For all the cost and efficiency improvements in solar panels in the last few years, all land-based photovoltaics have one serious Achilles Heel: performance is dependent on the weather. If clouds are in the way, even the best solar panels don't work that well.
That's why Jean-François Guillemoles wants to look above the clouds. A solar researcher from France, he's proposing floating solar balloons that potentially could generate three times as much power-per-foot as their terrestrial brethren. His design would also be able to store energy as well as generate power.
"You get much more light up there, actually about the same amount everywhere on Earth," he says in an email. "There's no need to put solar farms in deserts."
Guillemoles, a senior researcher at CNRS, a French research institution, is currently working on the idea with a Japanese group. The consortium, called NextPV, hopes to have a prototype within two years.
The balloon would capture solar energy and sends it to a fuel cell, which would convert the current into hydrogen and keep the balloon afloat. At night, the cell would recover the hydrogen and convert it back into a charge, feeding it down to the ground.
Guillemoles argues that balloon are lighter than solar panels, so need less energy to make and transport. Plus, they can go anywhere and wouldn't take up land that could be used for other purposes (like growing crops).
"Such a solar generator would be very easy and fast to install as well as to move or remove when required," he says. "And, land use is minimal. It has the potential to make solar energy more sustainable and faster to deploy at large scale."
The biggest challenge is making the fuel cell light enough, he adds.
With solar generation now being incorporated into all sorts of surfaces—including the windows of large buildings—the need to find land for solar may not be so acute in the future. Still, Guillemoles's idea is an intriguing one, and it's not like we don't know how to make high-altitude balloons. Google, for one, is already building balloons to spread internet access around the world.