Fiber Optic cables and power transmission?

[AgentZap]

We got into a discussion last class about who had the largest fiber optic networks in Florida. My teacher said Level 3 came in second and Florida Power and Light had the most, but his explanation was that FPL (our power utility) will start to use them as a way to transmit power.

I was under the impression that fiber optic cables are made of glass and it is my understanding that glass is a poor conductor of electricity. Therefore, wouldn't fiber optic cables be a terrible conductor of electricity?

 

[TuxDave]

As far as I know that's true but who's to say that they're going to use optical cables to use electricity to transmit power. What's stopping them from using the electricity to power a laser, and on the receiver converts the photons back to electricty again? Sure it's not 100% efficient transmitting electricity over wire isn't 100% efficient either.

 

[f95toli]

I doubt that would be an efficient way to transmitt power, if I remember correctly laser diods have an efficiency of about 60% at most. You also need a way to convert the energy back to electricty which at best is maybe 50%. Hence you end lossing 75% of the power. just in the conversion Copper cables are not 100% efficient either but not far from it unless you need to transmitt power of long distances.
Another question is of course what kind of laser you would use? High powered lasers are still only rated at a few kW, chemical lasers can of course generate much more energy but they do it by effectivly "burning" chemicals.

So, no I don't think that would be a good way tro transmitt power.

 

[Heisenberg]

Yes, glass would be useless to transmit electricity. I suppose you could do what TuxDave suggested, but it would be horribly inefficient IMHO. You'd had losses at the laser, in the fiber optic cable itself, and in the receiver in addition to the losses normally incurred when using transformers to step the voltage up or down. Nevermind how powerful of a laser you would need to transmit any meaningful amount of power in the first place. It's just not technically feasible. Your teacher must have his facts wrong, or there's more to the story.

 

[PowerEngineer]

It is true that many electric utilities have strung a lot of fiber over the last couple of decades. The reason has everything to do with the fact that their existing transmission line right-of-ways provide ready-made routes crisscrossing the country, and has nothing to do with the transmission of electrical power. Fiber can be either added as a separate "line" on the electrical towers, or it can be incorporated directly into the ground wires that are often strung to shield the actual power lines from lighning strikes.

 

[silverpig]

Optical power transmission is a very interesting research area (one I sort of am dipping into...), but isn't really feasable right now. Microwave power transmission would be much more appropriate, but I don't think microwaves travel too well down fibre

 

[spidey07]

your teacher is full of it.

They are laying down all the fiber to provide broadband services over power lines.

 

[Bobthelost]

Originally posted by: spidey07
your teacher is full of it.

They are laying down all the fiber to provide broadband services over power lines.

:thumbsup:

 

[vorgusa]

hmm I wonder if there is a distance/speed in transmitting power.. maybe without all the transistors or equipment...

 

[AgentZap]

I asked him to clarify and apparently its something being looked into for powering low wattage appliances of the future

 

[BrownTown]

and why couldnt you do that with normal power lines? All the fiber I hear about laid down by companies is for voice/data, not power.

 

[EvilSponge]

Hello,

Your teacher is not making sense. I'm an ex optical tech used to work for Cisco and HP fiber optical cable is a drawn glass fiber with a 9 micron core. This glass strand is coated in plastic then covered by a a kevlar sleeve then lastly another sleeve of plastic. At either end is a collumating lens at the connector tip to concentrrate the photons or light energy. To send current down such a cable would be highly unlikely.

-Eric