European space agency considers plan for orbiting solar farms that beam energy into homes on Earth

Satellites for such a project would need to be several kilometres in size, scientists say

The European Space Agency (ESA) is considering a proposal for a three-year study to assess whether solar farms in orbit could produce energy from the Sun and beam it down to Earth.

ESA described in a statement earlier this month that as part of the Solaris project, giant orbiting satellites would harvest sunlight on a permanent basis and convert it into low-power density microwaves that can be safely beamed down to receiver stations on Earth.

The satellites for such a project, ESA noted, are required to be several kilometres in size, and the ‘rectennas’ that would be collecting the energy beamed onto the Earth’s surface would also need to be several times larger.

Such space-based solar power generation projects are based on the idea that sunlight is over ten times as intense at the top of the atmosphere than it is down on Earth’s surface.

The space agency would consider the idea at its Paris HQ on Tuesday.

Experts say the proposal would consider the kinds of technological advancements required for the project, including in areas such as in-space manufacturing and robotic assembly, high-efficiency photovoltaics, high-power electronics, and radio frequency beam forming.

Launching such a huge satellite into orbit would also be a large hurdle, requiring several more launches to assemble the power-generating structure which weighs thousands of tonnes more than the International Space Station.

But with launch costs continuing towards a downward trend across the world, ESA hopes that the construction of such a space-based power-generating satellite would become economically feasible.

In further studies, researchers would also need to confirm the effects of low-power microwaves on human and animal health as well as the compatibility with aircraft and satellites.

Scientists estimate that one such giant satellite in geostationary orbit could potentially provide about two gigawatts of power each – which is about the energy generated by about six million solar panels on Earth’s surface.

The energy potentially generated from one such satellite in orbit will also be equivalent to that from a conventional nuclear power station, and is capable of powering over one million homes, ESA says.

“Considering the climate and energy crises, and the rapid strides we’re making in space capabilities, now is the time to investigate if Space-Based Solar Power can be part of the solution – it’s the responsible thing to do,” Sanjay Vijendran, ESA’s lead for the SOLARIS proposal, had said in September.

The ESA also said such a project could ensure that “Europe becomes a key player– and potentially leader – in the international race towards scalable clean energy solutions for mitigating climate change”.

“Through Solaris, Europe would extend the technological state-of-art in a diverse set of key technologies relevant to applications both on Earth and in space, such as high-efficiency solar cells, wireless power transmission and robotic in-orbit assembly,” the space agency said.