Efforts to transmit solar power from space to Earth

Researchers are conducting experiments to generate solar power in space and transmit it wirelessly back to Earth.

Simulation of the British-designed CASSIOPeiA solar power satellite. Photo: Space Solar — Simulation of the British-designed CASSIOPeiA solar power satellite. Photo: *Space Solar*

Ali Hajimiri, a professor of electrical engineering at the California Institute of Technology (Caltech), has spent a decade researching ways to launch solar cells into space and beam the energy back to Earth, according to CNN . This year, Hajimiri and his colleagues took another step toward making solar power generation in space a reality. In January 2023, they launched Maple, a 30-centimeter-long prototype equipped with a flexible, ultralight transmitter. Their goal is to collect energy from the Sun and transmit it wirelessly in space. The amount of electricity the team collected was enough to power two LED bulbs.

The researchers’ broader goal, however, was to see if Maple could beam energy back to Earth. In May 2023, the team decided to conduct an experiment to find out what would happen. On a rooftop in the Caltech campus in Pasadena, California, Hajimiri and several other scientists were able to pick up Maple’s signal. The energy they detected was too small to be useful, but they had succeeded in transmitting wireless electricity from space.

Producing solar power in space is not a very complicated idea. Humans could harness the Sun’s enormous energy in space. It is a source of electricity that is available all the time, unaffected by bad weather, cloud cover, time of night or season. There are many different ideas for doing this, but here’s how it works. Solar satellites measuring more than a mile in diameter are launched into high-altitude orbits. Because of the massive size of the structures, they are made up of hundreds of thousands of smaller, mass-produced modules, like Lego bricks, that are assembled in space by automated robots.

The satellite's solar panels will collect solar energy, convert it into microwaves and transmit it wirelessly to Earth via a very large signal transmitter, which can be transmitted to a specific location on the ground with high precision. The microwaves can easily penetrate clouds and bad weather, heading to the receiving antenna on Earth. Then, the microwaves are converted back into electricity and fed into the grid.

The receiving antennas are about 6 kilometers in diameter and can be built on land or offshore. Because the grid-like structure is nearly transparent, the land beneath them can be used for solar panels, farms, or other uses. A single solar-harvesting satellite in space could provide 2 gigawatts of power, equivalent to two medium-sized nuclear power plants in the United States.

The big barrier to the technology has been the high cost of putting power plants in orbit. That’s started to change over the past decade as companies like SpaceX and Blue Origin have started developing reusable rockets. Launch costs are now around $1,500 per kilogram, about 30 times less than they were during the space shuttle era in the early 1980s.

Proponents of the idea say that space-based solar power could provide energy to developed countries that have huge energy needs but lack the infrastructure. It could also serve the many remote Arctic towns and villages that are in total darkness for months each year, and help communities that lose power due to natural disasters or conflicts.

While there is still a long way to go between concept and commercialization, governments and companies around the world believe that space solar power can meet the growing demand for clean electricity and help tackle the climate crisis. In the US, the Air Force Research Laboratory plans to launch a small experimental vehicle called Arachne in 2025. The US Naval Research Laboratory launched a module in May 2020 on an orbital test vehicle to test solar power generation hardware in space conditions. The China Academy of Space Technology aims to launch a solar battery satellite into low orbit in 2028 and high orbit in 2030.

The UK government has conducted an independent study and concluded that solar power generation in space is technically feasible with designs such as CASSIOPeiA, a 1.7 km satellite that can deliver 2 gigawatts of power. The European Union is also developing the Solaris program to determine the technical feasibility of solar power in space.

In California, Hajimiri and his team have spent the past six months stress-testing prototypes to gather data for next-generation designs. Hajimiri’s ultimate goal is a series of flexible, lightweight sails that can be transported, launched, and unfolded in space, with billions of components working in perfect sync to deliver energy where it’s needed.

An Khang (According to CNN )

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