Electronics > Power/Renewable Energy/EV's

Where does the power go ?

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PinheadBE:
Hi there,

Here's a somewhat dumb question, but it haunts me for a couple of nights now while it probably shouldn't....

All our means of producing electrical power are running 24/7.
But, obviously, at some times, all of the power which is produced is not used.  For example, during the night.

So, if I simplify the whole grid to one producer (say a 1 GW nuclear power plant) and a bunch of consumers which at a certain time consumes only 500 MW, where do the other 500 MW go ?  |O

The decay of uranium in the reactor produces the same amount of heat which is transformed in the same amount of steam which in turn makes an alternator turn at the same speed, but the counter-eletromagnetic force exerced on it may be lowered (due to the lower consumption on the grid).
So, where does the remaining power go ?

(The same reasoning could be applied with other energy sources such as a wind farm or a coal power plant; the nuclear reactor is only used as an example)

Sorry if this is, indeed, dumb, but pls, help me to regain some restorative sleep....  :=\

Thanks, and good night  :-+

stmdude:

--- Quote from: PinheadBE on August 19, 2017, 08:24:56 pm ---The decay of uranium in the reactor produces the same amount of heat
--- End quote ---

The decay is actively controlled by "control-rods", which can increase or decrease the output of the reactor.

Now, the demands of the grid can change faster than the control-rods can change the power-output of the reactor, which is (one of the) reason that the voltage in your outlet actually varies.
In my home, I've seen 210V -> 240V RMS.

Someone:
Wikipedia has a good introduction to this:
https://en.wikipedia.org/wiki/Load_following_power_plant
There aren't many references to learn more details, so you'd need to hunt down some industry information to learn more about how each specific type of plant handles load changes. But for the very fast changes its often just pouring extra energy into the condensers, simply dumping that energy as heat into the atmosphere.

IanB:

--- Quote from: PinheadBE on August 19, 2017, 08:24:56 pm ---All our means of producing electrical power are running 24/7.

But, obviously, at some times, all of the power which is produced is not used.  For example, during the night.

So, if I simplify the whole grid to one producer (say a 1 GW nuclear power plant) and a bunch of consumers which at a certain time consumes only 500 MW, where do the other 500 MW go ?
--- End quote ---

Broadly speaking, the amount of power generated is continuously adjusted to match the demand. The grid managers use models and historical data to predict how the demand will change at various times of the day and so they can plan ahead for how to adjust generator output.

If there is excess power generation at any instant it can also be stored for later use, for example in hydroelectric facilities by pumping water up into a higher reservoir.

Ian.M:
Also https://en.wikipedia.org/wiki/Demand_response
e.g an industrial consumer with a large electric smelter, furnace or kiln can get a preferential tariff for scheduling their peak power usage to suit the grid management authority, and can also load-shed on electronic request for short periods up to a few minutes without significantly affecting the process due to the large thermal inertia.

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