Could one solution to climate change be to harvest the power of sunlight where it shines brightest on the planet? Should we solar panel the Sahara desert?
Four experts discuss the radical proposal with the BBC World Service Inquiry programme.
Gerhard Knies: Scientifically sound and economically viable
Dr Gerhard Knies co-founded TREC, a network of experts on sustainable energy that gave rise to the Desertec initiative, which aimed to provide Europe with clean energy by harnessing sustainable power from sun-rich deserts.
"Fifteen minutes after I learned about the nuclear accident at Chernobyl, I made an assessment of how much energy comes from the sun to the earth. It was about 15,000 times as much as humanity was using, so it was not a question of the source, it was a question of the technology.
"When the climate change issue became more prominent, I said we have to pull forward this solution, because it solves the industrial vulnerability problem of our civilisation, and at the same time, the climate vulnerability.
"My strategy was to look for amplifiers. A very good one was The Club of Rome, with its president, Prince Hassan from Jordan. We had a seminar with experts. We included European participants, but also people from North Africa, Jordan and the Middle East. They all said 'Yes, that would be great for us to have such a thing.'
"We did a study so that we had numbers which are scientifically sound, based on the present knowledge in a clear way. We got support from Greenpeace and from several scientific institutions and big companies.
"We didn't want politicians in the game; it should just be scientifically sound and economically viable. But politicians liked it, and when the Desertec Industrial Initiative launched in Munich in July 2009, we were flooded with politicians. When they see the potential for a solution they get interested.
"The Desertec Initiative was made to study the plan from the angle of industry and see if they find flaws or if everything was right to pave the way for investments, but not to do the investments. [After that work was done] they began to fight about which direction it should go in and dissolved.
"The second stage is now called the Desert Energy Industrial Initiative and they want to organise implementation, and that is beginning.
"At the time when [the idea] was conceived, North Africa looked quite different. Now, this turbulence changes the whole business environment, and the region has to go through that. But the demand, the need to tap into the solar energy in deserts, has not disappeared."
Tony Patt: Beware political complications
Tony Patt is professor of climate policy at the Swiss Federal Institute of Technology in Zurich. He leads the research for the European Research Council on whether the Saharan sun could power Europe.
"The technology is good. It's matured a lot in the last few years in terms of thermal storage. That allows you to take the heat that you capture from the sun and store it for, let's say, up to a day, and produce the power later. That means you can generate it around the clock.
"And the Sahara desert is so big that if there is cloudy weather, it's localised, and with thermal storage, it can provide absolutely reliable power.
"Where I'm from in the US, Boston gets a huge amount of electricity from northern Quebec, which is about 1,000 miles away, via a single power cable. They're not hard to build as long as you get political approval from all the jurisdictions you're going through.
"They don't lose much power. Maybe over 1,000 miles you lose 2%.
"The biggest potential pitfall is that it's politically complicated. You're not going to develop solar energy in the Sahara unless you have a very strong state involvement, both on the side of the consumers and the project developers.
"Solar electricity is still a little bit more expensive than electricity from fossil fuels. It's becoming competitive, but it's not clearly competitive yet. So it's nothing that the private sector is doing on its own.
"There are a lot of political battles that need to take place to figure out where we're going to build the infrastructure, how it's going to get paid for. And perhaps more critically, how and when we're going to turn off the old infrastructure.
"Over the last 15 years, Germany has taken vast steps to support solar energy, but that was tied to building it within Germany, creating jobs for Germans. There's less of a clear case for European governments to support what is still more expensive energy when it's people in other parts of the world who are getting those jobs."
Daniel Egbe: Africa must share the benefits
Danie Egbe is an evaluator for the World Bank, a chemist, an academic and the founder of ANSOLE, a network of Africans for Africa, with a focus on renewable energy. He co-authored a book on renewable energy in Sub-Saharan Africa.
"Africa has an acute energy problem. Only around 30% of sub-Saharan Africans have access to electricity. Economic growth in Africa is now around 5.5%, but this is hampered by lack of energy.
"The presentations which were given in the past have arrows showing how energy will be funnelled to the north. But there was no arrow pointing down to sub-Saharan Africa.
"As an African, knowing the history about the exploitation of the continent, where there is a big gap when it comes to riches, and Africa is still poor due to the colonial past and the slave time, nobody can just come and do things as if we are still in the past.
"Things have changed. Africans are self-confident now, they want to participate in their development, and they want to have part of their resources, they are not just there to always give to the rest of the world and remain poor.
"The African Network for Solar Energy is there to see that the African interest is taken into consideration.
"I'm not against a big solar project. They can exist, but can only be in certain parts of the countries. If I want to supply electricity to very remote areas, the off-grid approach is the best, where somebody has his own solar panel, or a group of villagers can share one, and they control the production.
"If those conditions are fulfilled, why not? Solar energy is for the whole world. But let's not just come and say 'Okay, Joe has something, I come and take it from him and I leave him alone.' No I have to see, 'Okay, Joe has something, maybe he can share it with me, and we can benefit from it?'"
Helen Anne Curry: Technology alone is rarely the answer
Helen Anne Curry is a lecturer in the Department of History and Philosophy of Science at Cambridge University
"I am interested in exploring the persistent optimism that surrounds new technologies, even after multiple failures.
"The technological fix is appealing; it's exciting to think we can solve problems without fundamentally having to change the way we live, the way we get to work every day or the number of cheap flights we take.
"But you can't just take one point in the system and say 'that's solved'; there is much more that extends outwards.
"Think of the work that was done to solve local air pollution in the mid-twentieth century, which was to build super-tall smokestacks.
"But they don't eliminate the pollution from the air. They just throw it up much higher in the atmosphere, so in fact it circulates further. One of the subsequent problems of building these was they created acid rain in places that didn't have this kind of concentrated industry.
"We can use our science and technology knowledge to bring other peoples of the world into the quality of life that the global north has enjoyed for far longer.
"Yet if you look back on 60 years of policy work and intervention, there's a lot of ways in which we've failed. We haven't been able to deliver the social, scientific and technological progress which we envisioned.
"I think the only reason to pursue [solar panels in the Sahara] would be if it were a stopgap measure in which the long-term goal would be to reduce consumption of energy and to change our lifestyles to be more sustainable, so that subsequent generations don't have to deal with as many problems as we're going to leave them."