CNG United provides information about the pros and cons of coverting a vehicle to compressed natural gas. The biggest downside is that the Compressed Natural Gas (CNG) tank takes up extra space. The second is an infrastructure problem because there are not many CNG fueling stations.
The current price of natural gas to an equivalent gallon of gas is $0.63 US. This varies up to $2.00 per gallon.
The most likely application for conversion would be agricultural vehicles and possibly long distance trucks. Buses would be another quick adapter since they have a specified route and a central fueling station.
According to NGV global News there are plans to add an additional 1,000 plus CNG fueling stations in the US during the next three years. This is a cooperateve venture between DeBartolo Development, along with Keystone Consulting Group, a real estate investment company and Peake Fuel Solutions.
There is also a push towards having home CNG fueling stations. This is similar to rural areas where there is no piped natural gas and a CNG tank is ues for furnace fuel. The same tank could be used to fuel vehicles.