2012-12-04 - Tapping solar energy to meet shortfall in electricity supply
When it comes to lavish natural resources, South Africa beats almost all. The country at the southern tip of the African continent possesses some of the world’s biggest deposits of coal, iron ore, gold and diamonds, as well as masses of other valuable minerals, including platinum and palladium.
But digging up all those minerals leave the country’s extractive industries with a voracious appetite for power. Electricity demand has been further stoked by rapid population growth. The determination of post apartheid governments to take electricity into more homes as a symbol of success and equality has reinforced demand. Before the end of apartheid, less than 40 percent of households had electricity; now, more than four out of five can flick a switch.
Supply, sadly, has not kept up. The country will need 52 gigawatts (GW) of new generating capacity in the next 20 years. While construction of new power plants is progressing, the system’s inability to cope has triggered regular, and sometimes sweeping, rationing and even blackouts. As a short term solution consumers have been asked to reduce demand. But the challenge has been worsened by an aging infrastructure and grid that have not kept pace with the times.
Those times are now more sensitive to the environment. South Africa’s power generation is among the world’s most polluting. Between 85-90 percent of electricity comes from the country’s readily available coal reserves, producing prodigious greenhouse gas emissions. Nuclear power accounts for just 5 to 10 percent, while renewables such as solar and wind power produce only 1 percent.
Yet few countries are better placed to exploit the power of the sun. Blue skies testify not just to South Africa’s touristic appeal, but also its capacity for solar energy. Government statistics show the Northern Cape province, for example, is among the sunniest 3 percent of regions in the world, with minimal cloud or rain year round.
Annual solar irradiation in South Africa. Image courtesy of: http://www.solarhomes.co.za/.
The technology for generating electricity from photovoltaic (PV) panels has been improving, with costs falling and efficiency on the increase. Solar power has the additional advantage that supply broadly tracks demand, with output peaking during daylight hours when demand is heaviest.
Improvements in transmission technology have helped to make solar power more practical. The latest generation direct current (DC) power lines reduce transmission losses compared with conventional alternating current (AC) counterparts. That means power can be sent over ever longer distances from remote generating sites to end users. And recent breakthroughs in DC circuit breakers mean future lines can be meshed together into a grid, rather than just providing less flexible point to point connections.
The government, sorely under pressure over power outages, has recognized the potential. Pretoria’s 20 year plan for renewable energy envisages 8,400 megawatts (MW) coming from wind and the same again from solar. By 2030, 42 percent of all energy should be renewable, according to last year’s Integrated Resource Plan for Electricity. To spark the new investment, independent power producers are being offered the carrot of up to 30 percent of the market under the Renewable Energy Independent Power Producers auction programme. That means taking a big bite out of the 90 percent market share currently enjoyed by Eskom, the near monopolist.
One important step in attaining these goals has just come with the award of a $225 million contract for two advanced PV power projects in Limpopo province, South Africa’s most northerly region and gateway to neighboring Botswana, Zimbabwe and Mozambique, as well as power hungry home to many large mines.
The two new plants, located close to Polokwane, the provincial capital, will be supplied by ABB and will generate 33 MW and 31 MW, respectively. They are among the first utility scale PV plants being built under the first phase of the government’s long-term renewable programme.
The plants will mitigate around 130,000 tons of carbon dioxide emissions a year, which will contribute to the pledged made by Pretoria at the United Nations Conference on Climate Change to make a 34 percent cut in CO2
emissions by 2020. More solar power will be a crucial way to get there.
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