Marine CNG Overview
Compressed natural gas (CNG) is not new. Indeed all natural gas shipped by pipeline is compressed. CNG is also used extensively as transportation fuel with over 12 Million CNG vehicles in service worldwide.
Marine CNG is the transportation by ship of natural gas stored under pressure. For this purpose natural gas is simply mechanically compressed, as it is in a pipeline. Unlike liquefied natural gas (LNG), CNG does not require complex and expensive refrigeration. As a result, while the energy density of CNG is about half that of LNG and will therefore require more shipping capacity, CNG loading and discharge facilities are much simpler, much less expensive and have a significantly smaller footprint. The result is that CNG provides a significantly more economic solution, which is easier and quicker to permit and implement, for the transportation of smaller volumes of gas over shorter distances. CNG has the added benefit that the majority of investment is in the ships and therefore can be redeployed to other projects as required.
The model for marine CNG service uses one or more ships on a given route to shuttle natural gas between receipt and delivery points on a specific route, much like a passenger ferry service. Loading and discharge of gas may be carried out onshore or offshore. The facilities required are relatively simple and small in scale. Other key advantages of marine CNG include:
- Safety, reliability and good economics.
- Cost-effective, flexible loading and unloading options using simple jetty and/or buoy systems.
- Small footprint at loading and unloading points.
- May be used in a supply/delivery chain with LNG, pipelines and liquid fuels.