Rhein on Energy and Climate

Siemens, one of the global giants in power equipment, wants to become the major manufacturer of solar thermal power plants. To this end, it will acquire the Israeli company Solel, which has pioneered that technology during the past two decades.

Solar thermal power technology concentrates the sunlight by sophisticated mirror systems and produces steam up to 1000 centigrade that drives turbines in the same way as in coal- or gas fuelled power plants.

Read also: Solar Energy from the Sahara: When Will it be Feasible?

Solar thermal power plants have been in operation in California for 25 years, demonstrating their viability and profitability.

Compared to photovoltaic power generation solar thermal power offers the following advantages:

  • It can generate electricity also during night thanks to heat storage.
  • It is better suited for large-scale power plants, say of 100-500MW, connected to the grid.
  • The deployment of mirrors needs less space than that of PV modules.
  • It is more resistant to sand storms thanks to the glass mirrors, which can be automatically cleaned.
  • The generation cost is lower than that of PV electricity. But as the experience during the last two years shows this cost advantage may be lost if there are new breakthroughs in PV production technologies.

The two solar technologies are in principle complementary, solar thermal for big power plants connected to the grid and PV for small-scale decentralised electricity generation in the vicinity of consumption centres, either small power plants or panels installed on buildings.

Solar thermal installations are ideally suited for the arid “solar belt” running around the earth from Mexico/Arizona to the Sahara, parts of the Indian subcontinent north of the equator and Chile, South Africa and Australia south of the equator.

Read also: DESERTEC Takes Off

The potential is huge. A tiny part of the Sahara would theoretically suffice to supply humanity with all the electricity it needs. The technical obstacles on the way are considerable, especially long-distance transmission, but surmountable, though at an extra cost due to transmission losses.

To optimise the technology and lower the production costs, Siemens will have to develop standard power plants, say 100 MW, 200 MW to start with, including storage facilities.

The company hopes to build the first “Desertic” solar power plants in 6-8 years. It will have to convince utilities in sunny countries like India, China, South/North Africa and southern USA of the superiority of solar thermal power plants over CCS and other non-fossil technologies.

If it succeeds, it could be a giant step towards competitive solar electricity generation. The Siemens CEO has sufficient self-assurance to call it the “Apollo project” of the 21st century. But we are far from such ambition: The global capacity of solar thermal power plants is not expected to exceed 3 GW by 2015 compared to more than 150 GW of wind power plants! Rendez-vous in 2020!

Brussels 16.10.09 Eberhard Rhein

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