CNG Information:

• Compressed Natural Gas

• Technology

• CNG compared to LNG and LPG

• Advantages of Compressed Natural Gas

Compressed Natural Gas (CNG)

Compressed Natural Gas (CNG) is a substitute for gasoline (petrol) or diesel fuel. It is considered to be an environmentally "clean" alternative to those fuels. It is made by compressing methane (CH4) extracted from natural gas. It is stored and distributed in hard containers, usually cylinders.

Argentina and Brazil, in the Southern Cone of Latin America, are the two countries with the largest fleets of CNG vehicles. Conversion has been facilitated by a substantial price differential with liquid fuels, locally-produced conversion equipment and a growing CNG-delivery infrastructure. A 'Blue-network' of CNG stations is being developed on the major highways of the Southern Cone (including Chile and Bolivia) to allow for long-haul transportation fuelled by CNG.

In response to high fuel prices and environmental concerns, compressed natural gas is starting to be used in light-duty passenger vehicles and pickup trucks, medium-duty delivery trucks, and in transit and school buses.

CNG has grown into one of the major fuel sources used in car engines in Pakistan, Bangladesh and India. The government of Punjab, Pakistan, the most populous province of that country, has mandated that all public-transport vehicles will use CNG by 2007. Pakistan is the largest user of CNG in Asia, and third largest in the world. As of 2005.

According to the International Association for Natural Gas Vehicles, Pakistan has the third-largest number of natural gas vehicles. In the Middle East and Africa, Egypt is a top ten country in the world with more than 63000 CNG vehicles and 95 fueling stations nationwide. Egypt was also the first nation in Africa and the Middle East to open a public CNG fuelling station in January 1996.[1]

During the 1970s and 1980s, CNG was commonly used in New Zealand in the wake of the oil crises, but fell into decline after petrol prices receded.

Brisbane Transport and Transperth in Australia have both adopted a policy of only purchasing CNG buses in future; the former purchasing 216 Scania L94UB and 180 MAN 18.310 models, with the latter purchasing 451 Mercedes-Benz OC500LE buses, including 58 articulated buses. Brisbane Transport has also ordered up to 30 articulated CNG buses on MAN chassis'.

Technology:

CNG can be used in Otto-cycle (gasoline) and modified Diesel cycle engines. Lean-burn Otto-cycle engines can achieve higher thermal efficiencies when compared with stoichiometric Otto-cycle engines at the expense of higher NOx and hydrocarbon emissions. Electronically-controlled stoichiometric engines offer the lowest emissions across the board and the highest possible power output, especially when combined with EGR, turbo charging and intercooling, and three way catalytic converters. The octane rating of CNG is far more greater than Petrol and if handled correctly it can produce same or more power output from an engine provided the Compressed Natural Gas is compressed properly and accurate amounts of BTU Figures attained.

CNG may be refueled from low-pressure or high-pressure systems. The difference lies in the cost of the station vs. the refueling time. There are also some implementations to refuel out of a residential gas line during the night, but this is forbidden in some countries.

CNG cylinders can be made of steel, aluminum, or plastic. Lightweight composite (fiber-wrapped plastic) cylinders are especially beneficial for vehicular use because they offer significant weight reductions when compared with earlier generation steel and aluminum cylinders, which leads to lower fuel consumption.

CNG compared to LNG and LPG:

CNG is often confused with LNG. While both are stored forms of natural gas, the key difference is that CNG is in compressed form, while LNG is in liquefied form. CNG has a lower cost of production and storage compared to LNG as it does not require an expensive cooling process and cryogenic tanks. CNG requires a much larger volume to store the same mass of natural gas and the use of high pressures.

CNG is also often confused with LPG, which is a compressed blend of propane (C3H8) and butane (C4H10).

The Advantages of Compressed Natural Gas:

The Environmentally Clean Advantage

• Compressed natural gas is the cleanest burning fuel operating today. This means less vehicle maintenance and longer engine life.

• CNG vehicles produce the fewest emissions of any motor fuel.

• Dedicated Natural Gas Vehicles (NGV) have little or no emissions during fueling. In gasoline vehicles, fueling emissions account for at least 50% of a vehicle's total hydrocarbon emissions.

• CNG produces significantly less pollutants than gasoline.

• Tailpipe emissions from gasoline operated cars release carbon dioxide, which contributes to global warming. This is greatly reduced with natural gas.

The Maintenance Advantage

• Some fleet operators have reduced maintenance costs by as much as 40% by converting their vehicles to CNG.

• Intervals between tune-ups for natural gas vehicles are extended 30,000 to 50,000 miles.

• Intervals between oil changes for natural gas vehicles are dramatically extended--anywhere from 10,000 to 25,000 additional miles depending on how the vehicle is used.

• Natural gas does not react to metals the way gasoline does, so pipes and mufflers last much longer.

The Performance Advantage

• Natural gas gives the same mileage as gasoline in a converted vehicle.

• Dedicated CNG engines are superior in performance to gasoline engines.

• CNG has an octane rating of 130 and has a slight efficiency advantage over gasoline.

• Because CNG is already in a gaseous state, NGV's have superior starting and drivability, even under severe hot and cold weather conditions.

• NGV's experience less knocking and no vapor locking.

The CNG Cost Advantage

• Natural gas is cheaper per equivalent gallon than gasoline (an average of 15% to 50% less than gasoline).

The Safety Advantage

• Surveys indicate that NGV's are as safe or safer than those powered by other fuels. A 1992 AGA survey of more than 8,000 vehicles found that with more than 278 million miles traveled, NGV injury rates per vehicle mile traveled were 34% lower than the rate for gasoline vehicles. There were no fatalities reported--even though these vehicles were involved in over 1,800 collisions.

The Financial Incentive Advantage

• Some States offers a 50% investment tax credit for each vehicle converted to natural gas. This 50% credit on state income tax features a three-year, carry-forward option.

• A federal tax deduction is also available for the cost of conversion.

CNG Conversions

• Converting a gasoline-powered car to CNG requires only minor engine modifications. To learn more about converting your car, please contact a certified CNG conversion technician.