There are a lot of anti-EV talking points knocking around, and it’s hard to address them all.
I just want to focus on this specific question which is interesting:
- When my air conditioner turns on, does someone at the power plant have to throw another lump of coal in the boiler?
The answer is (kind of) yes. Here’s how it works (imagine for simplicity there is only one generator on the system):
Start with the system in balance - the same amount of power being generated as is being used (including losses).
You turn on an appliance, increasing the load on the system. The immediate effect is that the system frequency and voltage will drop.
The governor on the steam turbine generator will try to maintain the speed at 3600 rpm by opening the inlet valves and admitting more steam to the turbine. At this point, we don’t have to add more fuel to the boiler yet because there is a lot of energy stored in the form of steam in the boiler drum, and it’s possible to draw down some of this.
As we draw off more steam, the drum level controller will say “Increase the firing rate to maintain a safe level in the drum”. More pulverised coal and air will then be blown through the burners to generate the required amount of steam.
There are lots of other boiler configurations and ways that a system can provide frequency response but ultimately if you use more electricity, more electricity will need to be generated.
Now, in a system with more than one generating unit, it is not the local power station or the average of all the units that is relevant; it is the marginal unit on the system at any given moment. When you plug in your EV, where is that additional kWh generated? It could be for example that your baseload is coal and nuclear but the marginal unit is coming from a gas-fired power station providing operating reserve.
Where I live, the marginal unit at night is often wind power. How can that be - either the wind is blowing or it’s not, right? Well, the explanation is that wind turbine generators are often curtailed off so as not to exceed certain operational constraints. An increase in demand is met in the first instance by increasing wind generation, the marginal cost of which is zero.