The Storage and Transportation of LNG: What Could Go Wrong?
| March 11, 2021
Lonnie E. Click, a fire chief in Benton County in southern Washington, was at his desk when he first heard the call: an explosion at a liquified natural gas storage facility.
The call was outside his jurisdiction but, based on what he was hearing on the radio, he decided to head to the scene. From atop a hill, Click could see smoke coming from the plant 20 miles away.
Federal investigators would later describe a “rolling detonation” at the facility on March 31, 2014, that set off a large fire and explosion that injured five workers and could be felt up to six miles away.
The explosion was so forceful that pieces of metal greater than 2,000 pounds were propelled more than a quarter of a mile, Click recalled at a 2016 conference.
Some 200 people in nearby Plymouth and communities within a two-mile radius were evacuated as the vaporized liquid, which could ignite and set off another fire or explosion, “flowed like water coming out of your faucet,” Click said.
The plant’s control room took a “significant hit” and all safety systems were destroyed, he said. No operable monitoring equipment was left at the plant, which had two 90-foot-tall storage tanks with a capacity of 1.2 billion cubic feet of LNG.
“The initiating event – an explosion with subsequent fire. All bets are off,” Click said. “It’s not a normal operation anymore.”
Firefighters were on the scene into the next morning in what was the most serious LNG accident in recent American history.
LNG: A record of safety but with notable exceptions
For more than seven decades, the United States has used LNG commercially and, for the most part, safely. Tanker ships have traveled more than 128 million miles without a serious accident at sea or in port, the Congressional Research Service said in a 2009 report.
But “the safety record of onshore LNG terminals is more mixed,” the report said. Since 1944, there have been 13 serious accidents involving LNG facilities.
Improved technology and standards have made LNG facilities safer but, the report said, “serious hazards remain” because LNG is “inherently volatile and is usually shipped and stored in large quantities.”
And when things go wrong with LNG, they can go catastrophically wrong.
In one of the deadliest LNG-related disasters in three decades, an explosion in 2004 flattened a large part of an Algerian port, killing 30 people and injuring 70 more.
And in 1944 in Cleveland, a tank with the equivalent of 90 million cubic feet of LNG exploded, setting off the most disastrous fire in city’s history and creating a hellscape that killed 130 people and displaced nearly 700.
A second tank exploded, setting off a tidal wave of fire that ultimately consumed 217 cars, 79 homes and two factories.
“The vaporizing gas also flowed along the curbs and gutters and into catch basins, through which it entered the underground sewers, exploding from time to time, ripping up pavement, damaging underground utility installations, and blowing out manhole covers,” according to a Case Western Reserve University history of the fire.
“An LNG accident would be a “black swan” event, a rare occurrence with potentially severe outcomes.”— Patrick Hardy, chief executive of Hytropy Disaster Management, a disaster preparedness firm
In the past 10 years, there have been 22 reportable LNG incidents, resulting in a total of $82.1 million in property damage and related costs, federal data show. At $45 million, the costliest was at the Williams Companies plant in Plymouth, Wash.
What happened in Algeria, Cleveland and Plymouth underscores the potential dangers of LNG as New Fortress Energy proposes to haul the super-cooled natural gas nearly 200 miles by rail and highway from a plant in Wyalusing, Pa., to a Delaware River port in Gibbstown, N.J.
The project would mean up to 100 LNG rail cars – critics call them “bomb trains” – and hundreds of highway tankers snaking through or near densely populated communities, such as Allentown, Reading, Scranton and Wilkes-Barre and sections of Philadelphia and its suburbs.
New Fortress has not publicly disclosed its rail and highway routes but a map created by the FracTracker Alliance shows various paths could potentially cut through as many as 18 Pennsylvania and New Jersey counties, 15 of them in the Delaware River watershed.
In 2019, an affiliate of New Fortress secured a groundbreaking special permit from federal regulators to transport LNG by rail in cryogenic tankers that project supporters say would offer multiple layers of protections.
An environmental assessment for the special permit dismissed the accidents in Plymouth and Cleveland as not analogous to transporting LNG by highway or rail.
It said the Cleveland disaster resulted from “embrittlement of the inner metal tank because it was unsuitable for cryogenic temperatures” and the Plymouth explosion was caused by “human error” – failing to properly purge flammable vapors from piping during maintenance activities.
The National Transportation Safety Board objected to the special LNG rail permit, saying the project sponsors extrapolated findings based on data about the accident history of similar hazardous materials transported in a small fleet of similar rail tank cars.
“Making engineering assumptions based on the performance of pressure tank cars with completely different features and operating parameters” (as was done in a risk analysis by a consultant company hired by New Fortress) “does not provide a statistically significant or valid safety assessment,” the agency said.
The environmental group Earthjustice, which opposes the LNG-by-rail plan, has warned that the project “would allow an unprecedented, abrupt opening of the United States mainline rail system to long, heavy, hard‐to‐handle unit trains of LNG, using a 50‐year-old rail tank car design” that has never been used to transport LNG.
Bradley Marshall, a staff attorney for Earthjustice, said what happened in Cleveland could happen with the rupture of rail tankers carrying more than 30,000 gallons of LNG: A leak makes its way into a sewer system and ignites.
“It would easily destroy an entire city that way,” he said.
Predicting LNG’s uncontrolled behavior
Patrick Hardy, chief executive of Hytropy Disaster Management, a disaster preparedness firm, described an LNG accident as a “low-probability, high-consequence” catastrophe, or what emergency managers refer to as a “black swan” event, a rare occurrence with potentially severe outcomes.
In the event of an LNG accident, emergency response guidance dictates evacuating a mile in every direction – a daunting prospect in a densely populated area like Philadelphia, where Earthjustice said it would mean the speedy relocation of some 36,000 people.
Fred Millar, a rail safety and hazardous materials transportation expert, said a worst-case scenario of an LNG release would be a dense, ground-hugging vapor cloud that travels far downwind and explodes in a confined space.
The vapor cloud would not have to be confined in a conventional structure but could be trapped “under a rail car, between two homes, in a ditch or ravine or being held up by a wall or even dense vegetation,” he wrote in affidavit filed by Earthjustice.
LNG in its liquid state is not flammable but the vapors from a release or spill are flammable at concentrations of 5 to 15 percent. If LNG were to spill near an ignition source, the evaporating gas could burn above the spill, resulting in a “pool fire” that would spread as the spill spread.
“Such a pool fire is intense, burning far more hotly and rapidly than crude oil or gasoline fires, and it cannot be extinguished,” two Democratic members of Congress, Peter DeFazio of Oregon and Tom Malinowski of New Jersey, noted in a letter to the Pipeline and Hazardous Materials Safety Administration in 2019. “The risks of such an incident include thermal radiation” that could be felt up to a mile away from an explosion.
LNG has long been safely moved by marine vessels and highway tankers but transporting it by rail changes the equation, Hardy said.
“It creates a new system of issues,” he said, adding that factors such as how many curves a train might take along a route and the number of crossings it makes, should be considered.
Vandalism of rail tracks is also not unheard of, he added. “Kids screw around with trains,” he said.
From 1997 to 2018 in Bradford County, Pa., home to Wyalusing, there were nine casualties in railroad accidents, two of which were fatal. Both fatalities were related to individuals trespassing on the tracks, according to the county’s hazard mitigation plan. And from 1977-99, there were three derailments that resulted in unspecified hazardous materials being leaked, the report said.
“Railroad collisions and derailments exert so much crush force. Cars pile up on each other and are fire and explosion hazards.”— Fred Millar, rail safety and hazardous materials expert
The primary risk associated with transporting LNG in a rail tanker would be a derailment, a breach of the vessel and a fire. This could range from a relatively small fire from a controlled release to an explosion in what is known as a BLEVE, boiling liquid expanding vapor explosion.
“Railroad collisions and derailments exert so much crush force,” Millar said. “Cars pile up on each other and are fire and explosion hazards.”
A nick or puncture of the outside casing of a rail tanker could potentially compromise its protective vacuum, undermining the overall effectiveness of the insulation that keeps LNG super-cooled to 260 degrees below zero, said Wendy J. Buckley, president and chief executive officer of Specialty Transportation and Regulatory Services.
What would happen would be akin to a crack in a window of an airplane at a high altitude – it would depressurize the cabin, or in this case, the tanker car.
“The loss of insulation would allow heat transfer to occur from the surrounding air into the inner tank,” she said. “This would warm the very cold material inside, causing it to ‘boil’ and turn to vapor, similar to the way a pot of water turns to steam when it boils. This vapor would increase the pressure in the tank. The faster it warmed, the more intense the pressure increase would be.”
The upgraded rail tanker, known as a DOT-113C120W9, features two pressure relief devices instead of one, so it could vent much faster and “therefore forestall catastrophic failure much longer” than an older model DOT-111 tank car model, which had a single hull with one layer of steel and no vacuum buffer, she said.
The likelihood of a chain reaction of one tank car after another breaching and catching fire is great, and would require the cars to be relatively close to each other, she said.
“However, even when a train derails and several cars end up piled up together, it’s never all 110 cars in the heap,” she said. “It would be statistically impossible for all 110 cars to end up in a single heap and explode simultaneously or for all 110 cars to catch fire in succession due to a cascading BLEVE.”
How do the rail tankers perform?
The rail tankers permitted to transport LNG would feature thicker outer shells and would need to be manufactured from scratch. But the existing models upon which those tankers are based have not been immune to trouble.
From 1980 to 2017, there were 14 cases of DOT-113 tank cars being damaged. In two of those cases, the outer jacket and inner tank were breached – the most serious kind of damage.
There were four additional instances in which tankers lost their cargo because of damage or failures related to valves or fittings, federal records show.
In May 2011 in Moran, Kan., three tankers with ethylene were breached in a derailment and caught fire.
More than 50 people had to be evacuated and the fire – “a large orange glow” in the sky that could be seen from at least 10 miles away, according to federal records – burned through the night.
The fire consumed the contents of one tanker and two other tankers were breached with explosives to expedite the consumption of their contents. Adjusted for inflation, the derailment did more than $2 million in damage.
The other serious derailment happened in October 2014 in Mer Rouge, La., after a train struck a tractor-trailer that was stuck on the tracks. A DOT-113 tanker and a tank car similar in design filled with refrigerated liquid argon were breached. About 50 homes and businesses had to be evacuated.
No injuries or fatalities were reported in either derailment but DeFazio and Malinowski noted that federal regulators acknowledged there is little emergency responders can do if a cryogenic liquid rail tanker is breached.
“Response and mitigation techniques beyond evacuation for breaches in cryogenic tank cars do not exist or are impractical during a derailment scenario,” a draft environmental statement for the special rail permit said.
Other derailments generally do not result in a loss of the entire cargo compared to breaches of cryogenic tankers.
The average quantity spilled per derailment involving cryogenic liquids carried in DOT-113 tankers was 45,769 gallons, or about 10 times greater than the average quantity spilled for all rail incidents involving hazardous materials from 2005 to 2017.