lasers

Can you use a laser to transmit electricity? Have we done this practically,
or is it only a theory? If so, what is the efficiency? Does anyone know
the efficiency of a typical high tension line?
Tim Gard
Reply to
Tim Gard
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You would have to first define what is meant by transmit and then how that applies to electricity.
Considering that ordinary matter is a combination of charged particles, electricity can be transmitted by sending matter from one place to another.
Bill -- Fermez le Bush--about two years to go.
Reply to
Salmon Egg
Ack!! You smoked me Salmon ... (pardon the pun) I'll have to cook that for a while ...
Tim Gard
Reply to
Tim Gard
I want to transmit energy in the form of light ... laser light specifically.
And light is matter.
Based on this, consider my original post question;
Can you use a laser to transmit electricity? Have we done this practically, or is it only a theory? If so, what is the efficiency?
I believe this has been done, I just wasn.t sure. Or how efficient it was.
Tim Gard
Reply to
Tim Gard
----------------------------
---------- Not really - note that I have seen electrical discharges produced in air by high concentrations of energy from a laser. but that isn't of much use. The energy efficiency of a laser is actually quite abyssmal. The advantage of a laser from an energy point of view is that one can get high energy density. For transmission, the old fashioned power line is cheaper and more efficient.
Reply to
Don Kelly
I smell a troll at work.
Reply to
contrex
And with *that* nose we should all be wary gnome!
Tim
Reply to
Tim Gard
Don,
That is what I learned about fifteen years ago and wondered if we had any advancement since my last contact with it.. Could losses be overcome in a controlled atmosphere such as argon? Is the efficiency converting back from light to electricity still as bad as it was? Copper power lines are dismal, and that science is ancient. With all our technology, have we not bettered that yet?
Tim
Reply to
Tim Gard
As far as I am aware, it is not the medium through which the laser is transmitted that would determine the efficiency (obviously it does play a role, but not the largest one). The ineffieciency is inherent in the genereation of the laser beam itself. Although several methods do exist, the cheapest one being the diode pump (I think), none of them are very good efficiency wise.
In the generation process, large amounts of energy must be put into the system to excite atoms into a meta-stable state in order for population inversion to take place and hence produce laser light. Photons have to be kept inside the system long enough to keep this light continuous, thus one side of the generator is usually totally reflective, the other side partially reflective. This keeps many of the photons inside. So think about it - put lots of energy in, get few photons out. I could be wrong about this but I am unaware of a laser with more than 50% efficiency.
The next problem is that of divergence. Any laser beam will diverge as it propogates. Focussing the beam is a very difficult and costly procedure (except for crude focussing). This would probably make power transmission over any sort of reasonable distance uneconomical. I am very rusty on the topic, so I hope I am not talking rubbish.
Hope this was helpful.
Reply to
hbennie
Yes, we use aluminum cable with steel cores.:) Why do you say copper lines are dismal? Have we anything that comes remotely near them for energy transmission. Unfortunately not. If one could transmit power 100 miles with an efficiency of the order of 90-95% as is the situation, then why would one use lasers at possibly 2% efficiency (optimistic) conversion and over such a distance, collect about 1-2% of that and convert it back to electricity with a device with 20% efficiency? Perfectly co-linear lasers do not exist so there is beam spreading. There is also energy loss due to scattering in the medium. I doubt whether a controlled atmosphere with any gas would do. A vacuum would be better but in either case- how straight a tube can you make over a long distance? A small kink would result in disaster as the beam would destroy the pipe. In addition, you are then looking at the capital costs involved which would make overhead power lines look cheap.
Changes that have taken place with power lines are the use of bundled conductors and also the development of higher voltage systems as well as reactive controls for such systems. The basic "wires hung from insulators" still is very good compared to anything else.
Admittedly my own experience with high power lasers is limited to association with a person who built and tested such lasers. A 20KW CO2 laser needed a large power supply that in itself took up about twice the volume of an ordinary living room and needed connections to a cooling system that was intended for building cooling. The advantage was that it could concentrate a lot of energy in a small area- so could burn through firebrick quite easily, weld aluminum to stainless steel and cut or weld pipe such as used oil pipelines (it's intended purpose). --
Don Kelly snipped-for-privacy@shawcross.ca remove the X to answer ----------------------------
Reply to
Don Kelly

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