A Power Plant--Efficiency materials can be studied in their steady-state condition energy systems also can be in steady state no change occurring over time. if some of the energy out is useful and the rest is wasted rate of energy IN =rate of energy USED +rate of energy WASTED E=energy USED ×100 energy IN UNEPrate of energy IN =rate of energy USED +rate of energy WASTED if some of the energy out is useful and the rest is wasted A Power Plant- -Efficiency materials can be studied in their steady-state condition no change occurring over time energy systems also can be in steady state