Compressed Natural Gas

In countries where Compressed Natural Gas (CNG) is not an established source of fuel, people often have a negative perception about the safety of CNG. Furthermore, CNG is often confused with Liquid Petroleum Gas (LPG) where severe accidents have occurred. As a result, some countries such as Thailand, have stopped supporting LPG and are turning to CNG for their transport fuel needs.

CNG is not a new technology, having been in the market for over 70 years. It is widely proven and its technological advances are constant. While not fail-proof, it offers a significantly reduced risk to people and infrastructure.

CNG is lighter than air. Should CNG escape from its storage containers, it will immediately disperse into the atmosphere (it is only 70% the weight of air). Unless CNG escapes in a completely sealed room – which is highly unlikely – it should never accumulate to the point of explosion.

On the other hand, LPG, petrol, and diesel are heavier than air and have the tendency to form pool fires, which increase the risk of fire and explosion during an accident or leakage. CNG does not form pool fires and is thus easier to manage and handle.

CNG does not easily set alight. It requires a 600 ⁰C temperature for it to ignite, while petrol and LPG ignite at 450 ⁰C.

CNG is a high-pressure technology and by definition has to be compressed into CNG Cylinders. Components before the pressure reduction station, or regulators for vhicles, are designed to withstand this pressure level and thus are intrinsically safer than LPG systems. Cylinders are manufactured under very strict safety norms and are subject to tests with pressures much higher than the ones during regular refilling.  Design and testing pressure is 1.5 times the working pressure for vehicles and 250 bar for industrial applications.

Natural Gas distribution to the refuelling station usually occurs via pipelines, whereas LPG for mobile use is almost always transported by tanker truck on public roads and therefore more prone to accidents. If CNG is transported by virtual pipeline systems (truck transport of CNG cylinders) the safety characteristics of more rigid pressure equipment apply. Due to their robustness, structure, shape and location inside the vehicle, the cylinders are much less dangerous than a petrol tanker in case of collision.

There may be safety issues if CNG is not handled correctly and, as in any operational environment, safety training and awareness apply.