The idea of solar energy beamed back to earth from space was born a century ago by astronautics pioneer, Konstantin Tsiolkovsky, and then popularised by Isaac Asimov in his 1941 short story Reason. Although the first designs for a solar power satellite with microwave-based transmission were developed by Czech-born NASA engineer, Peter Glaser, in 1968, it has taken decades for complementary technologies to catch up to even make testing the concept feasible.
Space-based solar power (SBSP) uses photovoltaic panels on satellites to generate electricity and beam it back to Earth in microwave form. The energy is then converted back to electricity at a rectenna receiving station connected to the grid. By deploying a network of geostationary satellites, it is theoretically possible to transmit energy around the globe before beaming it back to Earth. The technology would be a breakthrough, generating abundant renewable energy 24 hours per day, regardless of the weather or season. This would overcome the primary challenge of renewables – intermittency – and reduce the need for storage.
Reusable Rockets and Small Satellites
One of the greatest hurdles to commercialising SBSP is the prohibitive cost to launch into orbit, but the advent of reusable rockets and small satellites has brought down the price dramatically. Private companies, like SpaceX and Rocket Lab, charge between USD 3,000-30,000 per kilogram of payload to low earth orbit, a fraction of the cost when launches were dominated by government space agencies.
The emergence of cheaper small satellites, or CubeSats, is also creating a landscape favourable to innovation in space. Researchers can afford to experiment with new technologies by launching prototypes into orbit and iterating quickly.
Caltech Experiment Proves Transmission is Possible
While the efficiency and durability of photovoltaic panels have improved exponentially and the cost of launching satellites into space has plummeted, transmitting power back to Earth remains a challenge. Electricity must be converted into microwaves, with the beams steered back through the earth’s atmosphere. Transmission can be degraded by factors, such as atmospheric absorption, diffraction, and weather.
Researchers from The California Institute of Technology (Caltech) recently achieved a milestone by demonstrating that the transmission of energy from space is possible. The Caltech Space Solar Power Project (SSPP) launched the Microwave Array for Power-transfer Low-orbit Experiment (MAPLE) onboard the Space Solar Power Demonstrator (SSPD-1) earlier this year. In progressively ambitious experiments, the researchers lit up two LEDs in orbit to test energy transfer in space. Next, they successfully transmitted a “detectable” amount of power to antennae on the roof of the Moore Laboratory at Caltech. This may prove to be the first step toward developing a commercially viable system.
Governments Recognise Space-based Solar Potential
With sustainability and energy security coming sharply into focus over the last year, governments have sat up and paid attention to the potential of SBSP. The UK’s energy security secretary, Grant Shapps, recently announced the winners of £4.3M in funding to develop the technology. The grants were devised to tap into the 10GW of space-based solar power potential that an independent study estimated would be available to the UK. Public entities in the EU, China, Japan, and the US have made similar announcements over the past 12 months, signalling a rapid shift in momentum for SBSP.
A Revolution of Space-based Power and Communications
Although SBSP is still undeniably an experimental technology, recent developments hint at a future where clean energy could be beamed down to Earth. Even accounting for transmission loss, each solar power satellite is estimated to deliver the equivalent of a nuclear power station to the grid.
Access to power remains a major obstacle to data centre operators, whether they are hyperscale cloud providers, city-based facilities at capacity, or small regional edge data centres. In recent years, cloud hubs, such as Singapore and Ireland, have imposed strict controls on new data centre builds due to concerns about escalating power consumption. Rising prices for natural gas have made the business case for renewable sources for data centre power even more attractive and space-based solar is an alluring candidate to add to the future mix.
Power transmitted to Earth could be coupled with low latency connectivity provided by satellites in low earth orbit from the likes of Starlink. The pairing of power and connectivity from satellites means even remote locations could be served. Advances in energy and communications have ignited progress since the discovery of fire and the emergence of language and these space-based innovations will undoubtedly play a key role in the next industrial revolution.
