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.
Natural gas is the fuel of choice for thermal power generation and many industries because it is cost effective, easy to handle and efficient. In addition, markets are increasingly demanding natural gas to respond to public pressure to reduce emissions by using cleaner burning fuels.
While they will continue to carry the bulk of natural gas transported nationally and internationally, pipelines and LNG have physical and economic limitations.
Marine CNG is an economic alternative for transporting small to moderate volumes of natural gas over medium distances.
Marine CNG is an ideal solution for monetizing lower volumes of gas because it enables producers to access regional markets that may not be economic to serve with pipelines or LNG. Marine CNG is often the most economical solution for moving volumes of up to 500 MMscf/d over distances up to 2000 km.
Marine CNG Advantages
Marine CNG transportation systems, can be better optimized to meet the specific needs of a particular project than a fixed pipeline. And in locations where financial and political instability may inhibit large-scale infrastructure investment, the ability to redeploy marine CNG assets significantly reduces investment risk.
Compared with LNG and pipelines, marine CNG offers the following advantages:
- CNG has a lower cost of production and storage compared to LNG, as it does not require a cooling process and cryogenic storage.
- Because CNG does not require temporary conversion to a liquid state it does not require large plants at either receipt or delivery points for the conversion process.
- Pre-investment in a fixed forecasted capacity is not necessary.
- Marine CNG shipping solutions are scalable and redeployable; meaning that the fleet’s capacity can be optimized for the volume of gas to be transported by simply adding or subtracting from the number of ships in the fleet and ships can be redeployed for other applications as necessary.
Natural gas is an essential component to sustainable energy development around the world. For example, the use of compressed natural gas (CNG) as a replacement for heavy fuel oil in power plants significantly reduces all polluting emissions.
- Carbon dioxide (CO2) by 29%
- Oxides of nitrogen (NOx) by 78%
- Oxides of sulphur (SOx) by 99.9%
- Particulates by 92%
Marine CNG not only supports the expansion of natural gas usage by land-based customers, but enhances the marine environment as well: The CNG ships themselves are equipped with dual fuel engines and burn natural gas from their own cargo. As a result these ships will be among the cleanest running in the world.
Reducing emissions from the shipping industry is a target for greenhouse gas reduction. Marine CNG custom built ships with gas engine technology will enable Marine CNG fleets to deliver natural gas with minimal environmental impact.