[mapleoin]

Don't know where you are, but green energy providers, at least in the UK, either have a relationship with the producer where they buy directly from them, rather than from the grid, or buy specific types of energy from the grid. It IS possible to buy energy from a specific source and energy is traded constantly during the day on the energy exchange.

Bulb for example have more information about where their energy comes from: https://bulb.co.uk/energy/