Compressed Natural Gas
The greener combustion fuel
No one could really describe compressed natural gas as a completely green. But it is significantly less damaging to the environment than fossil fuels. As many experts would confirm, alternative energy also involves making the most of current resources. Compressed natural gas is the most efficient way of doing this.
What is compressed natural gas?
CNG is made by compressing natural gas (methane) to less than 1% of the volume it occupies at standard atmospheric pressure. It can then be stored in cylinders and is used to propel cars, power trains and even to heat houses. Most current usage, however, focuses on powering vehicles as the cylindrical storage units are fairly easy to transport.
How compressed natural gas works
When natural gas – usually methane - is extracted from the ground, it is already a useful energy source. Many homes in Europe are heated using piped gas from Asia. Compressed natural gas involves packaging it into small containers, thereby increasing its pressure. Car systems work in similar ways to vehicles powered by conventional fuel. Tanks in cars can be filled up with CNG in the same way as petrol. When an engine needs fuel, the gas travels along a high pressure pipe to a converter where its pressure is reduced to the pressure needed in the engine. Once the pressure is regulated, gas is pumped via a fuel injection system along with air into a carburettor.
Advantages of compressed natural gas
Compressed natural gas releases much less greenhouse gases and is also more efficient than petrol engines. As they contain no benzene, they do not foul spark plugs with lead. Finally, compressed natural gas is, at the time of writing, cheaper per unit energy than crude oil, the raw ingredient of petrol, although prices often fluctuate.
Disadvantages of compressed gas
Space is a big issue for compressed natural gas vehicles because their fuel is stored in its gaseous state. Fuel tanks on vehicles are not able to store the same volume of energy as their petrol counterparts. This leads to the need for bigger tanks, reducing the amount of boot and back seat space. Gas leaks also pose a potential hazard to drivers of compressed gas vehicles and activities common in petrol cars, such as smoking whilst driving, endanger the safety of drivers. Some performance issues also hamper development of CNG vehicles. There is generally a 5-15% reduction in power, reducing acceleration.
Future of Compressed gas
Many analysts argue that in years to come, CNG vehicles will replace petrol powered ones as the most common cars on the road. The fact they are most environmentally friendly, natural gas is more easily accessible for developed countries and their engines are becoming increasingly more efficient has led many to invest heavily in such vehicles. However, as they still rely on a finite resource means they may not be as successful as some manufacturers hope.
Compressed gas in Australia
While it is rare to see compressed gas cars on Australia’s streets, both Perth and Brisbane’s transport authorities have announced they will only buy CNG buses in the future. Authorities in New South Wales and Victoria have also begun investing in such vehicles.
Compressed gas around the world
Worldwide, there were 12.9 million gas vehicles in 2010. Perhaps not surprisingly, compressed gas is most common in areas with large supplies of natural gas – leaders are Pakistan with 2.74 million and Iran with 1.95 million. The leading region is Asia-Pacific with 4 million CNG vehicles. The western world has been less keen to embrace this technology, but it is increasing
Compressed gas is certainly the most likely candidate to power cars in the future. With manufacturers across the world waking up to such possibilities, it won’t be long before we see compressed gas cylinders on forecourts in the future.
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