Dubai announced this February that it would begin using solar energy, namely, from photovoltaic (PV) cells, to power reverse osmosis desalination plants to produce 305 million gallons per day (MIGD) of potable water by 2030. Dubai Electricity and Water Authority (DEWA), a government-owned utility, hopes to use 100 percent renewable energy to desalinate water and save $13 billion by that year.
It is an ambitious goal for the sheikhdom that relies on 470 MIGD of desalinated water through an extremely energy-intensive process that currently only uses fossil fuels. The decision underpinning Dubai’s move was a successful run of a pilot program to desalinate water in Ghantoot, Abu Dhabi, in 2016 with the help of 100 percent solar energy. Now DEWA is planning to reach an industrial scale with the solar technology.
Abu Dhabi is on the same path. On May 13, 2019, Abu Dhabi reached a deal with Spanish company Abengoa to build the world’s largest reverse osmosis desalination plant powered by solar energy, which will aim to provide fresh water to four and a half million people in this emirate. The level of water desalination in the United Arab Emirates (UAE) is one of the highest in the Middle East and North Africa, hovering at around 24 percent. The transition to clean energy for water desalination is part of Dubai and Abu Dhabi’s overall decarbonization efforts. The UAE aims to increase the share of clean energy in its total energy mix up to 50 percent by 2050 and decarbonize the electricity sector by 70 percent, as part of its Energy Strategy 2050 plan. Solar-powered reverse osmosis desalination has also generated acute interest in Saudi Arabia. The Saudis plan to launch a commercial solar desalination plant by 2021.
Developed in the 1950s, reverse osmosis technology, which purifies water by using permeable membranes to remove unwanted chemicals, is gaining ground in the Middle East, where fossil fuel-run thermal plants account for about 90 percent of their desalination requirements. Because reverse osmosis is relatively more energy-efficient than thermal desalination, it is starting to displace thermal plants in the Middle East.
The sun-drenched Arabian Gulf nations have one of the highest levels of solar irradiance in the world. At this juncture, the levelized cost of electricity (LCOE) from solar PV projects in Saudi Arabia and the UAE is already as low as $0.03 kilowatts per hour (kWh). By comparison, the weighted average LCOE from PV solar power worldwide was at around $0.12/kWh in 2016. As defined by the U.S. Department of Energy, LCOE “measures lifetime costs divided by energy production” of a generating plant. It relies on calculations of the present value of the total cost of building and operating the generating unit throughout its assumed lifetime.
A 99 percent drop in the global prices of PV solar cells this decade has increased their installations worldwide, as illustrated below. They are now cost-competitive with fossil fuels to purify water in certain desalination plants, and they are particularly favorable in remote areas with no or limited access to the power grid. Prices of solar cells are expected to drop even further in coming years.
Solar Cell Prices and Installation Rates
*Estimate. Sources: Bloomberg, Earth Policy Institute
The idea behind transitioning to solar-powered desalination is to free up oil and gas for exports and to make the process cleaner and more efficient. At the same time, the burgeoning population rates in the Gulf region have boosted demand for water, which will continue to grow.
While the rates of converting seawater to potable water are only going to increase in the region, there are several problems related to desalination, particularly the thermal method, to meet the growing demand.
Thermal water desalination is still used in the Middle East. This technique produces more than just water – it generates massive amounts of potentially environmentally hazardous brine, which is often released into the sea. This byproduct of desalination is often warmer and more saline than the sea water, potentially posing a danger to marine life. But brine does not have to be discharged into the sea. It can also be placed into evaporation ponds or it can be secured underground.
According to Manzoor Qadir, a researcher from the United Nations University in Canada, close to half of the world’s desalination takes place in the Arabian Gulf where “oversight tends to be relatively weak.” Saudi Arabia is the world’s largest producer of desalinated water, followed by the U.S., the UAE, China, Spain, and Kuwait. Biologists are also concerned about the presence of chemicals, such as copper and chlorine, in the brine from using fossil fuels in thermal desalination plants. They can pollute the sea and may end up in the food chain. As Gulf countries continue to embrace the reverse osmosis method and clean energy to power them, it may be possible to cut down on the chemical-ridden brine.
That brings us to the question of whether reverse osmosis is the best way to purify water in the Arabian Gulf and what kind of clean energy technologies, in terms of cost and efficiency, are best suited for desalination. Compared to thermal desalination, reverse osmosis does not require heat to evaporate saltwater. But because of high water salinity in the Arabian Gulf, some observers argue that evaporation techniques may still be necessary and the reverse osmosis approach may have some limitations to purify saltwater in the region without added costs. As the countries in the region embrace reverse osmosis with the goal of making the desalination process cleaner and cheaper, they will need to find innovative ways to achieve it.
The type of solar technology used can determine its cost competitiveness to desalinate water. Concentrated solar power (CSP) uses mirrors to focus sunlight toward thermal salts that generate electricity and heat. CSP can store power for hours, which is beneficial to some types of desalination plants to help vaporize saltwater. While PV solar cells cost much less than CSP, they only produce electricity but not heat. Thermal energy generated from CSP can reduce the cost of saltwater evaporation. Therefore, CSP will be costlier than PVs, but it could be a better fit for use in the Gulf region than the PV-based desalination. The cost of energy to desalinate water will never be low, especially given the massive scale of purification needed to satisfy the water demand in the Middle East. Moreover, the use of fossil fuels has made the process not only costly, but also dirty. The relative social and economic costs of different types of energy used to desalinate will vary to a certain degree. However, at this juncture, it makes good environmental and economic sense to use clean energy.
The arid Gulf region has one of the scarcest supplies of water in the world, and some predict its water may run out in a few decades due to climate change and overuse. Indeed, water consumption in the Gulf is one of the highest in the world. The United Nation’s Food and Agriculture Organization reported that water is overexploited in the Arabian Peninsula by over 500 percent. While cleaner and more efficient technologies, such as solar-powered reverse osmosis desalination plants, are now less expensive, and water desalination in the Gulf is bound to increase with the expected rise in population rates, government subsidization of water remains highly problematic. Subsidization hides the real cost of this scarce and vital commodity, and it will continue to devalue it by causing more waste and inefficient use. According to research conducted by Germany’s Max Planck Institute, the changing climate will make the region drier and hotter with more frequent dust storms in coming years, and continued water subsidization will only exacerbate the situation.