Typical large turbine systems in power plants go from 1 HP turbine (physically small) to one or more LP turbines as steam expands. Many also have intermediate stages that reheat steam or condenser stages that drive more efficiency and output. (sample schematic from a large nuclear turbine in attached image). Presently CoI goes from 2 HP to 1 LP which is different from the real world.
Power turbine tech tree could be expanded to have progression from LP boilers/turbines early game to then advance to HP boilers/turbines in the mid game. Could also expand to develop into advanced turbines with condensers & heat exchangers when moving into nuclear as the steam source in late game.
