Meeting the Natural Gas Vehicle Challenge

Though natural gas vehicles (NGVs) have been around since the 1930s, they have never been able to break through the barriers to their widespread application in America – special infrastructure requirements, a shortage of fueling stations, and awkward, expensive fuel tanks that must be filled at pressures as high as 3600 psi. Moreover, until just a few years ago, the U.S. was importing natural gas, so there was no strategic benefit to converting our transportation fleet to its use.

But in the last two years, a major change has occurred in the energy market. Natural gas reserves have started growing…and fast. The Energy Information Administration has revised its Annual Energy Outlook (AEO) for 2011 to reflect a 25 percent increase in natural gas production in the lower 48 states, relative to its 2010 forecast. Further projected increases in well productivity lead to a near-doubling for predicted shale gas production in 2035 compared to the 2010 reference case.

Most new natural gas comes from deep underground rock structures, including shale. Recent improvements in hydraulic fracturing, or ‘fracking,’ a controversial process that some critics claim can hurt the environment, have made it economical for natural gas companies to extract a greater supply of such gas from unconventional sources.

Unlike those for gasoline, the compressed natural gas (CNG) markets are relatively insulated from geopolitical shocks. The price of CNG has been, and will likely continue to be, cheaper and more stable over the long term than that of gasoline. CNG currently costs the equivalent of about $2 per gallon, roughly half the current price of gasoline. What’s more, natural gas burns cleanly, emits far smaller amounts of criteria pollutants, and is already available to half of all homes in America through existing connections. Most important, America has sufficient natural gas and does not have enough oil.

The combination of increasing natural gas supplies and low cost compared to conventional motor fuels provides a unique opportunity to reduce our dependence on imported petroleum by using CNG as a vehicle fuel.

The drawbacks to natural gas: It has been tried in cars before and has failed. The liquefying of natural gas consumes too much energy. There are currently fewer than 1,000 publically available CNG refueling stations in the United States, in comparison to nearly 200,000 gas stations. The moment you leave the driveway, you will suffer from massive range anxiety. Where is there another natural gas station?

So we need solutions that will allow us to use our new-found natural gas wealth. We cannot pay for infrastructure. We need low-cost fuel that comes without range anxiety, big storage tanks, and the need for expensive compressors in every house. No sacrifices.

A possible solution:  Bi-fuel natural gas/gasoline vehicles, with low pressure/low cost home refueling. The argument to create PHEVs (plug-in hybrid electric vehicles) has already been convincingly made. Yet in a side-by-side comparison, home-fueled NGVs might be much cheaper, and much simpler, than home-charged electric vehicles.

Bi-fuel vehicles that run on both gasoline and natural gas can use a fairly simple parallel-injector architecture. Bi-fuel allows the use of a relatively small, inexpensive CNG tank designed for a driving range of 50 miles on natural gas (the average driver only drives 27 miles, so why make the tank any bigger?). A bi-fuel vehicle also has a gasoline tank, so range anxiety is not a problem. And there is no need to compress the gas to 3600 psi, because gas volume is no longer a concern – home compressors can be made both inexpensive and durable.

The solution to America’s oil dependency involves using a range of alternatives to replace gasoline. This means using every American advantage to reduce our use of petroleum. Adding natural gas to the arsenal of alternatives will do much to break our oil addiction and increase our energy independence.


Don Hillebrand is Director of the Center for Transportation Research at Argonne National Laboratory