A gasoline gallon equivalent, or GGE, is the amount of an alternative fuel that holds the same energy as one gallon of gasoline. It lets a buyer compare prices across fuels on a fair, common measure.
Many alternative fuels are not sold by the gallon at all. Natural gas is sold by weight or volume of gas, and hydrogen by the kilogram. That makes a head-to-head price hard to read, because a gallon of one and a kilogram of another are not the same amount of usable energy.
The gasoline gallon equivalent solves it by anchoring everything to a familiar unit. You figure out how much of a given fuel carries the same energy as one gallon of gasoline, and you price it per GGE. Now a driver can stand at the pump and compare a dollar figure that means the same thing across every fuel.
For a fuel seller, the GGE is the honest way to post a price on an alternative fuel. It keeps the comparison square with the gasoline a customer already understands, so no one is fooled by a low number that buys less energy than it looks like it should.
In useThe station prices its compressed natural gas per gasoline gallon equivalent, so a driver can compare it straight against the gasoline price on the next island.
See also Energy economy ratio (EER), British thermal unit (BTU), Electric vehicle (EV)