providers, SMRs could power both membrane-based desalination systems – which perform reverse osmosis via electricity – and thermal desalination systems, which run on thermal energy. Like many worthwhile investments, there may be obstacles in implementation. But there are already around 20,000 nuclear desalination plants worldwide, and there’s potential for much greater use.
With this framework in place, nuclear technology challenges us to envision a world with more abundant energy – and more abundant, accessible, and safe water.
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