CNG stands for compressed natural gas, or natural gas (mostly methane) that is stored at high pressure. Used as an alternative fuel source to the traditional gas, diesel, and propane options, compressed natural gas is considered to be safer to use than other fuels because it’s lighter – and in case of a spill, will disperse more quickly when released. This market is experiencing a great deal of growth at the moment, primarily because of the increasing popularity of natural gas vehicles, as well as the projected increase of natural gas consumption in future years. Another bonus? Vehicles running off of CNG burn cleaner, which contributes to lowering carbon dioxide emissions and reducing engine wear.
High-Pressure Compressors Power CNG Refueling Stations
Like its name implies, compressed natural gas is produced by using high-pressure air compressors to compress natural gas – typically to less than 1% of the volume it occupies at standard atmospheric pressure. Below we outline how CNG refueling stations (or stations which deliver the CNG to the end-user) operate and deliver the CNG by using high-pressure compressors.
Online Station. Natural gas is transported to refueling stations via pipelines. These stations are placed at different points throughout the pipeline, as the natural gas needs to be continually compressed at different intervals. Once the gas arrives, the moisture is removed and the gas is then compressed in a high-pressure compressor. The gas is then served to the customer (in this case, a CNG vehicle) via a dispenser.
Mother Station. Virtually the same process as occurs at the online station. However, rather than be delivered to an end-user immediately, the CNG is stored in a trailer post-compression and awaits shipment to a power plant, industrial customer, or a daughter station.
Daughter Station. In this case, the refueling station isn’t connected with a gas pipeline. Instead, the gas is delivered via a trailer (in a cylinder) and is served to the customer via a dispenser. However, when the pressure in the cylinder drops to 190 bar, the compressor runs in order to bring the pressure back up to 220 bar.