A single kilometer-wide band of geosynchronous Earth orbit experiences enough solar flux in one year to nearly equal the amount of energy contained within all known recoverable conventional oil reserves on Earth today. - U.S. Pentagon's National Security Space Office, 2007
Most people think solar energy is best collected on the Earth. Actually, it makes more sense to collect sun power in Earth orbit and then beam the energy home via microwaves.
Orbiting comsats, even manned spacecraft, have used solar power since the 1960s. However, if you're going beyond the orbit of Mars, it makes much more sense to use nuclear power sources, but we'll corral our discussion to collecting the vast amount of sunlight falling on near Earth space with orbiting solarsats.
The idea of solarsats has been around since the 1950s, but with the price of oil rising steadily and fears of peaceful nuclear power generation here on terra firms, the 21st century may become the century of solarsats.
According to Jeff Keuter, president of the George C. Marshall Institute, space-based solar power developing a string of solar satellites around the Earth is technically feasible today, "It will require a great deal of money," he said, "but it is certainly possible."
An average of 341 watts of solar energy falls on every square meter of Earth. This includes both Earth's night side and north and south poles. Unfortunately, our atmosphere blocks a lot of the Sun's energy which is where solarsats come in to save the day. Free of Earth's blanket of air, an orbiting fleet of solarsats could collect up to 5 kilowatts of energy per square meter.
A recent U.S. government study suggests that a large solarsat, providing enough energy to light several large cities the size of Burlington, would cost $10 billion. The price tag excludes ground-based infrastructure to collect the solarsat's beamed microwaves and distribute the electricity, etc.
Science writer Frazer Cain is a proponent of solarsats but even he recognizes the sticker-shock factor.
"There are obvious safety risks from having a huge microwave beam striking the Earth," he said. "And the costs of launching and maintaining the solar satellites will be enormous. But it might just be the idea that keeps our energy hungry economies going after the fossil fuels run out."
But Cain has said a fully operational space-based solarsat could be in orbit by 2020, "but that is if we started work now."
Japan is currently spending millions of yen to develop a prototype solarsat that's still many years away from flying.
"...This is a far cry from planning to get full-scale operations underway in a little over a decade," Cain noted.
But not everyone is accepting the U.S government's inflated estimated price tag for a solarsat.
One new firm that is pioneering space-based power is Exploration Partners, LLC of New Mexico and Oklahoma. The firm is a shoe-string operation but it's one among a group of creative, emerging pioneers in solarsat financing and development.
Formed in 2005 by pioneers Royce Jones and Tom Taylor, E.P. developed two, low-cost space-solar power satellite designs. The designs were created with cost effectiveness and safety in mind.
A single E.P. solarsat could generate 100 megawatts of electrical power. Estimated costs? How does $250 million per satellite plus $150 million to launch in low Earth orbit sound? That's certainly lower than U.S government estimates.
According to E.P.'s Royce Jones, "The financing (for our solarsat plan) is pretty straight forward. Each power satellite is leased to the end user. We don't sell the power generated, they do. Since the satellites are small, i.e., only 20,000 kg., and can launch on a single existing launch vehicle, they are fairly inexpensive versus building a nuke plant. Each satellite, that we call SolarSat, can produce 100MW of power to the grid. There are two basic markets-the northern nations and the equatorial nations. Each market will have its own constellation of satellites."
What's in the Sky: On Saturday, Oct. 16, you'll have an opportunity to view Jupiter's Red Spot through a home telescope. The giant swirling 400-year-old Jovian hurricane will transit around 8:19 p.m.
Lou Varricchio, M.Sc., was a science writer at the NASA Ames Research Center in California. He is currently a member of the NASA-JPL Solar System Ambassador program. He received the U.S. Civil Air Patrol's Charles E. 'Chuck' Yeager Aerospace Education Achievement Award in 2009.