Which emits more SOx per unit amount of electricity produced: a coal-fired plant with a 90% efficient SO2 scrubber or an oil-fired plant with no scrubber? Assume the coal has a heat content of 13,000 Btu/lb and contains 3.5% sulfur, and that the oil has a heat content of 6.0(10)^6 Btu/barrel (42 gallons) and contains 0.9% sulfur. Assume the oil has a specific gravity of 0.92.