We may actually be able to beam solar power from space to earth

Space-based solar power attempts to capture the vast amounts of energy generated by the Sun from space, convert it into microwaves, and transport it to earth.
Space-based solar power attempts to capture the vast amounts of energy generated by the Sun from space, convert it into microwaves, and transport it to earth.


  • It’s a scientific innovation that could someday supply our planet with enough clean energy to save itv

In a 1941 short story, Reason, from Isaac Asimov’s Robot series, a certain Gregory Powell and Mike Donovon are assigned to a space station, carrying a very important role for humankind—supplying energy via microwave beams to all planets, including Earth. The whole process is controlled by AI, a robot called QT-1, who then decided to become the ‘Master’. But that is another story. Today’s column is about a new generative technology that is creating a buzz in scientific circles. Not Generative AI this time, but space-based solar power—a technology that promises to generate clean energy literally out of thin air. The reason for the excitement is a recent experiment in Caltech, and its potential to provide unlimited clean energy and ‘solve’ global warming.

I had written about another miraculous technology, nuclear fusion (bit.ly/3EUbEEI). Using widely available chemicals like deuterium and tritium, with nuclear fusion, one can theoretically extract from a glass of these materials an energy equivalent of a million gallons of oil! This could produce 9 million KWh of electricity, which would power your house for the next 800 years. Scientists have known of this phenomenon since Einstein’s times, and it is the energy that powers our Sun. As Anjana Ahuja writes in the FT (on.ft.com/3Ef6Auo): “The fireball at the heart of our solar system is powered by nuclear fusion. The crushing pressures in the sun’s core squeeze hydrogen nuclei together so powerfully that they overcome their natural repulsion and fuse. These nuclear clinches generate larger particles with masses that are not quite the sum of their parts. The missing mass becomes energy, a fiery embodiment of Einstein’s equation E=mc2 . The equation shows that, in terms of energy production, a tiny bit of mass goes a long way thanks to the colossal multiplier of c, the speed of light (300,000km per second), squared."

However, nuclear fusion is very difficult to achieve and ‘bottling the sun’ still seems to be a distant chimera. Space-based solar power uses a different approach—rather than creating the Sun in a lab, it attempts to capture the vast amounts of energy generated by the Sun from space, convert it into microwaves, and transport it to earth. Only about 0.00002% of the Sun’s total energy output actually reaches Earth—it might sound minuscule, but it’s roughly 173,000 terawatts of power, enough to keep our planet buzzing. However, this also means that there is an almost infinite amount of energy to be captured. Another FT article (bit.ly/494Jne7) reports on a successful Caltech experiment, where a detectable amount of solar power was successfully beamed wirelessly from space to earth. The minuscule amount wouldn’t be enough to light up a bulb, but it was the first tangible proof that it could be done. Many scientists believe that this technology has greater promise than nuclear fusion, primarily because the physics of it has been proven—unlike in fusion, where one needs to replicate the fantastically high temperature and pressure conditions of the Sun. We would need to fix massive solar panels to satellites circling the earth in constant sunlight, converting this captured energy into transmittable microwave beams and sending them to a receiving station on earth. The FT reports that “a single satellite could potentially deliver as much as 2GW of carbon-free power, enough to supply a city of 2mn people, 24 hours a day, seven days a week."

There is frenetic work happening in China, the US, UK, Japan and Europe to ‘chase the sun,’ rather than bottle it. Another big advantage of it is that from space, there is ‘line of sight’ everywhere, so the microwave beam can be sent anywhere on earth. The reusable Falcon rockets of SpaceX also make the economics of launching the capturing satellites more compelling. Though one loses about 90-95% energy in transit, the remaining energy is enough, given the 24x7 ball of fire above us. There are huge obstacles—the satellites would need to be enormous, about 1.5km across; as would the receiving antennas.

There could be unknown environmental or radiation issues. However, the promise at the end of it is insanely attractive: creating an infinite source of steady carbon-free energy to power our planet, and simultaneously stop warming it. As Paul Jaffe, a US Naval Research Lab engineer who has studied this for the last 16 years says in FT: “The Sun is the closest thing we have to an infinite energy source. You [could] create a global energy network that could provide energy potentially anywhere on Earth. Space solar could do for energy what GPS did for navigation."

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