Harnessing desert sun to power Europe
It is a beguiling idea - harvest sunshine, and a little wind, from the empty deserts of North Africa and the Middle East, and use it to produce clean power for the region and for Europe.
Desertec, a group based in Germany with heavyweight commercial backers including Siemens and Deutsche Bank, says the scheme would also bring the regions around the Mediterranean closer together, while providing jobs and stability for the countries in the south.
It has chosen Morocco, which is embarking on its own ambitious solar programme, for its first "reference" project - a plant meant to show that its grand vision is feasible.
Desertec expects to see the first electricity flowing through undersea cables from Morocco to Spain as early as 2014.
But its stated goal - using desert power to supply up to 100% of local needs and up to 15% of European demand by 2050 - has attracted critics who question whether such a vision is possible, or even necessary.
No-one doubts the physical potential of the desert to generate renewable power.
According to a study by the German Aerospace Centre (DLR), a state agency that provided data used by Desertec, less than 1% of suitable land in the North Africa and the Middle East would be needed to cover the current electricity consumption of the region, as well as Europe.
Many countries with intense sunshine also have large tracts of uninhabited land.
But creating a power network presents a range of problems, from nomads stealing solar components to the technological and political challenges of transporting and delivering electricity over such a vast area.
Paul Van Son, the Desertec Industrial Initiative's chief executive, stresses that his group has no detailed blueprint, but aims instead to create the broad conditions for a solar network to be developed.
"There is nothing which is unrealistic," he says.
"It's already happening today, there are installations in the deserts, solar installations, wind parks - it all works.
"There are electrical grids from Tunisia, Algeria for instance and Morocco to Spain and Europe. It's possible to transport electricity over long, long distances."
Desertec points to a pair of cables already installed between Morocco and Spain - though for now these are carrying power from north to south.
It says it will work closely with Medgrid, a French scheme to enable the construction of a Mediterranean transmission system.
While analysts acknowledge that the technology exists, and is getting cheaper, they say it is untested on an intercontinental level.
"What we'd be talking of is scaling up to a massive size technologies which so far have only really existed in quite small configurations," says Malcolm Keay of the Oxford Institute for Energy Studies.
"This would all be really quite novel and I think at the moment people are just feeling their way."
The technology that will initially be used in Morocco is concentrated solar power (CSP), a process in which sunlight concentrated by mirrors heats water, which produces steam to drive a turbine.
Crucially, the heat can be stored, allowing a secure supply even when the sun is not shining.
CSP has been getting cheaper, but not as quickly as photovoltaic (PV) power - the use of solar panels to convert sunshine directly into electricity. The DLR estimates that solar thermal power stations will become competitive with their fossil fuel equivalents between 2020 and 2030.
This will allow Desertec, which has estimated the cost of its 2050 vision at a mind-boggling $400bn, to "attract investment from the market in a very natural way", says Mr Van Son.
European renewable energy targets and Germany's decision this year to phase out nuclear power is likely to drive demand.
Still, heavy European financial involvement will initially be needed, which Mr Keay says would throw up a further set of challenges: "Major international treaties, legal frameworks for transport - all those sorts of things."
Valentin Hollain of Eurosolar, a German non-profit organisation that promotes renewable energy, queries the entire concept of Desertec.
He argues that big corporations are using large-scale projects like Desertec and Medgrid to retain their position into the next generation, and that a mix of renewable power supplied locally can meet demand while keeping prices down for consumers.
"I think it will always be cheaper than collecting energy in the desert and then bringing it to Europe with a massive infrastructure that will cost billions of euros," he said.
On the southern side, North African states heavily subsidise fossil fuels, something which would have to change if solar were to become genuinely competitive there.
That would require political will, something Mr Van Son says is increasing, partly due to the realisation that oil and gas will not last forever.
"Some countries were not convinced about solar energy at all, but this changed dramatically in the last two years," he says.
Morocco has so far shown the most enthusiasm.
Desertec is hoping that construction will start there next year on a 500 megawatt (MW) solar plant, though the exact location and technology mix are yet to be confirmed.
Confusingly, Morocco is also due to start building the first of five of its own solar plants in 2012, near the south-eastern desert town of Ouarzazate.
Morocco is the only North African country without significant oil and gas deposits, and it wants to produce 42% of its electricity from renewable sources - solar, wind and hydro-electric - by 2020.
A growing population and ambitious industrial programme mean the country's demand for energy is projected to quadruple by 2030.
"This is unsustainable," says Obaid Amrane, a board member of the Moroccan Agency for Solar Energy (Masen).
"Moroccan authorities have decided to put Morocco on a clean growth path, to explore and use the tremendous potential of renewable energy."
"We are preparing the post-fuel period for our children."
Who will benefit?
Mr Amrane is at pains to emphasise that the country's priority is providing power to its own population.
But along the way, he says Morocco - a country that presents itself as a haven of stability that is open to foreign investors - is keen to co-operate with Desertec and any other regional projects.
Still, the question of who will benefit from solar plants is likely to be a source of tension, both locally and internationally.
In Tasslamante, a few kilometres from the site of Morocco's first plant, villagers are doubtful as to whether the solar farm will bring the jobs, money and services that they hope for.
Moroccan authorities say they are sensitive to local concerns, which are unlikely in any case to hamper a $9bn project with backing from King Mohammed VI.
"Because the push came from the top it's been pretty efficient by North African standards," says John Marks, a North Africa expert at risk analysis firm Cross-Border Information.
As for the Desertec idea, mistrust could surface on both sides of the Mediterranean, says Mr Keay.
"There's going to be an unwillingness, I suspect, on the European side to trust suppliers from that source and to think that they're secure in the way indigenous suppliers are," he says.
The governments that emerge after the current unrest in the region could be more nationalist and less happy at the idea of sharing their resources with Europe, he adds.
"They will feel that because the Arab Spring has shown a lot of discontent they will have to do more and more directly for their population."