“You may pay an exorbitant fee relative to what you would pay from the grid but in the midst of a natural disaster, for example, you don't care about prices. That's how SBSP is going to start,” he says.
Then, once the concept is proven, market forces will take over, he predicts.
“Once the inherent advantages of space come through, SBSP will be ubiquitous, in terms of Earth getting its energy from space. But it will probably take decades,” says Anderson, albeit with one important proviso: “If the Japanese, the Russians, or the US work out how to harness [nuclear] fusion energy, I think that would certainly be equally, if not more, attractive.”
Beam me… down
Fusion energy has famously always been “50 years away”, as each experiment throws up new technological challenges. But it is perhaps better news for SBSP – at least on paper.
A series of reports over recent decades by agencies like Nasa and the National Security Space Office (NSSO) have largely concluded that – whilst expensive - there is no major technological barrier to getting SBSP off the ground. For example, solar cells are now a well understood technology that is only getting cheaper and more capable, increasing efficiency from 10 to 40% over the last four decades. New lightweight materials – including graphene and advanced polymers – have been developed. And, whilst many view the ISS as a cash cow soaking up millions of dollars of tax payers money, it has certainly taught us a thing or two about working in space and, crucially, assembling large structures up there. In addition, robotics – crucial for maintenance and perhaps the assembly of these solar plants – have come on leaps and bounds, driven by ever more sophisticated electronics and computing power.
However, there is still a crucial part of the system that needs attention: the wireless energy transmission. Although it sounds like a fanciful technology, wireless energy transfer has a long history. It was first being demonstrated in 1893 by inventor Nikola Tesla when he managed to wirelessly illuminate vacuum tubes by exploiting a phenomenon known as electrical resonance. Tesla was able to turn lights on and off from a distance by adjusting the frequency of the electromagnetic waves in their vicinity. Since then there have been various small scale demonstrations of wireless energy transfer for everything from military applications to powering televisions.
In theory, any electromagnetic wave can be used for wireless energy transfer. Radio transmissions work on similar principles and involve well-developed technologies.
But what works across the surface of the earth won't necessarily work as effectively from space. For a start, the distances involved are greater. Furthermore, these giant, orbiting solar farms have to generate their own powerful laser beams or microwaves in space and them direct them accurately to the earth's surface –a complicated process that consumes some of the solar energy created by the system.
Any energy beam heading earthward from space also has the small matter of travelling through our planet's atmosphere to contend with.
Since the Earth's atmosphere is opaque at most frequencies in the electromagnetic spectrum, scientists need ways of beaming energy through the haze of gas and water droplets without too much energy being dissipated in the process.
Visible light frequencies offer one opportunity. Microwaves offer another.
Out of the two, microwaves are the preferred choice as they work more efficiently over long distances than laser-based alternatives. Lasers can be blocked by bad weather and current designs for the devices used to generate and collect laser light are generally considered to be considerably less efficient than their microwave-based counterparts.