DESALINATION
The case for desalination According to the International Desalination Association, there are more than 18 000 desalination plants operating across the globe, with a cumulative installed capacity of 88.91 million m3/day. However, South Africa has been slow to adopt this technology – often labelling it too expensive – and remains highly reliant on surface water resources. By Danielle Petterson
W
ater is beginning to take centre stage globally as countries around the world are faced with exhausted water supplies. In South Africa, this is highlighted by Nelson Mandela Bay, which is currently in crisis, having declared ‘Day Zero’ amid a severe ongoing drought, and Cape Town, which narrowly escaped a similar fate. Desalination has taken off in several parts of the world. With its abundant coastlines, South Africa has significant potential for desalination plants, but desalination is often thought to be too expensive, largely due to its high energy requirements. However, Benoît Le Roy, CEO of the South African Water Chamber, argues that desalination can be financially viable and should be embraced if South Africa is to avoid a water crisis. He points to areas like the Middle East where desalination is cheaper than surface water is in South Africa. He likens the growing shift towards desalination to the mammoth growth we’ve seen in the renewable energy sector: “Renewable water is becoming a lot more efficient. This is being driven by private sector competition and, within that, the race to reduce energy footprints, the bolting on of renewable energy, and a shift from thermal to membrane and hybrid technologies.” As a result, the price of desalination has halved compared to 10 years ago.
Why South Africa should desalinate South Africa has exhausted its surface water and most of its groundwater
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resources, with the Department of Water and Sanitation predicting a potential 17% water deficit by 2030 unless serious action is taken to reduce losses and demand, while diversifying and boosting supply. Le Roy argues that by shifting the coastal cities to desalination, these areas no longer need to rely on water from rivers that stem from further inland. This would lead to more water being available in these rivers for use by inland areas. “If we add water reuse inland, our water balance changes completely and we no longer have a crisis. But there are a lot of solutions that need to be implemented in parallel.”
Financial feasibility
“In South Africa, we install small-scale package plants. And while there is a place for these small plants, they are generally not feasible compared to utility-scale plants in cities and metros. To date, we have not implemented one utility-scale desalination plant in South Africa and all of the backlash we’ve had with our small plants is because they were badly planned. When you implement these small-scale plants during a drought, they often tend to fail, because you rush the process and you implement the wrong size plant,” says Le Roy. He argues that the temporary desalination plants installed in Cape Town were a futile exercise, contributing only 1% of the city’s water demand. One of the key factors with desalination is that the plant needs to run continuously in order to be
“To date, we have not implemented one utility-scale desalination plant in South Africa and all of the backlash we’ve had with our small plants is because they were badly planned.”
financially viable. This is the major challenge with temporary desalination plants implemented during droughts. Australia has developed an innovative solution. When their dams are full, they draw on surface water resources to meet their water demands, and their desalination plants recharge aquifers in order to bank water for the future. During periods of low rainfall, they can rely on desalination to meet their needs. According to Le Roy, Australia has more than 12 utility-scale desalination plants that run 24/7. He adds that, by reducing stress on surface water resources, many of the country’s wetlands have begun to rejuvenate, attracting wildlife and contributing to eco-tourism. “In South Africa, we’re over-abstracting from our ecological reserve and that will harm our tourism. We need our wetlands to recover for our eco-tourism to thrive.”
