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A coal fired plant generates 600MW of electric power. The plant uses 4.8 x 10^6 kg of coal a day. The heat of combustion of coal is 3.3 x 10^7 J/kg. The steam that drives the turbines is at a temperature of 573K, and the exhaust water is 310K.

1.) What is the overall efficiency of the plant for generating electric power?

2.) How much thermal energy was wasted?

Ok..this is what I THINK I know....Qh= 3.3 x 10^7 J/kg

Th= 573K Tc= 310K

mass= 4.8 x 10^6 kg

Therefore Carnot effeciency is e=Th-Tc/Th

so Carnot eff. worked out is about 46%

AND I know that P=W/t = Fd/T = FV

Now...I get lost...I know I need to find the Work, to find my Qc...but they only gave me power in MW, and I need to find wasted thermal energy?? Any thoughts??

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# Homework Help: Problem with Q

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