This idea never made any sense to me. Why the heck would you spend billions of dollars to launch solar panels into space to gather sunlight then beam it to earth when you could just wait for the sunlight to get to earth naturally for free...
Anyway, space based solar power is the end game. Nothing on earth will ever provide the quantities of power (not even nuclear, fusion or fission) that capturing solar energy can.
Worth noting this isn't as much of a benefit as it's made out to be.
If you were designing a perfect power source, it would match demand, so produce more in winter in polar regions, and more in summer for regions with lots of AC. Similarly, you'd generally want more power during the day than at night.
This is part of the reason a mix of solar and wind that varies by latitude is an ideal mix.
Space power might get more bang for buck if it could target its power to different regions e.g. swapping from north to south as the seasons change, and/or following the day/night cycle and/or weather to maximise energy price.
(Source: The Case for Space Solar Power)
The moon is 10x further away, so the Earth subtends/shades a much smaller angle.
You can chalk my comments up to a grumpy engineer tired of the cyclical SBSP pushes that never go anywhere.
Here the only thing it's going to drive are thermal requirements-- which are admittedly significant problems. There's no need to continue to use large amounts of power for comms, etc, like on most GEO birds.
And, of course, the grid needs to deal with the power disappearing for an hour in the middle of the night for short periods of the year.
But you do need everything to survive the cold and thermal cycling.
You'd need propulsion to maintain position and orientation. You'd also need a number of propulsion units to balance solar pressure gradients as the collector entered and existed the Earth's shadow as well as the thermal expansion/contraction of the structure.
It's likely not a lot of power but a non-trivial amount of fuel.
High-impulse ion engines, etc, are a good match for this task.
A structure 100m on a side would be just at the bounds of current technology (the ISS's control moment gyros). With 30% efficient panels that's only about 4MW before conversion and path losses.
The high impulse ion engines to desaturate the gyros would still need to be refueled regularly. I think you're hand waving a lot of complexity that even if completely solved still leaves a solution that's orders of magnitude costlier than solar panels on the ground.
As to power disappearing with an adequately geographically integrated grid I don’t forsee that as really too much of a problem. Currently the grid deals with short term outs fairly well especially if they are planned for months in advance.
Lots of thin structure with 70 minutes to radiate, with the only thing shining on it the earth's albedo subtending a tiny angle. I'd imagine it creates rather significant demands on structure and electrical connections.
I've not run the numbers on a GEO solar spacecraft, but the smallsat group that I'm mentoring that would be "thicker" than a lot of the GEO craft... gets down to -30C without heaters during its 40 minutes in eclipse while much closer to Earth.
> As to power disappearing with an adequately geographically integrated grid I don’t forsee that as really too much of a problem. Currently the grid deals with short term outs fairly well especially if they are planned for months in advance.
Yup, that's the point I'm making. A space based solar power craft has smaller problems from eclipse than a typical comsat. Batteries, etc, are not nearly as much of a concern. It's mostly the thermals that are left.
Have pizza: https://www.youtube.com/watch?v=lGDUmGlMJzU
The article addresses this. To my mind 4 minutes per year is equivalent to the parent’s layspeak “no night” comment.
Why?
- You still get better duty cycle from the panels
- The time the power is missing is very small
- The need for storage, etc, is low because it's a short period of relatively low demand that is missing.
And a solar death ray aimed at the planet doesn't?
Regardless, I don't think long-distance transmission is a viable solution to solar intermittency.
Convincing governments you've not cheated with a gigawatt optical laser on your satellites (optical wavelengths being smaller than microwaves makes them easier to focus with smaller parts), that's a separate question. I assume an Iranian one of these would get destroyed by Israel for the same reason they attack their neighbour's nuclear reactors.
If you have enough satellites to not need the distribution grid, and they're all in geostationary orbit, then many are over the horizon at the same time and they can (in principle) be combined on the same place.
If they're in a low enough orbit that you only get a few over the horizon at any given moment, you get a substantial penalty from Earth's shadow.
On Mars this would be a great thing for colonies; get past the global dust storms, and it won't matter if you have only a handful of sites; on Earth… pick which failure mode you prefer.
The space based solution is possibly actually more reliable, as there are actually less components involved that could fail.
This is really the key, if you can make a solar panel that’s as light and thin as say mylar, and then unfold it when you get to space, we could put up several kilometers of solar panels without requiring much mass at all. It’s not like there’s wind or rain up there to wear it down.
Of course, there are loads of problems with the idea but I can see why it's intuitively appealing.
What is the "typically" you are referencing?
The 60% over a kilometer is not due to atmospheric absorption, it's due to losses at the transmitter and receiver (and beam spread exceeding the size of the receiver.) If microwaves lost 40% of their energy in a kilometer radar would have a hard time working.
Millimeter waves are more strongly absorbed in clear air, so they are not as good for this use case. They may be good for powering aircraft.
Really though I don't see this scaling to energy production for the masses due to the beaming logistics.
It'll mainly be used to recharge drones that never land and possibly fry enemy systems / missiles / etc.
With modern modular designs using phased array transmitters, even getting that much focus requires a reference signal from the ground target.