We Could Soon Be Getting Energy from Solar Power Harvested in Space

In SBSP, the energy is converted several times (light to electricity to microwaves to electricity), and some of it is lost as heat. In order to inject 2 gigawatts (GW) of power into the grid, about 10 GW of power will need to be collected by the satellite.

A recent concept called CASSIOPeiA consists of two 2km-wide steerable reflectors. These reflect the sunlight into an array of solar panels. These power transmitters, approximately 1,700 meters in diameter, can be pointed at the ground station. It is estimated that the satellite could have a mass of 2,000 tons.

Another architecture, SPS-ALPHA, differs from CASSIOPeiA in that the solar collector is a large structure formed by a huge number of small, modular reflectors called heliostats, each of which can be independently moved. They are mass-produced to reduce cost.

In 2023, scientists at Caltech launched MAPLE, a small-scale satellite experiment which beamed a tiny amount of power back to Caltech. MAPLE proved the technology could be used to deliver power to Earth.

National and International Interest
SBSP could play a crucial role to meet the UK’s net-zero target by 2050 – but the government’s current strategy does not include it. An independent study found that SBSP could generate up to 10GW of electricity by 2050, one-quarter of the UK’s current demand. SBSP provides a secure and stable energy supply.

It will also create a multi billion-pound industry, with 143,000 jobs across the country. The European Space Agency is currently evaluating the viability of SBSP with its SOLARIS initiative. This could be followed by a full development plan for the technology by 2025.

Other countries have recently announced the intention to beam power to Earth by 2025, moving to larger systems within the next two decades.

A Massive Satellite
If the technology is ready, why is SBSP not being used? The main limit is the enormous amount of mass that needs to be launched into space, and its cost per kilogram. Companies such as SpaceX and Blue Origin are developing heavy-lift launch vehicles, with a focus on reusing parts of those vehicles after they have flown. This can bring the cost of the venture down by 90%.

Even using SpaceX’s Starship vehicle, which can launch 150 tons of cargo into low Earth orbit, the SBSP satellite will require hundreds of launches. Some components, such as long structural trusses – structural elements designed to span long distances – could be 3D-printed in space.

Challenges and Risks
An SBSP mission will be challenging – and risks still need to be fully assessed. While the electricity produced is fully green, the impact of the pollution from hundreds of heavy-lift launches is difficult to predict.

Additionally, controlling such a large structure in space will require substantial amounts of fuel, which involves engineers working with sometimes very toxic chemicals. The photovoltaic solar panels will be affected by degradation, reducing efficiency over time from 1% to 10% per year. However, servicing and refueling could be used to extend the satellite’s lifetime almost indefinitely.

A beam of microwaves powerful enough to reach the ground could also harm anything that got in the way. For safety, then, the power density of the beam will have to be restricted.

The challenge of building platforms like this in space may seem daunting, but space-based solar power is technologically feasible. To be economically viable, it requires large-scale engineering, and therefore long-term and decisive commitment from governments and space agencies.

But with all that in place, SBSP could make a fundamental contribution to delivering net zero by 2050 with sustainable, clean energy from space.

Matteo Ceriotti is Senior Lecturer in Space Systems Engineering, University of Glasgow. This articleis published courtesy of The Conversation.