Savings derived from the use of GTI’s Bi-Fuel System are the result of either:

1) The differential between the cost per kWh charged by the utility and the cost per kWh to produce power with a Bi-Fuel generator or,

2) In the case of existing diesel prime power operations, the differential in the cost of diesel fuel and natural gas.

Utility Supplied Power:

Due to the premium prices which utility companies usually charge for on-peak electricity, it is often most viable to operate the Bi-Fuel generator as a peak-shaver, whereby power is produced on-site only during those hours when electricity is at it’s highest price from the utility. In order to determine the cost of producing power with a Bi-Fuel generator, several factors must be considered including:

Cost of natural gas
Cost of diesel fuel
Cost of maintenance program for generator
Cost of future engine overhauls

A typical example of Bi-Fuel savings for a 500 kW peak-shaving project would look as follows:
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)
On-peak utility costs per kWh	$0.12

BI-FUEL 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 Bi-Fuel cost per kWh	$0.067

SAVINGS
Bi-Fuel savings per kWh	$0.053
Bi-Fuel savings per hour	$26.50
Bi-Fuel 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 Bi-Fuel 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 Bi-Fuel 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

Bi-FUEL 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
Bi-Fuel savings per hour	$9.55
Bi-Fuel savings per 8000 hours	$76,400 (4 million 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.