Solar power from space?  Caltech's $100 Million Tactic Billionaire Makes a Secret Donation of Electricity from Orbit


Remembering, science fiction writer Isaac Asimov published a short story called "Reason" in 1941. This is a cautionary tale about robotics and artificial intelligence, but it is also remembered for its fantasy background: a space station collects solar energy and sends it to the planets via microwaves. Since then, space solar power has been an idea, and if we can master this technology and raise funds for it, it has the potential to change the world.





Donald Bren has read many books on solar energy and, as one of America's wealthiest real estate developers, he has the ability to help raise funds. The


California Institute of Technology just announced that since 2013, Brun and his wife Brigitte have donated more than $100 million to the school to help achieve orbital photovoltaic power generation.


That's a lot of money and, more importantly, the work has been spread out over a decade. A team at Caltech is aiming for the first launch of a test array in late 2022 or 2023.


"This is pretty bold stuff," says Ali Hajimiri , professor of electrical engineering and co-director of Caltech's Space Solar Power Project . The long timeline, he says, "allows you to take chances and take risks. Sometimes they pay off and sometimes they don't, but when you do that, in an educated and controlled way, you end up with things you never expected." . "


Bren, 89, made most of his fortune, estimated at $15.3 billion to $16.1 billion, building offices and homes in Orange County, California. He is majority owner of the iconic MetLife building in New York City. He has also donated land and money to environmental conservation. He gives few interviews (he declined to speak for this story), and although Caltech's Space Solar Power Project has been public, Bren's support was a secret until now.


High Earth orbit is a great place for a solar farm: the sun never sets and clouds never form. But to generate a significant amount of electricity, most previous designs were unrealistic and unaffordable, massive. Engineers came up with giant lattice structures, usually measured in kilometers or miles, to which photovoltaic panels or mirrors were attached, absorbing or concentrating sunlight to convert it into direct current and then transmitting it to the ground via lasers or microwaves. It may have taken hundreds of rocket launches to build a single installation. It was too big a technology to succeed.


"What was really required to make this compelling was to have a paradigm shift in the technology," says Harry Atwater , Howard Hughes Professor of Applied Physics and Materials Science at Caltech and leader of the project. "Instead of weighing a kilogram per square meter, we're talking about systems that we can manufacture today in the range of 100 to 200 grams per square meter, and we have a roadmap to get to the range of 10 to 20 grams per square. meter."


How? Without a single step, but perhaps the biggest change in thinking has been to make solar panels that are modular. Lightweight gallium arsenide photovoltaic cells would be joined into "tiles," the fundamental unit of Caltech's design, each of which could be as small as 100 square centimeters, the size of a dessert plate.


Each tile - and this is the key - would be its own miniature solar station, complete with photovoltaics, small electronics and a microwave transmitter. The tiles would be joined together to form larger "modules" of, say, 60 square meters, and thousands of modules would form a hexagonal power station, perhaps 3 km long on


a side. But the modules wouldn't even be physically connected. No heavy support beams, no bundled cables, much less mass.


"You can think of it as a school of fish," Atwater says. "It's a group of identical independent elements flying in formation."


Transmission to receivers on the ground would be via a phased array: microwave signals from the tiles synchronized so they can be aimed without moving parts.

Atwater says it would be inherently safe: microwave energy is not ionizing radiation and the energy density would be "equal to the power density of sunlight".


Space solar power is probably years away. Analysts at the Aerospace Corporation's Center for Space Policy and Strategy warn that "it won't be a quick, easy or complete solution". But there is ferment around the world. JAXA, Japan's space agency, is hard at work, as is China. Launch costs are falling and new spacecraft are on the rise, from Internet satellites to NASA's moon-to-Mars effort. Aerospace Corp. analysts say terrestrial power grids may not be the first users of solar-powered satellites.

Instead, they say, think of ... other space vehicles, for which a microwave beam from an orbiting solar farm may be more practical than having their own solar panels.


"Does it take a lot of extra work? Yes," says Hajimiri. However, "some of the ingredients that used to be the most prominent, we're moving in the direction of addressing them."


All of this has Caltech engineers excited. "It's important for us to be willing to take risks," Hajimiri continues, "and move forward with challenging problems that, if successful, would work to improve our lives."