The desalination of seawater through nuclear energy, an option for the future

Inequality in water distribution

If the total amount of available water was distributed equally among all the planet's inhabitants, each person would have 16,000 liters of water per day, or 5,800 m³ of water per year. Unfortunately, fresh water is not evenly distributed. In Iceland, for instance, rainfall produces 1.4 million liters per person per day and there are no problems with supply. This situation is quite different in Kuwait, where the amount of rainwater produces an average of only 16 liters per day per person.

The United Nations (UN) classifies the levels of water scarcity in three categories:

• Hydric stress: when the amount of available water in a country is below 4,600 liters per day and person (1,700 m³ per year).
• Water scarcity: when this quantity is below 2,700 liters per day and person.
• Absolute water scarcity: when rainfall falls below the threshold of 1,400 liters per inhabitant per day

According to this definition, 49 countries are affected by hydric stress to varying degrees, 9 of them have water scarcity and 21 absolute scarcity. Countries with high levels of hydric stress are in North Africa or Asia (western, southern and central). Some two billion people live in countries with high hydric stress, and about four billion (almost half of the world's population) suffer from severe water shortages for at least one month a year.

Use of unconventional water resources

In its 2019 Sustainable Development Goals Report, the UN indicates that in the past century global water consumption has more than doubled with respect to the population growth rate. Combined with socioeconomic development, changing consumption patterns and climate change, this increases the demand for water. Conventional water sources such as precipitation and snowmelt can no longer suffice to meet the needs of the populations in regions with scarcity.

The use of water and treatment of waste water require electricity for its supply, distribution and transportation. According to a study by the International Energy Agency (IEA), these operations represented approximately 4% of world electricity consumption in 2014. The IEA estimates that by 2040 electricity consumption in the water sector will have doubled.

Technologies for water desalination

There are approximately 16,000 desalination plants in operation in the world. Together, they produce about 95 million m3 of desalinated water per day.

Before the 1980s, 84% of the world's desalinated water was produced using multi-stage flash technology (MSF) and multi-effect technology (ME), and later on membrane technology such as reverse osmosis. In 2000 11.5 million m3 of water were desalinated per day, the same volume as with thermal technologies, and all these technologies together produced 93% of the total desalinated water. Since then, the number and capacity of desalination plants has exponentially increased  while thermal plants have experienced very slow growth.

Energy for the supply and treatment of water

According to the UN, water supply and wastewater treatment produce between 3 and 7% of global greenhouse gas emissions. A large amount of these emissions is caused by generating the energy necessary to operate the systems, or  from the biochemical processes involved in the treatment of water and wastewater.

This amount of energy will increase. IEA forecasts that electricity consumption for desalination will increase to about 345 TWh in 2040, compared to 40 TWh in 2014.

Nuclear power, a low-emissions electricity provider

The first desalination facility attached to a nuclear power plant was built by the Soviet Union in 1973 at the Aktau site (currently Kazakshtan) until its closure. According to the International Atomic Energy Agency (IAEA), Kazakhstan has a nuclear desalination relaunch project in collaboration with Russia. Subsequently, several countries such as India, Japan and Pakistan began to use nuclear units to desalinate seawater in addition to producing electricity. Other countries such as Saudi Arabia, Argentina, China, South Korea, Egypt and Russia have construction projects for nuclear desalination plants.

According to the IAEA, nuclear desalination is a viable option to meet the growing demand for fresh water. IAEA has calculation programs available to Member States, to help them assess the value of nuclear desalination. With these programs they can perform economic and thermodynamic analysis for coupling different energy resources with various desalination processes.

Agua dulce para la agricultura mediante técnicas isotópicas

Agriculture accounts for around 70% of the world's freshwater consumption, but less than half of this water is used efficiently. The rest is lost through evaporation, infiltration and runoff. This water, whether from precipitation or irrigation, carries nutrients, pesticides and chemicals to surface and groundwater, which affects water quality and the environment.

Isotopic and nuclear techniques are helping to improve irrigation and soil management by setting more efficient water use practices. These techniques are being gradually incorporated into agricultural water management, since isotopes such as oxygen-18 and deuterium can help determine the source and movement of water in plants and soils. Scientists can use isotopes to measure how much water a plant consumes, how much it "transpires," and how much evaporates from the ground. This information helps develop strategies to improve crop production, reduce water loss and prevent damage to soils, water, and ecosystems.

En resumen, la tecnología nuclear ofrece una solución ecológica y sostenible para aumentar, optimizar y mejorar los recursos hídricos en todo el planeta, tanto para el consumo como para la agricultura.