Natural Gas

What is natural gas?

Natural gas is the same fuel that is used in millions of homes for heating, hot water and cooking. It is the lowest carbon hydrocarbon fuel. It is generally over 90% methane (CH4) and is non-toxic. There are two forms of natural gas: gas extracted from underground and renewable biogas from digestion or landfills.

What is compressed natural gas (CNG)?

Compressed natural gas (CNG) is natural gas that has been compressed to 3,000 – 3,600 psi for use as a transportation fuel.

What are the advantages of CNG?

There are numerous advantages, including:

  • Very favorable economics (30-65% less expensive than equivalent gasoline energy)
  • All-domestic resource (>99% of fuel used is extracted in the U.S. and Canada)
  • Lower harmful emissions
  • Reduced greenhouse gas emissions (25-30% less CO2 than gasoline)
  • Higher octane rating than gasoline
  • Same energy per gallon as gasoline

What are the disadvantages of CNG?

Fuel tanks are larger, heavier, more expensive, and may interfere with vehicle storage space over conventional gasoline tanks.  CNG refueling stations are not as abundant as gasoline refueling stations.

What does the U.S. supply of natural gas look like? When will it run out?

Current rough estimates from the U.S. government are that proven reserves in North America will last for over 100 years at current rates of consumption. These estimates have increased substantially in the last 3 years and are likely to continue to increase as new, highly efficient production techniques come into greater use. Visit the EIA website for more details.

How is natural gas or CNG different than propane or LPG?

Natural gas is composed primarily of methane (CH4) which—with just one carbon atom and 4 hydrogen atoms—is the hydrocarbon with the lowest carbon content available. Propane (also called liquefied petroleum gas (LPG) or "propane autogas") is C3H8. Propane is a liquid at a pressure of about 180 psi and is sold in liquid gallons. The HD-5 propane formulation is used as a transportation fuel and has a limit of 5% propene content. Propane gas content is somewhat less regulated than pipeline natural gas, and sometimes can contain high levels of sulphur. A gallon of propane contains approximately 84,000 BTUs—27% less than gasoline and 25% less than E-10. Fuel economy will be proportionately reduced by this amount. Propane has almost twice the carbon content as methane.

Refueling

Where are there CNG fueling stations?

Currently, there are over 1,000 CNG fueling stations in the United States. The number is increasing every day. Many websites, such as CNGNow offer fueling locators. Apps are also available on most smartphones to help locate a fueling station near you.

Can I drive my CNG vehicle across country?

Yes, this is possible by planning your fuel stops in advance. This would get easier as more CNG stations open. Remember there is always the safety of gasoline mode operation on a bi-fuel truck as well.

How long does it take to fill up? What is fast-fill vs. slow- or time-fill?

Generally, filling time is three to eight minutes at a commercial fueling station. This is considered a fast-fill. Slow-fill or time-fill usually occurs overnight and is a method frequently employed in home or private fueling.

Can I fuel at home? How much would that cost and how long does it take?

Yes. Home fueling units are available from companies such as BRC. They require a gas line and electrical power to the place they are located. Systems that make approximately .5 GGEs per hour using time-fill cost about $4,500 (USD) plus installation. Systems up to 2 GGE per hour would cost about $20,000 (USD). Generally home fuelling will reduce refueling gas costs to below $1 per GGE.

What is the usable capacity of the natural gas fuel tank?

The tank cannot be completely filled using fast fill due to temperature induced pressure rise. The tank is effectively empty when it still contains approximately 120 psi. These two factors can result in an effective, usable tank capacity of about 85% of its rated size.

Can I use the entire capacity of the CNG fuel tank?

When the pressure of the CNG tanks reach approximately 125 psi, the tank is considered empty. That leftover pressure is equivalent to 1-2 GGEs of unusable fuel. The usable capacity of each tank depends on how the vehicle is fueled. For a fast fill, the usable amount is approximately 70% of the cylinder's total volume. For the standard 18.4 GGE tank, full capacity would be an estimated 13-14 GGEs. For the optional 24.5 GGE tank, full capacity would be an estimated 17-18 GGEs. When doing a timed fill, the usable amount can reach closer to the total volume of the tank.

What is the range on CNG, on gasoline, and combined?

The estimated range on CNG is 200 miles with the smaller 18.4 GGE tank and heavy engine loads, ranging up to 325 miles with the larger 24.5 GGE tank and light engine loads. The gasoline tank contains 35 gallons and should allow another 450 miles range. Combined ranges would therefore be 650 to 775 miles.

Can I use "field gas"?

Yes, however gas quality must be checked for the presence of particulates, harmful use of non-pipeline gas, and inert gases. A minimum of 88% methane is generally required.

Pricing

How much does CNG cost at the pump?

CNG prices are $1.50-$2.00 (or more) below gasoline. See price data on our website. CNG is sold in gasoline gallon equivalents (GGE). A GGE is the amount of CNG it takes to equal the amount of energy in one gallon of gasoline. The energy contained in 1 CNG GGE is equal to the energy in one gallon of gasoline.

Isn't the price of natural gas going to increase if everyone starts using it in their cars and trucks?

There are vast untapped reserves of natural gas in the U.S. and Canada. There are many wells that are either shut down or currently producing below capacity because prices are so low. Future production is rapidly scalable and growth as a transportation fuel will have little-to-no impact on the supply and demand relationship (pricing) for the foreseeable future. Visit the EIA website for more details.

Won't the price of gasoline fall if everyone switches to natural gas?

Demand for petroleum-based fuels such as gasoline and diesel is growing worldwide as the economies of other nations including Brazil, Russia, India and China all continue to expand and the demand for personal and commercial transportation increases. The potential for global petroleum production increases are limited in both the short-term and long-term, hence constrained supply and growing demand is likely to result in continued long-term price increases. Large scale changes in the U.S. to natural gas and away from petroleum—if they were to happen—would be easily offset by accelerating global petroleum demand. Petroleum is easily transported and will move to where prices are highest.

How do I know the price of natural gas will remain stable?

While it is impossible to predict the future, the vast reserves in the U.S. and Canada, the rapid scalability of existing production and the very high current supply would suggest supply will continue to easily keep pace with demand and that prices will stay low as a result.

Can I buy fuel using a regular credit card?

Probably. Please check with your local fuel station.

Performance

What kind of fuel economy can I expect with CNG?

Because the energy content in a GGE is identical, you can expect the same fuel economy as you would find in a vehicle fueled with gasoline.

Is there a performance difference with CNG versus gasoline?

Under normal driving conditions, performance on CNG is equal to that on gasoline. However, you may experience a 10% reduction in peak power at wide open throttle. The Westport WiNG Power System does not change the towing or hauling ratings for a vehicle.

How difficult is it to "convert" a car/truck to run on CNG?

In order to safely use CNG, a significant number of safety and emissions requirements should be met. Westport recommends any installation be government certified for emissions and safety and backed by a manufacturer and OEM warranty.

I heard vehicles that run on natural gas will not start when it's cold?

This is not true. Older calibrations with less sophisticated sensors and pressure regulators sometimes had these problems. All Westport vehicles are fully tested to -20 °F (-29 °C).

I heard CNG vehicles lose power and will not go up hill?

This is not true. Performance of the Westport WiNG Power System will be the same as when the vehicle is running on gasoline, except in very high-load (wide open throttle) conditions where there may be approximately up to a 10% loss in torque/power due to the reduced volumetric efficiency of the engine as a result of using a gaseous fuel which displaces some volume of air. Loss of power is due to using gaseous fuel which displaces some air volume.

Gasoline and diesel engines are getting better all of the time, what future potential does CNG have?

CNG is a very clean, high octane fuel and, as a result, highly efficient engines with higher compression ratios and lower-cost emissions-control equipment are possible for the future.

Alternatives

How does natural gas compare to other fuels?

Natural gas is the lowest cost vehicle fuel. It is a gas, not a liquid, so it requires pressure vessel storage. If released, it disperses to the atmosphere and does not pool or pollute the ground or water like petroleum-based fuels.

Is there such a thing as a hybrid natural gas vehicle?

While these are very possible, there are none in regular production today. Unfortunately, the more efficient a vehicle is, the more difficult it is to achieve a payback on an investment in an alternative fuel or hybridization—so adding one technology might make adding a second to the same vehicle less attractive in terms of payback.

Why wouldn't I be better off to just get a hybrid that uses gasoline rather than switching to CNG?

Hybridization is an efficiency improvement strategy for vehicles, not an alternative fuel. It can be applied to any vehicle using any type of fuel/energy. A cost-benefit analysis should always be performed by an economically conscientious consumer to see if the up-front cost of an investment can be paid back over time in fuel savings. Generally, hybrids require a stop-and-go driving cycle and a change in driving behavior to be cost-effective.

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