Question

Calculate the efficiency of a fossil-fuel power plant that consumes 382 metric tons of coal each hour to produce useful work at the rate of 755 MW. The heat of combustion of coal is 28.0 MJ/kg

Answer 1

Answer:

A metric ton is 1000kg, so that the heat generated by burning 380 metric tons during one hour is

(380000kg)(28MJ/kg)=10.6×10

6

MJ

.

The work done in one hour is

W=(750MJ/s)(3600s)=2.7×10

6

MJ

where we use the fact that a watt is a joule-per-second.

the efficiency is

ε=

10.6×10

6

MJ

2.7×10

6

MJ

=0.253=25%