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Technology Detects Gas Leaks on a Roll
New car-mounted technology is offering one of the nation's largest utilities a fast, ultra-sensitive method of detecting gas leaks.
Utilities giant Pacific Gas & Electric is seeking out pipeline leaks using the new tool, which is said to be 1,000 times more sensitive than traditional equipment and can distinguish whether detected gas is from a pipeline or a natural source, like a sewer or landfill.
PG&E has been under constant scrutiny for its troubled pipeline network since a line in San Bruno, CA, exploded in 2010, flattening a neighborhood and killing eight people.
'Go to the Moon' Technology
After more than a year of testing, PG&E recently rolled out six SUVs equipped with the technology, which the company says "will revolutionize the way natural gas leaks are detected."
The gas leak detection tool, Picarro Surveyor, measures and maps methane plumes and can detect gases at parts per billion, versus the parts-per-million levels that handheld devices measure. It can also distinguish between different forms of the same gas, the developers say.
"This is like NASA technology, go-to-the-moon type of technology," said Bob Stotler, PG&E gas operations superintendent.
"The system distinguishes natural-gas leaks from other sources of methane in real time, eliminating false positives and saving hours of laboratory gas analysis,” said Eric Crosson, Ph.D., the Chief Technology Officer of Picarro.
'Whole New League'
PG&E, headquartered in San Francisco, CA, is one of the largest combined natural gas and electric utilities in the United States, delivering energy to about 15 million people in northern and central California.
The company's pipeline safety record has come under intense scrutiny in the aftermath of a 2010 pipeline explosion in San Bruno, CA, which leveled a neighborhood and killed eight people. In March, PG&E agreed to pay more than $70 million in a municipal restitution package to the city, in addition to earlier commitments to fund replacement and repair of the city's infrastructure and other costs related to the accident and restoration of the neighborhood.
Restoring Faith
PG&E now says that the Picarro Surveyor technology will help restore customers' faith in the utility.
"I truly believe that PG&E adopting this technology and embracing it and being a forefront leader in the industry that it is a true testimony that that's our goal and we want to prove that to our customers," said Stotler.
Kevin Knapp, vice president of gas operation maintenance and construction at PG&E, added, "This technology is going to put us in a whole new league in terms of our ability to safeguard our system.”
According to Picarro, there were 19,662 miles of gathering pipelines in the U.S. in 2011, originating at more than 460,000 wellheads, and nearly two million miles of main and individual service pipelines for distributing gas for commercial and residential use.
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| San Bruno Fire Department |
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In 2010, a pipeline explosion in San Bruno, CA, leveled a neighborhood and killed eight people. PG&E agreed to pay $70 million in restitution to the city. |
Information from Picarro added that methane "has more potent atmospheric implications" than any other greenhouse gas and will do 72 times more damage to the atmosphere over 20 years than an equal amount of carbon dioxide.
How it Works
The Picarro Surveyor uses a patented form of cavity-ring down spectroscopy (CRDS), which measures the near-infrared absorption spectrum to determine what small gas-phase molecules may be present in the air and in what concentration, the company explains in a white paper.
Using a three-mirror cavity and a tunable, single-frequency diode laser to create a continuous laser wave, CRDS can automatically and continuously detect gases in the air by measuring the amount of time it takes for the light intensity generated by the laser wave to decay. Tuning the laser to different wavelengths where the targeted gas absorbs light can determine the precise concentration of gases, according to Picarro.
As the surveyor-equipped vehicles drive slowly along the side of the road, a stainless steel sensing tube mounted on the front of the car sucks in air, while the surveyor in the trunk analyzes the molecules, Mounted on top of the car, a 10-foot-tall anemometer measures wind speed.
Everything comes together in a web-enabled device mounted on the dashboard (in PG&E's case, an iPad), where a cloud-based processing platform power's the technology's data analysis, mapping, archiving and reporting features.
The device can be used to conduct a survey, view results in real-time, access and share results securely and locate emission and leak sources. The display will almost instantly show a teal bubble if there's a potential leak.
Putting it to Use
In a recent report sponsored by the Pipeline Research Council International, and led by PG&E, the technology was tested in three regions in California (Diablo, Livermore and Sacramento) and in southern Nevada.
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| Picarro |
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The Picarro Surveyor uses a patented form of cavity-ring down spectroscopy (CRDS), which measures the near-infrared absorption spectrum to determine what small gas-phase molecules may be present in the air and in what concentration. |
In Diablo and Sacramento, the Picarro Surveyor located several leaks that traditional methods failed to find, including seven Grade 1 leaks (those requiring immediate response) and 10 Grade 2+ leaks (those requiring a scheduled priority repair within 90 days or less), according to a white paper from Picarro.
PG&E has noted two occasions in which the Picarro Surveyor has been able to locate leaks that the crew previously struggled with.
After walking surveys and seven separate investigative digs failed to locate a suspected leak in Northern California's East Bay, the Picarro Surveyor found the problem immediately, which was a natural methane source unrelated to PG&E.
In Santa Clara, CA, PG&E crews spent months searching for a small leak on a distribution feeder pipe off the Lawrence Expressway. The surveyor was brought in and identified the location of the previously undetectable leak.
"We will find more leaks with the technology, and that's what we want to do is find leaks and fix leaks so that we can provide a safe and reliable natural gas system for our employees and our customers," Stotler said.
According to PG&E, it is the world's first utility to use this technology, and the company plans to use more of the surveyors thoughout its service area.
Currently, PG&E is required to survey its entire system every five years, but the company is requesting in its General Rate Case that complete surveying be done every three or four years.
