Scientists, Industry Rip Feds? LNG Accident Study

The liquefied natural gas industry has responded to a recent Federal Energy Regulatory Commission examination of potential LNG accidents by saying that the threat posited in the FERC report is unrealistic. LNG critics, however, say a worst-case scenario could expose populations to intense fires, or even explosions, if an LNG tanker were torn open by a crash or attack. Local public officials are unsatisfied and want a fuller analysis to help them determine whether new ports are worth the risk. However, all sides are relieved at the scientific approach FERC is taking because it appears that the commission is writing standards for LNG ships. FERC currently has standards for the location of LNG facilities on land, but not for ports. The report, by the ABS Group of Irvine, estimates what would happen if a one- or five-meter hole appeared in the side of an LNG ship. After being held up in secrecy, the report was released last month ( Circuit , May 14, 2004). Officials of the city of Malibu, who are considering whether to relax their opposition to an offshore LNG port, requested studies of how LNG could spill, the probability of a spill, and the probability that vapor clouds could ignite. In other words, they don?t want to know just the effects of a fire; they also want to know the chances of one. Since this study was intentionally not written as a risk analysis, the people of Malibu will have to wait. Some scientists were dismayed by the physics and math in the report, saying that it contains a programming error and several incorrect physics constants. Phani K. Raj of Transportation Management Systems, who has studied LNG fires for 30 years, wrote, ?I have never seen a more shoddily analyzed and written report.? Calling it ?high school physics,? he called for more careful study before FERC makes any rules about the location of new LNG ports. On behalf of the industry, the technical committee of the Center for LNG insistently points out that the study examines two sizes of holes without explaining how those holes would occur or whether they are plausible. The report says these hole sizes are reasonable but provides no explanation of where they might come from. Bob Moran, a spokesperson for the Center for LNG, would not reveal what would be acceptable to the industry. However, he said a study to be released in late June by the Norway-based risk-analysis firm DNV is being conducted by metallurgists, naval architects, and fluid engineers, who together will be able to create more realistic models of how a tank might leak. The center also noted that some of the assumptions in the report were contradictory, such as assuming both calm seas and high winds. Turbulent waters would slow the spread of an LNG spill, as would still air. LNG critics were kinder to the assumptions and said that in some cases the predictions of potential consequences didn?t go far enough. Academic engineers, including Tom Spicer, professor and codirector of the Chemical Hazards Research Laboratory at the University of Arkansas, say the report underestimates how far a pool of LNG would travel before it became too diluted to burn. The report assumes that the pool of liquid would spread in a circle, but Spicer says the wall of a ship would cause fluid to spread in a semicircle with a much larger radius. ABS also states that the friction of the LNG riding along on the water would slow the spread of the frigid fluid. The engineers respond that bubbles of boiling methane would create a low-friction film between the two fluids, causing the LNG to spread further, just as an ice cube slides on a layer of water. Once the LNG has spread out in a pool, it evaporates, becoming flammable. The report assumes that LNG is all methane, which is flammable but not explosive unless it is confined. The University of Arkansas response says current imports of LNG contain as little as 85 percent methane, with much of the remainder consisting of ethane and propane. The university also concluded that ?LNG vapor clouds containing these amounts of heavier hydrocarbons, known in the industry as ?hot gas,? have the propensity to detonate with violent overpressures that can cause serious damage?a scenario that has been downplayed in the ABS report.? Some of the more worrisome possibilities for an LNG release were outside the scope of the study. The Boston Fire Department points out that a leak of fluid at ?260 degrees could weaken the steel walls of a tanker, ?embrittling? them and risking further failures. Other comments suggest that the shipping chamber could fail as it leaked because of the creation of a vacuum at the top of the chamber. The Boston Fire Department also writes that the standards for thermal hazards from LNG fires are lax because the standards body, the National Fire Protection Association, relied on an expert committee dominated by industry members rather than fire professionals. The comment calls attention to a chart appearing toward the end of the report. It shows that the standards for land-based LNG facilities allow schools and hospitals to be so close to a potential fire that their outdoor areas could be exposed to heat that kills half of all people present within a minute. The public comment period for the ABS study closed at the end of last week, and FERC will now have to decide whether to accept the report and use it as a guide for future decision making about sites for dozens of proposed LNG terminals nationwide.

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Scientists, Industry Rip Feds? LNG Accident Study

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