Twenty-two thousand miles above the Earth, an array of silicon glitters in the sunlight, quietly beaming power down to the planet below and providing energy to millions. One-hundred million miles away, a single photon leaves the sun, rocketing at the speed of light towards Earth. Upon arrival, the photon hits the silicon array of the solar cells in geosynchronous orbit, where the cell transforms the raw energy of the sun into microwaves, which are beamed down to a receiving station on Earth. Once at the receiving station, this power is fed onto the electric grid where it can now be used to power cities and homes. Behold, the possibilities of space-based solar power.
Does space-based solar power (SBSP) seem like something out of science fiction? “My impression is that it’s more the sort of thing that has appeared in science fiction than anything people have really tried to do,” says David Schiminovich, Associate Professor of Astronomy at Columbia University in New York and a lead scientist on GALEX, a space telescope operated by NASA’s Jet Propulsion Laboratory in partnership with the California Institute of Technology. There is no end to the examples of futuristic worlds in fiction powered by the sun’s unlimited resources. Still, SBSP is not as far-fetched as it might seem. After all, ground-based solar power is steadily contributing more and more to the energy grid both nationally and globally. In 2011, 0.2 percent of the United States’ energy came from solar while by the end of 2013, 0.6 percent of U.S. energy was solar produced. In California, solar generates enough energy to power over 900 thousand homes. Additionally, according to the Federal Energy Regulatory Commission’s Office of Energy Projects, 100 percent of new electric generation that went online in the U.S. in November 2013 was from renewables. The United States is slowly integrating solar energy, no trace of science fiction about it.
No one argues that any one type of renewable alternative energy alone can replace our current dependence on fossil fuels – a dependence that is responsible for spewing tons of carbon emissions and pollutants into the atmosphere, causing dramatic damage to Earth’s climate and altering habitats and threatening life for both humans and animals worldwide. Ground-based solar, for example, is still only 21 percent efficient with the most advanced technology and is highly dependent on geography to function well. Sun-soaked California and Arizona get enough sunny days a year to make solar an enticing option while rainy and overcast Seattle is likely never going to rely on solar power.
Though it comes with its fair share of issues, space-based solar does have the capacity to provide a huge percentage of energy needs. “Part of it is just to get over the atmosphere,” says Schiminovich. Once outside the atmosphere in space, solar cells receive 30 percent more power from the sun, as the sunlight does not get filtered out, losing valuable energy. Additionally, weather patterns would never interrupt the sun’s rays, and if positioned properly, the space-based solar farm could be operational far longer than on the ground – night could be effectively lessened in orbit and the seasons would affect SBSP far less. While space-based solar will likely never, at least in the near future, provide 100 percent of Earth’s energy needs, it could easily become the dominant form of power for the planet.
The single greatest obstacle to space-based solar is cost. At $20,000/kg to launch into geosynchronous orbit, a solar farm in space would require billions of dollars to create. “What has made me pessimistic is that it is so costly to get into space reliably,” David Schiminovich says. “The only way it would take off is if it were something people were making real money off of. It has to be like oil – somebody realizes they can get these things up there for low enough money and then sell the energy at high enough prices to make a huge profit. I don’t think ‘saving the planet is enough’ for people. It has to be about the money, which is a sad thing to say, but true.”
Schiminovich acknowledges, however, that the advent of the commercial space industry opens the door to SBSP looking more and more viable. “SpaceX, and other commercial space companies are really working hard to lower the cost of launch,” he says.
Shiminovich’s work on GALEX and as one of the experts on the James Webb Telescope, which is being touted by NASA as the successor to the Hubble Space Telescope, also leads him to point to the question, “How do you build something that large in space?” as a major factor in building space-based solar power stations. “At least for telescopes, part of the idea is that a four meter mirror is the largest you can fit into a launch vehicle, maybe as large as eight meters, but larger than that? No way,” he says. “So then you’ve gone to assembly in space – you would load up the elements and then have the robotic arm of the International Space Station assemble parts in orbit. It would look like a Pringles can unfolding,” he explains. Schiminovich asserts that currently the only experience anyone has with this large-scale building in orbit is the International Space Station, though again SpaceX and others are looking into and playing around with what can be done.
Currently, there are a number of countries and individuals hard at work on taking space-based solar out of the realm of science fiction, with plans to launch as soon as 2025. In the meantime, ground-based renewables are taking up more and more slack from the fossil fuel industry, and with proper commitment from governments and corporations globally, the future of space-based solar looks ever brighter.