The incremental heat rate “the heat rate” is the ratio of input

fuel to the corresponding output power

From the incremental heat rate curve, the incremental fuel

rate is deduced With F is the input fuel and P is the output

power The reciprocal of the incremental fuel rate is known as

the incremental efficiency

To operate at the maximum fuel efficiency, the point of the

minimum heat rate has to be defined

Multiplying the incremental fuel rate by the fuel cost, the

incremental fuel cost is obtained in ($/MWh)

Example

The input fuel in (Btu/h) for a power plant with minimum and maximum power of 10 and 100 MW

respectively is given by:

F=(40+4*P + 0.012*P2)*106

where P is the generated power in (MW). Plot the input

output curve of the plant. Calculate the heat rate and plot its

curve against the output power.

Assuming a fuel cost of 0.12*10-6 $/Btu, calculate

the incremental fuel cost in $/MWh and plot its

curve against the output power.

The fuel is given as:

F=(40+4*P + 0.012*P2)*106

Also, the heat rate can be calculated from equation

Heat rate = The fuel cost as a function of the output power is:

C=0.12*10-6 *F= 4.8 + 0.48*P + 0.0014*P2 ($/h)

The incremental fuel cost is:

Ifr = 0.48 + 0.0028*P ($/MWh)