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Navigation: Glossary

Generator Fuel Curve Intercept Coefficient

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Type:	Input Variable
Units:	fuel units/hr/kWrated
Symbol:	F0

The generator fuel curve intercept coefficient is the no-load fuel consumption of the generator divided by its rated capacity. If you plot a straight line of fuel consumption versus the power output of the generator, the y-intercept of that line divided by the generator size is equal to the fuel curve intercept coefficient.

For example, if a 50-kW generator consumes 8.48 L/hr at 25 kW output, and 15.3 L/hr at rated output, the slope of the fuel curve is (15.3-8.48)/(50-25) = 0.273 L/hr/kWoutput. So the y-intercept is 8.48 - (0.273*25) = 1.655 L/hr. Dividing by 50 kW (the size of the generator) gives the fuel curve intercept coefficient of 0.033 L/hr/kWrated. This fuel curve is shown below.

genCurveImage

The Fuel Curve Calculator helps calculate the fuel curve slope and intercept coefficient.

If the generator is running in a particular time step, HOMER calculates the fuel consumption rate for that time step using the following equation:

equations_F

where:
	F	= fuel consumption rate [L/hr]
	F0	= generator fuel curve intercept coefficient [L/hr/kWrated]
	F1	= generator fuel curve slope [L/hr/kWoutput]
	Ygen	= rated capacity of the generator [kW]
	Pgen	= output of the generator in this time step [kW]

If the generator is not running in a particular time step, the fuel consumption for that time step is zero.