Generator
From Frostpunk 2 Wiki and Guides
The Generator in Frostpunk 2 is more abstract than the first game. It is still roughly in the middle of the playable Nation, situated within the Central District, but its management is now automatic.
The Generator still generates 
Heat, and if Heat is not fulfilled, the generator will no longer protect against Cold. In order to produce heat, the generator can consume 
Coal or oil as resources, and will automatically scale its input accordingly and automatically.
The Steward can choose to overdrive the generator to improve the fuel to heat ratio. If the overdrive gets too high, a dangerous accident may occur that damages the population.
According to a loading screen tip, all other districts have Power Hubs.