30/09/2022

The UK government is reportedly considering a £16 billion proposal to build a solar power station in space.  It has been identified as a potential solution, to enable the UK to achieve net zero by 2050.  

With global energy demand projected to increase by nearly 50%  by 2050, space-based solar power could be key to helping meet the growing demand on the world’s energy sector and tackling global temperature rise. 

Space-based solar power involves collecting solar energy in space and transferring it to Earth. Recent technological advancements have made this prospect more achievable. 

At a Space Enabled Net-Zero Earth conference held in London, the initiative's chairman Martin Soltau said that all technology required to develop a space-based solar power plant already exists; the challenge is the scope and size of such a project. "The study concluded that this is technically viable and doesn't require any breakthroughs in laws of physics, new materials, or component technology," Soltau said.  

The space-based solar power system involves a solar power satellite – an enormous spacecraft equipped with solar panels. These panels generate electricity, which is then wirelessly transmitted to Earth through high-frequency radio waves. To receive the energy from space, the system would need a giant Earth-based antenna, dubbed the rectenna. The rectenna receives the microwave radiation sent from space and converts it into direct current electricity, which is used for high-voltage transmission.  

"The rectenna is like a big open net with small dipole antennas and would have to be 7 by 13 kilometers [4.3 to 8 miles] in size," Soltau said. "That's very large, but in the U.K. context, it would occupy only about 40% of the area of an equivalent solar farm." 

Unlike from terrestrial solar power systems, a space-based solar power station is illuminated by the Sun 24 hours a day and could therefore generate electricity continuously.  

Andrew Ross Wilson, an aerospace engineering researcher at the University of Strathclyde in Scotland, agrees that a space-based solar power station is a realistic conception. According to Ross, about the potential radiation from this beamed electricity, the risk is negligible - "You're more likely to receive more radiation from the phone in your pocket than you would if you were standing under one of the beams," he said.  

Challenges   

The operation of space-based solar power stations faces several practical challenges. 

• A space-based solar power station is based on a modular design, where a large number of solar modules are assembled by robots in orbit. Transporting all these elements into space is difficult, costly, and will take a toll on the environment.
• Solar panels could be damaged by space debris, Further, panels in space are not shielded by Earth’s atmosphere. Being exposed to more intense solar radiation means they will degrade faster than those on Earth, which will reduce the power they are able to generate.
• One space-based solar power station will require many space shuttle launches. Space shuttles are not currently reusable, though companies like Space X are working on changing this. Being able to reuse launch systems would significantly reduce the overall cost of space-based solar power.
• Another challenge is wireless power transmission across large distances – in this case, from a solar satellite in space to the ground. Based on current technology, only a small fraction of collected solar energy would reach the Earth. 

Pilot projects are already underway

 The US Naval Research Laboratory tested a solar module and power conversion system in space in 2020. Meanwhile, China has announced progress on their Bishan space solar energy station, with the aim to have a functioning system by 2035.

In the UK, a £17 billion space-based solar power development is deemed to be a viable concept. The project is expected to start with small trials, leading to an operational solar power station in 2040. 

The solar power satellite would be 1.7km in diameter, weighing around 2,000 tonnes. The terrestrial antenna takes up a lot of space – roughly 6.7km by 13km.  

With extremely high initial costs and slow return on investment, the project would need substantial governmental resources as well as investments from private companies. But as technology advances, the cost of space launch and manufacturing will steadily decrease. And the scale of the project will allow for mass manufacturing, which should drive the cost down somewhat. 

Whether space-based solar power can help us meet net zero by 2050 remains to be seen, but it seems that in the future, the technology is likely to play an important role in the global energy supply.

Source: World Economic Forum, Jovana Radulovic, A solar power station in space? Here’s how it would work - and help us get to net zero