What Is It?
The world has enormous quantities of natural gas, but much of it is in areas far from where the gas is needed. To move this environmentally friendly fuel great distances across oceans, natural gas must be converted into liquefied natural gas (LNG). LNG is natural gas that has been cooled to -260F, changing it from a gas into a liquid 1/600th its original volume. This dramatic reduction in size allows it to be shipped safely and efficiently aboard specially designed LNG vessels. After arriving at its destination, LNG is warmed to return it to its gaseous state and delivered to natural gas customers through local pipelines.
LNG is not new. It has been transported and used for more than 40 years, and has a strong safety record. More than 150 LNG tankers are safely transporting LNG across the world's oceans. In fact, the industry has made more than 33,000 carrier trips without a major accident or fire. Worldwide, there are 40 import terminals designed to receive LNG shipments, 17 LNG liquefaction export terminals and more than 200 storage facilities where LNG is kept until needed. Japan, with 25 LNG import terminals, has gone without a major safety incident in its 35-year history.
An LNG spill would not damage the ground or leave any residues as it evaporates. In water, LNG is insoluble and would simply evaporate, making water spill cleanup unnecessary. LNG is not a flammable liquid, so it will not explode or burn. Like other fuels, when it vaporizes and mixes with oxygen, it is flammable – if it is exposed to an ignition source. Even then, there is a limited flammability range – if the concentration of natural gas in the air is below 5 percent or greater than 15 percent, it will not ignite.
Throughout the process of converting natural gas to and from LNG, stringent safety and security measures are employed.
Liquefaction: Turning Natural Gas Into Liquid
The process of cooling natural gas into a liquid is called liquefaction. Like any industrial facility, security issues for liquefaction facilities are tailored to regional and local concerns. Security can include physical barriers, personnel and equipment access control, site surveillance and intruder alert systems.
Shipping LNG Safely and Securely
LNG ships are double-hulled and heavily insulated, with an extensive cargo safety system. LNG is not stored under pressure. As in all modern oil tankers, sophisticated radar and positioning systems alert the crew to other traffic and hazards around the ship. Distress systems and beacons automatically send out signals if the ship is in difficulty.
Ships also employ anti-piracy and boarding measures, and must comply with the requirements of the International Ship and Port Security code. While the ship is at sea, the cargo control room is manned continuously when cargo is being transferred to and from the ship.
LNG Import and Regasification Terminals
Returning LNG to a gaseous state is done at LNG import and regasification terminals, which are designed and constructed according to stringent national codes and international standards. Extensive safety systems monitor equipment and restrict access to terminal property 24 hours a day, 365 days a year. Perimeter fencing, motion detection, closed-circuit TV and lighting are also deployed. Safety features include methane detectors, ultraviolet or infrared fire detectors, and regular personnel training.