Improving methane leak detection to fight global warming
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When it comes to the pollution that causes global warming, we've focused most of our attention on carbon dioxide. But at the United Nations climate summit underway in Dubai, world leaders are also hoping for stronger commitments to reduce methane, a far more potent greenhouse gas that accounts for more than one-quarter of global greenhouse gas emissions.
Natural gas, which is primarily methane, remains an important fuel for the U.S. energy industry, both for electricity generation and for heating and cooking. While climate scientists say we need to eliminate it and other fossil fuels, as long as we use methane, leaks are a problem. That's mainly because methane can leak at all stages of its production and use — from wells, refineries, pipelines and even at homes and buildings.
Companies that produce or deliver methane are beginning to track and reduce those emissions. Piedmont Natural Gas, which is part of Charlotte-based Duke Energy, has a cutting-edge program that it says has reduced measurable methane leaks by 85% at its facilities.
And this summer, Piedmont's Integrated Methane Monitoring Platform got $1 million from the U.S. Department of Energy to expand monitoring to its natural gas suppliers and customers.
"We have a goal within Duke Energy for the natural gas business to be net zero Scope 1 emissions, meaning leaks to be eliminated off of our pipe system, by 2030," Piedmont President Sasha Weintraub (shown at left) said in an interview. "We believe it's the right thing."
Duke and Piedmont also want to see methane emissions reduced at both their suppliers and customers, known as Scope 2 and Scope 3 emissions, Weintraub said.
"We're gonna go upstream and downstream, meaning that we're working with an interstate pipeline company and their equipment to see if we can use technology to detect methane leaks. And then downstream, we're working with customers of ours, and seeing at the customer level, large scale gas users, if this type of technology can also find leaks, really beyond the meter on their property," Weintraub said.
Piedmont is working with the Transco pipeline, which runs from upstate South Carolina through North Carolina, including Mecklenburg County, to Virginia. It's owned by The Williams Cos. and supplies natural gas to Duke Energy.
This system eliminates walking
Weintraub said government regulations require gas companies to physically walk their pipelines every three to five years using sensors to identify leaks and repair them. The expanded system with new technology could make a big difference in finding leaks on Piedmont's 35,000 miles of pipelines over five states.
"This technology will allow us to eliminate the walking and get us to that net zero (goal)," Weintraub said.
This new monitoring system uses satellite images, sensors and other new technologies to detect leaks and measure methane emissions in real time on natural gas distribution systems, according to Piedmont officials.
"We'll do a satellite pass, and every three to six months when this pass happens, we'll find new leaks, we'll go fix them. We don't need to spend any energy finding them," Weintraub said. "So think of it a little bit like Whac-A-Mole. Get to zero, some new leaks pop up, get back to zero, new leaks pop up and just keep that cycle."
What those satellite images show is a color-code cloud in areas where leaks are found. Piedmont is learning how to translate the maps into exact amounts of lost gas over time.
Weintraub is especially interested in better measuring how much methane escapes Piedmont's pipes. Right now, federally required reports rely on the company's estimates. Those are based on miles and types of pipe, the number of gas meters, and historical data on leaks.
"But it's not necessarily representative of the actual leaks on the system," he said. "What we are working on is trying to measure in near real-time what actually are the fugitive emissions coming off of that."
Piedmont currently reports losing about 0.1% of all the methane it uses. That's a tiny amount, but methane traps more heat in the atmosphere than carbon dioxide. Although methane doesn't last as long as carbon dioxide, the United Nations Environment Program says it's 80 times more harmful than CO2 for 20 years after it is released.
The grant covers a year of piloting various technologies, said Rachel Mattix, who is on the Piedmont team. "Our deliverable to the DOE is really a plan that can be handed to any sort of gas company, whether it be upstream, downstream or local distribution company, a plan of how can they implement based on our lessons learned. We don't want to have to reinvent the wheel, and we don't want others to have to reinvent the wheel," Mattix said.
Measuring greenhouse gases such as methane not only helps companies like Piedmont, but it helps provides a more accurate picture of progress nationwide. That's a goal of the Biden administration.
On Wednesday, the Biden administration announced plans for a national system to measure emissions of carbon dioxide, methane and a third greenhouse gas, nitrous oxide. That system is to be developed by agencies, including the National Oceanic and Atmospheric Administration. Plans call for initial prototypes tracking emissions in the Washington, D.C.-Baltimore region and in Indianapolis. NOAA said it will combine atmospheric measurements with emissions inventories.