In what one believer calls “the church of space solar power” (SSP), the doctrine is utopian. New work underway may make it achievable, too.
Advocates contend that if mankind could tap the boundless energy of the Sun flowing through near-Earth space, convert it to microwaves for transmission to the ground and plug it into the electric power grid, many of civilization’s problems could disappear.
The most obvious is pollution from fossil fuel burned for electricity, which probably explains why brown-sky -China is spending more on SSP research than any other nation.
Next would be the environmental damage wrought by extracting fossil fuel—oil spills, strip mining and mountain-top removal and fracking. The impact of large rectifying antennas (rectennas) sprawled across desert wastelands to receive “manna” microwaved from the heavens would pale by comparison to the mess fossil energy makes today.
And since oil, coal and other fossil-energy resources are unevenly distributed around the planet, obtaining them and keeping them requires a geopolitical system based on the threat—and often application—of dangerous military force. Moscow denies it, but its recent annexation of the Crimean peninsula probably was motivated as much by the Black Sea oil and gas reserves as by the cultural heritage of Mother Russia.
The lure of abundant renewable energy has attracted some powerful adherents to the SSP “church.” One of them is former Indian President Abdul Kalam, who assigns the same importance to electricity from space for the future of India and other nations, developing and otherwise, as the ballistic missiles he helped develop in his role as a pioneering aerospace engineer.
“By 2050, even if we use every available energy resource we have—clean and dirty, conventional and alternative, solar, wind, geothermal, nuclear, coal, oil and gas—the world will fall short of the energy we need by 66 percent,” he writes.
At a recent conference on the state of play in SSP research, engineers and others actively working in the field described advances in the technologies that could make SSP a reality across the board, and the world map, in a single human generation.
“Space solar power has as a concept never been more appealing and more promising than it is right now,” says John Mankins, aveteran who spent a decade as manager of advanced concepts studies at headquarters. “The new technical architecture, which exploits all of the technological advances of the past 30 years in terrestrial technology—electronics, robotics, materials—makes the approach to space solar power both affordable and scalable.” Added to that, he says, is the growing demand for energy that Kalam noted, as supply and environmental pressures on fossil energy increases.
“The market for new energy has never been stronger,” says Mankins, a co-chair of the SPS 2014 Symposium in Kobe, Japan, in April.
Mankins has just published The Case for Space Solar Power, a 488-page tome that draws on his extensive work in the field inside and out of government. And he and his colleagues were encouraged asprepared to demonstrate reusable-rocket technology with its Falcon 9 launch vehicle while the symposium was underway in Kobe (AW&ST April 21, p. 24; April 28, p. 25).
Launch cost remains the primary hurdle to SSP, because the collectors alone would measure kilometers across. At today’s rates, the price for orbiting the massive spacecraft needed to make it work keeps the cost per kilowatt hour for electricity from space well above that of power generated on Earth today.
“I have studied the space solar power thing, and I cannot figure out how solar power in orbit can overcome the transportation costs relative to solar power on the ground,” says formerAdministrator Michael Griffin.
Daunting as they are, the bad economics have not shut down SSP research completely. While NASA has no active program at the moment, the U.S. Naval Research Laboratory (NRL) tested a critical SSP prototype in the space-like conditions of a small thermal vacuum chamber. Spearheaded by Paul Jaffe, a spacecraft engineer at NRL, the project used tile-shaped “sandwich” modules that position solar cells on one side, an antenna on the other and the electronics necessary to convert direct current from the arrays into radio waves for power beaming in the middle.
“People might not associate radio waves with carrying energy because they think of them for communications,” says Jaffe. “They don’t think about them as carrying usable amounts of power.”
The Pentagon has toyed with SSP applications over the past decade, in studies and now with Jaffe’s work, as a way to deliver power to forward-
deployed forces. The military utility of that approach became obvious as casualties mounted on the tanker convoys carrying diesel fuel for generators at bases in Iraq and Afghanistan. But the same principle would apply as a quick way to deliver emergency power in large scale natural disasters.
Researchers in China, Japan and Europe are spending public and private funds to work on SSP technology, although not in large amounts. In China, where most space spending goes for the prestigious human spaceflight program, the figure has reached $30 million annually. That exceeds Japan, which is serious about SSP, given its lack of energy resources and experience with nuclear power after the 2011 earthquake and tsunami, and Europe, which runs small SSP studies at the European Space Research and Technology Center (Estec) in Noordwijk, the Netherlands.
Isabelle Dicaire, a physicist at Estec who recently studied the use of SSP-generated beam energy to defuse tropical storms by changing their internal dynamics, notes that Hurricane Katrina was a $100 billion disaster. Against figures like that, she told the Kobe symposium, the cost of SSP collectors might be more acceptable.
There is, of course, no way to calculate the dollar cost of climate change triggered by the greenhouse gases generated when fossil fuel burns. Mankins, who has been a technology consultant doing business as Artemis Innovations Management Solutions since 2005, says it does not really matter in the near term. He and his colleagues are proposing an SSP concept that would draw on the past three decades of technology development to start small, and relatively cheaply, and begin generating revenue long before the first kilowatt of energy generated in space is used as electricity on the ground (see following article).
Even a small prototype SSP collector can revolutionize mobile telecommunications from space by boosting the power of communications satellites, Mankins says. He has just launched a new company that hopes to work toward commercial power from space with an innovative approach to high-bandwidth mobile communications using the same modular approach to collecting the Sun’s energy in orbit.
“You don’t have to buy into billions of dollars to see whether you’ve got something,” he says. “A modest investment, on the order of millions, will give you strong confidence.”