Maritime Security: Public Safety Consequences of a Liquefied	 
Natural Gas Spill Need Clarification (21-MAR-07, GAO-07-633T).	 
                                                                 
Liquefied natural gas (LNG) is a supercooled liquid form of	 
natural gas. U.S. LNG imports are projected to increase to about 
17 percent of natural gas supplies by 2030, from about 3 percent 
today. To meet this increase, energy companies have submitted 32 
applications for new terminals. If a terrorist attack on an LNG  
tanker caused a spill, potential hazards, such as fire, 	 
asphyxiation, and explosions, could result. The Department of	 
Energy (DOE) recently funded a study to conduct small- and	 
large-scale experiments to refine and validate models that	 
calculate how heat from large LNG fires would affect the public. 
This testimony is based on GAO's recently released report,	 
Maritime Security: Public Safety Consequences of a Terrorist	 
Attack on a Tanker Carrying Liquefied Natural Gas Need		 
Clarification (GAO-07-316). To prepare this report, GAO examined 
the results of six recent unclassified studies on the effects of 
an LNG spill and convened a panel of 19 experts to identify areas
of agreement on the consequences of a terrorist attack on an LNG 
tanker. 							 
-------------------------Indexing Terms------------------------- 
REPORTNUM:   GAO-07-633T					        
    ACCNO:   A67088						        
  TITLE:     Maritime Security: Public Safety Consequences of a       
Liquefied Natural Gas Spill Need Clarification			 
     DATE:   03/21/2007 
  SUBJECT:   Emergency preparedness				 
	     Hazardous substances				 
	     Homeland security					 
	     Importing						 
	     Liquefied natural gas				 
	     Maritime security					 
	     Natural gas					 
	     Port security					 
	     Ships						 
	     Tanks (containers) 				 
	     Terrorism						 
	     Transportation terminals				 
	     Water transportation				 
	     Public safety					 

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GAO-07-633T

   

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                 United States Government Accountability Office

Testimony

GAO

Before the Committee on Homeland Security, House of Representatives

For Release on Delivery                                  MARITIME SECURITY 
Expected at 10:00 a.m. EDT                                                 
Wednesday, March 21, 2007                                                  
                              Public Safety Consequences of a Liquefied       
                              Natural Gas Spill Need Clarification            
                              Statement of Jim Wells, Director Natural        
                              Resources and Environment                       

GAO-07-633T

MARITIME SECURITY

Public Safety Consequences of a Liquefied Natural Gas Spill Need
Clarification

  What GAO Found

The six studies GAO reviewed examining the potential effect of a fire
resulting from an LNG spill produced varying results; some studies also
examined other potential hazards of a large LNG spill and reached
consistent conclusions on explosions. Specifically, the studies'
conclusions about the distance at which 30 seconds of exposure to the heat
(heat hazard) could burn people ranged from less than 1/3 of a mile to
about 1-1/4 miles. Sandia National Laboratories (Sandia) conducted one of
the studies and concluded, based on its analysis of multiple attack
scenarios, that a good estimate of the heat hazard distance would be about
1 mile. Federal agencies use this conclusion to assess proposals for new
LNG import terminals. The variations among the studies occurred because,
with no data on large spills from actual events, researchers had to make
numerous modeling assumptions to scale up the existing experimental data
for large LNG spills. Three of the studies also examined other potential
hazards of an LNG spill, including LNG vapor explosions and sequential
failure of multiple tanks on the LNG vessel (cascading failure). All three
studies considered LNG vapor explosions unlikely unless the vapors were in
a confined space. Finally, the Sandia study examined the potential for
cascading tank failure and concluded that only three of the five tanks in
a typical tanker would potentially be affected, and that such failure
would increase the duration of the LNG fire.

GAO's panel of experts generally agreed on the public safety impact of an
LNG spill caused by a terrorist attack, disagreed on specific conclusions
of the Sandia study, and suggested future research priorities. Experts
agreed that the most likely public safety impact of an LNG spill is the
heat impact of a fire and that explosions are not likely to occur unless
LNG vapors are in confined spaces. However, the experts did not all agree
with the heat hazard and cascading failure conclusions reached by the
Sandia study. Finally, they suggested priorities to guide future research
aimed at clarifying uncertainties about heat impact distances and
cascading failure. DOE's recently funded study involving large-scale LNG
fire experiments addresses only some of the research priorities the expert
panel identified.

                 United States Government Accountability Office

United States Government Accountability Office Washington, DC 20548

Mr. Chairman and Members of the Committee:

I am pleased to be here to discuss the results of our recently released
report on the public safety consequences of a terrorist attack on a tanker
carrying liquefied natural gas (LNG).^1 As you know, LNG is a supercooled
liquid form of natural gas, which, if spilled, poses potential hazards,
such as fire, asphyxiation, and explosions. U.S. imports of LNG, now about
3 percent of total U.S. natural gas supplies, are projected to be about 17
percent of U.S. supplies by 2030. To meet this increased demand, energy
companies have submitted 32 applications to federal regulators to build
new terminals for importing LNG in 10 states and 5 offshore areas. Access
to accurate information about the consequences of LNG spills is crucial
for developing risk assessments for LNG siting decisions. Despite several
recent modeling studies of the consequences of potential LNG spills,
uncertainties remain about the risks such spills would pose to the public.
One of these studies, conducted by Sandia National Laboratories (Sandia)
in 2004, is used by the Coast Guard to assess the suitability of waterways
for LNG tankers traveling to proposed LNG facilities. In this context, DOE
has recently funded a new study that will conduct small- and large-scale
LNG fire experiments to refine and validate existing models that calculate
how heat from large LNG fires would affect the public.

My testimony today summarizes the results of our report. Specifically, I
will (1) describe the results of recent unclassified studies on the
consequences of an LNG spill and (2) identify the areas of agreement and
disagreement among experts concerning the consequences of a terrorist
attack on an LNG tanker. To address these issues, we examined six
unclassified studies of the consequences of LNG spills. We also convened a
Web-based panel of 19 experts to identify areas of agreement and
disagreement on LNG spill consequence issues. Because some additional
studies are classified, we will be issuing a separate classified report
with related findings at a later date.

^1GAO, Maritime Security: Public Safety Consequences of a Terrorist Attack
on a Tanker Carrying Liquefied Natural Gas Need Clarification,
[3]GAO-07-316 (Washington, D.C.: Feb. 22, 2007). This report was prepared
at the request of this Committee, the House Committee on Energy and
Commerce, and Representative Edward J. Markey.

  Summary

The six unclassified studies we reviewed all examined the heat impact of
an LNG fire but produced varying results; some studies also examined other
potential hazards of a large LNG spill and reached consistent conclusions
on explosions. Specifically, the studies' conclusions about the distance
at which 30 seconds of exposure to the heat could burn people-- also
termed the heat impact distance--ranged from less than 1/3 of a mile to
about 1-1/4 miles. These variations occurred because, with no data on
large spills from actual events, researchers had to make numerous modeling
assumptions to scale up the existing experimental data for large LNG
spills. These assumptions involved the size of the hole in the tanker, the
number of tanks that fail, the volume of LNG spilled, key LNG fire
properties, and environmental conditions, such as wind and waves. Three of
the studies also examined other potential hazards of an LNG spill,
including LNG vapor explosions, asphyxiation, and the sequential failure
of multiple tanks on the LNG vessel (cascading failure). All three studies
considered LNG vapor explosions unlikely unless the vapors were in a
confined space. Only the Sandia study examined asphyxiation and concluded
that asphyxiation did not pose a hazard to the general public. Finally,
only the Sandia study examined the potential for cascading failure of LNG
tanks and concluded that only three of the five tanks on a typical LNG
vessel would be involved in such an event and that this number of tanks
would increase the duration of the LNG fire.

Our panel of 19 experts generally agreed on the public safety impact of an
LNG spill, disagreed on specific conclusions of the Sandia study, and
suggested future research priorities. Experts agreed on three main points:

(1) the most likely public safety impact of an LNG spill is the heat
impact of a fire; (2) explosions are not likely to occur in the wake of an
LNG spill unless the LNG vapors are in confined spaces; and (3) some
hazards, such as freeze burns and asphyxiation, do not pose a hazard to
the public. However, the experts disagreed with a few conclusions reached
by the Sandia study that the Coast Guard uses to assess the suitability of
waterways for LNG tankers going to proposed LNG terminals. Specifically,
all experts did not agree with the study's 1-mile estimate of heat impact
distance resulting from an LNG fire: 7 of 15 thought Sandia's distance was
"about right," 8 were evenly split on whether the distance was "too
conservative" or "not conservative enough," and 4 did not answer this
question. Experts also did not agree with the Sandia National
Laboratories' conclusion that only three of the five LNG tanks on a tanker
would be involved in a cascading failure. Finally, experts suggested
priorities to guide future research aimed at clarifying uncertainties
about heat impact distances and cascading failure, including large-scale
fire experiments, large-scale LNG spill experiments on water, the
potential for cascading
failure of multiple LNG tanks, and improved modeling techniques. DOE's
recently funded study involving large-scale LNG fire experiments addresses
some, but not all, of the research priorities the expert panel identified.

                                   Background

As scientists and the public have noted, an LNG spill could pose potential
hazards. When LNG is spilled from a tanker, it forms a pool of liquid on
the water. As the liquid warms and changes into natural gas, it forms a
visible, foglike vapor cloud close to the water. The cloud mixes with
ambient air as it continues to warm up, and eventually the natural gas
disperses into the atmosphere. Under certain atmospheric conditions,
however, this cloud could drift into populated areas before completely
dispersing. Because an LNG vapor cloud displaces the oxygen in the air, it
could potentially asphyxiate people who come into contact with it.
Furthermore, like all natural gas, LNG vapors can be flammable, depending
on conditions. If the LNG vapor cloud ignites, the resulting fire will
burn back through the vapor cloud toward the initial spill. It will
continue to burn above the LNG that has pooled on the surface--this is
known as a pool fire. Small-scale experiments to date have shown that LNG
fires burn hotter than oil fires of the same size. Both the cold
temperatures of spilled LNG and the high temperatures of an LNG fire have
the potential to significantly damage the tanker, causing a cascading
failure. Such a failure could increase the severity of the incident.
Finally, concerns have been raised about whether an explosion could result
from an LNG spill.

The Federal Energy Regulatory Commission is responsible for approving
applications for onshore LNG terminal sitings, and the U.S. Coast Guard is
responsible for approving applications for offshore sitings. In addition,
the Coast Guard reviews an applicant's Waterway Suitability Assessment,
reaches a preliminary conclusion on whether the waterway is suitable for
LNG imports, and identifies appropriate strategies that reduce the risk
posed by the movement of an LNG tanker.

    Studies Identified Different Distances for the Heat Effects of an LNG Fire,
    but Agreed on Other LNG Hazards

The six studies we examined identified various distances at which the heat
effects of an LNG fire could be hazardous to people. The studies' results
about the distance at which 30 seconds of exposure to the heat could burn
people ranged from less than 1/3 of a mile (about 500 meters) to about
1-1/4 miles (more than 2,000 meters). The studies' variations in heat
effects occurred because (1) different assumptions were made in the
studies' models about key parameters of LNG spills and (2) the studies
were designed and conducted for different purposes. Since no large-scale
data are available for LNG spills, researchers made numerous modeling
assumptions to scale up the existing experimental data for large spills.
Key assumptions made included hole size and cascading failure, waves and
wind, the volume of LNG spilled, and the amount of heat radiated from the
fire. For example, studies made assumptions for the size of the hole in
the LNG tanker that varied from less than 1 square meter up to 20 square
meters. Additionally, the studies were conducted for different purposes.
Two studies were academic analyses of the differences between LNG and oil
spills; three specifically addressed spills caused by terrorist attacks,
which was a concern in the wake of the September 11 attacks; and the final
study developed appropriate methods for regulators to use to estimate heat
hazards from LNG fires. Results of these studies can be found in our
report being released today.

Some studies also examined other potential hazards, such as explosions,
asphyxiation, and cascading failure, and identified their potential
impacts on public safety. Three studies examined the potential for LNG
vapor explosions, and all agreed that it is unlikely that LNG vapors could
explode if the vapors are in an unconfined space. Only one study examined
the potential for asphyxiation following an LNG spill if the vapors
displace the oxygen in the air. It concluded that fire hazards would be
the greatest problem in most locations, but that asphyxiation could
threaten the ship's crew, pilot boat crews, and emergency response
personnel. Finally, only the Sandia study examined the potential for
cascading failure of LNG tanks and concluded that only three of the five
tanks would be involved in such an event and that this number of tanks
would increase the duration of the LNG fire.

    Experts Generally Agreed That the Most Likely Public Safety Impact of an LNG
    Spill Is the Heat [ o] Effect of a Fire, but That Further Study Is Needed to
    Clarify the Extent of This Effect

The 19 experts on our panel generally agreed on the public safety impact
of an LNG spill, disagreed with specific conclusions of the Sandia study,
and suggested future research priorities.^2 Specifically:

Experts agreed that the main hazard to the public from a pool fire is the
heat from the fire, but emphasized that the exact hazard distance depends
on site-specific weather conditions; composition of the LNG (relative
percentages of methane, propane, and butane); and the size of the fire.

2We considered experts to be "in agreement" if more than 75 percent of them
indicated that they  completely agreed  or generally agreed  with a  given
statement. Not all experts commented on every issue discussed.

     o Eighteen of 19 experts agreed that the ignition of a vapor cloud over
       a populated area could burn people and property in the immediate
       vicinity of the fire. Three experts emphasized in their comments that
       the vapor cloud is unlikely to penetrate very far into a populated
       area before igniting.

         oWith regard to explosions, experts distinguished between
            explosions in confined spaces and in unconfined spaces. For
            confined spaces, such as under a dock or between the hulls of a
            ship, they agreed that it is possible, under controlled
            experimental conditions, to induce explosions of LNG vapors;
            however, a detonation--the more serious type of vapor cloud
            explosion--of confined LNG vapors is unlikely following an LNG
            spill caused by a terrorist attack. For unconfined spaces,
            experts were split on whether it is possible to induce such
            explosions under controlled experimental conditions; however,
            even experts who thought such explosions were possible agreed
            that vapor cloud explosions in unconfined spaces are unlikely to
            occur following an LNG spill caused by a terrorist attack.
          oOur panel of 19 experts disagreed with a few of the Sandia
            study's conclusions and agreed with the study authors'
            perspective on risk-based approaches to dealing with the hazards
            of potential LNG spills. For example:

     o Seven of 15 experts thought Sandia's heat hazard distance was "about
       right," and the remaining 8 experts were evenly split as to whether
       the distance was "too conservative" (i.e., larger than needed to
       protect the public) or "not conservative enough" (i.e., too small to
       protect the public). Officials at Sandia National Laboratories and our
       panel of experts cautioned that the hazard distances presented cannot
       be applied to all sites because of the importance of site-specific
       factors. Additionally, two experts explained that there is no "bright
       line" for hazards--that is, 1,599 meters is not necessarily
       "dangerous," and 1,601 meters is not necessarily "safe."
     o Nine of 15 experts agreed with Sandia's conclusion that only three of
       the five LNG tanks on a tanker would be involved in cascading failure.
       Five experts noted that the Sandia study did not explain how it
       concluded that only three tanks would be involved in cascading
       failure.
     o Finally, experts agreed with Sandia's conclusion that consequence
       studies should be used to support comprehensive, risk-based management
       and planning approaches for identifying, preventing, and mitigating
       hazards from potential LNG spills.

The experts also suggested priorities for future research--some of which
are not fully addressed in DOE's ongoing LNG research--to clarify
uncertainties about heat impact distances and cascading failure. These
priorities include large-scale fire experiments, large-scale LNG spill
experiments on water, the potential for cascading failure of multiple LNG
tanks, and improved modeling techniques. As part of DOE's ongoing
research, Sandia plans to conduct large-scale LNG pool fire tests,
beginning with a pool size of 35 meters--the same size as the largest test
conducted to date. Sandia will validate the existing 35-meter data and
then conduct similar tests for pool sizes up to 100 meters. Of the top 10
LNG research priorities the experts identified, only 3 have been funded in
the DOE study, and the second highest ranked priority, cascading failure,
was not funded. One expert noted that although the consequences of
cascading failure could be serious, because the extreme cold of spilled
LNG and the high heat of an LNG fire could damage the tanker, there are
virtually no data looking at how a tanker would be affected by these
temperatures.

                                  Conclusions
											 
It is likely that the United States will increasingly depend on LNG to
meet its demand for natural gas. Consequently, understanding and resolving
the uncertainties surrounding LNG spills is critical, especially in
deciding where to locate LNG facilities. While there is general agreement
on the types of effects of an LNG spill, the study results have created
what appears to be conflicting assessments of the specific heat
consequences of such a spill. These assessments create uncertainty for
regulators and the public. Additional research to resolve some key areas
of uncertainty could benefit federal agencies responsible for making
informed decisions when approving LNG terminals and protecting existing
terminals and tankers, as well as providing reliable information to
citizens concerned about public safety.

To provide the most comprehensive and accurate information for assessing
the public safety risks posed by tankers transiting to proposed LNG
facilities, we recommended that the Secretary of Energy ensure that DOE
incorporates the key issues the expert panel identified, particularly the
potential for cascading failure, into its current LNG study.

DOE concurred with our recommendation.

Mr. Chairman, this concludes my prepared statement. I would be happy to
respond to any questions that you or Members of the Committee may have.

  Contacts and Acknowledgments 
  
For further information about this testimony, please contact me at (202)
512-3841 or [email protected].  James W. Turkett, Janice  M. Poling,  and
Carol Herrnstadt  Shulman also made  key contributions  to
this statement.

(360817)

References

Visible links
3. http://www.gao.gov/cgi-bin/getrpt?GAO-07-316
*** End of document. ***