Space-Based Solar Power: Can We Achieve Unlimited Clean Energy by Beaming Sunlight Back to Earth?

Solar power has become the fastest-growing form of renewable energy today, accounting for 3.3% of the global electricity production of our modern society. This makes it the third largest source of the renewable energy market, followed by hydroelectric power and wind.

(Photo: Wikimedia Commons/ NASA)

However, several technical issues arise when generating solar power, especially since it relies on the use of solar panels.

Challenges in Generating Solar Energy

Here on Earth, solar panels comprise multiple solar cells, the little devices that convert radiation from the sun into electricity. They have existed since the late 1800s and currently generate about 4% of the global electricity.

Critics of solar technology argue that solar panels do not often work in countries blighted by cloudy weather for much of the year, such as the UK. Another problem is that solar panels take up a lot of space in the ground and can be an eyesore, especially on green land that can be freed up for other uses.

Sending Electrical Power Through Air

To address this problem, scientists from California tried to provide a solution by sending solar panels to space to harness the power of the Sun. For the first time, solar energy was beamed wirelessly to Earth from a spacecraft.

Known as the Microwave Array for Power-transfer Low-Orbit Experiment (MAPLE), the spacecraft is equipped with solar panels that can withstand the harsh environment of space, including solar radiation and wild temperature swings. It was launched aboard the Transporter-6 mission from Cape Canaveral.

MAPLE contains an array of flexible, lightweight microwave power transmitters driven by electronic chips made using low-cost silicon. The transmitters were made flexible to fold into a package that can be transported in a rocket and then unfold once in orbit.

The spacecraft transmitters convert the solar energy into a form that can be transmitted to Earth, such as microwaves or lasers. The array of transmitters can beam the energy to specific locations, like receiving stations on Earth that feed the power into the national grid.

This experiment is led by the Space Solar Power Project (SSPP) of the California Institute of Technology (Caltech). It aims to harvest solar energy in space and transmit it to the Earth as a permanent power source.

For the first time, the transmitted energy from MAPLE was detected by a receiver on Caltech's campus in Pasadena, California. The signal received by the scientists appeared at the expected time and frequency and had the right change in frequency as predicted based on its travel from orbit.

The scientists hope this project will provide a cleaner alternative to fossil fuels and renewable energy resources like nuclear, wind, and geothermal. According to Caltech electrical engineering professor Ali Hajimiri, they have received confirmation that MAPLE can transmit power successfully to receivers in space.

They have also been able to program the array to direct its energy toward Earth, which is detected right at Caltech. After testing the solar power on Earth, the research team confirmed that it can survive the trip to space and operate outside our planet.

Space-based solar power is not a new concept; it was conjured by science-fiction writer Isaac Asimov in 1941. It was thought to yield eight times more power than solar panels placed at any location on the surface of the Earth.