Can solar-powered desalination alleviate global water scarcity?

June 5 is World Environment Day (WED), the United Nations’ principal vehicle for encouraging worldwide awareness and action for the environment. The theme for 2014 is Raise your voice, not the sea level. To mark the event, we look at how solar power could be used to alleviate water scarcity.

01 Sandia Labs on Flickr
Photo: Sandia Labs on Flickr

Last April, Saudi Arabia started producing purified water at the world’s largest desalination facility. Costing USD 7.2 billion, the Ras Al-Khair Desalination Plant, northwest of Jubail, has a production capacity of just over 1 million cubic meters (Mm3) of drinking water a day – capable of meeting the needs of the 3.5 million people living in the city of Riyadh. However, this precious freshwater comes at a colossal cost. On average, 15 times more energy is needed to produce desalinized water than what it takes to use other local water sources. In the Gulf States, cheap oil and gas make this economically viable. However, rising concerns about climate change are leading many to question whether desalination has a future.

The greatest need for desalinized water, however, is in countries that have a lot of sunshine. So, if solar energy is used to power the process, could desalination become a more realistic prospect for water-scarce regions? At present, the technologies that would be needed to achieve this are expensive. However, as costs fall and the value of water rises, might there be a point when desalination based on solar energy becomes a smart choice?

That is what two researchers from the International Water Management Institute (IWMI) set out to discover. They looked at the historical trends in desalination and broke up the cost of the process into energy based and non-energy based. Then, by comparing cumulative production and the market price, and assuming that the photovoltaic (PV) technology will be the dominant form of energy used in the desalination process, they worked out the viability of large-scale adoption of desalination in the future for areas within 100 km of the coast.

The results of the study, recently published in the Journal of the American Water Resources Association (JAWRA), show that, in most regions where it is already a reality, desalination becomes viable by 2040. For PV technology, less than 1 million MW per annum growth is required till 2050 to make it affordable. Globally, desalination with renewable energy can become a viable option to replace domestic and industrial water demand in the 100-km coastal belt by 2050.

[pullquote type=”pullquote1″ content=”Currently, one-fifth of the world’s population lives in water-stressed basins” quote_icon=”no” align=”center” cite=”says Aditya Sood, one of the authors of the study.”]Currently, one-fifth of the world’s population lives in water-stressed basins[/pullquote] “By 2030, this could be as much as a third of everyone on the planet. So, the future planning of water resources management needs ‘out-of-the-box’ solutions. As the traditional sources of freshwater run out in many regions, seawater or brackish water will have to fill in the gaps in water supply.”

Huge desalination projects are already springing up everywhere from California to Australia. Globally, there are, perhaps, as many as 20,000 desalination plants producing more than 20,000 m³ of water per day. Tremendous strides have been taken to make the process more energy efficient, but costs are still relatively high. How fast the future growth in production takes place, say the authors, will depend on the investment made in this sector, and also on the policies and incentives given by the governments in different countries to support and encourage these technologies.

Sood urges some caution, however. “The environmental cost of desalination has not been considered in this analysis,” he says. “For instance, discharging hot briny effluent back into the ocean can devastate marine ecosystems. However, in Australia and other countries, strict environmental standards are addressing these issues. If we apply best practices globally, the impacts of large-scale desalination can be mitigated and it could become a viable alternative to other water sources.”

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Sood, A.; Smakhtin, V. 2014. Can desalination and clean energy combined help to alleviate global water scarcity? Journal of the American Water Resources Association (JAWRA). 13p. doi: 10.1111/jawr.12174

This work was funded by the CGIAR Research Programs on: