- Date: Jun 25,2008
Obviously on day to day basis NGV converted cars are becoming a normality in our roads. Before you start dumping RM 4000 ++ for any NGV system, lets have a closer look at the real benefits and drawbacks of NGV as a vehicle fuel.
Compressed Natural Gas (CNG) is a substitute for gasoline (petrol), diesel, or propane fuel. It is considered to be a more environmentally “clean” alternative to those fuels and it is much safer than other motor fuels in the event of a fuel spill: natural gas is lighter than air, so it disperses quickly when leaked or spilled.
It is made by compressing natural gas (which is mainly composed of methane (CH4)),to less than 1% of its volume at standard atmospheric pressure. It is stored and distributed in hard containers, at a normal pressure of 200–220 bar (20–22 MPa), usually in cylindrical or spherical shapes .
Natural gas vehicle or NGV is a alternative fuel vehicle that uses compressed natural gas (CNG) or, less commonly, liquefied natural gas (LNG)) as a clean alternative to other automobile fuels.
Liquefied petroleum gas (also called LPG, LP Gas, or autogas) is a mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles, and increasingly replacing chlorofluorocarbons as an aerosol propellant and a refrigerant to reduce damage to the ozone layer.
1. What is NGV
NGV or methane is the lightest hydrocarbon. It is often extracted from underground but not always associated with oil and coal deposits. Methane is a by-product of decomposing organic matter including the rotting of dead plants, garbage dumps as well livestock manure.
2. NGV cars are cheaper to run
This is true due to the huge price gap between petrol and NGV although the fuel consumption of an NGV vehicle per liter is higher compared with petrol. However NGV do need some extra maintenance on top of your current maintenance list and possible replacement are:
i) Reducer. It drops the gas pressure from 220 bar to 1.8 bar. This component uses a diaphragm. It needs to be serviced and the diaphragm replaced at regular intervals.
ii) The Gas Injectors. All modern system today use multiple gas injectors with one injector for each port. There parts will wear out and leak, and have to be replaced as and when necessary.
iii) Pressure Sensors
iv) Gas ECU. Normally ECU are supposed to last the life of the vehicle, they can fail at any time.
v) Refuelling Valve
Also regular NGV tune-ups are necessary to reap the full benefits of using NGV. It also known that a higher compression ratio allows engine to get more power. However, this cannot be done yet because of shortage of filling stations. Vehicles have to be set up to run on duel fuel and this, the compression and ignition timing cannot be set at the optimum.
Note that NGV has an Octane rating of 130 compared with 97 for premium petrol and there is a power loss of between five and 15 percent when switching to NGV but in actual practice is hardly noticeable.
There have been some safety concerns with the use of NGV. Be assured that so far as the gas tank and other NGV components are concerned, all suppliers use equipment that have been certified by safety standards. For example, all tanks need to pass a fire, drop and gun test according to ISO requirements. It’s only need is to be retested once every five years.
The weak link in the chain is the actual installation and thigh pressure line that runs underneath the car. This line can subjected to damage and subsequent leaking.
Although NGV is a flammable gas, basically NGV is as safe, if not safer than petrol. It has a narrow flammability range and must have and ideal conditions in order to ignite. NGV will not ignite if the mixture is too rich or too lean. It als disperses quickly as is lighter than air compared to petrol and LPG which are heavier.
4. NGV cars are cleaner than Hybrids car
This is partly true because if NGV run at proper compression ration, it is very clean burning with practically no CO, NOx or emissions. Overall , NGV vehicles can be said to be “Green” car or “Greenhouse Neutral” because the fuel coms from organic material.
5. NGV Vehicle Maintenance
i) Lubricating Oil. NGV is cleaner burning and it is not a liquid. As such, there is practically no oil contamination and the oil stays cleaner for a longer period.
ii) NGV is a “dry” fuel and lacks the lubricating properties of a liquid fuel. Therefore is it important that a vehicle using NGV has hardened valve seats.
iii) Weight problem.Some concerns about the weight of the fuel tank and its effect on the rear suspension. With the increasing use of GRP woven tanks , weight is no longer a problem and so as the worries of suspension and braking.
6. Traveling Range KM?
A major complaint about NGV use is that of range and the need to fill up regularly. Unfortunately , NGV conversions are retro-fits and the vehicles were not designed to carry such large fuel tanks. In order to have sufficient gas capacity , one has to sacrifice boot space.
One needs to look at the total cost of operating with NGV compared with using petrol. An average conversion is about RM4000 for normal car and RM6000 for any large vehicle that would benefit the most from such a NGV conversion. Cost per km for NGV usage compared with petrol is about 7 cents per / km and 20 cents per / km respectively for such a vehicle. thus, the saving in fuel cost is 13 cents per km . This mean owner of NGV car would need to travel about 46,000km for ROI ( return of investment ) with the initial NGV installation cost.
It may take at least three years for normal commuter to recover the cost and this is based on assuming that the price of NGV will not increase.
To know more about NGV parts and indicators list.
Source: NST +