Assume that we use a type of coal with an energy content of 25kJ/g but can only release 80% of it as heat at a temperature of 600 C. If the cooling water is taken from river at a temperature of 20 C, and the efficiency of the power plant is 70% of the Carnot efficiency (Carnot efficiency is for a reversible process, a practical process is irreversible and has an efficiency lower than Carnot efficiency).

a. (5 pts) what is the Carnot efficiency?

b. (2 pts) what is the actual efficiency energy conversion efficiency?

c. (8 pts) How much coal we need per day do we need to supply to the plant to generate 1 MW (megawatt) of electricity.