In this article on a robot winning a prize for climbing up a wire, simulating a space elevator, I was interested to read that the robot was powered from a ground based laser system and not, as I was expecting to see, a solar powered system. Although it did use solar panels to capture the laser light.
As the test took place in the Mojave desert, one of the areas identified as being able to get good sunlight for powering the planet, I would guess that it didn’t generate as much power using sunlight than it can using other forms of light. This brings up some interesting thoughts on power transfer.
In previous posts we surmised that to transfer power from solar arrays in space we would use microwaves. Now instead if we could put a satellite in orbit comprising just solar panels and a laser array and using the large surface area of the solar panels in space to generate a focused laser beam pointing down to Earth on to a much smaller solar panel receiver and therefore up the efficiency of both the collection and the transfer.
Of course there are many things that could go wrong here but I wonder what sort of power that would output. Of course it doesn’t have to be in space, even a high altitude balloon could do it.
The reason I was thinking about this is we have no, as far as I am aware, microwave weapons that work over any sort of distance but we do have experimental lasers in a flying 747 which is designed to shoot down aerial missiles. There must be a reason for that and I’m going with power at the receiving end.
But how does laser power actually compare to microwave power in power transfer efficiency and power generated per square inch? Anyone have any idea?
It sounds a good idea but – isn’t there always a but – you would have to look at the efficiency of the system and how much energy reaches the ground depending on the atmospheric conditions.
The actual efficiency of the system might not matter out in space – need more power, just add a few more solar panels – plus there is enough room up there, in theory. The losses through the atmosphere are a different order of magnitude – I loose a lot of the satellite broadcasts here when it snows, microwave, yes I do need a larger dish and there are space constraints on doing that. Then there is the eco lobby – what with cooking birds and the heating of the atmosphere for various reasons in both cases. The military can do it because they are the military and it isn’t on continuously.
Ivan,
Totally agree on the buts. That is what I’m not sure about is a laser more efficient than microwaves for transmission through the atmosphere?
The difference with your sat signalis it is not targetted. It transmits across a wide area usually covering all of Europe plus large portions of Russia and the MIddle East. That energy concentrated into a narrow beam pointing at your dish wouldn’t have a problem with snow at all.
When you talk about military I assume you mean the 747 laser system. It isn’t on continuously because they can’t power it. Even as it is they have to charge the banks first before firing. As you say our collectors can just add a few more panels on.
It may not be a solution but I suspect that we will have something like this working long after our wind turbines have fallen down.
Lord T,
I would say we need something like it working BEFORE the wind turbines fall down.
You are heading me towards opening boxes that contain some of my reference books just to work out power rating over atmospheric dispersion and hoe it ties in with the inverse square law – something I haven’t had to deal with since setting up a microwave telephone link in Papua New Guinea nearly 25 years ago.
One thing I do know is that it will be ‘interesting’ which ever system is used if there is much pollution in the atmosphere and the current densities are high. Maybe this is something we should throw at PaAnnoyed from Counting Cats – after all it is 50 years since I was at university.
The other thing is – where do we site the ground stations/collectors? I’m sure where ever they are will provoke some greenie to get upset. Plus they need to be reasonably convenient to where the power is used.
We also have to consider the efficiency of the conversion system. Both have their strengths – and weaknesses – but without having figures to hand I can’t say which would present the simplest engineering problem.
Oh, I thought you were going to tell us the answer to your final question.
Ivan,
I meant this would be in place and still in use whilst the wind turbines fell into disuse.
Got the old brain cells going here then. Funny, whenever I installed a microwave link a nice engineer gave me all the figures I needed. Basically the price.
Personally, there are plenty of places to site there. Top of hills, just of the coast in floating facilities and in existing power station sites, ones that are obsolete of course. Whatever is best.
James,
It wasn’t a quiz. Despite what you think I don’t know all the answers.
Why solar panels in space? Why not a huge mylar mirror, focussed on a single collector, say liquid sodium, with microwaves beaming the energy back down, a la Tesla.
The problems that I see are a) precise focus of the beam, so you don’t vaporize a city and b) unfriendly control of the beam (see a)
Timothy,
Nothing wrong with a mylar mirror. I was thinking solar panels because they are increasing in efficiency almost every day and with microasteroids impacting items in space, and potential a Hasselblad, if it takes out a few it will make little difference we just add a few more. A damaged mirror may stop producing at all.
But in general I’m all for anything like that.
As far as the beams are concerned it is an issue but no more than control of a nuclear power station, a Trident SSBN or a B1. There are ways we can manage those risks.
Lord T – the mirror can be a kilometer square, yet launched in one mission. What are a few holes? It isn’t as if it will collapse due to atmospheric pressure.
Timothy,
When I was thinking about damaged mirror I was more thinking about the frame being twisted so it focused somewhere else from a solar wind or an impact. I agree that a few holes would make little difference same as a few missing panels.
I’m with you on this. Sounds like it’s worth a try.