GGE (Gallon Gasoline Equivalent)

GGE — Gallon Gasoline Equivalent — is an energy-content normalisation unit primarily used in the United States to express the price or volume of an alternative vehicle fuel in terms of the energy contained in one US gallon of gasoline. One GGE represents 114,000 BTU or about 33.7 kWh (121 MJ) of energy, the standard lower heating value of US automotive gasoline. It is the apples-to-apples unit for comparing prices of CNG, biomethane, hydrogen, propane, ethanol and electricity against the gasoline benchmark.

For compressed natural gas and CBG the conversion is straightforward but worth memorising. One GGE of CNG = approximately 5.66 lb (2.57 kg) of CNG at 100% methane, or about 3.0 kg of typical pipeline-quality CNG accounting for inerts. So a US retail price of $2.50 per GGE of CBG translates to roughly $0.87 per kg of CBG. In Indian metric terms, since SATAT prices CBG at around ₹54-55 per kg, the GGE-equivalent price works out to approximately $1.85-1.95 per GGE — broadly in line with US RNG benchmark pricing.

GGE is used in four practical contexts. Cross-border price comparison between Indian SATAT-notified prices and US RNG transactions for benchmarking and offtake negotiations. Fleet TCO analysis where vehicle range, fuel economy and dispenser pricing are converted to per-mile or per-kilometre cost on a common energy basis. Carbon-intensity reporting under California's Low Carbon Fuel Standard and similar programmes, which express emissions in g CO₂-eq per MJ that can be converted via GGE. Equipment specification for compressors, dispensers and tank capacities, often rated in GGE per minute or GGE storage volume.

The caution is that GGE is a US convention, not an Indian standard. Bureau of Indian Standards uses kg of CBG at 50 MJ/kg net calorific value as the unit of trade under SATAT, and IS 16087:2016 specifications are written on the metric basis. When working between Indian project plans and international benchmarks the conversion factors must be applied consistently — and any reference data in GGE should be checked for whether it uses higher or lower heating value, which can vary by 10%.