How do you purchase and receive energy from a supplier on a particular grid without interfering with other suppliers?

Question

I know that I could choose to buy electricity from a specific provider. If I wanted clean renewable power I could choose a power company that operates hydro plants and they’d take my money every month.

But there are other users on the grid and power plants from different companies feed the grid as well so everyone actually draws power from power plants that aren’t operated by their suppliers, except their respective suppliers get paid for the energy used. This wouldn’t be a big deal if a power company could supply all of its customers. If my hydroelectric supplier has a capacity of 10000 MW and the company’s customers suddenly turned on all their devices, leading to a demand that would exceed capacity, some of the demand would be drawn from other suppliers due to the fact that they’re on the same grid. I don’t understand how other suppliers prevent this. How do they make sure Company A’s customers do not take more power from the grid than Company A can provide so Company B doesn’t inadvertently supply Company A’s customers without getting paid?

In: Economics

Answer 1

Oh, you can’t.
I mean, the energy you are using is energy. The grid can’t differentiate your green electricity from a coal electricity.

Try to imagine it like this, there are 2 water sources that go in the same river.
When you take water from the river you can’t say for sure whose water you are taking.
BUT if you pay the water to supplier A, then supplier A will be required to augment his production capabilities, to meet all the demands that require “Supplier A” water.

The same applies to green electricity. If supplier G (for green) sells 1 MWh of certified green electricity it means that he has enough renewable production to ensure 1MWh of electrical production.
If many users decide that they want to buy their electricity from Supplier G, he will now sell 2MWh, so he will have to increase his certified electrical production accordingly.
This means he will have to buy more PV plants or more wind turbines until he can certify that he is producing more energy that the one needed by his customers.

Edit: since electricity can’t be easily stored. Right now the grid does this calculation year round.