You can't generate solar power at night unless your panels are in space. A startup that wants to beam orbital sunlight straight into existing solar farms has just emerged from stealth, claiming a world-first power-beaming demo, but with a lot of critical information left unreported.
Overview Energy announced on Wednesday that, after three years developing its technology in stealth mode, it managed to get a Cessna Caravan plane to send power to a solar installation on the ground from an altitude of 3 miles (5 kilometers). It's the first time, the company said, that anyone has managed to send energy to a stationary ground target from a transmitter in motion.
Maybe this is the first power transfer from an airplane in motion, but we note that the California Institute of Technology said in 2023 that it had successfully beamed power from an orbiting satellite to a ground station, albeit a negligible amount.
As with similar space-to-ground power transmission concepts, Overview wants to lob a constellation of solar-collecting satellites into orbit that will turn solar energy into a power source available even at night when the sun is on the other side of the globe. Unlike competitors like Aetherflux, which aims to do so using an optical laser-based power-beaming system, or Northrop Grumman and Space Solar UK, both of which are developing microwave-based wireless power transmission concepts, Overview's tech uses a wide-beam, low-intensity near-infrared laser aimed at standard commercial solar panels.
Near-infrared, the company says, tackles many of the problems raised around other methods. It's safe for humans and animals, the company argues, because the beam is wide and low-intensity, and it doesn't require any custom ground receiver hardware, instead being absorbed by standard solar panels.
"Our airborne milestone proved that the core transmission system works in motion—the same foundation that will operate in orbit," Overview founder and CEO Marc Berte said in the company's stealth-breaking press release. "Space solar energy will only matter when it powers real demand on Earth, and we're designing for that scale from day one."
There are problems with Overview's design, however. Optical beams in the infrared and near-infrared range are easily scattered and absorbed by clouds or water droplets, meaning cloudy or rainy weather can significantly reduce transmission performance compared with microwave radio systems, which penetrate the atmosphere more reliably.
In addition to that small hitch, Overview didn't actually report any energy transmission figures from its November Cessna flight. It's unknown how many watts of power Overview transmitted from its aircraft to solar panels on the ground, or how long transmission lasted - critical data points for understanding how successful the demonstration was.
The company noted in Thursday's press release that its system was validated in laboratory conditions as able to transmit an unspecified amount of energy in the thousands of watts range, and Berte told Space News that the flight test involved transmitting "multiple thousands of watts," but without specific numbers or a duration there's a lot left unanswered.
It's also worth pointing out that DARPA bested Overview's transmission distance by more than two miles when it sent 800 watts of power to a receiver 5.3 miles from a laser emitter over the summer. The research institute also explained that it kept power transmission going for just 30 seconds - not exactly enough energy or duration to say the system is ready for operation, but a considerable advancement nonetheless.
Overview Energy also made no mention of how efficient its system is, which is an important factor to consider. DARPA's laser demonstration, for example, only topped out at 20 percent efficiency, and even that was at shorter distances than the full 5.3-mile range the agency beamed the energy at.
We reached out to Overview to get answers to all those essential unanswered questions, but didn't hear back.
If Overview's tech isn't efficient, doesn't transmit much energy ("multiple thousands of watts" still isn't much more than what's needed to power a small home appliance), and can't keep the juice flowing, then its stated goals are going to be hard to meet.
The company said it intends to get a low-Earth orbit demonstration satellite up and running by 2028, and plans to launch its first geosynchronous orbit satellite by 2030, when it intends to begin commercial operations "with the world's first megawatt transmission from space."
That's an incredibly ambitious timeline given that it's still only capable of beaming a few thousand watts from an airplane at a 5-kilometer altitude. An impressive first, to be sure, but hardly indicative that this is anything other than another set of goals designed to land investors for a tech project that's going to need a lot of cash to have even a hope of success. ®
Source: The register