Ali Hajimiri believes there is a better way to power the planet – one that doesn’t get the attention it deserves. The Caltech electrical engineering professor envisions thousands of solar panels floating in space, unclouded and unhindered by day-night cycles, wirelessly transmitting massive amounts of energy to receivers on Earth.
This year, that vision moved closer to reality when Mr. Hajimiri and a team of Caltech researchers proved that wireless power transfer in space was possible: solar panels they attached to a Caltech prototype in space have successfully converted electricity into microwaves and transmitted it. these microwaves to the receivers about a foot away, lighting two LEDs.
The prototype also transmitted a tiny but detectable amount of energy to a receiver atop their laboratory building in Pasadena, California. The demonstration marks a first step in wirelessly transferring usable energy from space to Earth — an energy source that Mr. Hajimiri believes will be safer than direct rays from the sun. “The beam intensity must remain lower than the solar intensity on Earth,” he said.
The search for alternative energy sources is one of the topics that will be addressed by leaders from business, science and public policy at The New York Times Climate Forward event Thursday. The Caltech demonstration was an important moment in the quest to realize space solar power – a clean energy technology that has long been overshadowed by other long-term clean energy ideas, such as fusion nuclear and low cost clean hydrogen.
If space solar power can operate on a commercial scale, said Nikolai Joseph, senior technology analyst at NASA’s Goddard Space Flight Center, such stations could contribute up to 10% of the world’s energy by 2050.
The idea of space solar power has been around since at least 1941, when science fiction writer Isaac Asimov set one of his short stories, “Reason,” on a solar station that transmitted power by micro -waves to Earth and other planets.
In the 1970s, when a five-fold increase in oil prices sparked interest in alternative energy, NASA and the Department of Energy conducted the first significant study. study on the subject. In 1995, under the leadership of physicist John C. Mankins, NASA I took another look and concluded that investments in space launch technology were needed to reduce costs before space solar power could be realized.
“There was never any doubt about the technical feasibility,” said Mr. Mankins, now president of Artemis Innovation Management Solutions, a technology consulting group. “The cost was too prohibitive.”
Today, however, the calculus could change.
The advent of Elon Musk’s SpaceX has led to a sharp drop in the cost of rocket launches. From 1970 to 2000, the average cost of launching a rocket into low Earth orbit was around $18,500 per kiloram, or 2.2 pounds of weight; today the cost has dropped to $1,500 per kilogram. This reduction has helped significantly reduce estimates for building power plants beyond Earth’s atmosphere.
A 1980 review by NASA concluded than the first gigawatt of space solar power (enough energy to power 100 million LED bulbs) would cost more than $20 billion ($100 billion today). In 1997, NASA estimated that this figure had fallen to around $7 billion ($15 billion today); today it is estimated to be closer to $5 billion, according to a study carried out for the European Space Agency in 2022.
“I used to be a critic of space solar,” said Ramez Naam, a climate and clean energy investor. Mr Naam is now actively looking for space solar companies to invest in. “The dramatic change in the cost of space launches has changed everything,” he said.
Space solar power requires the wireless transmission of electrical energy through space using microwave or laser radiation. Unlike laser beams, microwaves can penetrate clouds and precipitation, making them the ideal candidate for maximizing solar capacity.
However, there are technical obstacles. Although Mr. Hajimiri’s team at Caltech proved that wireless microwave energy transfer in space was possible — and even transmitted a detectable amount of energy to Earth — it did not transmit enough energy to Earth to convert it into a usable form.
“No one has demonstrated power radiation over more than a few kilometers,” said Paul Jaffe, a U.S. Naval Research Laboratory engineer who specializes in power beam technology. Mr Hajimiri thinks this is possible. The Caltech engineer says he is working on technologies that would allow a wide array of lightweight, sail-like spacecraft, using billions of small transmitting antennas, to create a focused beam that could travel thousands kilometers to Earth and transport megawatts of energy.
The scale of space-based solar power structures is also daunting. The largest building in space today is the International Space Station, which measures 357 feet from end to end. Space-based solar power systems would be thousands of feet wide, and an army of robots would be needed to assemble the structures autonomously in orbit.
In addition to overcoming technical challenges, researchers must also ensure the security of wireless energy transport to Earth. Microwave and laser beams pose a known risk to human health when operating at certain power densities. The researchers say the power density of space solar power would be designed to operate within limits set by international governing bodies. Yet no studies have focused on the effect of space radiation on human health, the environment or the atmosphere – a crucial step for public acceptance of the technology.
Then there will inevitably be regulatory challenges. Transmission of radio waves from orbit – including telecommunications, GPS and weather satellites – requires a license to avoid interference from different users. Solar-powered satellites would likely need approval from the International Telecommunications Union, a United Nations agency, to protect and license their operating frequencies.
The complexity of these challenges places the expected arrival of most space solar energy projects in the 2030s or 2040s, if they ever get to that point. That doesn’t stop researchers from pursuing their dream of harnessing an uninterrupted, inexhaustible supply of energy from space.
Sanjay Vijendran, an engineer at the European Space Agency, has devoted much of his life to Mars exploration projects, but climate change has brought his attention back to Earth. “Could space do more to directly contribute to the climate crisis? Mr. Vijendran remembers asking himself and his colleagues in 2020. The result was Solarisa program that he directs and which will publish by 2025 a report on the technical and economic feasibility of space solar energy.
Michigan-based Virtus Solis and UK-based Space Solar are among the startups working on space solar power. Government agencies – including NASA, the US Air Force, the Japan Aerospace Exploration Agency, the European Space Agency and the Chinese Academy of Space Technology – plan to share reports on space solar power over the of the decade. Since 2019, the US Naval Research Laboratory has launched several power transmission demonstrations.
Dr. Jaffe believes there is no certainty that space solar power will work or even be necessary. “It could be that we create a portfolio of alternatives that perform well enough for our projected energy, which would make space solar power unnecessary,” he said.
Mr. Vijendran is also willing to admit that space solar power might not work without adequate funding. But he believes it is absolutely necessary to explore this option, especially given how little money is being invested in this technology compared to other solutions.
“We invest billions every year in nuclear fusion research,” Mr. Vijendran said. “If you invest a billion a year in space solar power, we’ll get there in 10 years. »