Space-based Solar Arrays

[Cycloloco]

There are two big projects proposed for future power supplies, usually intended for electricity generation. One is nuclear fusion and the other is solar power from geostationary orbiting satellites. Fusion gets a certain amount of publicity and a lot of money and the timescale for it to work in practice is 40-50 years ahead. Unfortunately it has been the same period ahead for the last 50 years.

There is one other big project which has been suggested since the 1960s, gets a lot less publicity and very little money. The project is to build geostationary solar collectors about a kilometre in diameter and beam the energy down to Earth as microwaves.

I don't propose to explain it all. Instead I offer two URLs:
http://en.wikipedia.org/wiki/Solar_power_satellite
http://www.spacedaily.com/news/ssp-03b.html
and there are lots of others on the internet.

This is a hi-tech project with some similarities to fusion. It is long-term and requires billions to develop so it requires gov't support and it needs it before we run out of fossil fuels.

I could have put this message under 'solar power' but it seems more appropriate to 'Others' because it is a big project, far ahead, and may never be made to work, like fusion.

If we concentrate funding on fusion we may be limited to materials on Earth. Space-based solar gives a greater chance of building up expertise to start using resources on the Moon or elsewhere. (That's my optimistic side. Sometimes I think we will end up as small groups of hunter-gatherers or farmers. This is one project which gives the possibility of a smaller population remaining hi-tech.)

[genoxy]

The project is to build geostationary solar collectors about a kilometre in diameter and beam the energy down to Earth as microwaves.

Sound great! "Would you like any Worcestershire Sauce with your New-York steak and Yorkshire pudding, Sire?"

[Cycloloco]

It's building support. See:

http://environment.newscientist.com/cha ... space.html

Pentagon backs plan to beam solar power from space
16:46 11 October 2007
NewScientist.com news service
Dan Cho, Washington, DC

Kilometre-sized solar panel arrays would gather sunlight in orbit, then beam it to Earth in the form of microwaves or a laser.

A futuristic scheme to collect solar energy on satellites and beam it to Earth has gained a large supporter in the US military. A report released yesterday by the National Security Space Office recommends that the US government sponsor projects to demonstrate solar-power-generating satellites and provide financial incentives for further private development of the technology.

Space-based solar power would use kilometre-sized solar panel arrays to gather sunlight in orbit. It would then beam power down to Earth in the form of microwaves or a laser, which would be collected in antennas on the ground and then converted to electricity. Unlike solar panels based on the ground, solar power satellites placed in geostationary orbit above the Earth could operate at night and during cloudy conditions.

[adam2]

Entirely possible in theory, but most unlikely to be viable in practice.
Consider the vast amount of energy (probably FF derived) required to make the rocket fuel and the spacecraft.

Consider the large number of rocket launches required and the risk of fatal accident, either to the crew or persons on the ground.

Consider the embodied energy not just of the solar cells (which would also apply to ground based cells) but also of the spacecraft and the receiving station.

Also this would appear likely to worsen global warming, since the space based PV array would be capturing and sending to earth additional energy, which ultimatly would end up as heat.
(this objection does not apply to ground based PV which captures and puts to use, energy that would have fallen on earth in any case)

And finally a laser or microwave beam powerful enough to transmit useful power would be an excellent space based weapon, a true "death ray" as depicted in science fiction novels for decades.
What if the guidance system fails, or is subverted by terrorists or rogue states?

[clv101]

Very silly idea in my opinion. Come back when we've installed a few tens of thousand square km on the surface of the Earth.

[RenewableCandy]

Quite, because the power flux down here (at least when it's not cloudy) is only some 30% less than in space...so all that rocketry and risk for a lousy extra 30%.

Oh and the geostationary orbit band is filling up with space junk, but I've already done that one on another thread...

[Bandidoz]

Quite, because the power flux down here (at least when it's not cloudy) is only some 30% less than in space...so all that rocketry and risk for a lousy extra 30%.

Oh and the geostationary orbit band is filling up with space junk, but I've already done that one on another thread...

And would more than 30% be lost through the double-conversion?

Not to mention the consideration of space debris....
http://uk.youtube.com/watch?v=JuFBUS0kiSA

[clv101]

Quite, because the power flux down here (at least when it's not cloudy) is only some 30% less than in space...so all that rocketry and risk for a lousy extra 30%.

Oh and the geostationary orbit band is filling up with space junk, but I've already done that one on another thread...

It's not 30% less, it's ~three times less when you take into account night and dawn/dusk angles.

[Cycloloco]

It's still being worked on. Could be working in 15-20 years?
Now said to depend on the proposed Skylon space plane to build an array.

http://eandt.theiet.org/magazine/2014/1 ... -power.cfm