It sounds a bit like the plot of a certain James Bond film-turned-N64 video game, but there's a scientist out there by the name of John Mankins, who wants to build a massive solar collector in space and then fire the concentrated solar energy at the Earth's surface. It also might not help that much of the scientific community considers Mankins a bit of a kook.
But before you run off screaming that a mad scientist wants to incinerate the Earth with frikkin' lasers, be forewarned: this giant solar chalice, dubbed the Solar Power Satellite via Arbitrarily Large PHased Array (or SPS-ALPHA), just might be a feasible source of safe green energy. To begin with, Mankins seems to have seen a few Bond films in his time and has drawn a line in the sand concerning firing lasers at our home planet.
Instead, he'll be focusing the solar energy collected by his array into less-dangerous microwaves. And those other scientists that think Mankins' designs are impossible could very well be using data as old as the 1970s to formulate their opinions of him — this "kook" just might be on to something awesome.
To reap the energy rewards of the SPS-ALPHA, we'll not only have to construct the array itself, but a number of land-based collectors. Each collector would have to be massive to collect the entire beam of microwaves as they travel all the way down to the Earth's surface — somewhere between 6 to 8 km in diameter. The receiver would be comprised of millions of rectifier diodes, quantum devices that are capable of collecting and utilizing up to 90 percent of the energy they collect.
The reason that multiple massive collectors would have to be constructed is that SPS-ALPHA would optimally be deployed in a non-geostationary orbit — one that would keep it facing the Sun at all times. As the Earth rotates below it, multiple countries would have equal opportunity to reap the benefits of the array. Ideally speaking, SPS-ALPHA would thus be capable of lending power to nearly one-third of the world's populace during daylight hours by 2025.