Solar power and the Sahara desert

The start of something big?

Jul 8th 2009
From The Economist print edition

Solar electricity may be about to attract real money

IT IS an old idea. Build solar power stations in the Sahara desert and transport the electricity produced to Europe using high-voltage, direct-current (HVDC) cables. It is simple in theory, but hard in practice—and very, very costly. But it is a carbon-dioxide-free way of making a lot of electricity, and a collecting area the size of Austria could supply the world.

A meeting on July 13th might get the ball rolling. Munich Re, the world’s largest reinsurance company, has invited 20 large companies (including Siemens, Germany’s engineering giant; power suppliers RWE and E.ON; and Deutsche Bank, Germany’s biggest) to join it in forming a consortium called Desertec. If all goes well, this will eventually build a legion of solar power stations in Africa and Arabia, and connect them to Europe.

The power stations in question will be “solar thermal”, rather than the better known sort relying on photovoltaic solar cells. In other words, instead of converting the sun’s rays directly into electricity using expensive semiconductor-grade silicon, they will use cheap metal mirrors to focus those rays either onto boilers that make steam to drive turbines, or onto containers of special low-melting-point salts that will store heat overnight, so that it is available to drive turbines during the hours of darkness.

Munich Re’s interest in the matter is to reduce the effects of global warming. “Climate change affects our core business of weather-related natural catastrophes,” says Peter Höppe, the head of the firm’s “geo risks research” department. Munich Re hopes that introducing solar power on a large scale will at least slow the process down a bit.

Large-scale investment would also provide economies of scale and stimulate innovation, thus reducing the cost of solar electricity. At the moment, no form of solar power is as cheap as coal-generated electricity, but solar-thermal is reckoned by many to be a better bet to get there than photovoltaics—a task that is also made easier by the extra cost of the permits to emit carbon-dioxide that the European Union now requires the operators of coal-fired power stations to hold.

If the scheme were implemented in full, it would involve spending €400 billion ($560 billion) at today’s prices, over the next 40 years, building enough solar power stations to satisfy 15% of European demand in 2050—together with most of North Africa’s and Arabia’s—and about 20 trans-Mediterranean HVDC cables which, unlike conventional AC power lines, can transmit power over long distances and through water without significant losses. A bold proposal, then. But not a completely outrageous one. As the old Chinese proverb has it, even a journey of 1,000 miles begins with a single step.

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