Power plants in space sound like a science fiction idea – and in fact it is a science fiction idea: in 1941, the story of Isaac Asimov Reason describes a space station that transmits energy collected from the Sun to other planets using microwave beams. Today, the technology required to do this exists and space solar power (SBSP) is taken seriously.
The idea is that a vast satellite, several kilometers long, would generate electricity via thousands of photovoltaic panels. This would then be transmitted to Earth using high frequency radio waves. On the ground, this beam of microwave energy would be intercepted by a field of radio antennas in the shape of an ellipse, converted into electricity and distributed to the grid.
But is this really a realistic prospect?
Brian Ryan, vice president of innovation for National Grid, admits people think he’s “crazy” when he talks about it. “It’s a bit over there,” he says, “but it’s not that far over there. I think we will see space solar power play a huge role in our energy ecosystem over the next 20 years… The potential is limitless.
A report for the UK government published last year by engineering consultancy Frazer-Nash described SBSP as “technically feasible” and potentially affordable, compared to other sources of clean electricity. The United States also thinks that SBSP technology is worth studying: a military project is underway, as is that of the famous California Institute of Technology. The Japanese space agency is working on a space solar farm. China reportedly aims to launch its first station by 2035 and has already started construction in the city of Chongqing.
Why do we think this is a good idea?
SBSP could potentially solve various thorny energy problems. Global energy demand is estimated to double by 2050, and the search is ongoing for sources that do not use fossil fuels or come from reprehensible regimes. There’s plenty of clean energy available in space: a narrow band around Earth could supply more than 100 times humanity’s projected global energy needs in 2050, the Frazer-Nash report notes.
Unlike the renewable energy sources on the surface of our planet, the SBSP would not be intermittent. The weather is always nice in space, and power plants would be in high geostationary orbit – that is, remaining in a fixed position relative to the Earth – providing electricity almost continuously. This would mean both more power in absolute terms and also that SBSP would be able to supply baseload power – the minimum amount of electrical power required by the power grid at any given time. Currently, renewable energy sources cannot provide baseload electricity; only fossil fuels and nuclear power plants can do that. Finally, the SBSP could be broadcast in different parts of the world, as needed.
What energy can it give?
Prototype designs for SBSP stations each envision sending at least one gigawatt of power to Earth. One gigawatt is enough to power around 750,000 homes and is comparable to the power of a nuclear power plant. John Mankins, a former NASA scientist who is a leading expert on SBSP, believes his design would generate three gigawatts, but one gigawatt would be lost in the process of bouncing back to Earth.
Wouldn’t that be very expensive?
Yes, the main costs being the need for multiple rocket launches to detonate the components in space, and for the robotic assembly of the SBSP station in orbit. A solar-powered satellite would have to be “an order of magnitude larger in mass and extent than any spacecraft currently in orbit,” the Frazer-Nash report acknowledges.
Nevertheless, the cost of placing objects in space has decreased significantly in recent years. According to a 2018 NASA study, it had been reduced by 20 in the previous decade. Frazer-Nash estimates that developing the technology and launching a working solar satellite would cost around £16bn, far less than the £23bn projected cost of the planned Hinkley Point C nuclear power station.
Is everyone convinced?
No. In 2012, Elon Musk – who runs both a solar energy company and a space company – called SBSP “the dumbest thing ever”. And that certainly has downsides. The technology involved has not been tested on a large scale. Transport to space is only part of the problem. Once built, it would be vulnerable to damage from space debris. Repairs would be exceptionally difficult to carry out. Antenna receiving stations on Earth would require large tracts of land and would likely be controversial.
SBSP is expected to compete with normal solar power, which is now the cheapest form of electricity in history. There are also security concerns, and given the sensitivity of rival superpowers to controlling space, this would require extensive international cooperation.
So is this going to happen?
In March, UK Science Minister George Freeman said the SBSP was “taken seriously” by the government. “We are ready to be bold,” he said, and to “support him.” But in the short term, SBSP is likely to be confined to specialized areas, such as military use.
One of the most advanced projects is the US Air Force Research Laboratory’s Project Arachne, scheduled to launch in 2025. It is designed to show that the technology works and that it could be used to transmit power to forward military bases (supplying power is often one of the most dangerous parts of a land operation, involving vulnerable convoys or supply lines).
Arachne is also designed to examine the possibility of using an SBSP station to power interplanetary spacecraft. The Air Force Research Lab points to similarities to GPS, which started life as a military asset but is now put to good use by civilians everywhere, every day.