Cape Town, a top tourist destination in Africa, is about to run out of water and the city is rushing to complete temporary desalination plants, drawing attention to a technology that makes perfect sense, but that has traditionally been considered too expensive to scale up.
The threat of a city being low on water is enough to drive investors away, desalination expert Dawid Bosman warned in a Mail & Guardian report:
“Developments have stalled, licences for new factories, food processing plants, bottling plants, breweries are not going ahead. There are reports of significant job losses in the agricultural sector,” Bosman said.
Desalination makes perfect sense as climate change and growing global populations put increasing pressure on dwindling resources. But the process of removing salt from seawater and making it potable is expensive and uses a lot of electricity.
Three desalination plants are under construction in the Cape Town area at Monwabisi, Strandfontein and the V&A Waterfront. The latter will be located in “an open-air parking lot”.
The plan to remove the salt from seawater and make it drinkable was described as a last resort by a South African water research commission in 2012, Mail & Guardian, reported:
Because of the amount of electricity used in the desalination process, the technology is extremely expensive and would significantly increase the price at which the water would have to be sold,” the commission concluded.
Cape Town was ranked No. 1 in 2017 as a business tourism destination in Africa by the International Congress and Convention Association (ICCA).
Now it’s in a race against time to keep the taps from running dry on April 16 — the date that has been designated as “day zero”.
Cape Town is also at the forefront of Africa’s green movement, ranking among the top five cities in the world for climate-consciousness, but that didn’t help the city avoid the water crisis, Straits Times reported.
In 2015, South Africa recorded its lowest annual rainfall since record-keeping began in 1904. While much of the country recovered from that particular year of drought, Cape Town’s Western Cape province continued to experience poor rainfall, leading to this water crisis, AFKInsider reported.
The temporary desalination plant at Strandfontein Pavilion is on schedule, according to News24. The process removes salt from seawater to make it suitable for drinking.
The Strandfontein plant, which will cost $19.8 million to build, will start producing 528,000 gallons a day (2 million liters) in March and ramp up to 1.85 million gallons (7 million litres) per day.
All three Cape Town area desalination plants are expected to start producing water in March, and tenders for three additional desalination plants are being considered by the city.
This is expected to assist in temporary relief from the water crisis until the rains return and water supply can be re-established. Winter rains are expected in June, July and August, according to AFKI.
Israel is home to the world’s largest and cheapest modern seawater desalination plant, according to MIT Technology Review. The Israeli plant called Sorek provides 20 percent of the water consumed by Israeli households. Built for about $500 million, it uses conventional desalination technology of reverse osmosis. “Thanks to a series of engineering and materials advances, the technology produces clean water from the sea cheaply and at an unprecendted scale,” Technology Review reported.
Tight water restrictions have been imposed on residents in Cape Town for months. As of Feb. 1, city residents can only use 13.2 gallons (50 liters) per person per day as a means to avoid “day zero”, according to ENCA.
For the sake of comparison, the average American uses between 80-100 gallons per day, the U.S. Geological Survey estimates.
What’s the reasoning behind building temporary desalination plants?
“Given the severity of the drought and the uncertainty around rainfall, we needed to be flexible in our approach and allow for both permanent and temporary solutions in order to ensure that we minimise any risk of acute water shortages,” said Xanthea Limberg, Cape Town mayoral committee member for water, in an AllAfrica report.
The Strandfontein plant involves a two-year contract, after which time the plant will be removed and the area rehabilitated. Desalination in this case represents a temporary solution.
The plant will pull water from around 0.6 miles out at sea through a pipeline, before it is filtered through reverse osmosis which will split the sea water into half clean water and half brine, which will be returned safely to the ocean.
South Africa’s 1,860-mile coastline could support a whole fleet of eco-friendly desalination plants, and it stands to reason that desalination technology could provide a long-term solution to the country’s water shortage issues.
South Africa is the main user of desalination technology in sub-Saharan Africa. Algeria is a North African example of how desalination can be used on a large scale.
Mossel Bay in the Western Cape is the site of South Africa’s largest desalination plant, with drinkable water supplied to state oil company PetroSA’s gas-to-fuel refinery.
Ghana and Namibia also have operational plants. In April 2015, West Africa’s first desalination plant opened in Ghana, with the Accra Sea Water Desalination plant providing fresh water for 500,000 residents in the Accra vicinity, WaterWorld reported.
The Arabian Gulf region is home to the world’s main producers of desalinated water. In 2008 Gulf states were collectively producing about half of the global total, but only around 1 percent of the world’s population is dependent on desalinated water, according to TheConversation.
This is expected to increase to about 14 percent by 2025, and if Cape Town’s situation is an indication of global warming’s acceleration of water scarcity, desalination may be an important technology for African countries to embrace in the near future.
The world doesn’t have a shortage of water; it has a shortage of cheap water,” said Richard Muller, a professor of Physics at U.C. Berkeley, in a Quora post. “And the cost of desalination has a physics limit: it will always take 1 kWh or more of energy to desalinate a cubic meter of seawater.”
Muller is the author of “Now, The Physics of Time.”
AFKInsider editor Peter Pedroncelli contributed to this report.
