Why is a heat engine never $100\%$ efficient?

(N/A) heat engine operates by taking heat $Q_H$ from a high-temperature reservoir,performing work $W$,and rejecting the remaining heat $Q_L$ to a low-temperature sink. According to the Second Law of Thermodynamics,specifically the Kelvin-Planck statement,it is impossible for any device operating in a cycle to receive heat from a single reservoir and convert it entirely into work. For an engine to be $100\%$ efficient,it would require $Q_L = 0$,which implies that all heat absorbed is converted into work. This would violate the Second Law of Thermodynamics,as some energy must always be dissipated to the surroundings to maintain the entropy of the universe. Therefore,the efficiency $\eta = 1 - (Q_L / Q_H)$ is always less than $1$.