Sure, when it's burned, natural gas generates fewer greenhouse gas emissions per unit of energy than carbon-heavy alternatives such as coal and bitumen.
The devil, of course, is in the details. The details are the various ways that natural gas, i.e. methane, leaks into the atmosphere before any of it reaches the appliance or furnace where it is consumed.
It leaks through fracking. It leaks at the wellhead. It leaks in transmission to the end user. Lots of it leaks.
A new study has found that leaks of methane, the main ingredient in natural gas and itself a potent greenhouse gas, are twice as big as official tallies suggest in major cities along the U.S. eastern seaboard. The study suggests many of these fugitive leaks come from homes and businesses—and could represent a far bigger problem than leaks from the industrial extraction of the fossil fuel itself.
...When burned for heat or power, methane emits less carbon dioxide (CO2) than fossil fuels such as coal. But when leaked directly into the atmosphere, its warming effect can be dozens of times stronger than CO2, depending on the time scale over which the warming is measured.
The new findings come courtesy of data gathered by aircraft over six U.S. cities: Washington, D.C.; Baltimore, Maryland; Philadelphia, Pennsylvania; New York City; Providence; and Boston. In 2018, researchers flew at altitudes between 300 and 800 meters and measured concentrations of methane, ethane, CO2, and carbon monoxide, among other gases.
...The team’s analyses suggest the five biggest urban areas studied—which together include about 12% of the nation’s population—emit about 890,000 tons of methane each year, the researchers report this week in Geophysical Research Letters. The vast majority of that, at least 750,000 tons, comes from methane leaks from homes, businesses, and gas distribution infrastructure, rather than natural sources and other human-driven sources such as landfills. For comparison, the team notes, that’s well over triple the amount emitted by gas production in the Bakken shale formation in the U.S. Midwest.
It’s also much more than the amounts estimated by the Environmental Protection Agency (EPA). A 2016 report suggested methane emissions in the six major urban areas the researchers studied totaled only 370,000 tons. “It’s easy to say that the EPA inventory is low, but it’s not as easy to say why it’s low,” Kort says. One possible reason for this huge discrepancy: The EPA estimate includes leaks from the natural gas distribution system, but it doesn’t include leaks from homes and businesses.In eastern North America, the urban gas distribution infrastructure can be many decades old. Gas pipes, like water lines, don't age well and have to be replaced. That's costly, especially for a problem that is largely out of sight/out of mind.
In British Columbia we're under the thumb of gas friendly governments, NDP and Liberal, who pretend natural gas/LNG is a clean fuel. Justin Trudeau has claimed Canada deserves some sort of climate credits for getting LNG to Asian markets.
So, the 2016 EPA methane emissions estimate is half what the researchers observed, and the reason is a failure to count end-user emissions? I can see that lighting a furnace, stove or dryer results in small emissions of unburnt methane, but half the emissions observed? I think you're right to point to aging infrastructure as a likely additional culprit. I also think it's likely the industry underreports actual emissions to the EPA.
The link below, Cap, will take you to a graphic depicting fugitive emissions in Boston in a survey undertaken by, if memory serves, a team from Harvard.
Vehicle-mounted sensors were taken down Boston streets recording gas leaks coming out of the roads, from sidewalks and from buildings. Those are leaks that are continuous, round the clock.
When it comes to climate change ...
fracked LNG is worse than dilbit
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