Gasoline, diesel, and electricity are all energy currencies which can be used to power transportation. Compressed natural gas can also be considered a currency as it provides this energy service directly. When considering the cost of running an alternative fuel vehicle—the cost of the energy in the vehicle (the fuel) is one important piece of determining the vehicle cost.
Historical average fuel prices in US for gasoline, diesel, compressed natural gas, and electricity are shown in figure 1. The prices are reported in gasoline gallon equivalent (GGE). Gasoline and diesel prices are highly volatile and depends on the energy market. At the same time, electricity prices have been relatively stable since 2000. While natural gas prices are not as stable as electricity prices, they tend to be more stable than gasoline and diesel prices.
In order to understand the economics of these vehicles, the up front costs and maintenance of these different vehicles must also be taken into consideration (most electric vehicles are more expensive than gasoline or diesel vehicles). The convenience of the alternative fuel vehicle infrastructure must also be taken into consideration and greenhouse gas emissions for different vehicles.