A renaissance for space solar power?
by Jeff Foust
|“We think it’s now more technically feasible than ever before,” Mankins said. “We think we have a path to knowing whether or not it’s economically feasible.”|
One obstacle facing space solar power is that most people have not heard of it, and many of those who have associate it with the huge, expensive concepts studied back in the 1970s. Those proposals featured arrays many kilometers long with massive trusses that required dozens or hundreds of astronauts to assemble and maintain: Mankins joked that a giant Borg cube from Star Trek would have easily fit into one corner of one of the solar power satellite designs. “You ended up with a capital investment—launchers, in-space infrastructure, all of those things—on the order of $300 billion to $1 trillion in today’s dollars before you could build the first solar power satellite and get any power out of it,” he said.
Those concepts, he argued, are outdated given the advancements in technology in the last three decades. The efficiency of photovoltaic arrays has increased from 10 to over 40 percent, thus requiring far smaller arrays to generate the same amount of power. Advances in robotics would allow assembly of “hypermodularized” systems, launched piece by piece by smaller vehicles, with little or no astronaut labor. “We think it’s now more technically feasible than ever before,” he said. “We think we have a path to knowing whether or not it’s economically feasible.”
Another big problem has been finding the right government agency to support R&D work on space solar power. Space solar power doesn’t neatly fit into any particular agency’s scope, and without anyone in NASA or DOE actively advocating it, it has fallen through the cracks in recent years. “NASA does science, they do astronauts, and they do aeronautics, but they don’t do energy for the Earth,” Mankins said. “On the other side, the Department of Energy doesn’t really do energy for space.” That situation, at least in regards to those two agencies, shows little sign of changing.
Marty Hoffert, a New York University professor who has been a long-time advocate of space solar power, contrasted the current plight with that of fusion, the one other energy source Hoffert believes could provide energy security to the world. While space solar power goes virtually unrecognized by the US and other governments, an international consortium is spending up to $20 billion on a test fusion reactor, ITER, in France. “For half that money I think we could deliver a working solar power satellite, whereas ITER is just going to show the proof of feasibility” of controlled nuclear fusion without generating any power, he said.
“Certain ideas just fall through the cracks because there isn’t a champion in the agency,” in either the DOE or NASA, Hoffert said.
In recent months, however, a new potential champion for space solar power has emerged, and from a somewhat unlikely quarter. Over the last several months the National Security Space Office (NSSO) has been conducting a study about the feasibility of space solar power, with an eye towards military applications but also in broader terms of economic and national security.
Air Force Lt. Col. Michael “Coyote” Smith, leading the NSSO study, said during a session about space solar power at the NewSpace 2007 conference in Arlington, Virginia last month that the project had its origins in a study last year that identified energy, and the competition for it, as the pathway to “the worst nightmare war we could face in the 21st century.” If the United States is able to secure energy independence in the form of alternative, clean energy sources, he said, “that will buy us a form of security that would be phenomenal.”
|“The military would like nothing better than to have highly mobile energy sources that can provide our forces with some form of energy in those forward areas,” Smith said.|
At the same time, the DOD has been looking at alternative fuels and energy sources, given the military’s voracious appetite for energy, and the high expense—in dollars as well as lives—in getting that energy to troops deployed in places like Afghanistan and Iraq. Soldiers, he noted, use the equivalent of one AA battery an hour while deployed to power all their devices. The total cost of a gallon of fuel delivered to troops in the field, shipped via a long and, in places, dangerous supply chain, can run between $300 and $800, he said, the higher cost taking into account the death benefits of soldiers killed in attacks on convoys shipping the fuel.
“The military would like nothing better than to have highly mobile energy sources that can provide our forces with some form of energy in those forward areas,” Smith said. One way to do that, he said, is with space solar power, something that Smith and a few fellow officers had been looking at in their spare time. They gave a briefing on the subject to Maj. Gen. James Armor, the head of the NSSO, who agreed earlier this year to commission a study on the feasibility of space solar power.
There was one problem with those plans, Smith said: because this project was started outside of the budget cycle, there was no money available for him to carry out a conventional study. “I’ve got no money,” he said, “but I’ve got the ability to go out there and make friends, and friends are cheap.” So Smith and his cadre of friends have carried out the research for the study in the open, leveraging tools like Google Groups and a blog that hosts discussions on the subject.
Smith made it clear, though, that he’s not looking for a quick fix that will suddenly make solar power satellites feasible in the near term. “If I can close this deal on space-based solar power, it’s going to take a long time,” he said. “The horizon we’re looking at is 2050 before we’re able to do something significant.” The first major milestone, he said, would be a small demonstration satellite that could be launched in the next eight to ten years that would demonstrate power beaming from GEO. However, he added those plans could change depending on developments of various technologies that could alter the direction space solar power systems would go. “That 2050 vision, what that architecture will look like, is carved in Jell-O.”
The idea of a demonstration satellite was endorsed by Shubber Ali, an entrepreneur and self-described “cynic” who also participated on the NewSpace panel. “The first step in this case needs to be a cheap, simple satellite, just to prove that we can beam power back down,” he said. A satellite that generated just 10 kilowatts of power—less than some commercial GEO communications satellites—could be developed for on the order of $100 million, he said.
|If space solar power is to become a reality, Smith said, it will have to be because of a “massive collaborative effort” in which the DOD will play a small, but not leading, role.|
Ali said there needs to be a “coalition of the willing” that includes the DOD and other government agencies like NASA and DOE, as well as “the usual suspects” in the commercial space sector, to help advance space solar power if it appears it can be feasible. That group, he said, should also include oil companies. “We like to think of ‘Big Oil’ as a big, ugly, evil set of companies that are just taking our money at the gas tank,” he explained, “but the reality is that they are not idiots and they do take the long view.”
Smith agreed, and noted that his team had already met with some representatives off major oil companies, in part because “we realized we didn’t want to get ‘Tuckered’ out of the business,” a reference to Preston Tucker, who clashed with the established Detroit automakers in the 1940s.
If space solar power is to become a reality, he said, it will have to be because of a “massive collaborative effort” in which the DOD will play a small, but not leading, role. “This is not the Department of Defense’s job. We do not want to be in the energy business, we don’t want to be a producer of energy,” he said. “We just want to be a customer of a clean energy resource that’s out there.”