Talk:Solar power satellite
From Academic Kids
Any reason this article isn't at solar power satellite, which to me seems like the appropriate name according to the naming conventions? --Robert Merkel
Newcomer ignorance. Mine. Rectified a bit since. user:mirwin
By the way, the article is overly optimistic about SPS's, and needs a little neutral point of view put into it by listing some of the critical views on the topic. --Robert Merkel
Perhaps. Some of what you seek is either at the bottom or solicited there. I put a reference to it at the top to encourage interested adherents of more pessimistic or alternate worldviews to seek them their.
Another Wikipedian started to wikify it but apparently got tired of it quickly. user:mirwin
Why does the cost of building a space elevator matter for the launch cost of solar satellites? Such an elevator would not be used only to launch this particular type of satellite, so the construction costs would be spread out over far more than this. Shouldn't only the estimated launch costs of $1-10/kg matter here?
Does anyone know how long solar cells can last in space? They have to endure hard radiation, particles from the sun and micrometeorites. By now there should be much practical experience from existing satellites. 84.160.230.74 15:57, 31 Mar 2005 (UTC)
Wouldn't a satellite which directly focusses sunlight onto a solar thermal plant on earth be more efficient? The beam would be narrower than the microwave beam and the loss in thermal->electric conversion is less than that of solar cells. Clouds between the satellite and the ground station would quickly evaporate due to the intensive illumination. 193.171.121.30 02:12, 6 May 2005 (UTC)
- It's not possible to use mirrors or lenses to focus the light from the sun more narrowly than the light from the sun already is. If you've ever fiddled around with a magnifying glass you should kinda know how this goes. You can make the image brighter though by collecting more light with a bigger lense. The microwave transmission technique actually gives a narrower beam, inspite of the wavelength being considerably longer. Sunlight-pumped lasers could also be used in principle; but in practice it's a weapon.WolfKeeper 02:19, 2005 May 6 (UTC)
- Sorry, I don't quite understand you - you can focus sunlight from a larger mirror area onto a small spot on earth's surface where it can be used e.g. to evaporate and heat steam for a turbine which drives a generator to produce electric energy. A narrow beam is not necessary but a small spot at the earth's surface - and this spot can be made smaller at lower wavelengths with the same arperture size. I actually didn't mean narrow beam but small spot at the ground station. 193.171.121.30 12:45, 6 May 2005 (UTC)
- Basically, what I'm saying is that it doesn't work. There are optical restrictions inherent in mirrors and/or lenses that prevent this from working. The angle that the light hitting the ground makes is the same as the angle that the sun makes at the satellite. This restricts how small the image it projects onto the ground can be. By making the mirror larger, you can make the image brighter, but not smaller. Because the satellite is so far away from the earth, the focused image is going to be very large. Something like that anyway... That's why the SPS was invented to circumvent this restriction. WolfKeeper
- Thank you for the explanation - I should have given it a second thought before. 193.171.121.30 18:22, 6 May 2005 (UTC)
Economic feasibility - don't we need to use the cost of power at the power stations, rather than the cost to consumers? (since the SPS power is still in one place and needs to be distributed) Ojw 12:54, 22 Jun 2005 (UTC)
- Please explain the distinction that you're trying to make. Afterall, ignoring sunk costs, the SPS makes power for free. The real costs are in building it, managing it, and delivering the power to the grid. --Flatline 16:54, 2005 Jun 22 (UTC)
- Distinction is: we are assuming that the SPS power station can sell electricity for the same cost that you pay at home. The calculation uses the $/kWh cost taken from the back of somebody's electricity bill, and not for the price that the power stations themselves are selling at.
- If the two prices were equal, then there wouldn't be any money left over to buy power lines, transformers, fat-cat salaies, electricity meter-readers and everything else that the distribution company needs to get the electricity from an SPS antenna in the middle of a desert, to the consumers scattered around the nearest city.
- This is different to (for example) solar-power roof tiles, where the power is generated at the consumer's home, so you can use the retail price of electricity to calculate how much it's saving you.
- Ojw 18:28, 22 Jun 2005 (UTC)
