As per the second law of thermodynamics , there is an increase in the entropy of an isolated system as the isolated system moves towards thermal equilibrium i.e the maximum entropy state of the system. In other words the entropy of a system always increases and it can never decrease. Thus. a system never yields as much energy as was put in. This increase in entropy happens because the more and more energy is transferred or changed from one form to the other, the more and more energy is wasted and released which then adds to the total entropy of the system.
