eli5 How electricity production and distribution works?


Let’s say in an isolated area there are fifty homes and a power station capable of producing 1500kW per day. Each home consumes 30kW per day on average.

Now explain the following two situations to me like I’m 22.

1. A new home has joined the party. Will the power station be able to supply power to the new house or does it need to be extended its capability? Or an existing home decided to purchase a refrigerator, graphic card or whatever and increased their demand. How will the increased demand be fulfilled?
2. Twenty homes went on a vacation. So, 900kW per day is enough to full fill thirty homes’ needs. But the power station will continue to produce 15000kw as usual. Where will the remaining 600kw go?

I’ve given an analogy of fifty homes with 1500kW but compare the situation with a country. Not every house consumes the same amount of electricity every day. How do the government produce and distribute electricity in an efficient manner? Does electricity get wasted? Where does the extra electricity go? It is obvious that there is no big battery to store em! 🤷🏻‍♂️

In: 2

The powerplants make more high voltage energy (potential) than is needed. The distribution lines are all very high voltage, and there are transformers on the line that step the high voltage down to low voltage for use at the houses. What is needed gets used, and what isn’t needed never really went anywhere because it never really existed, its all just potential

AC grids have a frequency (normally 50 or 60 Hz), which is the speed at which all the rotational generators are spinning on the grid (solar, wind, etc use digital inverters for this). Each generator works to maintain that frequency, when it’s spinning at that frequency it’ll produce it’s rated output voltage (which will be transformed up/down as needed).

So, you push down your toaster. A new path is opened up for current to flow, so say 10A @ 240v flows through it. At the generator, say it’s generating at 2.4kV that’s 1A of additional load.

That 1A will create a magnetic field in the generator that will directly oppose the movement of the spinning bit. The spinning bit will slow down slightly as a result.

In response to the slower spinning, the generators regulator system will increase the power to the generator – e.g. it will release more water from the dam, steam from the boiler, etc.

If you can’t do this fast enough (e.g. the boiler can’t heat up quickly enough, all the dams are maxed out) then you have a problem. The grid might ask big industrial users to reduce their load (e.g. if you have a giant fridge, you can turn it off for a bit without it loosing temperature).

If the frequency drops below the target it’s essentially a grid emergency. At this point an emergency load management system will do something drastic like cutting off power to a suburb (automatic load shedding).

So first off, a couple of misconceptions to dispel. The first is that the government doesn’t dictate energy production, it’s private businesses (in the US at least). The second is that there is no place where there is one power plant, we’re connected by multiple very large grids spanning multiple states (except Texas) with many power plants. The last is that power plants don’t generate a constant amount of power, they have a max they can deliver and can ramp up or down depending on demand, and if demand exceeds the capabilities then the distributer buys power from other plants on the same grid to make up the gap. If there isn’t enough capacity we experience “rolling black outs” where the distributors switch off power to different areas to keep the grid on at other places, but not all at once and forever – just where it is most needed.

The way plants generate power depends on the source. Gas, coal and nuclear are really easy to ramp up and down – burn more fuel or move control rods to spin turbines more. For renewables we do actually need energy storage because peak demand rarely overlaps peak production, but the “batteries” usually use water pumped uphill – to generate on demand they let it flow back downhill to spin hydro electric generators.

The way that more demand manifests in power plans is actually pretty simple. When the demand outpaces production the turbines slow down and the generated frequency dips. To keep in sync with the grid they need to spin up more power. Power plant operators are in constant communication with distributors controlling the grid to make sure production meets demand, 24/7.

Each group of 8-10 houses is a branch in the electric tree. Your branch has a transformer that connects you with a feed line. This transformer also isolates your branch, so that if there is a short only one branch goes out.

Your transformer pulls power from the feed to satisfy the demand of your branch. If you are making more solar than you are using, if flows out through your meter into your neighbor’s house. Unless your whole branch makes more electricity than it uses, it’s unlikely that you have a two-way branch transformer. Mostly your excess solar is running the neighbor’s air conditioner, or something like that.

This benefits everybody because if there was more demand on the feed, then in your substation the regulator (a special kind of transformer that makes sure that the feed doesn’t brown-out) might run out of regulation and then everybody has a problem. By reducing the net load in your feed, less power is made in some distant power plant. This also means less is lost in transmission and distribution.

>Not every house consumes the same amount of electricity every day. How do the government produce and distribute electricity in an efficient manner? Does electricity get wasted? Where does the extra electricity go? It is obvious that there is no big battery to store em

Grid operators have personnel who forecasts electricity demand of all the consumers as a whole. This makes sure that the electricity generated by the power companies is close enough to the demand. The grid operator plans how much electricity to be requested from the power plant, which in turn gets transmitted to the distribution companies towards the consumer.

Since the power plant charges the same amount for the generated power requested regardless of the demand, it is up to the grid operator to ensure that the generated electricity would be used with the least wastage as possible.