{"id":109484,"date":"2018-02-08T18:47:38","date_gmt":"2018-02-08T16:47:38","guid":{"rendered":"http:\/\/www.myza.co.za\/desalination-global-examples-show-how-cape-town-could-up-its-game-the-conversation\/"},"modified":"2018-02-08T18:47:38","modified_gmt":"2018-02-08T16:47:38","slug":"desalination-global-examples-show-how-cape-town-could-up-its-game-the-conversation","status":"publish","type":"post","link":"https:\/\/www.myza.co.za\/press\/desalination-global-examples-show-how-cape-town-could-up-its-game-the-conversation\/","title":{"rendered":"Desalination: global examples show how Cape Town could up its game | The Conversation"},"content":{"rendered":"

Desalination: global examples show how Cape Town could up its game<\/a>: <\/p>\n

Cape Town has started down the road of desalination.<\/span> Shutterstock<\/span><\/span><\/figcaption><\/figure>\n

Day zero is looming for Cape Town and a dedicated and efficient long-term solution to South Africa\u2019s water woes must be found. The weather can\u2019t be controlled and drought patterns for the region are set to worsen. It\u2019s time to stop relying solely on rainfall and dam levels for clean water as a critical resource.<\/p>\n

South Africa boasts a coastline of over 2500 kilometres so it should be considering the oceans as an abundant water supply. Converting seawater to clean drinking water can be achieved by desalination, a proven technology that\u2019s been used around the world. Desalination involves removing the salinity (dissolved salts and minerals) from water. There are a number of ways of doing this, but the only process that ticks all the boxes in terms of catering for large volumes, environmental impact and cost, is reverse osmosis. <\/p>\n

South Africa has around 10 desalination plants dotted along the coast from Lambert\u2019s Bay in the west to Richards Bay in the east. The output from each is quite small and caters only for households in the immediate vicinity. <\/p>\n

Cape Town has started down the road of desalination. A temporary desalination plant is due to start producing 2000 cubic metres of water a day (going up to 7000 in phase 2) starting in March. The city will buy the water at a cost of around R30 per kilolitre. The contract is due to run for 2 years after which the equipment will be removed and the area rehabilitated.<\/p>\n

But the city needs to develop far more ambitious plans. With a population of around 4 million people it needs a water output of around 500 000 cubic metres per day to supply each individual with roughly 100 litres. Desalination plants have dramatically increased in number and sophistication around the world due to membrane technology breakthroughs and energy saving equipment. <\/p>\n

Three global examples in Saudi Arabia, Spain and Israel show that South Africa could increase water output in a timely and cost effective way.<\/p>\n

State-of-the-art desalination plants<\/h2>\n

The Ras Al Khair (Saudi Arabia) hybrid desalination plant has a drinking water output of 1 036 000 cubic metres per day. It is a hybrid plant because it relies on both multi-stage flash distillation (which is highly electrical and energy intensive) and reverse osmosis technology. It was built at a cost of US$ 7.2 billion between 2011 and 2014.<\/p>\n

In response to the worst drought Spain had in years, Barcelona built a seawater desalination plant with drinking water output of 200 000 cubic metres per day. It supplies drinking water to around 1.3 million people in the region. It caters to 20% of the population of Catalonia. Additionally, more than 5200 photovoltaic modules are installed on the roofs of eight buildings of the plant which generate approximately 1 MW of electricity annually. It is the largest reverse osmosis based desalination plant in Europe. Construction started in 2007 and the plant was inaugurated in 2009 at a cost of 230 million euros.<\/p>\n

The plant was built by Aguas Ter Llobregat, the public utility responsible for the supply of water to the city which also contributed \u20ac28 million to the cost. The public utility\u2019s involvement is remarkable given that it would be comparable to the Water and Sanitation Department for the City of Cape Town being in charge of the entire construction of a desalination plant.<\/p>\n

The Sorek desalination plant in Israel sets signi\ufb01cant new industry benchmarks in desalination technology, capacity and water cost. It provides drinking water output of 624 000 cubic metres per day or 26 000 kilolitres per hour, which is more than all desalination plants in South Africa combined produce daily. It is the largest seawater reverse osmosis desalination plant in the world, built by IDE Technologies. It opened in 2013 at a construction cost of around USD$ 500 million. Sorek will sell water to the Israeli water authority for 2.00 NIS which is around R7 per kilolitre. By comparison, the eThekwini municipality that serves the greater Durban area charges customers R16.20 per kl consumption. <\/p>\n

Challenges<\/h2>\n

Challenges remain despite the increase in global investments in reverse osmosis desalination plants. The only proven technology that is economically viable and uses manageable levels of electricity is desalination by reverse osmosis (and energy demanding multi-stage flash distillation). <\/p>\n

The main challenges for reverse osmosis are:<\/p>\n