Compressed or CNG is becoming and increasingly attractive fuel for many transportation uses. One reason for the increase in interest in CNG is that the emissions of a CNG vehicle are far less than that of a gas powered engine. Other factors that make the production of CNG vehicles is that the gas prices have risen in the past couple years. Availability Natural gas is, well, natural gas-the same stuff that heats your stove or your house.
It is largely produced domestically in the United States; it can be imported through pipelines or as a super-cold liquid on special tanker ships, but because this is a lot harder than pouring crude or refined oil into a tanker or a pipeline, we haven’t built up an import dependency for natural gas as we have for petroleum. Natural gas is distributed nationwide through an extensive network of pipelines, which feed electrical generation plants and domestic and industrial heating uses. In order to store a reasonable amount of fuel natural gas has to be compressed to around 200 times atmospheric pressure-or even more for the tanks aboard large buses! This is like the pressure a mile and a quarter under the ocean. Advantages It is very easy on the engine, giving longer service life and lower maintenance costs. CNG is the least expensive alternative fuel when you compare equal amounts of fuel energy such as gasoline. Because there is a huge and predictable demand for natural gas from domestic, industrial, and utility users, there is a large buffering effect against price fluctuations.
At the peak of the big gasoline price run-up in April, 1996, everyone was paying half as much for a gasoline- gallon-equivalent of 130-octane natural gas as I would have aid for a gallon of 92- octane unleaded gasoline! Yo get significantly better fuel economy on the open road because the high octane rating of the fuel allows timing and mixture to be adjusted for more efficiency without causing detonation (“knocking”). And because the fuel tanks have to withstand such enormous internal pressures, they are incredibly tough, with good results or safety. In addition, because natural gas is lighter than air and has very narrow flammability limits, if a leak develops it is very likely that the fuel will dissipate harmlessly into the air without causing a danger of ignition or explosion. Natural gas has, over the course of the 1990’s, proven to be the most effective fuel for reducing emissions in an internal combustion engine.
Other key advantages is the emissions that a CNG vechile is far less than that of a gasoline driven car. The catalytic converter developed for the NGV had a 1. 24 L volume and was composed of palladium / platinum . The exhaust emissions measured under durability running for petrol and CNG fuels are shown in Table below: DistanceCONMOGNOx CNG 4 k miles 0. 210. 0160.
06 50 k miles 0. 440. 0230. 11 Petrol 4 k miles 0. 690. 0280.
05 50 k miles 0. 790. 0550. 07 It can be seen that the CO and N MOG levels for the NGV are very favourable while NOx is more for a CNG vechile. Disadvantages Some of the disadvantages are that the tanks are quite bulky and heavy.
Locations of the tanks is another concern from putting them in the trunk to putting them underneath the vehicle. Some other problems that affect use of widespread CNG is the lack of refueling stations available to refuel and CNG vechile. High capital costs are involved in setting up a network of refuelling stations. This presents problems that must be resolved in the early stages of a national development programme. The build- up of custom at a new public station may be slow, with correspondingly long times for a return on capital. Another disadvantage is that cost to convert the vechile.
The first cost of a conversion will be in the range $1, 000 to $3, 500 and the payback from two to seven years, depending on annual mileage. Any future reductions in the cost of lightweight cylinders will have an important effect on the conversion cost. web htm web web web web web web >.