During the summer of 1913, in a field just south of Cairo, an American engineer, Frank Shuman, stood before a group of Egypt's colonial elite, including the British consul-general, Lord Kitchener, and switched on his new invention.
A flood of water soon spilled from a pump, saturating the soil by his feet. Behind him stood row upon row of curved mirrors held aloft on metal cradles, each directed towards the sun. As the sun's rays hit the mirrors, they were reflected towards a thin glass pipe containing water. The super-heated water turned to steam, resulting in enough pressure to drive the pumps used to irrigate the surrounding fields where Egypt's lucrative cotton crop was grown. It was an invention, Shuman said, that could help Egypt become much less reliant on the coal being imported at great expense from Britain's mines.
''The human race must finally utilise direct sun power or revert to barbarism,'' Shuman wrote to Scientific American magazine the following year. But the outbreak of World War I a few months later abruptly ended his dream and his solar troughs were broken up for scrap and the metal used for the war effort. Barbarism, it seemed, had prevailed.
Almost a century later, in November, a convoy of air-conditioned coaches swept through the affluent suburb of Maadi - where Shuman had demonstrated his fledgling solar panels - continuing south for 90 kilometres towards Kuraymat, an area of flat, uninhabited desert near the city of Beni Suef. The international delegation of chief executives, politicians, financiers and scientists came to visit a new hybrid power station that uses natural gas and solar panels to generate electricity. Before the coaches reached the security gates, its 6000 parabolic troughs - six metres tall with a combined surface area of 130,000 square metres - were visible from the perimeter road. The panels account for just a seventh of the power plant's 150-megawatt generating capacity, but the Egyptian government, which has been pushing to develop the site since 1997, hoped to prove to the delegation that it was the desert sun, not fossil fuels, that should be used to generate much more electricity across the Middle East and North Africa and, crucially, for Europe.
Gerhard Knies, a German particle physicist, was the first person to estimate how much solar energy was required to meet humanity's demand for electricity. In 1986, in response to the Chernobyl nuclear accident, he scribbled down some figures and arrived at this remarkable conclusion: in just six hours the world's deserts receive more energy from the sun than people consume in a year. If even a tiny fraction of this energy could be harnessed - an area of Saharan desert the size of Wales (about 20,700 square kilometres) could in theory power the whole of Europe - Knies believed we could move beyond dirty and dangerous fuels forever. Echoing Shuman's frustrations, Knies later asked whether ''we are really, as a species, so stupid'' not to make better use of this resource. Over the next two decades, he worked - often alone - to drive this idea into public consciousness.
The culmination of his efforts is Desertec, a German-led initiative that aims to provide 15 per cent of Europe's electricity by 2050 through a vast network of solar and wind farms in desert areas, connected to continental Europe by special high-voltage, direct-current transmission cables, which lose only about 3 per cent of the electricity they carry per 1000 kilometres. The cost of building the project has been tentatively estimated at €400 billion (about $500 billion).
Until now, Desertec has been seen by many observers as little more than a mirage; the fanciful plan of well-meaning dreamers. The technical, political, security and financial hurdles can each appear utterly insurmountable. But over the past two years the initiative has received significant support from some of the biggest corporate names in Germany, the country that has led the adoption and development of renewable energy, particularly solar, in Europe.
In the autumn of 2009, a consortium of companies, including E.ON, Munich Re, Siemens and Deutsche Bank, formed the Desertec Industrial Initiative (Dii). Germany's announcement last year that, after the Fukushima disaster, it was to speed up its phasing out of nuclear power suddenly pulled the Desertec idea into much sharper focus. Coupled with faltering international negotiations and increasingly dire warnings on climate change, it seems the time is right for an idea of such scale and ambition.
At its annual conference in Cairo, Dii confirmed to the world that the first phase of the Desertec plan was set to begin in Morocco with the construction of a 500-megawatt solar farm near the desert city of Ouarzazate. The 12 square kilometre plant would act as a ''reference project'' which, like Egypt's at Kuraymat, would help convince investors and politicians that similar farms could be repeated across the region.
''It's all systems go in Morocco,'' the chief executive of Dii, Paul van Son, told delegates. Talks were under way with Tunisia and Algeria about joining the ''first phase'' of Desertec, he said. Countries such as Egypt, Syria, Libya and Saudi Arabia would be expected to join in the ''scale-up'' phase from 2020 onwards, once extra transmission cables were laid across the Mediterranean and via Turkey, with the whole venture becoming financially self-sustaining by 2035.
Van Son swats away any talk that the Desertec project is built on a precarious foundation of presumption, naivety and hope. ''Yes, the current global financial crisis has clearly not been very helpful, but everyone also realises that being dependent on fossil fuels creates vulnerability,'' he said.
He rejects the notion that Desertec carries with it any whiff of neo-colonialism. Last year such sentiments were raised by Daniel Ayuk Mbi Egbe of the African Network for Solar Energy. ''Many Africans are sceptical [about Desertec],'' he said. ''[Europeans] make promises, but at the end of the day they bring their engineers, they bring their equipment, and they go. It's a new form of resource exploitation, just like in the past.'' Other speakers made similar points, not least that any electricity generated will first be desperately needed by poor local people.
''When the idea for Desertec was first announced there was anger and irritation from the Arab League,'' van Son admitted. ''They didn't understand it at first, but we explained that it would benefit their members, too. We explained it would be a co-operative process … it's a win-win for all, we stressed. The relationship is all positive now.''
Desertec should also be supported, its champions argue, because it will improve energy security by helping to diversify supply. At present, van Son says, Europeans are vulnerable to the so-called ''energy weapon'', when an energy-rich country holds its neighbours to ransom by restricting or denying supply. Think Russia and its gas, he says. Or a terrorist attack on an oil pipeline. Desertec would help dilute these threats.
He is bemused that the domination of Dii by German companies should arouse suspicion. ''Yes, the initiative came from Germany,'' he says. ''But there are 15 different nationalities involved, including companies such as HSBC and Morgan Stanley. This is just the start.''
A common question at the conference was: ''Who is going to pay for Desertec?'' There is talk of loans from development institutions such as the World Bank (the route being taken by Morocco). The presence of German banks suggests they are considering being key lenders, too. But much of the burden could fall on the European taxpayer, either through European Union subsidies or tariffs added to energy bills.
Angelika Niebler, a Christian Democrat Member of the European Parliament from Germany, travelled to Cairo as a member of that body's energy committee. She said it was too early to talk about EU financing but acknowledged: ''Energy is going to be a bigger priority for the EU in coming years than agriculture has been in the past and Desertec will surely feature.''
Hans-Josef Fell, a representative of Germany's Greens party, was also in Cairo for the conference. ''There is a fear in Germany that paying for green electricity direct from North Africa will be too heavy a burden on our consumers,'' he said. Germany's electricity prices are already among the highest in Europe, in part because of a huge wave of renewable energy installations across the country.
Europe, particularly Germany, seems to increasingly know what it wants from Desertec. But what of its regional partners? Obaid Amrane, a board member of the Moroccan Agency for Solar Energy, the government body overseeing Desertec's first plant, says his country has its own plans for the electricity generated there and at the four that will follow by 2020, and they do not necessarily include selling it to Europe.
''By 2020, we are expecting a doubling of electricity consumption in Morocco, as the population and standard of living grow,'' he says. ''At the moment, we are 97 per cent dependent on foreign energy, which is becoming increasingly unsustainable. But we are now aiming to have 42 per cent capacity of renewable electricity by 2020. We will build extra capacity beyond what Morocco needs if someone wants us to, but we will need a big share of the electricity produced by these projects.''
Such sentiments propose another challenge for Desertec: how will it guarantee that the electricity Europe needs is sent down the transmission cables and not consumed locally? And how will countries justify selling the electricity to Europe - where the retail price can be up to 20 times higher - if the local population is experiencing regular blackouts?
At the visitor centre at Kuraymat, bottles of chilled water were distributed before a tour of the parabolic troughs. The mid-morning November sun heated the engine oil-like fluid inside the troughs' receiver tubes - a technology not that far removed from Shuman's century-old design - towards 400 degrees.
The technical questions came thick and fast for Bodo Becker, the operations manager at Flagsol, the German company that specialises in building concentrated solar power plants in the deserts of the US, Spain and now Egypt. The leading query was how the troughs performed in such harsh conditions.
''We only have one sandstorm, on average, pass through here each year,'' he said, ''but we tilt the troughs down and away from the wind whenever it gets up beyond 12 metres per second, as they act like giant sails.''
Keeping them clean is the main challenge. ''Due to the dusty conditions, we are witnessing about 2 per cent degradation every day in performance, so we need to clean them daily. We use about 39 cubic metres of demineralised water each day for cleaning across the whole site.''
This surprised many delegates, as they had been told at the conference that such troughs needed cleaning weekly, compared with photovoltaic panels, which need cleaning monthly. Either way, it highlighted yet another challenge for Desertec: can enough local water ever be secured for cleaning? The Nile is just a few miles from Kuraymat, but some countries aim to push much deeper into their deserts to build such facilities.
''Dry cleaning'' technologies are being developed, but they reduce generating efficiency. Either way, the superheated transfer fluid requires cooling before it can loop back to the troughs for reuse, and, as with cleaning, water is the cheapest and easiest way to do this. Until ''dry cooling'' technologies are further advanced, solar farms might be confined to the desert fringes, near large bodies of water.
Some countries, such as Jordan, favour wind over solar as a source of desert energy, because it is more affordable and less water-intensive. But it will probably be many years before a single desert energy technology dominates the market. Some within the industry advocate photovoltaic panels, but currently concentrated solar power is more popular - even among its supporters there are loyalists for parabolic troughs and others for ''solar towers'', which rely on hundreds of pivoting mirrors to track the sun and direct its rays towards a fixed point at the top of a giant tower.
Whichever technology succeeds, it is already clear which nation will win out as Desertec develops in the coming decades. One member of the visiting delegation asked Becker where the troughs were made.
''The metal cradles were made here in Egypt, but the glass troughs were all made in Germany,'' he said. ''And only two companies in the world make the glass tube receivers, which is where the main intellectual property of this technology lies - Schott Solar and Siemens.'' Both companies are German.
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