Electricity question.....

[chadspad]

OK, without wanting to get completely jumped on for saying this and I agree people have to be more responsibile with their electricity usage but I seem to remember my friend, whose husband works for the electricity board in some capapcity, saying that electricity is produced regardless and any that isnt used up just goes round on like a circuit thing back into the ground, therefore people using less electricty is going to have no bearing on producing less - am I right or wrong?

[Martin]

there are certainly enormous losses involved in "the grid", and it can't react instantly to demand, so they tend to shovel power in sufficient to meet anticipated needs - and to make sure it's a constant supply they have to err on the side of over-production, so there is a lot of wasted power
I heard a lot at the BGG this year from people who are vehemently anti-grid in all ways, they view it as a tool to keep power centralised, and under government control - they want to see people generating their own power, either as individuals or communities
There is no getting away from the fact that the most efficient way is to generate the power as close as possible to where it's being used - even running a cable a hundred yards from a small turbine can be very expensive - you need a thundering great thick and expensive cable to minimise losses - imagine the problem over hundred of miles!

[Muddypause]

It is true that electricity needs a 'circuit' before it can flow. What is not true to say is that the electricity goes round the circuit, whether we use it or not. The 'circuit' is our houses, and is only 'completed' when we turn something on.

Martin's right about inefficiencies in the system, though I think there is probably an economy in scale on this - ie, if we all had our own little powerstation, the overall losses would be much greater, especially at low voltage.

But it is quite wrong to imply that electricity is produced anyway, regardless of whether anyone is using it. From what I know (not that I've ever been in a powerstation) the powerstation operators have quite a complicated job anticipating need, and increasing output to suit it.

Thing is, a generator responds to the load on it. If you have a dynamo on your bicycle, then when all your lights are off, the dynamo is easy to turn, and you waste very little effort on it beyond a bit of added friction. If you turn a light on, the dynamo becomes harder to turn, and you need additional effort to turn it. Something as small as a bicycle light may hardly be noticeable, but the maths works out that the energy which the light uses (plus any losses due to inefficiency) is exactly the same as the additional energy you have to put into peddling. If you turn two lights on, the demand on the dynamo increases a bit more, the dynamo will be harder to turn, and again the extra effort you have to put into peddling exactly matches the extra energy required to illuminate the extra light.

On a much larger scale, the same will be true at a power station, and there must be ways to increase the effort applied to the generators (by burning more gas, for example) when everyone puts the kettle on during the advert break of Corronation Street.

I suppose it would be possible for a powerstation to have the gas burners turned up to maximum the whole time, and any that is not used to turn the generator would simply be lost directly into the atmosphere as heat (it's a big steam turbine, by the way - the gas is used to boil water into steam which then turns the turbine attached to the generator. The same principle applies to coal and nuclear powerstations, too). But I think the shareholders in the power company would have something to say about wasting their profits on unnecessarily burnt fuel.

BTW, the cable thickness issue is the reason that electricity is stepped up to tens or even hundreds of thousands of volts when it is sent cross-country. Big thick cables are needed at low voltages, otherwise the resistance within the cable is too great for the voltage to overcome. Step the pressure up by 10,000 times, and you can send power over great distances through much smaller cables with relatively little loss. Of course you then have to step it back down to domestic voltage at the other end, and there are losses at each stage, but overall, the efficiency is improved this way.

[Muddypause]

Just in case anyone has any more questions about electricity, this should explain most of it.

[chadspad]

Thanks for your replies!

[wulf]

Just in case anyone has any more questions about electricity, this should explain most of it.

Thank you, mate! That has made the world around me look much more interesting....

Wulf

[Milims]

PMSL Muddy!!! That was soo funny - I think I might send it to my lecturer - I'm sure he could use it to teach some of the drongos in my class a thing or two!! lol.