As the climate changes, people are casting ever-fonder hopes on being rescued by some unknown technology, presumably wearing a mask and cape. Meanwhile, there’s a known technology that, flawed though it may be, aims to alleviate the mounting water scarcity affecting 40 to 60 percent of the world population. Now, though, a UN-backed paper – published Monday in Science of the Total Environment – reveals that the world desalination industry has grown much bigger than anybody had thought and that the nearly 16,000 desalination plants are emitting 50 percent more toxic brine waste than had been realized.
How could it be that nobody noticed the elephantine magnitude of global desalination? Because academic coverage of the industry has been based on incomplete data, explain the scientists: Edward Jones, formerly of the United Nations University and now affiliated with Wageningen University, with Manzoor Qadir and Vladimir Smakhtin of UNU, Michelle van Vliet of Wageningen and Seong-mu Kang of South Korea’s Gwangju Institute of Science and Technology.
The desalination plants aren’t generating salt per se, points out IDE Technologies, Israel’s biggest desalination company. They are redistributing the salt: They take in seawater (or other) and produce distilled water and concentrated brine. The question is what to do with that brine.
Not a very efficient process
Producing one liter of fresh water produces about 1.5 liters of brine, though there are big differences in the “recovery ratio” (freshwater to brine) between plants, based on the salinity of the source feed water and desalination technology used, Jones explains.
Every day, the nearly 16,000 desalination plants in 177 countries produce 95 million cubic meters of water and discharge 142 million cubic meters of brine.
Over a year, that’s enough to cover Florida under a foot of brine, the authors say.
Note that there are ecological upsides to desalination relating to sanitation, water softening and the quality of sewage effluents, report Rachel Einav and colleagues in Science Direct. But aside from the precious coastal land given to plants, there is the energy cost, pollution and potential risk to groundwater if rickety pipelines pass above them.
IDE says that when desalination plants are planned properly, any salinization of the immediate environment is negligible to nonexistent – so since it says its plants are planned properly, it sees no cause to change how it handles its waste. Which is to pour it into the sea.
Yet however inconvenient and expensive brine management is – typically taking up to a third of a company’s outlay – the global industry shouldn’t keep growing without better solutions than “so far so good.”
Solutions don’t just spontaneously arise, either. Remember the pesky problem of nuclear waste?
Their UN-backed paper didn’t focus on the nature of desalination’s environmental impacts, but Jones tells Haaretz that, generally speaking, the largest salinity increases are observable in the immediate vicinity of the outlet. Work is being done by others to quantify the impact on large water bodies (and predictions of future increases in salinity) due to desalination plants, he says.
Productive in Saudi Arabia, efficient in Israel
Meanwhile, in the Middle East, just four countries – Saudi Arabia, the United Arab Emirates, Kuwait and Qatar – produce 32 percent of global desalinated water but 55 percent of global brine waste.
How are the Middle Eastern quartet responsible for less than half the water but more than half the brine? Their recovery ratio is low.
Saudi Arabia alone is responsible for 15.5 percent of the global desalination capacity and produces 31.5 million cubic meters of brine a day, or 22.2 percent of total global production, according to the paper.
Israel produces 2.18 million cubic meters of desalinated water per day (2.3 percent of total global desalinated water) and 2 percent of the global brine, Jones says.
Uri Schor, spokesman for the Israel Water Authority, says the true figures are lower: In 2018, Israel produced 640 million cubic meters of desalinated water, which works out to 1.75 million cubic meters a day, and roughly the same amount of brine. (Jones explains that the UN’s quantification includes plants currently under construction that will shortly come online.)
The water authority reveals that 30 percent of Israel’s water supply currently stems from desalination.
In any case, Israel justifiably takes vast pride in its desalination industry, which helps it overcome the vagaries of nature and climate change-induced regional aridification. It is, however, a tiny country with a population of around 8.9 million, less than any single self-respecting megacity. So, while the Israeli desalination plants tend to have very large capacities, there aren’t many of them, Jones says.
Also, in Israel IDE says it minimizes potential ecological impact by diluting the brine with “fresh” seawater before returning it to the sea, in order to minimize the difference between its waste and the natural seawater, says spokeswoman Hila Koren. The company also uses diffusers to distribute the salt more uniformly in the seawater, she says, and points at its efforts towards sustainable treatment solutions and chemical-free pretreatment.
Koren adds that the IDE plants in Israel employ reverse osmosis, which doesn’t emit copper alloy contaminations like older plants in the Gulf.
Inquiring minds may wonder about the United States: It produces 10.9 million cubic meters of desalinated water a day and 5.3 million cubic meters of brine, according to the report.
How much spirulina can we eat?
One problem with brine dumping is that it depletes the oxygen dissolved in the receiving waters around the plant, explains Jones. “High salinity and reduced dissolved oxygen levels can have profound impacts on benthic organisms, which can translate into ecological effects observable throughout the food chain,” he says.
The toxic chemicals used in water pre-treatment or as anti-scalants and anti-foulants in the process don’t bring benthic life joy either.
“Development of energy-efficient, cost-effective and environmentally benign concentrate management systems is critical if desalination is to become a major part of a sustainable water future,” pointed out Pei Xu and colleagues in Environmental Engineering Science in 2013.
Which brings us to spirulina. The brine can be used to cultivate the protein-rich algae, which is being touted by some as a possible solution to feeding the10 billion people the world is expected to have by the year 2060. Technion students in Israel recently won a prize making “algafelafel” with it.
But how much algae can you eat, given any choices? What’s needed is large-scale utilization.
UNU’s Qadir points out that “reject brine” can be used in aquaculture, with increases in fish biomass of 300 percent achieved, and to irrigate forage shrubs and crops (although over time, it can cause progressive land salinization).
Another line of advance is using renewable solar and wind power for desalination plants, and last November Thomas Missimer of Florida Gulf Coast University and colleagues proposed that “free” geothermal energy could power the desalination industry.
The principle is to capture heat from hot dry rock areas with high heat flow. It suits the coastal area of the Red Sea because the sea lies between the African plate and the Arabian plate, which are pulling apart.
Dry hot rock technology is already used to generate electricity, Missimer says, and adding desalination functionality to the plant wouldn’t confer extra risk, in his view.
“There is a possibility that this technology could be used along the Red Sea of Israel,” Missimer tells Haaretz. Saudi Arabia is looking at possibly developing hot dry rock geothermal energy, he adds.
Tapping that crack in the earth that produces the odd big earthquake in order to run decarbonized desalination plants would be a boon for Israel. Score one for the Dead Sea Rift.