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Pentagon Urges Space-Based Solar Power
eldavojohn writes "The Pentagon issued a report indicating that space-based solar power 'has the potential to help the United States stave off climate change and avoid future conflicts over oil by harnessing the Sun's power to provide an essentially inexhaustible supply of clean energy.' The report, from the Pentagon's National Security Space Office, calls for funding the development of space-based solar power culminating in 'a platform in geosynchronous orbit bigger than the international space station and capable of beaming 5-10 megawatts of power to a receiving station on the ground.' The Pentagon's interest in such an effort stems from the need to acquire energy on the battlefield, which today often comes at a painful premium."
Warning: this is a 3.5MB PDF.
SBSB Interim Assessment
It would have to run for about two years just to collect as much energy as it took to loft it. Not to mention the cost and weight of the downlink equipment.
Then to recover the launch costs, that's never going to happen.
You doubt the entire thing will weigh (okay, mass) 4000 pounds? Look, I was with your back-of-the-envelope numbers up to that point, but 2000 pounds for 10 megawatts of solar panels, plus meteorite shielding, control/propulsion systems, and the microwave transmitter to beam the power back down? No way. 5000 pounds is a fair weight estimate for a modern communications satellite, and they're a whole lot simpler.
Do you even have an idea of how many square feet of PV cells you need for 10MW? There's a system in Portugal that's that big, you can see a photo of it here. Even figuring that you might get slightly more efficient cells and by putting them in orbit might be able to get more power out of each, you're still talking about a *huge* station.
I strongly suspect you are talking about a Shuttle launch or using one of the Russian or European heavy-lift rockets (I think an Ariane 5 can lift something like 10,000 kilos to geostationary orbit), and that's assuming you can lift it in one shot to begin with.
I think this is neat technology too, but let's not understate the difficulty here. This is an immense undertaking.
"Ladies and gentlemen, my killbot features Lotus Notes and a machine gun. It is the finest available."
Woops, you made an error of three orders of magnitude, that's five to ten gigawatts not megawatts.
From the report.
http://www.nss.org/settlement/ssp/library/final-sbsp-interim-assessment-release-01.pdf
Typical reference designs involved a satellite in geostationary orbit, several kilometers on a side, that used photovoltaic arrays to capture the sunlight, then convert it into radio frequencies of 2.45 or 5.8 GHz where atmospheric transmission is very high, that were then beamed toward a reference signal on the Earth at intensities approximately 1/6th of noon sunlight. The beam was then received by a rectifying antenna and converted into electricity for the grid, delivering 5 - 10 gigawatts of electric power.
The Sun is a giant fusion reactor, conveniently located some 150 million km from the Earth, radiating 2.3 billion times more energy than what strikes the disk of the Earth, which itself is more energy in a hour than all human civilization directly uses in a year, and it will continue to produce free energy for billions of years.
You gotta like that. The SUN is conveniently located!
The basic idea is very straightforward: place very large solar arrays into continuously and intensely sunlit Earth orbit (1,366 watts/m2) , collect gigawatts of electrical energy, electromagnetically beam it to Earth, and receive it on the surface for use either as baseload power via direct connection to the existing electrical grid, conversion into manufactured synthetic hydrocarbon fuels, or as low - intensity broadcast power beamed directly to consumers. 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. This amount of energy indicates that there is enormous potential for energy security, economic development, improved environmental stewardship, advancement of general space faring, and overall national security for those nations who construct and possess a SBSP capability.
A single kilometer - wide band of geosynchronous earth orbit experiences enough solar flux in one year (approximately 212 terawatt - years) to nearly equal the amount of energy contained within all known recoverable conventional oil reserves on Earth today (approximately 250 TW-yrs). The enormous potential of this resource demands an examination of mankind's ability to successfully capture and utilize this energy within the context of today's technology, economic, and policy realities, as well as the expected environment within the next 25 years. Study of space-based solar power (SBSP) indicates that there is enormous potential for energy security, economic development, advancement of general space faring, improved environmental stewardship, and overall national security for those nations who construct and possess such a capability.
Let's get it done!!!
The NHS system in the UK for 60 million people costs £105 billion a year. Which works out in dollars for around 300 million people something like 1.06 trillion dollars per year.
I'll let you work out where you're going to find something of the magnitude of a trillion dollars per year without borrowing.
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