Pentagon Urges Space-Based Solar Power 552
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."
5-10 Megawatts? (Score:3, Informative)
Direct Report Link (Score:5, Informative)
SBSB Interim Assessment [nss.org]
Dupe (Score:3, Informative)
Re:Could be a tremendously capable tool, but.... (Score:1, Informative)
Can never break even on energy. (Score:4, Informative)
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.
Re:USA USA USA (Score:2, Informative)
Re:Can never break even on energy. (Score:3, Informative)
I don't know if the report is correct, but it claims that almost all of the beamed energy could be absorbed by the ground based collectors. I don't know if absobed necessarily means converted to usable electricity, though. From page 29 of the report:
Re:The initial version may not be impressive but.. (Score:2, Informative)
That doesn't mean that this is a great idea, but the process described by my parent has historical precedent.
Re:Also the Fear of Where the Money Comes From (Score:5, Informative)
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 [dailytech.com]. 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.
Re:Also the Fear of Where the Money Comes From (Score:3, Informative)
That doesn't make any sense. The metawatt is a unit of power, not energy. Perhaps you meant megawatt-hours, which makes at least some of your numbers plausible. But the "15 hours of sunlight" per day, is definitely not. A geosynchronous orbit stays above the equator, hovering over a particular spot on the Earth's surface. As such, it will spend, on average, exactly 50% of the time in sunlight (ie. when it is sunny at the point on the Earth directly below it), and 50% of the time in darkness (ie. when the Earth is between the satellite and the sun). So, 12 hours a day. Possibly much less, if they do not continually move the solar collector - I can think of a few reasons why you would NOT want to continually move the collector to get best efficiency: 1) it is a moving part, and if it breaks there is no chance to fix it, 2) beaming the power back to earth requires extremely precise guidance, and moving the collector around is going to play havoc on it. For comparison, imagine shining a laser on a target 26,000 miles away, and turning at the same time. A one-degree shift in the angle corresponds to over 400 miles at the target! So, it might only be an effective couple of hours of light per day. Also, there is the question of how much the efficiency degrades if there is cloud in the way of the microwave beam. This depends on the precise frequency they use, but there will always be some loss.
Now, there are more interesting things you could do to increase the amount of sunlight hitting the collector, eg instead of beaming the power back to earth, beam it (or just have a cable) to another nearby satellite that does the transmission to Earth. Then you can move the entire collector satellite, no separately moving parts. But this increases the cost and complexity.
By the way, the article isn't very clear, but when they way "larger than the ISS", they almost certainly mean larger in WEIGHT, not SIZE. If a single 4000 pound satellite could produce 10MW power, they would have done it years ago!
Re:5-10Mw? That's stupid. (Score:2, Informative)
Re:5-10Mw? That's stupid. (Score:3, Informative)
Based on looking through a couple dozen of those reactor descriptions, I stand partially corrected. Most commercial reactors produce around 1GW, in the range 600MW-1400MW. I found a couple of reactors in the 1500MW range. Without actually counting, it looks to me like most US reactors are sub-GW. And I didn't find any that produce "thousands" of MW.
Re:Redistribution == Stealing (Score:2, Informative)
The minor "redistribution of wealth" from rich to poor represented by social welfare programs is just a small governor on the runaway "redistribution of wealth" of everyone to the rich created by public policy that favors speculation over labor; the issuance of land and resource deeds, corporate charters, copyrights, and patents; the reserve banking system; the inheritablity of wealth; and everything else the government does to create capitalism.
But "redistribution of wealth" is not the issue with health care. Basic health care should be understood as a public good, just like an army, or roads. If the interstate highway system was justified as a "defense" program, then in this age of bioterrorist threats we should certainly understand health care the same way.
If my neighbor starts to show symptoms of anthrax or bubonic plague (or bird flu or SARS), it's in my whole neighborhood's interest that he gets to a see a doctor pretty damn quick. The idea behind "health savings accounts" and similar schemes, that provide an incentive for people to not seek medical care, can be seen to be highly dangerous not just to the individual but to the community.
And since a generally healthy population is more resistant to a biological attack (and a healthy militia is a lot better than a sick one), preventive care can also be justified.
(And of course, much of the cost of contemporary health care is the cost of drugs, which is kept artificially high by our patent policy.)
Re:Sounds like a money-transference scheme (Score:1, Informative)
Re:Also the Fear of Where the Money Comes From (Score:2, Informative)
They also would have a cost per Kg 3 to 7x lower then what we have today.
That's 5 - 10 GIGAWATTS not megawatts!!! (Score:5, Informative)
From the report.
http://www.nss.org/settlement/ssp/library/final-sbsp-interim-assessment-release-01.pdf [nss.org]
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!!!
Re:Kumbayah, indeed. (Score:2, Informative)
Re:Actually, this could save money... (Score:2, Informative)
Re:American Agri-business Versus DOD (Score:2, Informative)
Re:Actually, this could save money... (Score:3, Informative)
Re:Redistribution == Stealing (Score:4, Informative)
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.