South Africa's waves to be used for clean green energy

An overseas company hopes to harness South Africa's wave power and establish three wave energy farms on our coastline.

The South African government has set targets to introduce renewable energy over the next decade, but there are no commercial renewable energy power plants in the country.

The British company, which has established a wave energy farm in Scotland and is setting one up in Portugal, believes South Africa's abundance of wave power can be harnessed to provide clean, green energy.

On Thursday Vincenzo Bellini said that his company had been in discussions with the department of minerals and energy, the central energy fund and the energy research centre at the University of Cape Town.

"We're still at the assessment and viability stage. We're looking at the possibility of setting up three wave energy farms, two off the West Coast and another off the Transkei coast. Green energy is wonderful, but it needs to be economically viable," Bellini said.

He said currently the price of wave energy was around 18 to 20 cents a kilowatt, which was well above the average of 2 cents a kilowatt for coal-powered energy. With development, this cost would be reduced.

The huge costs to human health and to the environment, particularly in the form of greenhouse gas emissions which cause climate change, were not included in the cost of coal-generated power.

With wave energy, there was no cost to health and minimal environmental impact.

"Also, the cost of decommissioning coal or nuclear power plants is not factored into the cost of conventional power generation. The cost of decommissioning nuclear plants is huge," Bellini said.

He is proposing three wave energy farms, with between five and ten semi-submerged structures 150m long and 3m in diameter. They would occupy a sea area of about one kilometre by half a kilometre, and be set up about two kilometres offshore.

The wave energy plant in Scotland generates 750 kilowatts. "The most damaging product on board is a fluid, which, if it escapes, is bio-degradable within five days. The noise pollution is low and there are no gas emissions," Bellini said.

The semi-submerged structures are made up of cylindrical sections linked by hinged joints. Each is held in place by a concrete anchor on the seabed. The mooring system allows it to align itself head-on to the incoming waves.

The waves cause the structure to articulate around the joints. This motion is resisted by hydraulic rams that pump oil through hydraulic motors. The motors drive electrical generators to produce electricity.

The power is fed down a single cable to a junction on the seabed which is linked to the shore.