Gasoline gallon equivalent (GGE) is a unit of measurement used to compare the energy content of alternative fuels to that of gasoline. The amount of an alternative fuel required to equal the energy content of one liquid gallon of gasoline is known as the gasoline gallon equivalent (GGE) or gasoline-equivalent gallon (GEG). It represents the amount of alternative fuel that contains the same amount of energy as one gallon of gasoline. GGE enables consumers to compare the energy content of competing fuels to that of a well-known fuel, gasoline.
When gasoline and other fuels are sold in different units and physical forms, it is difficult to compare their prices. GGE makes an attempt to resolve this. One GGE of CNG and one GGE of electricity contain the same amount of energy as one gallon of gasoline. GGE compares gasoline directly to alternative fuels, including those sold as a gas (natural gas, propane, hydrogen) and as metered electricity.
The GGE is typically used to describe alternative fuels such as compressed natural gas (CNG), liquefied natural gas (LNG), propane, and hydrogen. For example, one GGE of CNG contains the same amount of energy as one gallon of gasoline.
The actual volume of the alternative fuel required to equal one GGE of gasoline can vary depending on the energy content of the fuel. For example, because CNG has a lower energy content than gasoline, it takes about 1.5 cubic feet of CNG to equal the energy in one GGE of gasoline. Similarly, because propane has a higher energy content than gasoline, it takes about 0.7 gallons of propane to equal the energy in one GGE of gasoline.
Application
The GGE is often used to express the fuel efficiency of vehicles that run on alternative fuels such as compressed natural gas (CNG), propane, and ethanol. For example, if a vehicle can travel 20 miles on one gallon of gasoline and it takes 1.5 GGE of CNG to travel the same distance, then the CNG fuel efficiency of the vehicle is 13.3 miles per GGE.
The GGE is also used in regulations and policies that promote the use of alternative fuels, such as the federal Renewable Fuel Standard (RFS) in the United States. The RFS requires a certain volume of renewable fuels, such as ethanol, to be blended into the transportation fuel supply each year, and the volume is expressed in terms of ethanol GGEs.
The GGE is a useful tool for consumers and fleet operators to compare the cost and energy efficiency of different fuels when making purchasing decisions.
