October 24, 2003
Liquefied natural gas (LNG) is rapidly gaining in policy popularity and commercial interest in North America. Energy Probe believes that the potential for catastrophic explosions and the substantial financial risks associated with LNG need to be fully considered before making any decisions to expand our dependence on LNG.
Marine LNG off-loading terminals are proposed for sites near Saint John, New Brunswick and the Strait of Canso, Nova Scotia. Ontario has a small LNG facility, owned and operated by Union Gas east of Sudbury near the town of Hagar. (Almost all natural gas storage in Ontario uses underground storage in sealed natural cavities, a technology that has proven to be extremely safe.)
LNG and other liquefied flammable agents that are gaseous at normal atmospheric pressures and temperatures, such as propane, liquefied petroleum gas (LPG), and hydrogen, are capable of what are known as Boiling Liquid Expanding Vapor Explosions (BLEVEs).
An LNG release on water is particularly dangerous. If LNG contacts water, the LNG boils rapidly, sometimes called rapid phase transition (RPT). The result is that natural gas is released. The resulting gas expansion powers the dispersion of a “cloud” of liquid and gaseous natural gas. This cloud achieves a “super-fluid” effect similar to pyroclastic flows seen in some volcanic eruptions, where the rapid motion of the cloud is powered by the expansion of bubbles within it. Flammable vapor clouds can form if a spill does not ignite immediately.
LNG explosions have been relatively infrequent in Canada and the United States. In 1944, an LNG tank in Cleveland, Ohio exploded killing 135 people. In 1979, the failure of an electrical seal on an LNG pump permitted natural gas (not LNG) to enter an enclosed building. A spark of indeterminate origin caused the building to explode. As a result of this incident, the electrical code has been revised for the design of electrical seals used with all flammable fluids under pressure.
Japan relies heavily on LNG and has so far demonstrated a good safety record.
LNG spilled on or within the hull of a ship can cause brittle fracture of some common types of steel. There have been marine accidents where hull damage due to brittle fractures was incurred after LNG was spilled. Fortunately, LNG explosions did not occur in these instances.
Many proposed LNG terminals have been turned down over the years for reasons that often involve the combined effects of high cost and high risk. Examples include an LNG terminal on the Thames River in London, three LNG terminals that were proposed for California in the 1970s but cancelled, and a land-based LNG storage facility once proposed for Eastern Ontario by the former Consumers Gas Company (now Enbridge Gas Distribution).
LNG is usually thought to be cost effective only where natural gas prices average more than US$3.50 to US$4.00 per thousand cubic feet. Measured at the producer level, North American prices have only exceeded this level for two sustained periods over the last 20 years; however both periods of high prices occurred since June 2000.
For more information on LNG risks see: