Environmental math problems! please help me?

Problem: In one month's time, a coal fired electrical generating plant burns 30,000 tons of coal and generates 20,000 mwh (megawatt hours) of electricity. A pound of coal produces 5000 BTUs and one kwh (kilowatt hour) is equivalent to 3400 BTUs.



a) Calculate the efficiency of the power plant.



b) The Environmental Protection Agency (EPA) standard for power plants, such as this one, is that no more than 2.2 pounds of sulfur be emitted per million BTUs released by burning coal. Assuming coal contains 1% sulfur by weight, determine whether the power plant meets the EPS standard.Environmental math problems! please help me?a)

efficiency = power output / power input



1 (short) ton = 2000 pounds

1 (long) ton = 2240 pounds

1 (metric) ton = 2204.62248 pounds

Which measurement do you use? I'll assume short tons.

30000 tons = 30000*2000 = 60000000 pounds

60000000 * 5000 = 300000000000 BTUs burnt



20000Mwh = 20000000kwh

20000000 * 3400 = 68000000000 BTUs output



efficiency = power output / power input

efficiency = 68000000000 / 300000000000 = 0.22666... = 22.6666...%



b)

60000000 pounds of coal are burnt

so 1% of 60000000 = 600000 pounds of sulphur



What your question doesn't state is whether that is 2.2 pounds per million BTUs burnt, or per million BTUs output.



68000000000 BTUs = 68000 million BTUs

300000000000 BTUs = 300000 million BTUs



600000 / 68000 = 8.82... pounds of sulphur per million BTUs output for this plant

600000 / 300000 = 2 pounds of sulphur per million BTUs burnt for this plant



Presumably they mean 2.2 pounds by burnt output, so yes, they do meet the standard.