The challenges of desalination to alleviate global water stress | Environmental News

According to United Nations data, up to 1.1 billion people suffer from water stress in the world. The organization estimates that of the 1.4 billion cubic kilometers (km³) of water on Earth, only 200,000 km³ is fresh water available for human consumption¹. Faced with this problem, there are many solutions that are considered, studied and developed, one of them being the desalination.

Desalination is an alternative that has come a long way in recent years. It is a process that faces the challenges of reducing costs, avoiding the emission of gases and solving the polluting problems of the brineare main residue. However, it is a good option for alleviate the drought in developing countries if two conditions are met: the elimination, through alliances, of the technological gap, and the adoption of public-private collaboration as a fairer and more efficient model.

The first desalination systems were thermal processes: they used heat to evaporate water and condense it. This system lasted with various improvements until 1965, the year in which the reverse osmosis desalination: the current technology today.

Reverse osmosis: an emerging market

The reverse osmosis system is based on passing seawater through membranes that filter it and trap the salt. It takes a lot of energy to apply the pressure necessary for the water to pass through the membranes, but it is a much more efficient system than thermal distillation, so it is more cost-effective.

Reverse osmosis systems have been significantly improved in recent years, while gaining prominence due to the growing water crisis in many areas of the world.

Accelerated urban growth and the development of tourism in areas with endemic water stress have created favorable contexts for the adoption of desalination. In 2018, there were more than 17,000 desalination plants in the world, and globally, more than 200 million cubic meters (m³) water diaries. Currently, Saudi Arabia is the leading country in desalination: four out of every five liters of fresh water consumed comes from the sea; It is followed by the United Arab Emirates, the USA, Kuwait, Qatar, Japan and Spain.

62.3% of desalinated water is intended for human consumption, via municipal supply; 30.2% are used by the industry; 4.8% the energy sector and 1.8% is used for agricultural irrigation. Cities are the large consumers of desalinated water. Almost all of them are coastal or at sea level, so the energy cost of “raising” the water from the plants is avoided.

Desalination: projection and challenges

In recent years, climate change has increased the expectations placed on desalination and the sector has concentrated a large investment in R+D+i, boosting its growth forecasts. According to a report by The Brainy Insights, the global water desalination market is estimated to grow from $13.5 billion in 2021 to $28.83 billion in 2030, with an annual growth rate of 8.8%.

However, there are still doubts about the sustainability of the process. Although desalination prevents the overexploitation of rivers, aquifers and the dire consequences for the economy of a supply restriction, this still carries a certain gas emission and brine generation. This is one of the challenges of desalination, together with the need to make a system that is intensive in research and technological innovation more competitive.

In any case, desalination implementation strategies must indispensably include alliances between all sectors (agricultural, tourism and industrial, mainly) and public-private collaboration as a development model.

₁ NNUU 2019 figures: https://unesdoc.unesco.org/ark:/48223/pf0000367276_spa

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