Table Of ContentFlight Testing of an Advanced Airborne
Natural Gas Leak Detection System
TYPE OF REPORT: Final
REPORTING PERIOD START DATE: October 1, 2003
REPORTING PERIOD END DATE: December 31, 2004
AUTHORS: Dr. Dawn Lenz, Dr. Raymond T. Lines,
Dr. Darryl Murdock, Jeffrey Owen,
Dr. Steven Stearns, Michael Stoogenke
October 2005
DOE AWARD NUMBER: DE-FC26-03NT41877
ITT INDUSTRIES SPACE SYSTEMS, LLC
1447 ST. PAUL STREET
ROCHESTER, NY 14653
“This report was prepared as an account of work sponsored by an agency of the United States
Government. Neither the United States Government nor any agency thereof, nor any of their
employees, makes any warranty, express or implied, or assumes any legal liability or
responsibility for the accuracy, completeness, or usefulness of any information, apparatus,
product, or process disclosed, or represents that its use would not infringe privately owned
rights. Reference herein to any specific commercial product, process, or service by trade name,
trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement,
recommendation, or favoring by the United States Government or any agency thereof. The views
and opinions of authors expressed herein do not necessarily state or reflect those of the United
States Government or any agency thereof.”
ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
Abstract
ITT Industries Space Systems Division (Space Systems) has developed an airborne natural gas
leak detection system designed to detect, image, quantify, and precisely locate leaks from natural
gas transmission pipelines. This system is called the Airborne Natural Gas Emission Lidar
(ANGEL) system. The ANGEL system uses a highly sensitive differential absorption Lidar
technology to remotely detect pipeline leaks. The ANGEL System is operated from a fixed wing
aircraft and includes automatic scanning, pointing system, and pilot guidance systems. During a
pipeline inspection, the ANGEL system aircraft flies at an elevation of 1000 feet above the
ground at speeds of between 100 and 150 mph.
Under this contract with DOE/NETL, Space Systems was funded to integrate the ANGEL sensor
into a test aircraft and conduct a series of flight tests over a variety of test targets including
simulated natural gas pipeline leaks. Following early tests in upstate New York in the summer
of 2004, the ANGEL system was deployed to Casper, Wyoming to participate in a set of DOE-
sponsored field tests at the Rocky Mountain Oilfield Testing Center (RMOTC).
At RMOTC the Space Systems team completed integration of the system and flew an operational
system for the first time. The ANGEL system flew 2 missions/day for the duration for the 5-day
test. Over the course of the week the ANGEL System detected leaks ranging from 100 to 5,000
scfh.
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ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
Table of Contents
ABSTRACT....................................................................................................................................I
1.0 EXECUTIVE SUMMARY...............................................................................................1
2.0 REPORT DETAILS ..........................................................................................................3
2.1 EXPERIMENTAL METHODS...............................................................................................3
2.1.1 Background.............................................................................................................3
2.1.2 Objective.................................................................................................................3
2.1.3 The Physics behind DIAL gas detection.................................................................4
2.1.4 ANGEL System Overview........................................................................................6
2.2 RESULTS AND DISCUSSION - EARLY FLIGHT TESTS (BUFFALO, NY).............................11
2.2.1 Objective of Early Flight Tests.............................................................................11
2.2.2 Creation of a simulated natural gas leaks for flight testing.................................12
2.2.3 Flight One – (3 September 2004)..........................................................................14
2.2.4 Flight Two – (3 September 2004).........................................................................15
2.2.5 Flight Three – (7 September 2004).......................................................................15
2.2.6 Conclusions from early flight tests.......................................................................17
2.3 OVERVIEW OF RMOTC FIELD TEST (CASPER, WY) .....................................................17
2.3.1 RMOTC Field Test................................................................................................20
2.4 RMOTC SUMMARY AND DISCUSSION...........................................................................22
2.5 CONCLUSIONS................................................................................................................25
2.5.1 Post RMOTC flight testing....................................................................................26
2.5.2 Qualitative Comments on ANGEL Technology....................................................28
3.0 ACKNOWLEDGEMENTS ............................................................................................28
4.0 GRAPHICAL MATERIAL............................................................................................29
5.0 REFERENCES.................................................................................................................31
6.0 BIBLIOGRAPHY............................................................................................................32
7.0 LIST OF ACRONYMS AND ABBREVIATIONS.......................................................34
ATTACHMENT 1: ITT EQUIPMENT PROVIDER TEST REPORT..........................................................35
ATTACHMENT 2: ITT ANGEL CUSTOMER REPORT – 14 SEPT 2004 COLLECTION..............45
ATTACHMENT 3: ITT ANGEL CUSTOMER REPORT – 15 SEPT 2004 COLLECTION..............54
ATTACHMENT 4: ITT ANGEL CUSTOMER REPORT – 16 SEPT 2004 COLLECTION..............64
ATTACHMENT 5: ITT ANGEL CUSTOMER REPORT – 17 SEPT 2004 COLLECTION..............73
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ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
1.0 Executive Summary
The existing U.S. natural gas transmission infrastructure consists of over 300,000 miles of buried
pipeline. DOE estimates that natural gas consumption will increase by over 50% percent (to 34
trillion cubic feet) by 2020, placing additional demands on the country’s aging natural gas
infrastructure. This combination of aging pipeline materials, increased demand, and utility
deregulation presents an environment where natural gas emissions may occur with greater
frequency and volumes. The reduction of these natural gas transmission pipeline emissions is
critical to addressing several subjects of national importance, including: (1) natural gas
conservation; (2) public and environmental safety; (3) greenhouse gas emissions; and (4) the
overall cost of natural gas.
With the intent of improving the way pipelines are monitored for emissions, in 2001 a team of
Space Systems scientists and external consultants was tasked to assess the ideal manner in which
to remotely sense natural gas pipeline leaks from the air. Ultimately Differential Absorption
Lidar (DIAL) technology was selected as the most sensitive and effective technique for detecting
and quantifying the methane and ethane in gas pipeline leaks.
ITT Industries Space Systems Division (Space Systems) has developed an airborne DIAL system
designed to detect, image, quantify, and precisely locate leaks from natural gas transmission
pipelines. This system is called the Airborne Natural Gas Emission Lidar (ANGEL) system.
The ANGEL System is operated from a fixed wing aircraft and includes automatic scanning,
pointing, and pilot guidance systems. During a pipeline inspection, the ANGEL system aircraft
operates at an elevation of 1,000 feet above the ground flying speeds of between 100 and 150
mph.
The objective of this effort was to flight test the ANGEL system in an operational environment.
The two major phases of flight-testing for this effort consisted of early flight tests in Upstate
New York, followed by participation in a DOE/DOT funded Field Test of Remote Sensing Gas
Leak Detection Systems at the Rocky Mountain Oilfield Testing Center (RMOTC) near Casper
Wyoming in September of 2004.
During early flight tests, the major objective was to debug sensor operation in the test aircraft
and obtain initial characterization of ANGEL operation and capabilities. During this phase of
the effort ITT successfully tested a range of sensor functionality including, ability to operate the
system in test aircraft, laser power and stability, receiver system operation and sensitivity,
pointing system performance and accuracy, and the ability to successfully process and analyze
raw sensor data with ground processing algorithms and software.
In September, the Space Systems ANGEL System participated in a government funded field test
of remote sensing leak detection systems. The United States Department of Energy, National
Energy Technology Laboratory (NETL) and the United States Department of Transportation,
Office of Pipeline Safety (OPS) jointly funded this field test. This field test was held from
September 12-17, 2004 at the DOE’s Rocky Mountain Oilfield Testing Center (RMOTC).
RMOTC’s field site is the Teapot Dome Field, 35 miles north of Casper, WY. The test was
organized and run by the Southwest Research Institute (SWRI) in cooperation with the NETL,
OPS, RMOTC, a number of pipeline industry advisors, and the remote sensing system
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ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
technology providers. A total of 6 industry and government groups (technology providers) were
invited to participate in this test.
During the DOE RMOTC field demonstration, the functionality of all major ANGEL systems
was verified including gas detection, gas quantification, sensor targeting, laser scanning, data
logging, data analysis, mission planning and flight operations. The system was flown at every
opportunity from Sunday afternoon through Friday evening for a total of 11 flights.
Approximately 80 gigabytes of raw data was collected for each day of operation. Although no
usable DIAL data was collected on Sunday or Monday of the RMTOC demonstration, sensor
performance data collected on these early flights allowed the ANGEL team to identify and repair
a damaged optical component in the sensor. Much of the system’s capability was untested prior
to this demonstration and the event provided an unparalleled opportunity to operate, learn and
ultimately improve the system.
Space Systems was pleased to participate in the DOE/DOT facilitated Demonstration of Remote
Gas Leak Detection Systems at RMOTC. At this event we were able to demonstrate for the first
time many aspects of the ANGEL System’s capabilities. These included the ability to efficiently
detect, quantify, geo-locate and image natural gas leak plumes from the air. During this
demonstration the ANGEL team learned a number of very valuable lessons.
• We validated the concept of using Differential Absorption Lidar (DIAL) for gas leak
detection and quantification from a fixed wing aircraft. Integration of the sensor into the
test aircraft was completed at the Casper Airport. The first fully integrated ANGEL
DIAL data ever collected was on 14 September 2004, the second day of the RMOTC test.
The ANGEL system was successful at detecting and quantifying a majority of leaks of
500 scfh and larger.
• We confirmed that the ANGEL Intelligent Pointing and Scanning System allowed the
aircraft to fly the Virtual Pipeline end-to-end at high speed and inspect 100% of the
pipeline on a single pass. The ability to collect data accurately, rapidly, and efficiently is
critical to future commercial operations.
• We challenged the Beta version of our ground data processing software and it worked
well throughout the week. The experience of having to rapidly process vast quantities of
data during the demonstration is currently driving major improvements in the area of
automated data processing and analysis.
• We verified the relationship between laser output power and our ability to detect leaks.
This was one of the most important lessons learned at RMOTC. Increasing laser power
greatly improves our ability to lock on a set wavelength and greatly improves the signal
to noise ratio of the data.
Our understanding of the phenomenology of DIAL gas leak detection has been greatly improved
by our participation in this effort. Over the course of this study we imaged gas leak plumes of
various sizes and shapes literally hundreds of times. The data collected during this study has
been invaluable for gaining a better understanding gas leak behavior under a range of real-world
conditions.
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ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
2.0 Report Details
2.1 Experimental Methods
2.1.1 Background
The existing U.S. natural gas transmission infrastructure consists of over 300,000 miles of buried
pipeline. DOE estimates that natural gas consumption will increase by over 50% percent (to 34
trillion cubic feet) by 2020, placing additional demands on the country’s aging natural gas
infrastructure. This combination of aging pipeline materials, increased demand, and utility
deregulation presents an environment where natural gas emissions may occur with greater
frequency and volumes. The reduction of these natural gas transmission pipeline emissions is
critical to addressing several subjects of national importance, including: (1) natural gas
conservation; (2) public and environmental safety; (3) greenhouse gas emissions; and (4) the
overall cost of natural gas.
In the U.S., by regulation, all Class 1 and Class 2 pipelines must be inspected for leaks at least
once each calendar year. Class 3 and 4 pipelines must be inspected 2 to 4 times each year.
Current pipeline leak detection methods rely heavily on inspection crews walking (1–2 mph) or
driving slowly (4 mph) along the right of way using flame ionization detectors to sample the air
and detect the presence of hydrocarbons at, or near ground, level. This technique is slow,
inefficient, and prone to false alarms. Recently developed, truck-mounted optical systems that
detect methane are an improvement in some situations but are still quite limited.
With the intent of improving the way pipelines are monitored for leaks, a team of Space Systems
scientists and external consultants was tasked to assess the ideal manner in which to remotely
sense natural gas pipeline leaks from the air. Participants in this study included world-class
experts in active and passive remote sensing and experts in the integration of remote sensing
instruments into light aircraft. The approaches investigated included: Hyperspectral Imaging
(HSI), Radar Imaging, Backscatter Absorption Gas Imaging (BAGI), Gas Correlation
Spectroscopy (GCS), Active Gas Correlation Spectroscopy (AGCS), and Differential Absorption
Lidar (DIAL) [3]. This investigation indicated that an active remote sensing approach, using
DIAL, would be the most sensitive and effective technique for detecting and quantifying the
methane and ethane in natural gas pipeline leaks.
2.1.2 Objective
The objective of this effort was to flight test a high sensitivity, broad-coverage, natural gas leak
detection systems in an operational environment. Space Systems Airborne Natural Gas Emission
Lidar (ANGEL) System was designed to accurately detect, image, quantify, and geo-locate leaks
from natural gas transmission pipelines. The system operates in a wide variety of terrain and
weather conditions. The ANGEL System, when used commercially, will provide a major
breakthrough in speed, cost effectiveness, and safety of monitoring the nation’s natural gas
transmission pipeline system [1]. The two major phases of flight-testing for this effort consisted
of early flight tests in Upstate New York, followed by participation in a DOE/DOT funded Field
Test of Remote Sensing Gas Leak Detection Systems at the Rocky Mountain Oilfield Testing
Center (RMOTC) near Casper Wyoming in September of 2004.
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ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
2.1.3 The Physics behind DIAL gas detection
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Figure 1. Generic representation of DIAL on-line and off-line positions
Our chosen method of detecting methane plumes is an active remote sensing technology known
as Differential Absorption LIDAR (DIAL). DIAL is the use of at least two beams of light tuned
on and off of an absorption feature of the gas species to be measured. By comparing the light
from the on-resonance beam to the light in the off-resonance beam, the concentration of gases
from long range may be inferred (Figure 1).
Our design uses lasers to generate the light beams. The system takes light reflected from the
ground to generate a signal on a detector. Each wavelength is detected separately. The basic
LIDAR equation describing the light reflected from the surface is shown in Figure 2.
EE((ll)) == PPtt ·· xx((ll))xx((RR ))·· DD22 ·· rr((ll)) ·· TT22 ·· eexxpp(cid:231)(cid:230)(cid:231)(cid:230) -- 22(cid:242)(cid:242) RR NN((RR))ss((ll))ddRR(cid:247)(cid:246)(cid:247)(cid:246)
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Figure 2. Basic DIAL equation
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ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
The term E(l ) is the energy contained in the pulse that has traveled to the ground and back. This
return energy depends on many things as expressed by the right hand side of the equation. The
first term on the right hand side, gives the per-pulse energy of the transmitter. The second term
combines effects from the optical system alignment and spectral response. The next term shows
the effect of the receiver solid angle. These terms are governed largely by the lidar optical
design. The next two terms show the dependence on the surface reflectivity (assumed
Lambertian in this equation) and the atmosphere. The final term shows the effect of the
concentration of methane, N(R), and the optical properties of methane as represented by s (l),
the methane absorption cross-section.
These return signals are used to determine the methane concentration multiplied by the depth of
the methane plume. This quantity is called the concentration path length or CPL and is given by
the following equation:
C (cid:230) (cid:230) E (cid:246) (cid:246)
CPL = Nh = ( )(cid:231)(cid:231) ln(cid:231)(cid:231) off (cid:247)(cid:247) (cid:247)(cid:247)
2s l Ł Ł E ł ł
on
The CPL is an integrated concentration and can be thought of as giving a measure of the
concentration of a cylindrical shaped sample of the plume of height (or path length) h. (Figure 3)
CCCPPPLLL SSSaaammmpppllleee “““CCCooollluuummmnnn”””
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hh
Figure 3. Concentration Path Length (CPL) of a plume as measured from an aircraft.
The signal to noise ratio (SNR) for any given measurement determines the sensitivity of the
system and will be the number of signal photons divided by the total noise of the system and
solar reflected and thermal background photons incident on the system during the measurement
and other effects such as scintillation in the atmosphere and speckle, a surface roughness effect.
Both will reduce the overall SNR in a real system.
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ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
2.1.4 ANGEL System Overview
The DIAL Sensor in the ANGEL System [4] is built around solid-state laser sources
(Transmitter) combined with a telescope system (receiver) to collect the laser light reflected from
the ground surface. Figure 4 provides an artist conceptual drawing of the in-flight survey of a
natural gas transmission line right-of-way.
Figure 4 Conceptual view of the airborne ANGEL Service capturing leak survey data along a
pipeline right-of-way.
In addition to the DIAL transmitter and receiver subsystems, the ANGEL System onboard the
aircraft includes a computer controlled pointing and scanning subsystem designed to compensate
for aircraft motion while keeping the lasers scanning over pipeline. For a typical flight
operation, the Operations Center provides mission planning data for a selected pipeline to the
flight crew. This data is loaded into the airborne system. The aircraft and crew then proceed to
the starting point for a pipeline survey and fly the pre-selected natural gas pipeline route. During
the flight, the Payload ingests and records precise real-time position and attitude data. This
positional information is then used in conjunction with the targeting data from the Operations
Center to assure the continuous collection of raw sensor data along the route.
A scanning subsystem allows the collection of data over a wide swath of ground as the aircraft
flies above the right-of-way. The System also provides navigational aids to the pilot to assure
the aircraft is located in the correct position, thus allowing the pointing and scanning subsystems
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ITT Industries Space Systems Division– Final Report
Flight Testing of an Advanced Airborne Natural Gas Leak Detection System
to accurately acquire data over the pipeline right-of-way. Use of an automatic scanning and
pointing system combined with a pilot navigational aid allows the ANGEL system to fly a
smooth route while collecting data over a very irregular pipeline (Figure 5).
Figure 5 Space Systems ANGEL pointing results from a short section of the Virtual Pipeline
Route at RMOTC. The aircraft path is shown in yellow. The pipeline position is shown in red.
The position of each data point is shown in green forming a coverage swath 110 feet wide. The
sensor pointing and scanning system allows full coverage of the ROW corridor in a single pass.
2.1.4.1 Aircraft Platform Description
The airborne portion of the ANGEL System consisted of a test aircraft and an integrated sensor
payload. The test aircraft used was a modified Air Force owned Convair 580 (NC-131H)
Turboprop known as the Total In-Flight Simulator (TIFS), operated by General Dynamics. This
aircraft was used for both Early Flight Testing and for the Field Test at RMOTC. The TIFS
aircraft shown in Figure 6 is illustrated in Figure 7. Although the ANGEL System was later
integrated into a much smaller (and more economical) Cessna Grand Caravan following early
flight tests, the TIFS aircraft was chosen for early flight tests in order to accelerate the
development schedule and allow the ITT team to participate in the DOE sponsored RMOTC
field test in Wyoming. The TIFS aircraft is a very large and very powerful test aircraft with
ample room for the sensor and multiple operators, easy access to the sensor once installed, ample
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Description:2.2.2. Creation of a simulated natural gas leaks for flight testing The two major phases of flight-testing for this effort consisted of early flight tests in Upstate Paul Blaszkowiak, Janice Brooks, Dan Brake, Charles Cacciato, Mark.
