Solar energy from space: research group directs energy using microwaves

Isaac Asimov’s short story ‘Reason’ is about a mission in which two astronauts are sent to a space station to provide the Earth and other planets with solar energy via microwave radiation. The entire process is controlled by an AI that turns evil later in the story.

The short story could be from this decade, but it was published in 1941. This year, more than 83 years later, we are getting closer to Asimov’s fiction.

In January 2023, a research team from the California Institute of Technology (Caltech) sent the Microwave Array Power Transfer LEO Experiment, or Maple for short, into space. The purpose of the experiment, as in Asimov’s short story, was to send energy to Earth using microwave radiation. The team succeeded in this in March 2023. The experiment was successfully performed a total of three times.

Despite all the euphoria, it should be mentioned that only 1 milliwatt of energy could be transferred at a time. For comparison: a conventional LED lamp needs about 6 watts per hour, which corresponds to 6000 milliwatts. However, as the research group states in its report, the purpose of the experiment was mainly to test the feasibility of energy transport.

One reason for the small amount of energy is the size of the solar panel used. The area of ​​the satellite was 150 square centimeters. This is about the size of a sheet of A6 paper. According to the research group, a functional system should be at least one square kilometer in size. This can provide tens of thousands of households with electricity.

The idea of ​​the ‘Satellite Solar Power System’, or SSPS for short, was adopted by the US government and NASA in the 1970s, but was subsequently rejected. The main reason at the time was the high financial risk that would have to be taken without guaranteeing a satisfactory result.

There have been smaller projects in SSPS research since the early 2000s. China, India, Japan and the US, among others, have shown interest in it in recent years.

Theoretically, solar systems in space would have enormous advantages. Theoretically, they could produce energy almost 24 hours a day in a perfect position relative to the sun. But the problem is the cost. Transporting the necessary material to Earth’s orbit is so expensive that the energy produced would not be able to compete with traditional forms of energy on the open market.