Introduction: Canada temperature for car varies widely depending on where you are and what time of year it is but most of time it remains below 20 degree Celsius, which indicates that on average the weather is pleasant and most of the time it is severe cold.
Natural gas is mostly made up of methane. It has a simple structure which contributes to its cleaner-burning properties.Methane consists of one carbon atom and four hydrogen atoms and its chemical formula is CH4. Natural gas has about 27 % less carbon than diesel fuel or gasoline. There are several other characteristics also set natural gas apart from diesel or gasoline. For example:
- Natural gas is lighter than air. In its compressed form (CNG), natural gas will rise if released and will not puddle on the ground. In its liquid form (LNG), a small amount of natural gas will evaporate and will rise if released. A larger amount of LNG may run to the ground.
- Natural gas requires a much higher temperature to ignite than liquid fuels.
- Natural gas will only burn when there is the right mixture of air and gas. If there is less than 5%or more than 15% natural gas mixed with air, the gas will not burn.
- Natural gas will not rust other materials orpollute soil or groundwater.
Comparison between CNG and LNG:
- Compressed Natural Gas (CNG)
- CNG is natural gas that is compressed at high pressure to reduce its volume and tank size. CNG remains in gas form and is stored in tough cylinders at pressures of up to 3,600 pounds per square inch.
- CNG is lighter than air. It will rise if released and will not puddle on the ground. CNG is the most commonly used form of natural gas for transportation. Since 1960’s it is being used widely as vehicle fuel.
- As the temperature increases or decreases, the pressure in a CNG fuel storage cylinder also correspondingly increases or decreases. CNG cylinders are designed to accommodate these changes in temperature and pressure.
- CNG cylinders must have the pressure relief devices that are activated by high levels of heat in the event of an emergency. This design requirement ensures that there is no risk of cylinder breakage in extreme conditions.
- CNG has 7.5 mega joules of energy per liter.Compression reduces the volume by 300 times or more compared with natural gas at normal pressure.
- CNG fuel systems can be used for any type of vehicle but as fuel storage increases, so does vehicle weight. CNG is particularly well-suited for return-to base urban fleets including transit bus and refuse truck fleets.
- According to a report in March 2014, public and private CNG stations in Canada can distribute fuel to a settled pressure of 3,600 (psi). Prior to this time, public CNG stations were limited to 3,000 psi refueling.
- Liquefied Natural Gas (LNG)
- LNG is natural gas which is cooled to its liquid state at -162 degrees Celsius to reduce volume. LNG is stored in insulated, thermos-like tanks and as it warms up, it returns to its gaseous state. Regardless of the type of engine used in an LNG vehicle, the fuel is always delivered to the engine as a gas, rather as a liquid.
- Two forms of LNG vehicle fuel are available – saturated LNG and unsaturated LNG. Key difference between these forms is temperature. First form is warmer, which results in a higher tank pressure. LNG vehicle fuel systems which don’t include an internal pump in the LNG tank need to use saturated LNG.Vehicles using LNG are equipped with fuel systems that include an internal pump in the LNG tank or a pressure booster which can operate on either saturated or unsaturated LNG. By utilizing in saturated or cold LNG, vehicle range and tank hold times is increased.
- LNG refueling stations rely on bulk delivery of fuel via tanker trucks. As LNG needs to be stored at -162 degrees Celsius to stay in a liquid state, the fuel is delivered and stored in an insulated cryogenic vessel at the station and then pumped from the storage tank and dispensed similar to liquid fuels.
Decision Point: According to a study report for use of either CNG or LNG, the fleet of 18 Petteril trucks with Cummins Westport 8.9 litre engines has been operating over two years at winter temperatures as low as -16 degrees Celsius. The main report finding is that factory-built CNG trucks operate well with no issues in cold weather provided normal winter aids are used and the vehicle design is suitable for cold weather. And give satisfactory performance, fuel savings, and emissions benefits. Therefore in spite of all the facts, CNG is recommended to be used in Canada instead of LNG