Towers of Power

Thursday, 18 June 2009 09:52

Mirrors placed in deserts throughout the world could, one day, provide the planet with much of the electricity it needs, UN youth magazine Tunza reports. These mirrors would be a key component in masses of solar power stations of the type known as ‘solar power towers’ or ‘heliostats’.

The first of these solar power stations, the PS10, is already in operation in Spain’s Andalusian desert, just outside Seville. A second solar plant with twice the capacity, appropriately named the PS20, has also just been completed in Spain, where more projects are underway.

These ‘power towers’ are a type of solar furnace which use an array of flat, movable mirrors to focus the sun’s rays on a collector tower that contains a boiler, generating temperatures of up to 1,000 °C, with the resulting steam driving turbines that produce power. The advantage of the tower design above others is the higher temperature achieved, which allows energy to be converted to electricity more efficiently. Solar thermal energy is different from that produced by solar cells or ‘photovoltaics’, where energy is converted directly into electricity.

A U.S.-based company announced earlier this year that it had licensed its solar technology to energy providers in both the U.S. and India. The deal with the U.S. provider involved plans to jointly build solar thermal plants producing a combined 500 megawatts of electricity, while the Indian partner would build plants producing twice this amount over the next 10 years. In comparison, the single PS10 plant in Spain produces a mere 11 megawatts.

Another company is currently developing a number of thermal solar plants in California’s Mojave Desert, with construction of the first plant to start this year. It has already opened one plant in Israel’s Negev Desert. According to reports, plans are also underway for other companies to construct similar plants in Australia and South Africa.

The rapidly increasing global interest in thermal solar energy seems to be part of a wider trend, with industry figures suggesting that solar energy as a whole (of which solar thermal energy still only makes up a small part) grew at a record pace in 2008.

Photo: The PS10 'solar power tower' near Seville, Spain (Solúcar PS10/Solarweb)