Harvesting solar energy in space and beaming it back to Earth may sound like science-fiction – and it originally was. 

In 1941, writer Isaac Asimov wrote a short story called “Reason”, in which space solar farms collect energy and steer it with high-energy rays to Earth. 

Since then, various countries have been investigating making that idea a reality. 

The European Space Agency (ESA) is collecting ideas for space-based solar power (SBSP) projects, while the US military is reportedly already testing how to gather the sun’s energy and transport it. Last year, the UK government commissioned research into SBSP systems that would use solar power satellites to collect energy and convert it into high-frequency radio waves to beam it back to the ground. 

The US Department of Energy’s website says “solar power directly from space may arrive sooner than you think”. 

“Since clouds, atmosphere and night-time are absent in space, satellite-based solar panels would be able to capture and transmit substantially more energy than terrestrial solar panels,” the DOE says. 

“Solar panel equipped, energy-transmitting satellites collect high intensity, uninterrupted solar radiation by using giant mirrors to reflect huge amounts of solar rays onto smaller solar collectors. This radiation is then wireless beamed to Earth in a safe and controlled way as either a microwave or laser beam.” 

And this week, an ambitious space solar plan has been pitched to the Australian Government. 

Australian company Solar Space Technologies wants to launch solar panels into orbit – where the sun always shines (as long as you’re in the right spot). 

The power can be beamed back to Earth using microwave energy (it’s called “power beaming”). Once it’s received by a ground station it can be transferred to the existing electricity grid. The plan promises huge amounts of cheap energy with no carbon emissions. 

It would “provide Australia with a safe and low-cost affordable space solar power option for carbon emissions free electricity, and establish the foundations of a major new industry in Australia and globally – creating many thousands of high-quality, well-paid jobs”, according to SST’s submission to the space inquiry. 

SST is planning to put a small solar plant in low Earth orbit in the next five years, and a larger one in geostationary orbit in a decade. 

Founder Serdar Baycan – an architect with a long-term love of space – is working with John C Mankins. Mankins spent 25 years at NASA and Caltech’s Jet Propulsion Laboratory, and is the author of The Case for Space Solar Power.

Baycan said he has been working on sustainable practices for nearly 30 years, and is driven by the need to tackle climate change. 

“And the most clear and practical way to do that is space solar power,” he says. 

“The sun is always available. It’s a nearly inexhaustible supply and it can be brought to Earth virtually without any consequence and there is zero carbon emissions and it’s incredibly cheap – cheaper than anything else and available in abundance.” 

SST, as well as working with Mankins Space Technology in the US, has partnered with CSIRO, universities including Deakin, Swinburne and the International Space University, in France.

Baycan says they’ve been running simulations and terrestrial tests to prove the science, and that access to space is getting increasingly cheaper, proving the business case. 

SST’s platform, the SPS Alpha, would comprise a 7km backbone connecting an energy conversion array (including photovoltaic cells) to a heliostat array that could collect and direct the energy. It could be assembled in space by robots controlled from Earth.

A 6km receiver on Earth would collect that energy from microwave beams to transfer it into the grid. The SST submission says the modular system would be able to deliver anywhere from 100 megawatts to two gigawatts to a single receiver. That could then be scaled up with more satellites and more receivers. 

“A dozen satellites would provide for Australia’s electricity needs, complementing the existing systems, terrestrial solar and wind and other green energy,” Baycan says. 

Despite the apparent eagerness of governments to invest in SBSP, though, there are major obstacles to be overcome. While launch costs are plummeting, they’re still substantial. And at this point much of the technology is theoretical. 

The ESA points out there is a way to go. “Parts of solar power satellite systems have been demonstrated on a small scale in orbit, but to make this technology truly feasible, technology developments are required in many different areas,” it says. 

“For instance, we would need to improve our ability to manufacture and deploy very large structures, as well as to convert and transmit energy efficiently.”

Aerospace engineers from the University of Liverpool, UK, have pointed out that the structures will have to be enormous – they estimated as big as 10 square kilometres. The material would have to be as lightweight as possible to make it cheap enough to launch. 

While proponents including the US Government say it’s completely safe, considering how strongly (and wrongly) some people fear 5G towers, community resistance could be a factor. 

The Australian Strategic Policy Institute’s senior analyst Malcolm Davis also points out that the receiving antennae would be large, critical infrastructure, which would require political will. 

Capturing the Sun’s energy in satellites and power beaming it back to Earth? If it works, the truth could end up being stranger than fiction. 

Quelle: COSMOS