Sunlight, which is plentiful in South Africa, will not, like uranium and coal, become depleted.

Yet Eskom, the national power utility, plans to invest far more on coal-fired and nuclear power than on solar or wind energy. Of the additional 40 000 megawatts (MW) Eskom plans to build, about 20 000MW will be generated from nuclear.

Eskom has already earmarked more than R185 billion to build new coal power stations, including demothballing, upgrades and new plants.

Nuclear and coal present the environmental risks of dangerous waste and high carbon emissions. Eskom's pilot wind farm in the Western Cape has already contributed to the avoidance of 11 000 tons of carbon dioxide emissions.

Despite strong evidence of the benefits of renewable energy, Eskom's investment plans in this regard are slim. Of the R204 billion approved for generation projects, R1.1 billion has been allocated for renewable energy, a 100MW wind farm that is likely to be operating in 2010. Over and above this, about R2 billion is allocated for subsidies on installing solar water heaters in homes and businesses. Eskom has also investigated a 100MW concentrating solar power plant. By 2025, when Eskom should be generating about 80 000MW, the power utility plans 1 600MW to be from renewable energy.

In a world where carbon emissions are increasingly threatening the environment and as demand for nuclear fuel and coal rises, increasing the cost of these fuels and accelerating their depletion, should Eskom not be pushing renewable energy a lot harder?

Wind power

Wind power is a mature technology, used widely in Europe. In Germany it produces 20 000MW. According to a Merrill Lynch report on renewable energy published in August, the cost of wind power is declining.

"For plants in the best location, wind energy is fully cost comparative with fossil fuel," the report says.

Unfortunately, South Africa is not the best location; there is just not enough wind to generate sufficient sustainable electricity supply. Ompi Aphane, chief director of electricity at the department of minerals and energy, says windy areas in South Africa are on the coast.

To generate large amounts of electricity from wind turbines would require large tracts of land. A wind turbine that generates 5MW could have a 12m diameter. In comparison, an Airbus A380's wingspan is 80m. So to generate a large amount of power, say Koeberg's capacity of 1 800MW, you would need about 380 5MW wind turbines.

The BBC has reported some opposition towards wind turbines as an eyesore. In response to this, some wind farms in the UK are now being built out at sea.

The Guardian reported the government had approved a £1.5 billion (R20.5 billion) scheme to build the world's biggest offshore wind farm in the Thames estuary. The scheme could generate 1 000MW, or about 1 percent of the UK's energy requirements.

A UK 2005 department of trade and industry report said offshore wind power could provide 3 213 terawatt hours (3 213 million megawatt hours) of power - more than eight times the electricity the UK uses now.

Offshore wind power holds promise because wind speeds rise the further out to sea they are, and public opposition drops because of the lower visual impact. But, despite this, the UK, like South Africa, is pursuing nuclear energy.

Eskom needs to add generating capacity as quickly as possible to ensure reliable base load supply to support economic growth and increase its reserve margin from the current range of 8 percent to 10 percent, to the internationally accepted 15 percent.

Wind and solar power do not yet meet the energy parastatal's criteria for large-scale generation potential. Aphane says that assuming the additional capacity required could be derived from renewable energy, supply must meet demand simultaneously, as it is impossible to store large amounts of electricity.

Wind will be a small part of South Africa's future energy mix. Solar power holds more promise as an environmentally friendly solution to South Africa's energy crisis.

Already in South Africa there are well over 200 000 households, rural institutions and water pumps using solar panels, according to a February 2006 report titled The Potential Contribution of Renewable Energy in South Africa.