Are We Doing Enough To Find Solutions?

We asked climate scientist Dr Peter Johnston,futurologist Clem Sunter, and City of Cape Town Mayco member Xanthea Limberg for their takes on the water crisis in the Western Cape.

IS DESALINATION VIABLE FOR CAPE TOWN?

Dr Peter Johnston

Desalination is magic. You take seawater, pump it into the machine and magically get fresh water. It’s what we call a black box. It’s a process of reverse osmosis: the salt is taken out, leaving you with pure water.

But you first have to get a dam full of water. Our empty dams are nowhere near the sea, so if we want to put seawater in those dams, we have to pump it uphill. This would use a lot of electricity, so cost becomes significant.

Because of the volumes of water we’re talking about, it’s a huge job to integrate desalination with the existing dams.

For the next 10 years, we have enough capacity in the dams. So if it rains normally, we won’t need desalination. If we instal a desalination plant, we must use it. If the plant is not used, people will ask, ‘Why did you waste money building the plant?’

Desalination is a really good option for us if we do it in small quantities. So new suburbs located near the coast could be connected to a small desalination plant that will produce enough for that area. Unfortunately, there isn’t really space for a new suburb near the coast, unless you go up the West Coast. It’s very dry anyway, so it’s ideal to use desalination plants – in fact, they’ve already done so. To construct a desalination plant for the whole of Cape Town is silly. It would cost billions and it’s not going to be needed.

Clem Sunter

Desalination is used in the Middle East and Australia to make up for the shortfall of water caused by lower average rainfall, which is mainly due to climate change. Both Perth and Adelaide have desalination plants.