Satellite power stations?

Is it feasible to collect solar energy and convert it to electrical energy using a satellite with solar panels? When I say satellite I am really thinking of something much closer to the Sun, or would that matter?

I imagine the problem would be transmitting the energy back to Earth… There must be a way right?

Sure. The concept has even been tested, to a point. The electricity is converted to microwaves, and receivers on the ground convert it back into electricity.

Putting it closer to the sun would mean that it could gather more light, but you’d lose more in the transmission back to Earth; whether or not it would pay off, I can’t tell.

The big problem is getting the power back to Earth; you can’t run a cable down (although some people think this will be possible one day - search on “space elevator”), so you have to beam it down as electromagnetic radiation of some kind; so there’s a tight, intense beam of [some kind of] radiation (let’s say microwaves) going straight down through the atmosphere. What happens if something flies through the beam? What happens if a micrometeor hits your satellite and it wanders off target by a fraction of a degree? - the other end of the beam moves off target by a considerable distance, frying anything in the way.

Not In My Back Yard, as they say.

Also, of course, putting it closer to the sun means it can’t be in a geostationary (or do I mean geosynchronous?) orbit, so targeting your power beam becomes a whole new set of problems.

The alignment problem could be simply solved by a feedback mechanism. As long as the receiver is getting power from the satellite, it sends a signal back up. If the beam wanders off target, the signal stops, telling the satellite to shut down the transmission.

Here are some links on the topic:

http://www.space.com/businesstechnology/technology/solar_power_sats_011017-1.html
http://spacesolarpower.nasa.gov/

But there is a delay involved; the satellite gets knocked off target, a fraction of a second later, the beam wanders off spot on the Earth, the system reacts and sends the ‘stop’ (or probably stops sending the ‘OK’ signal) signal, which takes another fraction of a second to reach the satellite, meanwhile, the beam has been wandering off-target for 2x[however long it takes the signal to travel]

The beam will be wide and weak enough that a short exposure will not be harmful.

There will of course be multiple safeguards that shut off the beam in such a case. It’s no more dangerous than nuclear reactors which also rely on automatic and manual controls in case of an accident. Probably safer, since a bit of spilled microwave energy won’t kill anyone.

I believe that the round-trip time for a satellite in geostationary orbit is in the 100s of milliseconds - certainly long enough to be a concern.

Birds fly into windmills now, so I don’t think that is a HUGE issue.

No need to place the sattelite closer to the sun.

Main problem now is the cost of getting stuff into space.

Still long term, but probably nearer term

http://www.space.com/businesstechnology/technology/solar_power_satellite_000421.html

http://www.freemars.org/history/sps.html

google satelite solar power for more

Brian

I was thinking about things more like aircraft, which don’t have a big problem with windmills I think, but maybe if we made windmills that extend upwards through the entire depth of the atmosphere they would; oh I’m sure there would be safeguards and I’m sure they would work perfectly all the time.

My calculator says about 240 ms. Could be an issue, I agree.

Simple solution: restricted airspace (away from major routes). Sure, some planes are going to wander in, but it would not be a major deal. A plane flying through the beam is going to be in it for <30 seconds. The more dense the beam is, the shorter time it would be in. The less dense, the less of a deal it is to be in it. (I don’t know where the sweep spot is)

I’m not saying there aren’t issues. But how many people die getting caught in the circular current at the foot of dams? In coal mining accidents?

Brian

Another simple solution: make the beam weak and wide. 10GW beamed onto a 10x10km antenna farm is only 100W/m[sup]2[/sup]. You probably get more than that from your cell phone.

If my cell phone is putting out 100 W/m[sup]2[/sup], I want to know about it! :eek:

If you hold a 1-watt transmitter 1 inch away from your head, that’s 100 W/m[sup]2[/sup].

It is a pretty big issue. Large-scale wind farms like the windmills in Livermore CA apparently attract and kill a large number of raptors because lots of prey animals live in the weeds around them. There have been a number of protests from environmental groups. You know “big oil” has to love it when the fluffy-bunny crowd squares off against the renewable energy crew.

If you end up with piles of dead birds surrounding your energy transfer beam, I guarantee someone will make an issue of it. Any practical plan would have to include this kind of litigation in their cost of doing business.

I wouldn’t want anyone to think that I’m taking the position that it’s impossible or even unworkable (although it may look that way), I’m just trying to explore the issues as deeply as I can.

There are raptors in California?

Yep. California condors, bald eagles, peregrine falcons, to name a fes.