One thing that the BBC has been promoting (the science journalists rather than the environmental journalists) over the last few weeks is the "Solar Impulse 2" project, which is expected to continue over several more months, and is described on this webpage:
"In the footsteps of the great aeronautical firsts, Solar Impulse intends to achieve the First Round-The-World Solar Flight in 2015, after 12 years of research, tests and development. No fuel, but only solar energy and technologies of the future, to prove that pioneering spirit and innovation can really change the world."
"Our aim: Bertrand Piccard and André Borschberg do not plan to revolutionize the aviation industry but instead to demonstrate that the actual alternative energy sources and new technologies can achieve what some consider impossible. Solar Impulse wants to mobilize public enthusiasm in favor of technologies that will allow decreased dependance on fossil fuels, and induce positive emotions about renewable energies."
This looks as though it is part of the campaign to get world leaders to sign up to a new climate change agreement in 2015. There seems to be a left-liberal push to reduce the use of fossil fuel, campaigning for it to be left in the ground, and this might be an issue in any new agreement. I can imagine a thicko like John Prescott (who has been recently appointed as Ed Miliband's adviser on climate change, and would be strongly involved in negotiations by the UK on a new climate change agreement, as he was in the 1997 Kyoto Protocol, if Labour won the 2015 General Election) arguing that you don't really need fossil fuel if you can build a solar powered plane that can fly round the world.
The terminology used on the Solar Impulse project is somewhat different to what is normally encountered. Often renewable energy proponents claim they are using free fuel, in the sense that nobody is specifically selling wind or sunlight as a commodity to them. The Solar Impulse people are claiming not to be using fuel, so they are not actually regarding sunlight as a fuel.
However the NoTricksZone blog points out the claim not to be using any [fossil] fuel in this project is rather dubious, as it involves support planes which will be using aviation fuel: