Beyond the clouds – developing solar energy from space

Solar panels in space can always generate energy. But can that energy be beamed back to Earth? ESA is funding a TU Delft proposal for solar power from space.

Impression of energy-producing Cubesats beaming back to Earth. (Image: ESA)

Energy from space may be a step closer since scientists from the Faculty of Aerospace Engineering and their consortium partners received funding from the European Space Agency (ESA) to perform a feasibility study on generating space-based solar power and make it available for users on earth.

Out of about 100 proposals, only seven were selected to receive the EUR 100,000 grants to show the feasibility of and economic interest in their ideas. Six months after the kick-off in October 2023, ESA will select one or two studies for additional funding. “This first stage is all about further developing the idea,” says scientist Stefano Speretta. “We will concentrate on the technical and economic viability of wirelessly transferring power, generated by space-based solar panels, to Earth. It’s nothing less than an intensive race, as we already have to finish our theoretical analysis in March 2024.” 

A high-power radio beam will transfer the energy to Earth

The first step of their idea is to use a swarm of satellites equipped with solar panels to generate energy. A high-power radio beam will subsequently transfer the solar energy from space to Earth, where a network of dish-shaped antennas will capture the beams and convert the energy into electricity.

The consortium members will assess the different technologies needed to achieve this. The prime contractor, the Swiss Siron Orbital Systems AG, will design the wireless power transmission system, and the University of Strathclyde, Scotland, will be responsible for planning and calculating the ideal satellite orbits, the satellite formation and the design of the antennas. Scientists Stefano Speretta, Angelo Cervone and Mehmet Sevket, from TU Delft, will design the satellites as well as their propulsion and navigation systems.

Despite the promising potential of the project, Speretta sees several challenges that need to be overcome. One of them is how to place the energy-receiving antennas as efficiently as possible so that they take up the least possible space? Another aspect to consider is that when many satellites generate solar power, the transmission to Earth should be highly synchronised to maximise transfer efficiency. This means that all the satellites should be close to each other and be able to communicate to allow synchronisation.

‘The biggest challenge is focussing the energy beam’

“I think the biggest challenge is to focus the wireless radio beam containing the energy,” Speretta says. “Imagine a torch whose fairly narrow light bundle falls on a wall. The further you move away from the wall, the less focused and more diffused the light bundle will be. Similarly, when directing a high-energy radio beam from space to Earth, it has to cover more than 700 kilometres. This inevitably results in a less focused, more diffused energy beam.”

The scientists will have to resolve these challenges over the coming months, or at least give a realistic perspective on how to solve them, if they are to qualify for a continuation of their project.    

Hans Wolkers / Freelance wetenschapsredacteur

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