Capetonians may have the chance to opt for "green" electricity within a year, although they will have to pay a premium for the product, says city management.

The city's director of electricity, Neil Croucher, said that the option would become available once the privately-owned Darling wind farm came on stream.

The city has agreed to buy power from the farm, construction of which, he said, was expected to be completed in six to ten months.

This would make Cape Town the first city in South Africa to offer consumers the option of buying power from a renewable source.

He expected that with the loosening of Eskom's stranglehold on generation nationwide and opportunities for more competition, other green energy sources would become available.

He said South Africa's current generating capacity would be fully used by 2007, while three percent growth in the economy would require more than 1000 megawatts a year extra.

In addition, between 2010 and 2020 the current generation of power stations built in the 1970s and 80s would reach the end of their lives.

"So the hope is to create the environment where private investment can take place in power stations, and that's where we have a role to play in promoting what we believe are appropriate forms [of energy]," he said.

Croucher said the council did a survey some 18 months ago on the demand for green electricity which would be more expensive than its conventional equivalent - and there had been significant interest.

The interest had been stronger from environmentally aware corporations than individual consumers, though even these large users were unlikely for cost reasons to take all their electricity from a green source.

When green power did become available, council would conduct a marketing exercise, and the corporations were probably where it would start.

"If there's a huge demand, we will look to procure more green energy," he said.

Darling's output would be a "minuscule" three gigawatt hours a year, compared to the 9000 gigawatt hours in total consumed by the city annually.

However if there was a great demand for green power, he hoped the law of supply and demand would prompt the private sector to look at other sources.

"The importance for us [of Darling] is more the creating of the awareness, the testing of the appetite for it," he said.

"Nationally, we believe this is an important start. We've got no real renewable energy in South Africa and pretty dirty power stations.

"It'll be a first to test a market and the appetite for it, and a first as an independent power producer."

Croucher said no tariff had been set for the green product, "so I'd be hesitant to give a number".

Consumers who pay for green electricity will of course not necessarily be using current specifically generated by a renewable source.

Instead, they will take their electricity from a general pool into which council ensures it pumps as much green electricity as those consumers are paying for.

Croucher said this process would be open to independent audit, while there was also a possibility of using "green certificates".

Earlier, mayoral committee member responsible for trading services Saleem Mowzer announced that the city had completed a "state of energy" report, which he described as the most comprehensive assessment of energy use and consumption ever done by an African city.

"This makes the city of Cape Town among a handful of leading developing and developed cities of the world that have completed similar initiatives," he said.

He also said the city planned to develop an energy strategy, again an African first, aimed at promoting sustainable energy development.

Among other things, it would seek to promote energy efficient initiatives among residents and ensure everyone had access to safe and affordable energy sources.

The city this month hosts both the International Cities Energy Strategies Conference and the World Wind Energy and Renewable Energy Exhibition.

Cape Town currently gets the bulk of its electricity from Eskom.