Atlantic waves roll fresh water in from the sea
IT may look like a long-lost treasure ship, but the lump of metal at the bottom of False Bay could turn out to be far more valuable.
It’s an experimental desalination pump and has been quietly collecting barnacles under the noses of Capetonians for several years.
It uses wave energy surging in from the South Atlantic to force sea water into a landbased desalination plant, where it comes out as fresh water.
Traditionally, desalination plants need electricity, but South African oceanographer Simon Wijnberg’s invention uses the power of the sea itself. A 9m underwater lever is moved up and down by wave action, generating the pressure that powers the unit.
“There is heaps and heaps of energy out there,” Wijnberg said at his Cape Town home, from where he runs ImpactFree Water.
“Our idea is to use the energy directly — it’s much more efficient. We don’t have to convert to power which can get lost along the way. We do it directly by pressurising water and then feeding it through a membrane to produce fresh water.”
A first unit was installed in 2004, anchored to the sea bed by several metal piles. Initial success prompted a second unit in 2009, funded by the Water Research Commission. Now the Technology Innovation Agency has climbed on board in the hope of commercial development.
Although the project is still at the demonstration stage, initial estimates suggest a single unit can produce up to 24 000 litres of fresh water a day. Potentially, 10 such units can be put in the bay.
Wijnberg is hoping to install a unit off Robben Island: “We are engaging with the City of Cape Town and Robben Island Museum [through their agent, the Coega Development Corporation], to interest them in supporting the first semi-commercial deployment of the technology,” he said.
The concept was sparked by a diving trip to Indonesia, where Wijnberg saw coastal communities with a shortage of fresh water, an increasing problem for island nations faced with sea-level rise.
“My travels as an oceanographer have exposed me to the widespread devastation of the environment and the suffering of people who do not have access to sufficient potable water,” he said.
“My frustration at how little was being done back in 2000 led me to this project and the invention of a simple technology that could be used to help overcome these problems.”