CNG

CNG
What is CNG?

CNG stands for Compressed Natural Gas. It is a gaseous fuel and is a mixture of hydrocarbons, mainly methane in the range of 95%. Due to its low density, it is compressed to a pressure of 200 bar to enhance the vehicle on-board storage capacity.

Is CNG safe?

Yes, it is safe. The properties of CNG make it a safe fuel. It is lighter than air, and hence in case of leakage it disperses into the atmosphere rapidly. Its high auto-ignition temperature of 540 degrees centigrade as against petrol’s 360 degrees centigrade makes it even more safe fuel. CNG also has a narrow inflammability range of 5% to 15%, making it much safer than other fuels.

Which type of vehicles can be converted into CNG?

All spark-ignited engines can be converted to CNG, for which a specially designed conversion kit is required for the conversion process.

Can a car, which is fitted with CNG kit, run on petrol after its CNG gets over?

Yes, after conversion to CNG the vehicle can run on petrol whenever desired simply by flicking a switch on the dashboard.

What units are used for natural gas?

Compressed natural gas is reported as volume (m3) or weight (kg).

How far can you travel on a full tank of CNG?

In general, the range depends on the size and number of pressure vessels and on the gas consumption of the specific vehicle, as well as on the method of use (urban, non-urban) and type of journey.

Converted cars fitted with a 70-litre pressure vessel have the following average range of about 190 – 260 km.

The average range for buses is 450 km in urban traffic and more than 500 km on non-urban roads.

Will my fuel expenses reduce after conversion to CNG?

 Yes, the fuel bill on the basis of average running of vehicle reduces substantially when compared to other conventional fuels. The cost of CNG is less than half than that of petrol. This results in annual savings of at least 50% when vehicle is run on CNG.

What is the cost of converting a vehicle to a CNG-friendly one?

The cost of converting a vehicle to CNG depends on the type of your vehicle and CNG kit (i.e. a set comprising of a CNG pressure vessel, a regulator, a refuelling valve, a controller and interconnecting material to ensure the proper propulsion of the vehicle on compressed natural gas in accordance with valid legislation).

Who does the installation of CNG kits to vehicles in Trinidad?

Automotive Components Limited.

What is the pressure of CNG in a cylinder? Is refueling of a cylinder safe, given the pressure?

CNG cylinders are designed and built in such a way so as to withstand high pressure. The maximum pressure in a CNG cylinder is up to 200 bar. CNG cylinders are safe as they are manufactured as per specific requirements and tested before use, in accordance with international specifications and standards.

How do you refuel a vehicle with natural gas?

Natural gas from the gas pipeline network is compressed to a pressure of 20-30 MPa with the aid of a compressor. The compressed natural gas is stored in interconnected pressurized containers. The actual refuelling merely entails the release of compressed natural gas from the pressurized containers via a dispensing pump into the vehicle’s pressure vessel. The gun of the dispensing pump’s hose is connected to the vehicle’s refuelling valve via a quick-fastening system.

Depending on this refuelling method, the following are used:

a) fast filling station

The refuelling principle is described above.The refuelling time is the same as for pumping liquid fuel (3-5 minutes).

b) slow filling station

Refuelling takes place via a small compressor directly into the vehicle tank, i.e. without pressurized containers. Refuelling takes between 5 and 8 hours. This type of station is suitable for homes and smaller companies, but will require CNG to be piped to the home or company.

Does CNG kit require servicing?

CNG kit is safe and simple. It gives years of trouble free operation. It doesn’t require frequent servicing. Just as for all other fuels, it is advised to have routine services. An authorized person should be consulted for service.

Is CNG environmentally friendlier than any other fuel?

Yes, it is. As CNG mainly consists of methane which is the simplest hydrocarbon, it is a much cleaner and efficient fuel. The use of CNG significantly reduces harmful exhaust gas emissions like carbon monoxide, nitrogen dioxide and sulphur dioxide which causes harmful diseases like cancer, asthma etc. CNG also helps in reducing the effects of global warming.

Question: What are the benefits of using CNG?

How much do gas pressure vessels weigh and how much space do they take up in a vehicle?

In a converted vehicle, the pressure vessel for compressed natural gas is a cylinder shape and generally holds between 70 and 100 litres. Steel vessels weigh (expressed in kg) approximately the same as their volume (expressed in litres), i.e. a 70-litre vessel will weigh about 70 kg).

In these cars, the pressure vessel is usually located in the vehicle’s luggage area; in buses it can be found in the luggage area or on the roof (in the case of low-floor buses); in lorries it is under the chassis.

Question: Is there any disadvantage of CNG?

Deterioration of existing comfort:

This problem can be alleviated by installing gas cylinders on the roof (buses), under the chassis (passenger cars, trucks), or in a different place (spare wheel compartment).

Operating disadvantages:

Does CNG have any harmful effect on the engine?

Owing to CNG’s distinct features, it does not contaminate or dilute crankcase oil, giving a new lease of life to the engine. The absence of any lead content in CNG helps avoid lead fouling of plugs, thereby enhancing plug life. As CNG enters the engine in the form of a gas, no carbon is generated during the combustion of CNG reducing the chances of wear and tear.

Are cylinders used for filling CNG safe?

Ans. Cylinders used for storing gas are designed with very high safety factor in accordance with global standards. These cylinders are tested and certified for usage by statutory authorities and each cylinder is defined with an expiry date of usage after which they are to be tested again for safe use. These cylinders have been designed to take impact of collision in case of accidents.

In which countries is compressed natural gas most widely used?

More than 3.5 million vehicles in 50 countries run on natural gas today. Most CNG vehicles can be found in Argentina (more than a million), Brazil (550,000), Italy (380,000), Pakistan (280,000), India (137,000), and the USA (126,000).Most buses and coaches running on compressed natural gas can currently be found in the USA, Columbia, Australia, France and Sweden. In Europe, 400,000 vehicles run on compressed natural gas and there are almost 900 filling stations. Besides Italy, most compressed natural gas vehicles are in operation in Germany (20,000), France (4,500) and Sweden (2,000).

COST IMPACT

COST IMPACT
Fuel Costs TT1.07/LGE

60% cheaper than Gasoline

Conversion Cost TT8,500.00
Maintenance
  • Spark plugs and lubricants require fewer changes
  • Tune ups needed less often
  • Engines last 2 – 3 times longer than engines using gasoline
  • Elimination of spark plug fouling (CNG contains no lead)

Cost comparison :

Fuel Type Litres per month Fuel Cost per litre Fuel Cost per month
Premium 520 $4.00 $2,080.00
Super 520 $2.70 $1,404.00
CNG 520 $1.07 $   557.00

ENVIRONMENTAL IMPACT

SAFETY