Calculations

3b. Engine Energy Input Capacity / Fuel Use Calculator for Backup Electrical Generators and Other Emergency Engines

Generators. You need fuel consumption data for calculating air emissions for DEP permit applications. This calculator will estimate energy input capacity (MMBTU/hr) and consumption rate of various fuels, based on the electrical generator rating (kW) that you enter into the text block below. It is reasonably accurate (within 10%) for most types of reciprocating engine/generator combinations between 30 and 3000 kW, most types of fuels, and both firing methods (diesel or spark ignition). However, we recommend you use the manufacturer's specifications where available (see the manufacturers links below).


Generator Rating (kW):

Engines. This calculator also will estimate energy input capacity (MMBTU/hr) and consumption rate of various fuels, based on the engine horsepower (brake) rating (bhp) that you enter into the text block below. It is reasonably accurate (within 7%) for most types of reciprocating engines between 50 and 5000 bhp, most types of fuels, and both firing methods (diesel or spark ignition). We recommend you use the manufacturer's specifications where available, as noted above.


Engine Horsepower (hp):

The major manufacturers of engines for emergency electrical or mechanical power are:

One important thing to remember when calculating energy balance around an engine or engine/generator set is that the electrical or mechanical output energy of the device is not equivalent to the fuel energy input. The devices are typically only 30% to 40% efficicient. See the energy balance example below.