by Eric Berger: Such an initiative would require a 200-fold increase over current space-lift capacity…


Europe is seriously considering developing space-based solar power to increase its energy independence and reduce greenhouse gas emissions, the leader of the European Space Agency said this week.

“It will be up to Europe, ESA and its Member States to push the envelope of technology to solve one of the most pressing problems for people on Earth of this generation,” said Josef Aschbacher, director general of the space agency, an intergovernmental organization of 22 member states.

Previously the space agency commissioned studies from consulting groups based in the United Kingdom and Germany to assess the costs and benefits of developing space-based solar power. ESA published those studies this week in order to provide technical and programmatic information to policymakers in Europe.

Aschbacher has been working to build support within Europe for solar energy from space as a key to energy de-carbonization and will present his Solaris Program to the ESA Council in November. This council sets priorities and funding for ESA. Under Aschbacher’s plans, development of the solar power system would begin in 2025.

In concept, space-based solar power is fairly straightforward. Satellites orbiting well above Earth’s atmosphere collect solar energy and convert it into current; this energy is then beamed back to Earth via microwaves, where they are captured by photovoltaic cells or antennas and converted into electricity for residential or industrial use. The primary benefits of gathering solar power from space, rather than on the ground, is that there is no night or clouds to interfere with collection; and the solar incidence is much higher than at the northern latitudes of the European continent.

The plans

The two consulting reports discuss development of the technologies and funding needed to start to bring a space-based power system online. Europe presently consumes about 3,000 TWh of electricity on an annual basis, and the reports describe massive facilities in geostationary orbit that could meet about one-quarter to one-third of that demand. Development and deployment of these systems would cost hundreds of billions of euros.

Why so much? Because facilitating space-based solar power would require a constellation of dozens of huge, sunlight-gathering satellites located 36,000 km from Earth. Each of these satellites would have a mass 10 times larger, or more, than that of the International Space Station, which is 450 metric tons and required more than a decade to assemble in low Earth orbit. Launching the components of these satellites would ultimately require hundreds or, more likely, thousands of launches by heavy lift rockets.

The report by British firm Frazer-Nash even includes a photograph of SpaceX’s Falcon Heavy rocket and a schematic of its Starship vehicle. The reports also note that the initiation of a space-based solar power program could spur development of a fully reusable, super heavy lift rocket in Europe for this purpose. The bottom line is that the launch demands would be tremendous.

“Using projected near-term space lift capability, such as SpaceX’s Starship, and current launch constraints, delivering one satellite into orbit would take between 4 and 6 years,” the Frazer-Nash report states. “Providing the number of satellites to satisfy the maximum contribution that SBSP could make to the energy mix in 2050 would require a 200-fold increase over current space-lift capacity.”

The drawbacks

Although the concept of space-based solar power is alluring, it has no shortage of critics. Among the critics is Elon Musk, whom one might expect to favor a technology that is based in space and provides solar energy. But he has, rather infamously, been utterly dismissive of the technology.

“It’s the stupidest thing ever,” he said, several years ago. “If anyone should like space solar power, it should be me. I’ve got a rocket company, and a solar company. I should be really on it. But it’s super obviously not going to work. It has to be better than having solar panels on Earth. With a solar panel in orbit, you get twice the solar energy, but you’ve got to do a double conversion: Photon to electron to photon, back to electron. What’s your conversion efficiency? All in, you’re going to have a real hard time even getting to 50 percent. So just put that solar cell on Earth.”

And he is not alone. In an online analysis, physicist Casey Handmer outlined four areas in which costs will make space-based solar power prohibitively expensive: transmission losses, thermal losses, logistics costs, and a space technology penalty. By Handmer’s estimate, space-based solar power is at least “three orders of magnitude” more expensive than terrestrial-based energy sources.

“I can relax assumptions all day,” Handmer wrote. “I can grant 100 percent transmission efficiency, $10/kg orbital launch costs, complete development and procurement cost parity, and a crippling land shortage on Earth. Even then, space-based solar power still won’t be able to compete. I can grant a post-scarcity fully automated luxury communist space economy with self-replicating robots processing asteroids into solar panels, and even then people will still prefer to have solar panels on their roof.”

The reports commissioned by the European Space Agency do little to dispel the main concern of space-based solar power critics: that it cannot compete financially with terrestrial energy sources, including ground-based solar panels. Europe may lie at a higher latitude than is ideal for solar energy, and its landmasses are often clouded in. But even so, getting power from space will require massive subsidies from European governments to reach a cost parity with terrestrial power.

Maybe the war in Ukraine and scarcity of Russian natural gas will be enough to prod this project forward. It would be nice to see a major space agency take a crack at a technology that has been discussed as science fiction for literally decades. But the hurdles are high and the timeline a long one.

Somehow, in some distant future, the Earth will probably get its power from space. But will that be this century or 200 years from now? There is no question space-based solar power would be, by far, the most sweeping and ambitious project ever undertaken by the European Space Agency. Indeed, it would likely be the Apollo program of the 21st century. Only bigger.

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Source: Ars Technica