A continuous electric current of 2,000 amps is to be transmitted from a generator to a transformer located 150 meters away. A copper conductor can be installed for $20/kg, will have an estimated life of 25 years, and can be salvaged for $5/kg. Power loss from the conductor will be inversely proportional to the crosssectional area of the conductor and may be expressed as 0.01/A kilowatt, where A is in square meters. The cost of energy is $0.1 per kilowatt-hour, the interest rate is 10%, and the density of copper is 8894 kg/m3.

a) Calculate the optimum cross-sectional area of the conductor.

b) Calculate the annual equivalent total cost for the value you obtained in part (a).

c) Graph the capital cost, energy-loss cost, and the total cost as a function of the cross-sectional area A, and discuss the impact of increasing energy cost on the optimum obtained in part (a).