How is electric energy stored and distributed by electric companies?
In: Technology
There is basically 0 storage for grid electricity. With that being said basically all electrical systems generate power by spinning a big wheel, this wheel has to spin at a particular speed and when ever you plug something in you slow the wheel down very slightly, so there is some storage there. For everything to run correctly that wheel must stay at a pretty consistent speed. (Less than. 1% change)
They don’t really store and instead try to respond to demand. They aim to keep the frequency at 60hz. If it starts to drop below this then that means there is more demand in the system and they need to generate more power. If it starts to go above that means they’re generating too much and need to cut back on how much they send out.
Most of the more conventional types of power plants can adjust their power output to the demand pretty well, so storage is not really necessary in a lot of places.
In some instances, however, there is a need for storing the surplus in production during times of low demand to boost the available grid power on “rush hour”. Also, the increase in the use of renewable sources will lead to a more widespread use of storage.
There are hydroelectric plants that basically can reverse operation and pump back water into the basin, to let it flow back later when more energy is needed. There are battery parks. There is compressed air storage, where energy is used to compress air and, later, the compressed air is used to drive turbines. You can use electrical energy to obtain hydrogen to be used later in fuel cells (not sure if it’s already commercially used).
From a power plant, an “electric highway” at hundreds of thousands of volts goes out to a transformer station, from there multiple power supply lines at a slightly lover voltage go out to other stations, and again, until they end up in your neighborhood and at your home. Some of the stations are connected to stations of “other nets”, so that electricity can go where it’s needed.
Electric energy storage is not a thing, at grid scale. Pumped hydro is probably the closest thing, but it’s a tiny fraction of grid scale. Even giant Tesla battery stations are only for small scale fluctuations.
The electric grid is distributed by a grid of wires, at very high voltages. Transformers make the power you actually use, but it’s all made and used in real time. Transformers are tuned to be slightly less efficient as demand drops, turning more of the input power into heat. But mostly it’s automated computer control and many diligent workers on the job 24 hours a day that maintain the balance. They call power plants and tell them to make more or less power so that the power needed exactly matches the power produced. If they can’t do that, the only other choice is to shed load, and that causes a blackout. In the worst case, they drop the whole grid, as the ERCOT operators did in Texas last winter, and all the power is off on the whole grid until the balance can be reestablished.
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