The initiative believes that beaming electricity from space using the sun could help the U.K. meet its target of zero greenhouse gas emissions by 2050 more cost-effectively than many existing technologies. The requirement to stop carbon emissions entirely by mid-century is part of global efforts to halt progressing climate change outlined at the United Nations’ COP 26 summit that took place in Glasgow in November 2021.
The initiative bases its plans on an extensive engineering study conducted by consultancy Frazer-Nash and commissioned by the U.K. government last year.
The initiative has established a 12-year development plan that could see a demonstrator power plant, assembled by robots in orbit, beam gigawatts of power from space to Earth as early as 2035, Soltau said.
“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.
Over 50 British technology organisations, including aerospace giant Airbus, Cambridge University, and satellite manufacturer SSTL, have joined the U.K. Space Energy Initiative, which was created last year to investigate ideas for creating a space-based solar power plant.
Speaking at the Toward a Space Enabled Net-Zero Earth conference held in London, the initiative’s chairman Martin Soltau said on April 27 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 initiative explores a modular concept called CASSIOPeiA (for Constant Aperture, Solid-State, Integrated, Orbital Phased Array), developed by the British engineering firm International Electric Company.
The modular nature of the orbiting power plant means it could be expanded after the demonstration phase. Even the demonstrator, however, would be giant, several miles across, and require 300 launches of a rocket the size of SpaceX Starship to deliver to orbit, said Soltau. It would orbit 22,000 miles above our planet (36,000 kilometers) with a constant view of the sun as well as of Earth.
“The principal functions of the satellite are collecting the solar energy via large, lightweight mirrors and concentrating optics onto photovoltaic cells, just like we do on Earth,” said Soltau. “They produce direct current electricity, that’s then converted into microwaves via solid state radio frequency power amplifiers and transmitted in a coherent microwave beam down to Earth.” However, CASSIOPeiA would produce much more electricity than any terrestrial solar power plant of a similar size. Compared to a solar panel placed on Earth in the U.K., an identical solar panel in space would harvest over 13 times more energy, Soltau said. In addition to that, a space-based solar power plant would not suffer from the intermittency problem, which plagues most renewable power generation on Earth. Sun doesn’t always shine on our planet and the wind doesn’t blow consistently. That means alternative electricity generators or battery storage have to be in place to prevent blackouts in unfavorable weather. Space, on the other hand, would provide consistent power output.
On top of that, technologies that would make the electricity system work based only on Earth-based renewable power do not yet exist. “Energy storage technology doesn’t exist yet at the right price and scale,” said Soltau. “We need other technologies, because we don’t have a plan that adds up. Net- zero will be very difficult and space-based solar power can deliver an interesting option.”
The U.K. can cover over 40% of its current electricity needs by renewable power, but the demand for clean energy is set to triple over the next three decades, according to Soltau, as transport and heating infrastructure wean off fossil fuels. To meet such a demand with offshore wind farms, the type of renewable technology currently making the greatest contribution to the U.K.’s energy mix, would require “a band of turbines 10 kilometers [6.2 miles] wide around the entire mainland coast of Britain,” according to Soltau.
“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.” Speaking at the same conference, Andrew Ross Wilson, an aerospace engineering researcher at the University of Strathclyde in Scotland, agreed that a space-based solar power station is a realistic conception.
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 footprint of the ground-based infrastructure needed for the orbiting solar power plant would be much smaller.