I’ve been hearing at least two versions of how we should construct an orbital power station, that would harness the Sun’s power and transmit it through lasers or microwaves to Earth. Those concepts, along with classic solar and wind power fade when compared to this one.
A satellite called “Dyson-Harrop” can get 100 billion times more energy than humanity needs.
A Dyson-Harrop satellite features a long metal wire loop pointed at the sun. The wire’s length can vary from 300 meters to 1 kilometer and has a width of 1 centimeter. The wire generates a cylindrical magnetic field that captures the electrons from solar winds and funnels them into a metal spherical receiver, which produces a current.
Part of the produced current goes back into generating the wire’s magnetic field, and so on. The satellite would be kept floating in space by a ring-shaped sail.
Those who sustain the project want to transmit the power down to Earth through infrared lasers, because the infrared spectrum won’t be affected by the planet’s atmosphere.
A theoretical example suggests that a Dyson-Harrop satellite using a 1 cm-wide copper wire 300 meters long, a receiver 2 meters wide and a sail 10 meters in diameter could generate 1.7 megawatts of power, being able to power 1000 US households.
Going even further, a satellite with a 1-kilometer long wire and a sail 8400 kilometers wide (can you imagine the size of that?) can generate 1 billion billion gigawatts (1027 watts) “which is actually 100 billion times the power humanity currently requires”, says researcher Brooks Harrop, a physicist at Washington State University in Pullman who designed the satellite.
A quick feasibility study says that the solution is cheaper than installing the same amount of solar panels in space, since copper is cheaper than solar cells. “This satellite is actually something that we can build, using modern technology and delivery methods,” Harrop says.
The infrared laser that Harrop proposed is not the best solution for a satellite this size, though. To harness sufficient amounts of power, the Hyson-Harrop satellites have to float tens of millions of kilometers from the Earth, and even the best laser technology we have would not be able to get the light focused in a single beam, but rather on one that would stretch on a few thousands of kilometers on Earth.
Still, to make this work, the lenses would have to be “maybe 10 to 100 kilometers across,” says John Mankins, from Artemis Innovation, a consultancy firm specialized in solar power. “Two megawatts spread across areas that large are meaningless, less than moonlight,” he says. Even the wire couldn’t bear such huge currents, in his opinion.
Aside from the researchers’ views, I think that the issue could be solved by applying something that telecom systems used for decades or even centuries: relays. 1 billion gigawatts of power would be enough to afford losing a few for bringing the energy to Earth step-by-step, and focusing the beam closer and closer.