# Comparing the Energy of Natural Gas and Gasoline

By Erine Parker, CFPAI, CFPSD, CFPS, CFPMM, CFPMT, CFPMIP, CFPMMH, CFPMIH, CFPE

When you see a vehicle driven on natural gas, do you ever wonder how far it can go on a tank of fuel? How many times larger would a container of natural gas at 3,000 psi (207 bar) have to be to hold the same amount of energy as in a gallon of gasoline? Use 1,000 BTUs for a cubic foot of natural gas at atmospheric pressure and 125,000 BTUs for a gallon of gasoline.

##### See the Solution

Natural gas

P1V1 = P₂V₂

14.7 x 1 = 3014.7 x V₂

V₂ = .004876 (volume of 1 cubic foot of gas when compressed to 3,000 psi [207 bar])

1 / .004876 = 205.08163 SCF are compressed into 1 cubic foot container

205.08163 x 1000 BTUs/SCF = 205,081.63 BTUs/SFC

Gasoline

1 cubic foot = 7.48 gallons

7.48 x 125,000 = 935,000 BTUs

935,000/205,082 = 4.56 times as much energy.

Notes

1. You would have to pressurize a container to 13,747 psi (948 bar) to get the same energy
as gasoline.

2. Gasoline will vary in BTUs depending on the season.  The vapor pressure is lower in cold weather for easier starting, but you will lose some miles per gallon.