Energy | 13. October 2015

Sunshine over the Kalahari

Die Sonne über der Kalahari
Credit: Abengoa
Solar power station in South Africa. Khi Solar One in the Northern Cape region – designed for a capacity of 50 megawatts – will soon be connected to the grid. 

The Sun almost always shines in the Kalahari, which extends across the Northern Cape region in South Africa. The area enjoys 4000 sunlight hours and an average solar irradiance of up to 2800 kilowatt-hours per square metre per year; by comparison, Spain reaches no more than 2300. Therefore, it follows that the currently untapped potential for solar power is immense.

South Africa's main source of electricity is coal (90 percent). Could solar power stations bring about change? Experts in science, industry and politics will discuss this exact question at the SolarPACES Conference. They will also pool their opinions on innovation regarding solar thermal power plants, storage technologies and the use of solar energy to produce fuels.##markend##

The government of South Africa subsidises renewable energies

South Africa has ideal natural conditions for solar power, and South Africa's Department of Energy has launched an ambitious plan to promote renewable energy sources (Renewable Energy Independent Power Producer Procurement Programme; REIPPP). The underlying idea is that the renewable energy sector should contribute an output of 3750 megawatts by 2030, and hence play an important role in supporting South Africa’s somewhat unstable power supply system.

The demand for controllable energy is immense

Vikesh Rajpaul from Eskom, the largest electricity producer in South Africa, has an entirely different reason for describing the country as a 'hot spot' in the market for solar thermal power plants; the advantage of this technology compared with other renewable energy sources is that the solar heat collected by mirrors can be stored cost-effectively and without substantial losses. Therefore, unlike photovoltaic systems, solar thermal power plants can generate electricity during the evening and at night. Recognising this benefit, the South African government has responded by introducing an incentive-based feed-in tariff: 2.7 times the standard feed-in price is paid during the evening peak load period to ensure that sufficient electricity is available to meet the elevated demand at this time. This feed-in tariff sets the South African market clearly apart from other regions such as the United States or Spain. Experts are convinced that this will help advance solar thermal technology, which is struggling in competition with photovoltaic systems. All of these factors make South Africa an ideal venue for this year's SolarPACES Conference from 13 to 16 October 2015, which is being attended by scientists from the DLR Institute of Solar Research and the DLR Institute of Engineering Thermodynamics.

Excursus – Always next in line

Solar thermal technology – CSP technology (Concentrated Solar Power) – is a bit like the Crown Prince of renewable energies. Solar power plants use mirrors to concentrate the rays of the Sun onto one point. Just as in a conventional power plant, a turbine and a generator convert the heat produced into electricity. The first system was built in Egypt back in 1910. But, shortly afterwards, oil became such an inexpensive and universally available source of energy that the technology lay practically dormant, experiencing almost no development, until the oil crisis of the 1970s came along. Then, when renewable energies became interesting again, scientists and engineers returned to solar thermal technologies. At that time, photovoltaic systems were considered far too expensive. But nothing turned out the way it was predicted; photovoltaic systems became mass-produced commodities and now generate electricity at a lower cost than solar thermal power plants. Nevertheless, experts are not yet ready to consign the technology to the scrap heap. After all, unlike wind energy and photovoltaic systems, solar thermal power plants can feed controllable electricity into the grid, and therefore stabilise power supply in countries such as South Africa. Studies conducted by the International Energy Agency indicate that solar thermal power plants will account for 11 percent of the global electricity supply by 2050.

Initial projects

The first power plants have already been built as part of the South African REIPPP programme; the KaXU Solar One power plant in the Northern Cape region was connected to the grid in February 2015 to provide a capacity of 200 megawatts. Several other power plants with a total capacity of 500 megawatts are currently under construction, or in an advanced stage of planning, so the outlook is decidedly positive. But, how does the globally networked industrial sector perceive the opportunities? How is the research community contributing to the production of electricity and fuel without the consumption of fossil energy sources? I will keep my ears open at the conference, and report my findings here.

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About the author

Dorothee Bürkle worked at the DLR Corporate Communications Department until 2018. During that time she was a technical author for the research areas of energy and transport. Dorothee believes that energy and mobility are among the most important issues for the future of our society. to authorpage