Space solar power touted for energy needs
Orbiting solar panels Harvesting the Sun's energy from space could provide a cost-effective way to meet global power needs in as little as 30 years, says an international scientific group.
Orbiting power plants capable of collecting solar energy and beaming it to Earth appear "technically feasible" within a decade or two based on technologies now in the laboratory, a study group of the Paris-headquartered International Academy of Astronautics reports.
Such a project may be able to achieve economic viability in 30 years or less, says the report.
"It is clear that solar power delivered from space could play a tremendously important role in meeting the global need for energy during the 21st century," according to the study, led by Dr John Mankins, a 25-year NASA veteran and the US space agency's former head of concepts.
The 248-page report has been billed as the first broadly based international assessment of potential paths to collecting solar energy in space and delivering it to markets on Earth via wireless power transmission.
The study says government pump-priming likely would be needed to get the concept, known as space solar power, to market. Private-sector funding is unlikely to proceed alone because of the "economic uncertainties" of the development and demonstration phases and the time lags, the study says.
Space solar power is a potential long-term energy solution for Earth with "essentially zero" terrestrial environmental impact, according to the National Space Society, an advocacy group, which is publicising the report.
Scores of orbiting satellites
The idea is to put first one, then a few, and later scores of solar-powered satellites in geosynchronous orbit over the equator.
Each as wide as several kilometres across, the spacecraft would collect sunlight up to 24 hours a day, compared with half that, at most, for surface panels now used to turn sunlight into electricity.
The power would be converted to electricity on-board and sent to wherever it is needed on Earth by a large microwave-transmitting antenna or by lasers, then fed into a power grid.
The new report, conducted from 2008 to 2010 then subjected to peer review, found that the commercial case had substantially improved during the past decade, partly as a result of government incentives for nonpolluting "green" energy systems.
A pilot project to demonstrate the technology even as big as the 400-tonne International Space Station could go ahead using low-cost expendable launch vehicles being developed for other space markets, says Mankins.
A moderate-scale demonstration would cost tens of billions of dollars less than previously projected as a result of not needing costly, reusable launch vehicles early on, says Mankins, president of Artemis Innovation Management Solutions LLC, a California consultancy.
"This was a really important finding," says Mankins, referring to a relatively modestly priced pilot project.
Mankins' company has been awarded a NASA contract of a little less than $100,000 to pursue space-based solar power options - small "but at least it's a start," Mankins says.
Ultimately, tens of billions of dollars would be needed to develop and deploy a sufficiently low-cost fleet of reusable, earth-to-orbit vehicles to launch full-scale commercial solar power satellites, the study group estimates.
International interest in the concept has grown during the past decade, spurred in part by fears that in coming decades global production of petroleum and possibly other fossil fuels will peak and start to decline.
Adding to a quest for new energy sources are projected jumps in worldwide per capita demand for energy to fuel economic development and concern over the accumulation in Earth's atmosphere of fossil fuel-derived greenhouse gases.
For and against
Australian aerospace engineer John Page of the University of New South Wales is a proponent of space solar power.
"It's a more efficient way of using solar cells," he says.
Page says as long as the satellites are in the right orbit they will provide energy for more or less 24 hours a day.
"So it provides base load power, which is their great advantage," says Page.
While concentrated microwaves are dangerous, Page says the microwave beams that could deliver space solar power to Earth could be quite diffuse.
"If you've got a wide collection area then you don't have a problem with high intensity," he says.
Page says collectors could involve wires strung across a field to pick up the power and while you probably wouldn't want to live under these, crops could be grown underneath the collectors.
Sceptics deem space solar power a nonstarter, at least until the cost of putting a commercial power plant into orbit drops by a factor of 10 or more. Other hurdles include space debris, a lack of focused market studies and high development costs.
Australian retired aeronautical engineer Ian Bryce, says there are better alternatives.
"Much as I am a fan of space, and would love to see a large new space initiative, I see problems with space solar power," he says.
Bryce says even if the technology was fully funded from tomorrow, it would take too long to deliver power.
"A much more feasible way to generate electricity sustainably is solar thermal with storage," he says.
"This technology is here now, and plants can be ordered. At least 30 years closer than SSP [space solar power]."
The idea of harnessing solar power in space has been studied off and on for 40 years, including by the US Department of Energy and NASA.
US and Indian business, policy and national security analysts in September called for a joint US-Indian feasibility study on a cooperative program to develop space-based solar power with a goal of fielding a commercially viable capability within two decades.
The study group, co-sponsored by the Council on Foreign Relations think tank and Aspen Institute India, includes former US Dr Director of National Intelligence Dennis Blair and Naresh Chandra, a former Indian ambassador to the United States.