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"Rule of Thumb" Energy Equivalence Between Diesel Fuel and LNG
1 Gallon of Diesel Fuel = 1.7 Gallons of LNG
1 Pound of Diesel Fuel = 0.87 Pounds of LNG
The actual density comparisons in normal operations can vary.
LNG's density will decrease (the liquid will swell) as its storage temperature increases.
Computing the mileage equivalent to diesel uses the fuel's heating value but also depends
on the thermal efficiencies of the different engines.

Comparison Factors for Various Vehicular Fuels

Heating Values of Transportation Fuels (BTU's)

Source: www.afdc.doe.gov
Per Gallon Per Pound
HHV 1 LHV 2 HHV 1 LHV 2
Gasoline 124,800 115,000 19,600 18,500
Diesel Fuel 138,700 128,400 19,600 18,500
LNG 83,840 75,670 23,600 21,300
Methanol 64,250 56,800 9,750 8,570
Ethanol 84,100 76,000 12,800 11,500
Propane 91,300 84,500 21,600 19,800
Notes:
1. The HHV (Higher Heating Values) measure total energy of combustion and energy purchase quantities.
2. The LHV (Lower Heating Value) reflects the energy recovery in an engine
when the water vapor is not condensed back to a liquid phase.
Volume Comparison of CNG to LNG
Source: www.christypark.com/Compressability.htm
Standard Cubic Feet of Gas Compressed into One Cubic Foot
at the normal pressures and a temperatures for the fuels.
CNG-3000 PSI 259.7 scf/cf
CNG-3600 PSI 296.3 scf/cf
LNG 618 scf/cf (see table below)
The thickness of the pressure vessels effects the effective storage space.
Common LNG Conversion Factors
    GAS   LIQUID         ENERGY
    Cubic       Cubic Cubic Metric MMBtu
    Feet Mcf Pounds Gallons Feet Meters Tons (HHV)
GAS 1 Mcf = 1000 1 42.51 12.11 1.619 0.04583 0.01930 1.016
               
LIQUID 1 Gallon = 82.6 0.0826 3.51 1 0.134 0.003800 0.001590 0.08384
  1 Cubic Foot = 618 0.618 26.29 7.481 1 0.02831 0.01192 0.6276
  1 Cubic Meter = 21,820 21.82 928.6 264.2 35.32 1 0.4211 22.17
  1 Metric Ton = 51,820 51.82 2204.6 628.9 83.86 2.375 1 52.63
               
ENERGY 1 MMBtu = 984.7 0.9847 41.86 11.93 1.593 0.04511 0.01900 1
Note: The figures are computed for a LNG having a composition of 99.8% Methane and 0.2% Ethane.
The temperature is -160o C. The specific gravity is 0.422

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