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As a gas, most people have difficulty perceiving how much fuel they are buying as they have been accustomed to buying by the litre or gallon. To make it easier for people to understand, the gas industry has devised an gasoline volume equivalent.
Natural Resources Canada (http://oee.nrcan.gc.ca/) is the location where the following information was found:
Pacific Gas and Electric Company (http://www.pge.com/) is where the following information was found: Fuel Costs - An Energy Value Comparison As the adage goes, it is appropriate to compare apples to apples when evaluating fuel costs. As we have seen, liquid fuels are measured and sold by volume (gallons), not energy content. Natural gas is measured by volume or weight (standard cubic feet or pounds), but is sold by energy content (therms). To begin making an economic comparison of fuels, it is easiest to compare the prices based on energy content - after all, energy is what you are purchasing, not volume or weight. This method of comparing fuels yields a gasoline or diesel gallon equivalent price for CNG, sometimes abbreviated as gge or dge. Let's look at a gasoline/CNG comparison, using retail prices: Gasoline in California is now standardized at 110,400 Btu/gallon, regardless of refiner or location. In March 1998, the retail price of gasoline averaged $1.07 per gallon in California, according to the California Energy Commission. PG&E sells CNG at its fueling stations for $0.78104 per Therm (plus a monthly customer charge of $13.42 per account - no vehicle limit). A therm of CNG has an energy value of 100,000 BTUs. For comparison, how much does CNG cost for the equivalent amount of gasoline? The mathematical conversion is:
The cost of CNG for the equivalent amount of gasoline is $0.86 per gallon. Therefore, based on our assumptions, compressed natural gas is retailing at $0.21 less than gasoline, on an gallon equivalent basis. If your assumptions stay the same regarding the energy content of the fuels you are comparing, you can simply use a conversion factor to compare price. Using the assumptions above: Cost per Therm CNG x 1.10 = cost for gasoline gallon equivalent. For diesel fuel, assuming a diesel energy value of 125,000 BTU per gallon, the conversion factor in the equation would be 1.25. Standard Conversion Factor Adopted Nationwide. Because CNG fueling dispensers measure the weight of the natural gas, which is then converted to an energy value based on a measurement of the composition of the gas, it is not possible to display an energy value-based liquid fuel gallon equivalent on the dispenser. However, dispensers often show a gallon gasoline equivalent display, using the national conversion factor. The national standard conversion factor of 1.276 is an approximation based on the average energy value of a gallon of gasoline and the average energy value of 5.66 pounds of natural gas. Using the nationally accepted conversion factor, PG&E retails compressed natural gas for $0.996 per gasoline gallon equivalent. Note that because gasoline in California has a lower energy value than the national average, and natural gas in California has a higher energy value than the national average, the standard conversion factor overstates the cost of a gallon gasoline equivalent by about 16 percent. In California, 1 gallon gasoline = 5.66 lb NG / 1.16 = 4.88 lb NG according to PG&E.
Relating Gasoline and Natural Gas1 MBTU = 106 BTU (1 million BTU) When you convert from CF of natural gas (or of any fuel) to BTUs, you can use either the lower heating value (LHV) or the higher heating value (HHV). The higher heating value (HHV) includes the energy contained in the latent heat of evaporation of the moisture contained in the burned fuel (actually bringing all products of combustion to 25°C/77°F). Since most processes do not recover this heat, the LHV of the fuel is often used (actually bringing all products of combustion to 150°C/302°F). For natural gas, the ratio between the two is about 1.1. On the average, because the heating value of natural gas varies from gas well to gas well, the energy density of natural gas will vary from 1000 BTU/CF to 1050 BTU/CF HHV or 900-950 BTU/CF LHV. Because it is such a nice round number, 1000 BTU/CF HHV is often used in energy calculations. Therefore: 1 MCF contains about 1000 MBTU HHV. Gasoline properties from the US DOE HHV (liquid fuel-liquid water) Btu/lb 18,800–20,400 Using HHVs, 1 gallon of gasoline contains 124,800 BTU This is the equivalent of approximately 124.8 CF of natural gas. 1 gallon = 124,800 BTU Natural Gas Properties from the US DOE HHV (liquid fuel-liquid water) Btu/lb 23,600 Using HHV, 1 lb of natural gas contains 23,600 BTU. If gasoline contains 124,800 BTU/gal: 1 lb NG = 23,600 BTU / 124,800 BTU/gal gasoline To check, from information provided by Natural Resources Canada: 1 litre of gasoline = 0.65 kg NG = 0.93 m3 NG Therefore, if 1 gallon = 3.785 litre: 124.3 CF/gal and 5.424 lb/gal are close to those provided by US DOE
At the pumps
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