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The so-called "economic advantage" of CNG/LPG over other alternative fuels for transportation.
Tim Castleman
January, 2000
Southwest Gas Rates posted as of January 29, 2000:
Residential gas service
$7.00 monthly service fee
.79464 first 20 therms
.74920 per therm over 1st 20
On-site Compression
$18.50 monthly service fee
.43627 per therm
At 929 btu per cf of CNG, it will take 123 cf to = 1 gallon of gasoline
Using the average of 20 miles per gallon of gasoline, and the average of 1000 miles traveled per month, and the cost of gasoline at $1.25 per gallon, it will cost the consumer $62.50 per month or $750 per year to travel 12,000 miles using GASOLINE.
1000/20 = 50gals * $1.25 = $62.50 * 12mos = $750 per year using GASOLINE.
A therm is 100,000 btu and it is widely accepted that a gallon of gasoline contains 114,264 btu, therefore at an average of 20 miles per gallon it will require 57.13 therms to travel 1000 miles using CNG.
57.13 * .43627 = $24.92 + $18.50 monthly fee = $43.42 plus estimated tax of 3%, $1.30 = $44.72 * 12mos = $536.64 per year using CNG.
Monthly savings (62.50 - 44.72) = $17.78 monthly * 12 = $213.36 annual savings using ON-SITE compressed natural gas.
Now, figure in the added costs to HAVE on-site compression:
- Energy to run compressor ?
- Cost of compressor - $3,000 ?
- Cost to install compressor ?
- Cost to maintain the compressor ?
- Added cost of CNG system on a vehicle $3,000 to $5,000
The alternative will be to fuel your vehicle at a commercial retail outlet, with LPG currently selling for $1 to $1.99 per gallon, depending on where you MAY find it.
This becomes almost insidious when one considers the energy content of a gallon of propane vs. a gallon of gasoline, it simply requires more gallons of LPG or CNG to travel the same number of miles, and there is no dispute of that.
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