Caltech scientists will launch a space-based solar power satellite on Tuesday. The plan is to build a power station in orbit around the Earth which would beam energy back to the ground where it can be incorporated into the grid. Good thing about space solar? The sun is always shining up there.
The demonstrator mission, SSPD, will test three key elements of the satellites, including the photovoltaic cells and the unfurling mechanism. #Science
So they're experimenting to build an orbital system, that could send a high energy beam to almost any point on earth.
WHAT. COULD. POSSIBLY. GO. WRONG?
While there's plenty of space down here to collect, store, transform and transport the 10000 times more solar energy than the whole earth needs, with well-known & in comparison inexpensive technology 🤦
(But that would probably not be sponsored by military sources, I guess)
1) you'll need _many_ of those satellites for commercial scale.
Each with a beam of >200W/m2 (in normal operation) with a phase controlled (=highly steerable) antenna.
How many beams would you need to fry electronic infrastructure incl satellites, kill living things, make an area unpassable?
(hint: their paper speaks of up to 80% loss by atmospheric water)
And that's not calculating the effects on weather etc of those 80% energy in "normal" operation.
2) Efficiency will depend on weather down here, esp water in the atmosphere. I.e. heavy rain, snow = a _lot_ of power loss. You'll need storage capacity and a flexible power grid.
BTW: 200W/m2 is what todays solar cells collect on any roof top, parking lot or covered bike lane, while the area below and around is still usable. (You'll need storage anyway, see above)
PV _is_ the cheapest form of el. power now.
https://www.solarfeeds.com/mag/netherlands-unveils-worlds-first-solar-bike-lane/
3) Oh come on! Steerable high energy megawatt beams from space. Don't tell me Northop Grumman is in this for nothing (and probably others as well).
Every technology that might be usable for military will have connections and funding to get the know-how and probably the people who have it.
3) MWs are just not weaponisable from 35,000km, the wavelength is too long to focus into a collimated beam (as research link in response to your #1 post makes clear). It's a basic limitation of the physics.
If they start taking about laser transmission (NOT part of the current Caltech experiment), that's when you might want to start worrying. But you wouldn't need a whole power station for a space-based laser weapon anyway (far more efficient ways of being evil).
4) What could come out of this? Centralized power system. Can easily be switched off or redirected with a click. Think whole regions depending on it. Think one crazy billionair controls it. Think of a "too big to fail" company.
No, this would be a very stupid idea - unless you _want_ centralized control of vital infrastructure.
Did I mention solar flares yet? What do you do if a satellite fails? Go up and repair? "Bring it down" and replace?
Re: Centralised ownership:
Power station owners can always flick off the switch, OPEC can always cut production, etc. What has this got to do with SBSP?
Re: solar flares:
Communications satellites seem to do fine under current conditions! Yes, replacement time would be a problem if there was a Carrington event, but rest of the grid would be stuffed too. Meanwhile, the earth grid is vulnerable to extreme weather events. Better to put the eggs into different baskets, surely?
Very simple.
Regional, decentralized power, i.e. solar, wind, geothermal, can not be switched off so easy.
PV on roof tops, private houses, malls, parking lots can not be switched off by one mouse click or any company going bancrupt.
No disagreement that decentralised power is great and should be encouraged. But there's just as much solar being built as 'centralised' power stations as well (not to mention wind farms and other renewables). Are you against that? Energy transition requires a mix.
Also, it's a bit 'middle class' to think that rooftop is best for all. One potential pro for SBSP is that the ground infrastructure might be cheaper/faster to for underserved locations.
Base idea for my single switch assumption is, that one company will control most if not all power satellites.
So, this is centralization of power, not only electrical.
Now estimate the risks associated with this power and image the amount of security stuff that will follow. Such a single point of potential failure must be protected. From outside attacks as well as inside, much like nuclear plants.
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I don't buy the cheaper/faster.
You'll need the same kind of infrastructure on the ground as with PV - only much more space, even if my 200W/m2 is correct. Much more when 10W/m2.
And this space will not be usable for anything else. PV on buildings would be.
Every US person consumes 12000kWh/a ~= 1,37 kW cont. ~= 137m2 rectenna area p.Person @ 10W/m2.
Avg apartment size in the USA in 2019 was <84m2 (900sqft).
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So, where do you find more unused, unusable space for those antennas than people have to live in?
So, more energy density? More risk for every life form in the beam.
Once again: 10W/m2 is what every off the shelf PV gets from clouded sky. 200W/m2 is avg peak in northern germany (53°N).
Current PV costs on the ground: 4 €ct/kWh.
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Like I said, string them up over valleys not suitable for windfarms, or over farmland. Dual use.
Once again: same efficiency PVs in space would get cloud-free sunlight 22-23 hours out of every 24, without the basic 30% atmo absorbtion. I see your numbers and multiply them.
And again: There's no risk from a focused MW beam. From 35,000km even with many GWs we're in the ballpark of standing next to a microwave oven. Not exactly the stuff of Bond-villians.
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More false assumptions. A rectenna can be a loose wire grid of dipoles. Suspend it over spaced-out pylons or anchored over a valley. Rain and sunlight falls through. Can farm the land under it.
MUCH less materials required than glassing over surfaces with PVs directly. Likely much less resource loss and energy demand to manufacture, compared to a solar power station of the same Wattage, or all the installations of rooftop solar to match it.
2) PV efficiency on earth depends on weather to! PV is cheapest yes AND could be cheaper (perhaps) if operating in orbit. Daytime 90% instead of 50%, no clouds, can stay oriented with sun. No need to embed the cells in glass and steel and concrete them down.
SBSP would just be pure PVs in space, with launch cost to get them there and transmission cost back to earth via MW. The efficiency tradeoffs may or may not be net beneficial environmentally. Worth researching.
The rectennas would have to withstand the same weather conditions as PV.
They'll need the same infrastructure for transformers, switches, etc.
And they will need more space on the ground, if the energy density of the beam on the ground is less than 200W/m2.
(the more off the equator the rectenna is, the more space you'll need)
I'll give you the continous delivery - although clouds, rain and snwo will absorb a lot, so the output will also vary with the weather.
Yes to all that, the ground side will have to be wired in and cope with weather etc just like PV stations. Engineering a rectenna that's both robust enough and lightweight enough to make the whole thing worthwhile would be one of the main challanges (the other being similar research/engineering on the space side). It's highly uncertain whether it would work out.
But at this point we're a long way from "WHAT. COULD. POSSIBLY. GO. WRONG?", right? Let's wait for the research.
1) Again, your assumptions are off, so your conclusions are all over the place.
You say 200W/sqm is the approx PV generation efficiency. That's nothing to do with the received MW beam intensity on earth which is much lower (MWs spread out). SBSP would position PVs in space with much lighter (but it larger) wire mesh MW rectenna on earth. Standard ref is a 1GW station with 1km antenna, 10km rectenna, more like 10W/m2 received. Not enough to notice.
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