Electro-chemist Jean-Francois Guillemoles is looking above the clouds with his concept for floating solar balloons. The invention, which would be able to store energy as well as generate it, has the potential to generate 3 times more energy per square meter than a land based solar cell. So why not send solar cells above the clouds where the sun is always shining?

The main problem with conventional land based solar energy is that performance is to a high degree dependent upon the weather as clouds result in intermittent and uncertain energy production. At an altitude of 6 kilometers above ground however, there are very few clouds. And at an altitude of 20 km, there are no clouds at all. At this height, light comes directly from the sun with hardly any atmospheric diffusion and direct illumination is more intense. This concentration of solar energy results in more efficient conversion and higher solar yields. And at an altitude of 20 km, everywhere on earth, and not just the desert, has excellent potential for generating solar energy.

Solar balloons also offer the advantage that they are lighter and much easier to move than traditional solar panels. Plus, the balloons would not take up land space that could for instance be used agricultural purposes.

The idea is that the balloons are mounted with lightweight and flexible solar cells. These cells capture solar energy which is then sent to a fuel cell where the current is converted into hydrogen to keep the balloon afloat. At night, the cell recovers the hydrogen and converts is back to a charge, which is fed down to the ground. According to Guillemoles, the largest challenge to date is create a fuel cell that is light enough.

Guillemoles is collaborating with NextPV from Japan with the aim of producing a prototype within the next two years.