Question
A large electrical power station generates 1000 MW of electricity with an efficiency of 35.0%. (a) Calculate the heat transfer to the power station, $Q_h$ , in one day. (b) How much heat transfer $Q_c$ occurs to the environment in one day? (c) If the heat transfer in the cooling towers is from $35.0^\circ\textrm{C}$ water into the local air mass, which increases in temperature from $18.0^\circ\textrm{C}$ to $20.0^\circ\textrm{C}$, what is the total increase in entropy due to this heat transfer? (d) How much energy becomes unavailable to do work because of this increase in entropy, assuming an $18.0^\circ\textrm{C}$ lowest temperature? (Part of $Q_c$ could be utilized to operate heat engines or for simply heating the surroundings, but it rarely is.)
1. $2.47 \times 10^{14} \textrm{ J}$
2. $1.60 \times 10^{14} \textrm{ J}$
3. $2.85 \times 10^{10} \textrm{ J/K}$
4. $8.30 \times 10^{12} \textrm{ J}$
Solution Video

# OpenStax College Physics Solution, Chapter 15, Problem 55 (Problems & Exercises) (5:13)   