476Views11Replies

Author Options:

Power consumption question? Answered

Sorry if this is stupid, but I have always been curious about this. Since mains generators run constantly (or I assume they do...) does it matter whether or not you leave you electrical appliances on? Like people who say turn the lights off when you leave a room so that you save power. But the generators still go if your lights are on or not, so you're not really wasting energy, are you?

11 Replies

user
verence (author)2011-04-15

If you have your own power supply (wind, water, solar etc.) and you don't store unused power in batteries, you are right. What you don't use at the moment is lost.

For a nation wide (or even international as in Europe) power grid, the situation is much different.

1. The generators do NOT run constantly. Whole power plants get switched on and off during the day to adapt the power generation to the demand.
2. Unused available electricity is stored in different ways and can be recalled when needed without burning up more oil, coal etc.
3. Even a running generator does not generate an amount X of power all the time. In fact, a generator will only produce as much electricity as is used. (Where should the unused current go, anyway?)

So, yes, it does matter, if you switch unused stuff off or not.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)verence2011-04-16

2. Unused available electricity is stored in different ways and can be recalled when needed without burning up more oil, coal etc.


Not so much really, I can think of a few pumped storage systems, but that's about it. There's a fuel cell trial or two as well.

We really NEED storage systems.

Steve

Select as Best AnswerUndo Best Answer

user
ARJOON (author)steveastrouk2011-04-16

2. Unused available electricity is stored in different ways and can be recalled when needed without burning up more oil, coal etc.

they were stored in batteries long ago. now they run proportionally to power demand

Select as Best AnswerUndo Best Answer

user
iceng (author)ARJOON2011-04-16

Also, lets not forget storage batteries are only 50% efficient at best.

It takes twice ( 2X ) as much energy to charge a battery as you get ( 1X ) out of it later.

Confusing ?

How about, you can only get back 1/2 of the energy you store in a battery.

Even vacuum flywheel storage can do better.

A

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)iceng2011-04-17

Yes, but with vacuum flywheel storage, you can't turn corners.....

Select as Best AnswerUndo Best Answer

user
iceng (author)steveastrouk2011-04-17

Mount the wheel in horizontally.
I recall your country had some flywheel busses and the passengers were unnerved that the bus would rev the engine when approaching a stop.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)ARJOON2011-04-16

Not at the power levels we're talking about in grid systems they don't, and never have. This is one of the biggest pumped storage systems in the world

It can only supply its rated, 1.3GW output for five hours. Though there are bigger ones, Dinorwig is the world's fastest, and can go from spinning in air, on standby, to full 1.3 GW, in TWELVE SECONDS.

I've been there, when its been turned on like that. Its something I won't ever forget.

Steve

Select as Best AnswerUndo Best Answer

user
verence (author)steveastrouk2011-04-16

True, we need more storage system, especially, when whole countries want to go 'green' and get all their electricity from wind, sun waves etc. Too bad that the sun doesn't shine at night, when we need the most light ;-)

It's true, the wont fire up a nuclear power plan just because you leave a light on or two, but if a few thousand people leave their appliances run unused, that might make a difference.

Anyway, I don't know where 7654321 lives, but I have to pay for electricity. So, it will not only be wasting energy , but it's wasting your (or your parents) money.

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)verence2011-04-16

Nuclear stations are, as we know, buggers to turn down....So they were supposed to provide the baseload, always running flat out, and, at night, pump up Dinorwig to handle peak loads in the day time.

Select as Best AnswerUndo Best Answer

user
iceng (author)2011-04-15

If a single gasoline to electric generator is running while fully loaded it will use more gasoline then when it is running without any electrical load.

Confusing ?

Two identical generators A & B with full gas tanks.
Generator A will power 1 old style 60W lamp for a 60 Watt total load.
Generator B will power 5 old style 100W lamps for a 500 Watt total load.
Start both generators and walk away..

Which generator will run the longest ?

A

Select as Best AnswerUndo Best Answer

user
lemonie (author)2011-04-15


If they're on then they are using energy.
If they are not being used for a useful purpose then the energy they use is wasted.

L

Select as Best AnswerUndo Best Answer