Facts
and Assumptions

Fuel consumption @ 500 kW: 
35 gph (100% diesel) 
Peak hours per year: 
1500 
Gas ratio: 
70% 
Diesel cost: 
$0.95 per gallon 
Natural gas cost: 
$0.40 per therm (100 scf) 
Maintenance cost: 
$.020 per kWh (includes overhauls) 
Onpeak utility costs per kWh: 
$0.12 

BiFuel
Operations

Diesel use per hour: 
10.5 gallons (35 gph x .30) 
Diesel cost per hour: 
$9.98 (10.5 gph x $.095) 
Gas use per hour: 
34.3 therms* 
Gas cost per hour: 
34.3 therms x $0.40= $13.72 
Total fuel cost per hour: 
$23.70 
Total fuel cost per kWh: 
$0.047 ($23.70 ) 500kW) 
Estimated maintenance: 
$0.020 (includes overhaul costs) 
Total BiFuel cost per kWh: 
$0.067 

Savings

BiFuel savings per kWh: 
$0.053 
BiFuel savings per hour: 
$26.50 
BiFuel savings per 1500 hours: 
$39,750 (750,000 kWh) 

* 1 gallon
#2 diesel = 140 scf natural gas based on #2
diesel hhv of 140,000 btu/gallon and natural gas
hhv of 1,000 btu/scf; 35 gph diesel x .70= 24.5 x
140 scf = 3,430 scf = 34.3 therms 

In the case of
diesel prime power operations, the BiFuel System will
provide savings to the operator relative to the cost
differential between the two fuels. In this case,
operational costs other than fuel costs are not
considered as these costs will be equal to or less than
100% diesel operation during BiFuel operation: 
Facts
and Assumptions

Fuel consumption @ 500 kW: 
35 gph (100% diesel) 
Hours per year: 
8000 
Gas ratio: 
70% 
Diesel cost: 
$0.95 per gallon 
Natural gas cost: 
$0.40 per therm (100 scf) 

100%
Diesel Operation

Diesel use per hour: 
35 gph 
Diesel cost per hour: 
$33.25 
Diesel cost per year 
$266,000 

BiFuel
Operations

Diesel use per hour: 
10.5 gallons (35 gph x .30) 
Diesel cost per hour: 
$9.98 (10.5 gph x $.095) 
Gas use per hour: 
34.3 therms* 
Gas cost per hour: 
34.3 therms x $0.40= $13.72 
Total fuel cost per hour: 
$23.70 

Savings

BiFuel savings per hour 
$9.55 
BiFuel savings per 8000 hours 
$76,400 (4 million kWh) 
