Israeli water desalination technique could help relieve Cape Town’s thirst

Relying on solar energy, startup Tethys is more mobile, scalable, cheap and energy-efficient than other methods of getting drinking water from the sea

A man carries water at a source for natural spring water in Cape Town, February 1, 2018. (AP Photo/Bram Janssen)
A man carries water at a source for natural spring water in Cape Town, February 1, 2018. (AP Photo/Bram Janssen)

For months, Cape Town, a city of four million people, has been facing the doomsday scenario of taps running dry. The city’s Theewaterskloof Dam, a water reservoir which once supplied the city 50 percent of its supply, looks more like a desert area.

Two cataclysmic issues are at the center of Cape Town’s water crisis.  First, the scarcity of rainfall: in the past three years, the once reliable rains that fell during winter months have disappeared.

Second is the inequity in the distribution of water. South Africa’s mostly white wealthy populations have access to water from their taps and its poor, primarily black, inhabitants live in informal settlements that are not equipped with infrastructure to receive clean drinking water, experts say.

Since South Africa has a long coastline, two former Israeli rocket scientists, Dr. Moshe Tshuva, the head of the Energy Department at the Afeka-Tel Aviv College of Engineering, and Joshua Altman, the co-founders of Tethys Solar Desalinization (TSD), a Tel Aviv-based startup, say they may have a solution to Cape Town’s water issues.

“Cape Town has plenty of sun, coastal seawater, and a need for a quick, affordable solution. TSD can be the perfect solution for the city’s water shortage. Our system can be placed outside the city in any vacant area,  preferably near the seaside to pump freshwater production into the town’s reservoirs,” Tshuva, who has been involved in the research and development of solar plants and green energy projects since the early 80s, said in an interview.

Technology from Israel could be a boon to Cape Town as reservoirs run dry, Israeli researcher Dr. Clive Lipchin, who attended a water symposium in Johannesburg last month, said in an interview with The Times of Israel.

The company has created what it calls a “weather box,” which mimics and multiplies the natural atmospheric processes of evaporation and condensation to make filtered and clean freshwater from a variety of water sources, like the sea or brackish groundwater. The process uses solar heat to evaporate the water, leaving the contaminants at the bottom. The vapor is then collected and cooled back into liquid form, much like when it rains naturally, said Altman. The clean water is then collected into containers.

Dr. Moshe Tshuva, co-founder of Tethys Solar Desalination, and head of the Energy Department at the Afeka-Tel Aviv College of Engineering, demonstrating the desalination technology (Courtesy)

The modular solution can be deployed virtually anywhere with sunlight and a water source and is capable of producing up to 10,000 cubic meters a day, the company says.

Compared with existing methods of desalinization, TSD’s purification process offers three distinct advantages, the company says; it is off-grid — it does not require pipelines; it requires no external energy source except for the sun; and it has no negative environmental impact — a zero global footprint.

Current desalination techniques come in two varieties: a process similar to boiling water to separate it from the salt, and a reverse osmosis technique that forces water through a membrane to filter out the salt. Both methods create a brine as a byproduct, which is then generally pumped back out to sea and can upset aquatic ecosystems, and require a vast amount of energy, experts say.

Bringing water to geographically widespread populations involves large amounts of capital investment and energy consumption, which is generally shouldered by governments, said Altman.

“We want to privatize water and make it accessible to people across the world without the need to rely on infrastructure from the governments and municipalities. This is a powerful shift from the existing utility-based model currently used in many parts of the world,” he said.

By 2025, two-thirds of the world’s population may face water shortages, and water scarcity is one the largest global risks in terms of potential impact over the next decade, according to the World Economic Forum.

Photo depicting Tethys Solar Desalinization proposed pilot project (Courtesy)

Israeli technology may be particularly useful to Cape Town. Israel, with its arid climate and lack of freshwater, faced a years-long drought in the mid-to-late 2000s, depleting its natural freshwater stocks.

“Israel is a model for how that can be done in a very efficient way. We operate five of the world’s largest desalination plants and we do it very efficiently,” Lipchin, the researcher, said in the interview.

To date, TSD has secured $500,000 in seed funding and is currently past prototype development phase. The company expects to launch pilots in Israel and Jordan within the next six months and is seeking investors to raise $1.5 million for its series A funding round, said Altman.

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