Desert dreams of the solar age
As regularly as one hour follows the next, e-mails arrive in my inbox from people claiming to have the solution to the world's energy woes in their factory or garden shed or back pocket.
Most, as you'd guess, turn out to be no more convincing than a dentist's reassurance that "this isn't going to hurt" - why on earth does anyone bother inventing perpetual motion machines anymore? - but sometimes, what starts off as an idea with apparently insurmountable technical, political or economic obstacles turns out, eventually, to be a real contender.
Step forward, then, the idea of powering Europe from the Sahara Desert.
I would have to go back at least 10 years to find the first time that someone (an Australian professor, in that case) took me through the sums showing that enough solar energy fell on the sands of North Africa to provide all the world's electricity needs and much, much more.
(I'm sure the concept goes back even further, and I'd be interested to find out just how far back, if anyone has the details to hand.)
Yes, well, I thought; but how much would the electricity cost given the traditionally unfavourable economics of solar energy? What about the major investments needed in plant and transmission lines, and the huge gulf between the political mindsets of the EU and its would-be electricity suppliers?
Now, answers are appearing to some of those questions.
On Monday, a group of companies including some very big industrial concerns - Siemens, RWE, E.On - met with representatives of the German government and other political players to sign a memorandum of understanding that could eventually see the flowering of desert power - the Desertec Industrial Initiative.
Partners will now spend three years putting together viable financial packages that could plant solar facilities across large swathes of the Sahara by 2020.
There is talk of 400bn euros being invested. For comparison, that would dwarf the cost of the Iter fusion power project.
The conventional photovoltaic cell may play some role, but the major technology is likely to be concentrated solar thermal power - probably using approaches where water, or some other fluid, is heated to temperatures measured in hundreds of degrees Celsius and used to turn some kind of turbine.
Remember those startling high-tech photos of mirrors gleaming in a Californian dawn that filled the covers of glossy magazines back in the 1980s? That's a concentrated solar thermal power station.
So is the space-age tower rising from Spanish soil, just outside Seville, which may soon provide enough electricity to meet that city's needs.
The Desertec project's initial goal is "to produce sufficient power to meet around 15% of Europe's electricity requirements and a substantial portion of the power needs of the producer countries".
These will be in North Africa and the Middle East, probably stretching round as far as Jordan, whose Prince Hassan bin Talal declared that "partnerships that will be formed across the regions as a result of the Desertec project will open a new chapter in relations between the people of the EU, West Asia and North Africa".
But the dreams are even bigger. Why not power much more of Europe from the region? Why not electrify much of South America from the Atacama desert and the mountain tops of Patagonia? Sydney and Melbourne from the Simpson desert, and western China from the expanding Gobi?
One reason why not may turn out to be security of supply. Why trade dependence on Middle Eastern gas for dependence on Middle Eastern solar electricity, some would ask.
Another might be that "producer countries" raise concerns about colonialism, about the takeover of their territory to solve Europe's problems - just as some have raised concerns about Western investment in "carbon forests" in poorer tropical nations.
But, if the Jordanian prince is right, Desertec will see development flowing to impoverished desert peoples even as electricity flows in the opposite direction.
Politically, the project will build better bridges between the EU and countries that would like to be closer to it; other benefits could flow over those bridges.
For EU nations, one of the attractions is that it provides a partial route to the target of providing 20% of the bloc's energy by 2020 - a target that, in many observers' eyes, is considerably more ambitious than the 20% greenhouse gas reductions that the EU has also pledged.
Fifteen percent of electricity is a long way from 20% of all energy.
But it is a start. And bear in mind that Europe's electricity consumption is likely to grow; declining reserves of oil and gas will begin to tilt the economics of space heating and transport towards the electric road, and that's a movement that climate policies will probably accelerate.
The next three years, then, will determine if the economics really do stack up.
Many apparently good ideas have perished in the sands of time. One doubts that companies of this scale would be seriously interested in Desertec if they thought it was likely to meet the same end.