One-fifth of the world's population has no access to drinking water, and given the expected population growth there will soon be a higher deficit. One solution to this problem is water desalination, a technique that extracts salt from seawater and produces fresh water.
It can generate much more fresh water than what is being currently produced, and also it is more affordable
At present most desalination plants use fossil fuels, and to a lesser degree clean energy. For some time now nuclear energy has been used for desalination processes; however, the potential of nuclear energy is enormous. It can generate much more fresh water than what is being currently produced, and also it is more affordable and does not release greenhouse effect gasses.
With population growth, it will be necessary to set up large-scale desalination projects. According to the International Atomic Energy Agency (IAEA), these projects need large quantities of energy which can only be obtained from nuclear reactors.
The lack of fresh water could be the great global threat for the next decade
The areas that are most affected by the shortage of fresh water are arid and semi-arid areas in Asia and North Africa. In 2002, according to a UNESCO report, the deficit of drinking water in the world was around 230 billion cubic meters/year, and this amount was expected to rise to 2,000 billion by 2025. In fact, a report from the World Economic Forum published in 2015 highlighted the problem and indicated that the lack of fresh water could be the great global threat for the next decade.
According to this report, there are approximately 19,000 desalination plants throughout the world, providing water to municipal and industrial users. Almost half of the global installed desalination capacity is in the Middle East, followed by the European Union with 13%, the United States with 9% and North Africa with 8.5%. Seawater is the most common feed water, since it provides approximately 60% of the installed capacity. Brackish water makes up for about 20%.
Desalination technologies and differences in cost
Most desalination techniques involve a process known as reverse osmosis, where pressure is applied to seawater forcing it through a semipermeable membrane to extract the salt. A second process known as multi-stage desalination uses a steam-based procedure to filter salt and other minerals. The latter is less profitable than osmosis, even though it produces purer water. There are some hybrid plants that use elements from both methods.
Any process that produces fresh water requires a lot of energy, which raises costs. The cost of water varies significantly in different areas of the world. According to the United States Environmental Protection Agency, it is estimated that tap water costs an average of $2 per 1,000 gallons. However, the desalination project at Coquina Coast in Florida calculates the cost at $6.27 - 7.74 per 1,000 gallons.
The difference in cost depends on the source of energy used in the process. With nuclear energy it is possible to achieve an enormous economy of scale, which lowers the cost. A study carried out in Tunisia discovered that the costs of nuclear desalination were from one third to less than half of those related to desalination via fossil fuels, depending on the desalination technology that is used.
At present, desalination plants use mostly fossil fuels, which contributes to increase the levels of greenhouse effect gasses. In December 2015, the initiative "Global Clean Water Desalination Alliance – H2O minus CO2" was presented at the COP21 climate talks in Paris, with a call to its 17 member countries to use clean energy sources in their new desalination plants.
Several countries have implemented nuclear desalination, including India, Japan and Kazakhstan. The latter operated a 750-megawatt thermal power plant for over 25 years. This plant not only generated desalinated water but also produced heat and electricity. Desalination of water with nuclear energy is an established, proven and known technology with thousands of men hours.
As seawater desalination techniques improve and more countries opt to build double-purpose electric plants (co-generation), nuclear plants will need more advanced technologies plants
The future of nuclear desalination
Small nuclear reactors, known as Small Modular Reactors, are the most suitable kind for desalination, often with electricity co-generation with low-pressure steam from the turbine and hot sea water feed from the final cooling system. A small reactor can produce between 80 and 100,000 cubic meters a day.
As seawater desalination techniques improve and more countries opt to build double-purpose electric plants (co-generation), nuclear plants will need more advanced technologies plants, as well as more economical and efficient desalination systems.
Recently, Argentina and North Korea developed plans for a small nuclear reactor specially designed to generate both electricity and fresh water, with an installed thermal power of 5 to 330 megawatts. Russia designed a floating nuclear plant with 80- thermal megawatt power. Small reactor technology could be the key to increase desalination processes with clean nuclear energy.
Although nuclear energy has not yet replaced fossil fuels in water desalination projects, in the past few years it has acquired greater importance thanks to the advance of small nuclear reactor technology and especially as the climate change becomes a greater reason for concern.