Solar panels need a lot of space. So why not use the large expanses of water available to us to generate environmentally friendly electricity? The key problem here is the swell, which poses a threat to large floating installations on the water.

Scientists at TU Wien have now developed a new type of lightweight construction that can be used to build hundred-meter-long platforms that remain calm and stable in place even in high waves.

Stable in high waves

"The key trick is that 'Heliofloat' is supported by open floating bodies," explains Prof. Markus Haider from the Institute of Energy Technology and Thermodynamics. "If a platform were simply mounted on air-filled closed containers, the construction would either have to be uneconomically heavy and robust, or it would not be able to withstand strong waves for long."

The Heliofloat buoyancy chamber can be imagined as a barrel open at the bottom and made of a soft, flexible material that floats in the water.

© TU Vienna

Heliofloat's buoyancy bodies, on the other hand, can be imagined as a barrel open at the bottom and made of a soft, flexible material that floats in the water. There is air at the top that cannot escape, so the barrel floats - but the air is in direct contact with the water at the bottom. There is no enclosed air cushion, but the column of air above the water acts like a shock absorber. The flexible side walls of the "barrels" only absorb small horizontal forces.

Heliofloat is supported by several of these air tanks, which are open at the bottom, creating a large, flat usable surface at the top. If the air tanks are correctly dimensioned, the waves can go up and down underneath Heliofloat without significantly affecting the platform. The system floats calmly above the water. This would be impossible with closed and rigid air cushions, which would absorb the wave energy to a much greater extent, start to sway wildly and sooner or later destroy the platform.

Not just for solar energy

This new construction makes it possible to provide areas the size of a soccer pitch on the water in a very simple way. The research team at TU Wien has developed concepts for using the sun above the water with photovoltaics or with the help of parabolically shaped mirrored troughs - but many other possible applications are also being considered.

"Heliofloat platforms offer completely new possibilities for desalination plants or biomass production from salt water," says Dr. Roland Eisl, graduate of TU Wien and Managing Director of Heliofloat GmbH. "In hot countries, heliofloat platforms could be used to protect lakes from drying out." The evaporation surface becomes smaller, but Heliofloat platforms can let sunlight through into the water so as not to impair life in the lake.

Aquafarming could also be carried out on Heliofloat, and even the construction of sports facilities is possible - and in the future it may even be possible to build residential buildings on the water.

The research team at TU Wien and the TU spin-off Heliofloat are in talks with interested parties and relevant authorities and are still looking for further cooperation partners and investors who want to use Heliofloat platforms on a large scale.