By Karen Thorne | May 5, 2016
The world is parched, we are thirsty, and there’s likely nothing we can do to make it rain.
Worldwide, some 700 million people don’t have access to clean water. According to the United Nations, this figure will rise to roughly 1.8 billion within the next 10 years. To prepare for a growing population and the imminent shortage of fresh, potable water, scientists have found efficient means of warding off this epidemic by drinking…seawater. The process is called desalination, and it’s a technology that, at the risk of sounding hyperbolic, could be key to ensuring a better future for the human race.
Desalination is surprisingly simple. Through the process of seawater reverse osmosis (SWRO), desalination filters salt from seawater to produce fresh, drinkable water. By applying pressure, saline water is forced through a semipermeable membrane–basically very thin plastic sheets with tiny holes in it. In reverse osmosis, the membrane pores are incredibly small, only about 200 nanometers thick, allowing water molecules to squeeze past, but not salt. To put in perspective–a human hair is around 75,000 nanometers in diameter.
Christopher Gasson, publisher of Global Water Intelligence, said, “Unless people get radically better at water conservation, the desalination industry has a very strong future indeed.”
The International Desalination Association (IDA) has stated that there are 18,426 desalination plants worldwide in 150 countries. Today, more than 300 million people rely on desalinated water for some, or all, of their daily needs. As these needs increase, the technology must continue to improve.
The increasing prevalence of Seawater Reverse Osmosis (SWRO) technology is creating independent water resources worldwide where freshwater is scarce–a game-changing achievement. In the late 1950’s Sidney Loeb and a team of researchers, at the University of California, Los Angeles first developed viable SWRO membranes that achieved drinking water from high salt water through achievable pressure.
“That was the breakthrough,” said Professor Yoram Cohen, a chemical engineer who heads the Water Technology Research Center at UCLA. “It was the first time that people realized reverse osmosis can be practical for water desalination, and really tempted a lot of others to move into that direction and accelerated the development.”
The Reverse Osmosis technique has been deployed worldwide and is now coming back home to Southern California via the largest desalination plant in the Western Hemisphere. The plant, located in Carlsbad, began tapping the Pacific Ocean as recently as December 2015, which couldn’t have come soon enough, as California is still attempting to claw its way out of a 4-year drought. Fondly referred to as the “Salad Bowl of the United States”, California is responsible for one-third of the produce in the country with 80% of water usage going to agriculture–and it’ easy to see why. The average American eats a sliver of California avocado each week, which takes a whopping 4.1 gallons of water to produce.
In a normal year, Southern California imports over 50% of its water supply from two sources, Northern California and the Colorado River. As the Colorado River dries up, the Carlsbad plant represents an attempt to secure an independent water supply for the area. For roughly a billion dollars the plant provides approximately 7% of all of San Diego’s water.
Seawater desalination has long being deployed in drought-riddled nations like Australia and Saudi Arabia, but it hasn’t always been a viable, scalable technology.That’s changing in equally water-stricken Israel where Israel Desalination Enterprises, or IDE Technologies, the company that built the Carlsbad facility, have constructed Sorek, the world’s largest and cheapest desalination plant. The reverse osmosis plant, 15km south of Tel Aviv, is pumping out 165 million gallons of potable water a day andproviding approximately 20% of the country’s drinking water.
Israel’s conquest of seawater desalination is being hailed as an international success. Within one decade the country has moved from rain and groundwater reliance to supplying the country with over 40% of its water through desalination.
“Israel seawater desalination companies are exceptional innovators,” said Cohen. “Everybody knows the basis of a gasoline powered car—you have a steering wheel, internal combustion engine, wheels… The question is ‘How do you put it together in a way that makes it unique, makes it cheaper, makes it lighter?’”
Cohen explains that building a large-scale desalination plant is similar. “There are many companies building them, but how you go about building it is the key to how successful you are, and whether you will make any profit. Israel isn’t inventing a new type of desalination technology, but they are very clever in putting it together. That is where the special edge comes in.”
But even the best technology isn’t without its environmental challenges. For every gallon of successfully processed seawater, about one gallon of brine (water twice as salty as the sea) is discharged back in to the ocean. Critics of the Carlsbad initiative accuse the plant of harming marine life.
“This is one of the first questions asked in public outreach. ‘Where is that brine stream going?’” said Mark Lambert, CEO of IDE Americas. “But there are strict rules about how that water can be reintroduced into the environment, it has to be diluted close to the background salinity in seconds.”
Critics also contend that reverse osmosis desalination requires large amounts of energy. But according to Professor Cohen, so do our home refrigerators, air conditioners, and washing machines. Cohen believes the seawater desalination costs need to be compared apples to apples.
“Bottled water costs range from $1 to $3 per liter in the U.S., depending on the brand and location of purchase. In comparison, seawater desalination costs can be as high as about $0.45 per 100 liters and about $1.50-$2.00 per 1,000 liters for large-scale production. Of course, the above cost does not include conveyance of the water to the customer,” said Cohen.
As fresh water becomes more scarce and droughts more common, more countries are adding desalination to their water resource portfolios, in the hope of providing some reliable drought-proofing.
President John Kennedy once declared, “In this administration, we will put a man on the moon and make the desert bloom.” The president asserted that “If we could ever competitively, at a cheap rate, get fresh water from saltwater, that would be in the long-range interests of humanity and would dwarf any other scientific accomplishments.”
It may have been 50 years since Kennedy’s call to find ways to drink from the sea, but the progress has been made. Israel’s multi-scale desalination plant Sorek is well on its way to providing sustainable methods for quenching the world’s thirst.