By Andrew Reimers and Brittany Speetles
Concerns about global warming and water scarcity have motivated many researchers to consider the potential for nuclear desalination, i.e., integrating a desalination plant with a nuclear power plant, as a means of producing drinkable water. There are numerous benefits to integrating a desalination plant with a nuclear power plant such as carbon-free electricity, low-marginal cost of generating electricity compared to fossil fuels, and a consistent power supply, unlike intermittent renewable electricity sources like wind and solar. Nearly 46 percent of the world’s nuclear power capacity is within fifty miles of a coast according to data from the World Nuclear Association. In the U.S., several nuclear power plants are located near the coasts in states such as California and Florida where large-scale desalination plants have been constructed in the last decade. Thus, for locales with existing nuclear power plants and sufficient demand for desalinated water, nuclear desalination is an attractive option.
Nuclear desalination also has the potential to improve the economics of nuclear power. For example, nuclear desalination could help shield nuclear power plants from low electricity prices because some of the power generating capacity could be used for running the desalination plant instead of being sold into the electricity market below cost. Another possible benefit of nuclear desalination is that uranium could be extracted from concentrated brine more cost-effectively than extracting uranium from seawater, reducing the cost of nuclear fuel. First-order estimates of these benefits, however, suggest that they are likely to be marginal at best.
Regarding the extent to which nuclear plants can be shielded from low electricity prices, even the largest desalination plants in the world do not use enough electricity to make much of a difference. For example, the average power-generating capacity of nuclear power plants within fifty miles of a coast is approximately 2265 MWe, but the largest seawater reverse osmosis plant in the world, the Sorek plant in Israel, only requires around 75 MW to operate at full capacity assuming a specific energy consumption of 3.05 kWh for each cubic meter of freshwater produced by the plant.
In addition to high-purity water, another output of a desalination plant is concentrated brine. Extracting uranium from concentrated brine would likely be more cost effective than extracting uranium from seawater, but it would still be more expensive than conventional uranium production or importing uranium from abroad. Thus, extracting uranium from concentrated brine might only appeal to countries that are intent on having more direct control over their nuclear fuel cycle. For example, seven out of twenty-one countries with nuclear power plants near the coast have to import at least a fraction of their uranium. Even if uranium extraction from concentrated brine were more cost effective than conventional uranium production or importing uranium, this strategy would have a limited impact on the overall economics of running a nuclear power plant. Nuclear fuel is already a relatively minute percentage of the cost of nuclear power compared to other power generation technologies, and raw uranium is only a fraction of the cost of nuclear fuel.
Researchers should continue to investigate nuclear desalination as an economic means of augmenting global water supplies with minimal environmental impact. Nuclear desalination is a particularly attractive concept compared to powering desalination plants with fossil fuel or intermittent electricity sources. Even so, a summary analysis of some of the proposed ways in which nuclear desalination could improve the economics of nuclear power indicates that such benefits are likely to be marginal at best.
Andrew Reimers is a Ph.D. candidate in the Webber Energy Group at the University of Texas at Austin and an energy systems modeling intern at the National Renewable Energy Laboratory. His research focuses on thermodynamic and economic analysis of power generation and water treatment systems. Andrew blogs about current events related to energy and water at andrewreimersblog.com.
Brittany Speetles is a mechanical engineering student at the University of Texas at Austin and a researcher in the Webber Energy Group. Her research involves solar energy, desalination, and food waste management.