The Department of Energy (DOE) is taking another look at the potential safety and security risks of liquefied natural gas (LNG) tanker transportation in an attempt to reconcile three reports that reached conflicting conclusions. At the same time, the proposed siting of an ExxonMobil Corp. LNG terminal just south of the city limits of Mobile, AL, has stirred controversy over safety/security hazards there.

The DOE has directed the Sandia National Laboratories in Albuquerque, NM, to compare reports — published by Norman, OK-based Quest Consultants Inc., the National Oceanic and Atmospheric Administration (NOAA) and Massachusetts Institute of Technology Professor J. A. Fay — to “develop an understanding of the real risks” posed by LNG spills, said Sandia spokesman Chris Miller. The individual reports found that the LNG-related risks ranged from catastrophic to limited in nature.

The DOE-commissioned Quest study, which was issued in 2001, concluded that a large LNG spill, once ignited, would create a smaller fire and pose less hazards than critics had indicated. John Cornwell, who authored the report, was not surprised the department was taking another look at the possible dangers of LNG. Studies “are constantly under review,” he said, adding that the Quest report was a “snapshot in time at that moment.”

Rep. Edward Markey (D-MA) last month criticized the DOE and other federal regulators for using the Quest report to assure the public of the allegedly benign risks associated with LNG.

The ExxonMobil LNG controversy has sparked a series of articles by the local newspaper, the Mobile Register, the latest of which reported on a confidential study commissioned by Tractebel LNG North America LLC shortly after the Sept. 11 terrorist attacks that it says suggested a similar assault on an LNG tanker “could evolve into a chain reaction of explosions and fires” more severe than had been previously imagined.

This “scenario would almost inevitably lead to a catastrophic failure of the ship and a spill of LNG that would be much larger and much more dangerous than anything so far considered in federal studies and assessments of LNG hazards,” the Alabama newspaper said.

“Virtually every study used by federal regulators considers the loss of less than one-fifth of the cargo onboard a typical LNG tanker to be the ‘worst-case’ accident scenario,” resulting in a fire about a half-mile wide. But the Tractebel-commissioned study offered “several scenarios in which even a relatively small rupture in one of the five cargo tanks onboard a ship could ‘escalate’ and lead to ruptures in multiple tanks,” the newspaper review of the report said. Tractebel LNG owns the Distrigas LNG terminal in Everett, MA.

It’s “hard for us in the industry to imagine the breach of all five tanks onboard,” countered Paula Rockstroh, a spokeswoman for Tractebel North America in Houston, TX. This has never happened, “and the credit goes to the design of the [LNG tanker] vessels.”

The 95-page study was conducted by Lloyd’s Register of Shipping, a leading worldwide maritime industry consultant. The captain of the Port of Boston, a U.S. Coast Guard-appointed official, directed Tractebel to undertake the study, according to Rockstroh. He wanted to take a “fresh look” at the safety and security concerns associated with LNG in the wake of Sept. 11.

The study’s conclusions were “one of the tools” used by the Coast Guard when it reopened Boston Harbor after a three-week embargo on LNG shipments in the fall of 2001, she said. The busy harbor was closed to LNG tankers while a safety/security review was done. Since then, Distrigas reports it has received more than 100 tanker cargoes of LNG at its Everett facility “without incident.”

“We stand behind the study,” Rockstroh said. “We stand by the fact we did everything to analyze that [situation] safely,” and the company “shared everything possible” with local, state and federal safety regulators. “Absolutely, from Day One,” she responded, when asked if the Coast Guard was privy to all of the conclusions in the report.

The entire study apparently has never been made public. Requests by NGI to Tractebel and Lloyd’s Register for the report were denied. The Mobile Register said it obtained a copy of the study last week from sources who had been asked to review it earlier. The report “contains sensitive security information,” and “was never intended for widespread public distribution,” according to a joint statement issued by Tractebel and Lloyd’s Register Tuesday. “We don’t want to put a recipe for disaster in someone’s hands,” said Rockstroh.

In a press statement accompanying the study’s findings in late 2001, Lloyd’s Register said “the report indicated that if a ship was attacked, the likely consequence would probably involve a fire, not an explosion.” Congressional lawmakers, the DOE, the Federal Energy Regulatory Commission and the LNG industry often have cited the study as “proof that LNG tanker operations pose only limited threats to the public,” the Alabama newspaper said. But the information made public represents just a small portion of the report’s conclusions, and the actual study paints a more dire scenario, it noted.

“The analysis that receives the most attention in the Lloyd’s study is the possibility that a tanker could be lost completely as a result of multiple explosions of LNG and widespread fracturing of the hull,” the published account said.

“The authors of the study noted that if a breach of both hulls in a doubled-hulled tanker occurred as a result of an explosives charge placed by terrorists, ‘there is a risk of an explosive mixture forming’ within the confined spaces inside the ship. In the seconds after the deliberate blast, multiple ignitions could flare, exhaust themselves and flare again on the escaping cargo.”

The “ignition of this flammable mixture will result in a…partly restricted explosion event,” the article said. This “explosion event” could be compounded by a type of flameless explosion, caused when escaping LNG comes into contact with water, warms, and in a split second expands its volume 200 times,” it noted. “The explosion forces acting upon the tank sides are likely to be large.”

Both Tractebel and affiliate Distrigas attacked the Mobile Register article. It “took information out of context and seriously mischaracterized discussion on this issue by asserting that successive tank failure is the ‘analysis that receives the most attention'” in the report. The Lloyd’s Register report presented a “whole range of theoretical possibilities…to equip Tractebel LNG North America and…responsible public safety and regulatory officials with as much information as possible to create a comprehensive risk analysis,” they said.

The newspaper focuses on “only one of 19 overall findings” of the report, and “substantially overstates the likelihood that this particular scenario will occur,” Tractebel and Distrigas noted. “For this scenario to take place, there must be a confluence of several causal events: 1) a successful terrorist attack on the LNG vessel (itself highly unlikely to occur given enhanced security measures), resulting in 2) the breaching of the outer hull, resulting in 3) the breaching of the inner hull, followed by 4) brittle fracturing and weakening of the internal vessel structure, 5) immediate ignition within the inner hull, and 6) a detonation-type explosion.”

The probability of these events occurring in the “appropriate causal and temporal sequence is quite small, particularly the likelihood of immediate ignition within the inner hull,” they said. Because it is so unlikely, “this particular scenario forms only a small part of the report and in no respect can be considered [the] ‘analysis that receives the most attention.’ Instead, the majority of the report deals with the more credible scenario of LNG release and ignition outside of the hull.”

In addition, the companies accused the newspaper of “selectively” quoting from the Lloyd’s Register report, while excluding “relevant passages.” For example, they noted the study found that if the outer hull of a tanker is breached by an explosion, “there is a good possibility that the inner hull will deflect the residue of the explosive force and remain intact.”

The newspaper claims that previous government and industry references to the report mentioned only three or four of the 19 conclusions in the study. Also it notes that a terrorist attack succeeded in punching a 26-foot wide hole in a double-hulled oil tanker in October 2002 in Yemen.

The controversy has grown out of ExxonMobil’s decision to pay $38 million for a three-year option on 200 acres of land as a possible site for an LNG receiving terminal along Mobile Bay just outside the Mobile city limits.

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