Natural gas is “a bridge to a world with high CO2 Levels,” climatologist Ken Caldeira told me last year.
A major new study in Geophysical Research Letters by 19 researchers — primarily from NOAA and the Cooperative Institute for Research in Environmental Sciences (CIRES) — suggests natural gas may be more of gangplank than a bridge.
Scientists used a research aircraft to measure leakage and found:
The measurements show that on one February day in the Uintah Basin, the natural gas field leaked 6 to 12 percent of the methane produced, on average, on February days.
The Environmental Defense Fund (EDF) called the emissions rates “alarmingly high.” While the researchers conducted 12 flights, “they selected just one as their data source for this paper,” ClimateWire reports. Researchers actually measured higher emissions on other flights, but atmospheric conditions during those flights “gave the data more uncertainty.”
The Uinta Basin is of particular interest because it “produces about 1 percent of total U.S. natural gas” and fracking has increased there over the past decade.
This study confirms earlier findings of high rates of methane leakage from natural gas fields. If these findings continue to be replicated elsewhere, they would utterly vitiate the direct climate benefit of natural gas, even when it is used only to switch off coal.
How much methane leaks during the entire lifecycle of unconventional gas has emerged as a key question in the fracking debate. Natural gas is mostly methane (CH4). And methane is a far more potent greenhouse gas than (CO2), which is released when any hydrocarbon, like natural gas, is burned — 25 times more potent over a century and 80 to 100 times more potent over a 20-year period.
Even without a high-leakage rate for shale gas, we know that “Absent a Serious Price for Global Warming Pollution, Natural Gas Is A Bridge To Nowhere.” That was first demonstrated by the International Energy Agency in its big June 2011 report on gas — see IEA’s “Golden Age of Gas Scenario” Leads to More Than 6°F Warming and Out-of-Control Climate Change. That study — which had both coal and oil consumption peaking in 2020 — made abundantly clear that if we want to avoid catastrophic warming, we need to start getting off of all fossil fuels.
Still, the leakage rate does matter. A major 2011 study by Tom Wigley of the Center for Atmospheric Research (NCAR) concluded:
The most important result, however, in accord with the above authors, is that, unless leakage rates for new methane can be kept below 2%, substituting gas for coal is not an effective means for reducing the magnitude of future climate change.
Wigley, it should be noted, was looking at the combined warming impact from three factors — from the methane leakage, from the gas plant CO2 emissions, and from the drop in sulfate aerosols caused by switching out coal for gas. In a country like the United States, which strongly regulates sulfate aerosols, that third factor is probably much smaller. Of course, in countries like China and India, it would be a big deal.
An April 2012 study found that a big switch from coal to gas would only reduce “technology warming potentials” by about 25% over the first three decades — far different than the typical statement that you get a 50% drop in CO2 emissions from the switch. And that assumed a total methane leakage of 2.4%. The study found that if the total leakage exceeds 3.2% “gas becomes worse for the climate than coal for at least some period of time.”
Leakage of 4%, let alone 9%, would call into question the value of unconventional gas as any sort of bridge fuel. Colm Sweeney, the head of the aircraft program at NOAA’s Earth System Research Laboratory, who led the study’s aerial component, told the journal Nature:
“We were expecting to see high methane levels, but I don’t think anybody really comprehended the true magnitude of what we would see.”
The industry has tended kept most of the data secret while downplaying the leakage issue. EDF is working with the industry to develop credible leakage numbers in a variety of locations.