Estimate annual revenues from sulfur sales for a U.S. Bureau of Mines citrate FGD process that is removing 90% of the SO2 from a 40%?efficient 400?MW power plant. The coal is 5% sulfur and has a heating value of 20,000 kJ/kg. Sulfur can be sold for $150/metric ton, and H2S can be purchased from a nearby refinery for $160/metric ton. Also, calculate the net reduction of operating costs for the system (in mills/kWh) due to the net sulfur revenues.