Is natural gas a solution to mitigating climate change?

February 11, 2014 by Cynthia Eller
Oil rigs, still drilling for oil in the Los Angeles basin, are one source of atmospheric methane; natural gas pipeline losses are another.

( —Methane, a key greenhouse gas, has more than doubled in volume in Earth's atmosphere since 1750. Its increase is believed to be a leading contributor to climate change. But where is the methane coming from? Research by atmospheric chemist Paul Wennberg of the California Institute of Technology (Caltech) suggests that losses of natural gas—our "cleanest" fossil fuel—into the atmosphere may be a larger source than previously recognized.

Radiation from the sun warms Earth's surface, which then radiates heat back into the atmosphere. Greenhouse gases trap some of this heat. It is this process that makes life on Earth possible for beings such as ourselves, who could not tolerate the lower temperatures Earth would have if not for its "blanket" of greenhouse gases. However, as Goldilocks would tell you, there is "too hot" as well as "too cold," and the precipitous increase in greenhouse gases since the beginning of the Industrial Revolution induces climate change, alters weather patterns, and has increased sea level. Carbon dioxide is the most prevalent in Earth's atmosphere, but there are others as well, among them .

Those who are concerned about greenhouse gases have a very special enemy to fear in . Methane has a trifecta of effects on the atmosphere. First, like other greenhouse gases, methane works directly to trap Earth's radiation in the atmosphere. Second, when methane oxidizes in Earth's atmosphere, it is broken into components that are also greenhouse gases: carbon dioxide and ozone. Third, the breakdown of methane in the atmosphere produces water vapor, which also functions as a greenhouse gas. Increased humidity, especially in the otherwise arid stratosphere where approximately 10 percent of methane is oxidized, further increases greenhouse-gas induced climate change.

Fully one-third of the increase in radiative forcing (the ability of the atmosphere to retain radiation from the sun) since 1750 is estimated to be due to the presence and effects of methane. Because of the many potential sources of atmospheric methane, from landfills to wetlands to petroleum processing, it can be difficult to quantify which sources are making the greatest contribution. But according to Paul Wennberg, Caltech's R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering, and his colleagues, it is possible that a significant source of methane, at least in the Los Angeles basin, is fugitive emissions—leaks—from the natural-gas supply line.

Is natural gas a solution to mitigating climate change?
Locations of methane measurements in the greater Los Angeles basin overlaid on a Google Earth satellite image. Yellow and red colors represent an excess of methane.

"This was a surprise," Wennberg explains of the results of his research on methane in the Los Angeles atmosphere. In an initial study conducted in 2008, Wennberg's team analyzed measurements from the troposphere, the lowest portion of Earth's atmosphere, via an airplane flying less than a mile above the ground over the Los Angeles basin. These data eventually will be compared to more detailed measurements obtained by the Orbiting Carbon Observatory (OCO), a satellite developed by the Jet Propulsion Laboratory (JPL) and set for launch in July of this year. (The original OCO was launched in 2009, but the fairing that covered the observatory during its launch failed to separate from the rocket, causing the spacecraft to fall back into Earth's atmosphere where it burned or broke up over the Pacific Ocean. It was rebuilt with funds from the American Recovery and Reinvestment Act of 2009).

In analyzing chemical signatures of the preliminary samples, Wennberg's team made an intriguing discovery: the signatures bore a striking similarity to the chemical profile of natural gas. Normally, the methane from fossil fuel sources is accompanied by ethane gas—which is the second most common component of natural gas—while biogenic sources of methane (such as livestock and wastewater) are not. Indeed, the researchers found that the ratio of methane and ethane in the L.A. air samples was characteristic of the samples of natural gas provided by the Southern California Gas Company, which is the leading supplier of natural gas to the region.

Wennberg hesitates to pinpoint natural-gas leaks as the sole source of the L.A. methane, however. "Even though it looks like the methane/ethane could come from fugitive natural-gas emissions, it's certainly not all coming from this source," he says. "We're still drilling for oil in L.A., and that yields natural gas that includes ethane too."

The Southern California Gas Company reports very low losses in the delivery of natural gas (approximately 0.1 percent), and yet atmospheric data suggest that the source of methane from either the natural-gas infrastructure or petroleum production is closer to 2 percent of the total gas delivered to the basin. One possible way to reconcile these vastly different estimates is that significant losses of natural gas may occur after consumer metering in the homes, offices, and industrial plants that purchase natural gas. This loss of fuel is small enough to have no immediate negative impact on household users, but cumulatively it could be a major player in the concentration of methane in the atmosphere.

The findings of Wennberg and his colleagues have led to a more comprehensive study of greenhouse gases in urban settings, the Megacities Carbon Project, based at JPL. The goal of the project, which is focusing initially on ground-based measurements in Los Angeles and Paris, is to quantify greenhouse gases in the megacities of the world. Such cities—places like Hong Kong, Berlin, Jakarta, Johannesburg, Seoul, São Paulo, and Tokyo—are responsible for up to 75 percent of global carbon emissions, despite representing only 3 percent of the world's landmass. Documenting the types and sources of in megacities will provide valuable baseline measurements that can be used in efforts to reduce greenhouse gas emissions.

If the findings of the Megacities Carbon Project are consistent with Wennberg's study of methane in Los Angeles, may be less of a panacea in the search for a "green" fuel. Natural gas has a cleaner emissions profile and a higher efficiency than coal (that is, it produces more power per molecule of ), but, as far as climate change goes, methods of extraction and distribution are key. "You have to dig it up, put it in the pipe, and burn it without losing more than a few percent," Wennberg says. "Otherwise, it's not nearly as helpful as you would think."

Explore further: Wetlands the primary source of Amazon Basin methane

More information: "On the Sources of Methane to the Los Angeles Atmosphere." Paul O. Wennberg, Wilton Mui, Debra Wunch, Eric A. Kort, Donald R. Blake, Elliot L. Atlas, Gregory W. Santoni, Steven C. Wofsy, Glenn S. Diskin, Seongeun Jeong, and Marc L. Fischer. Environmental Science & Technology 2012 46 (17), 9282-9289. DOI: 10.1021/es301138y

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4 / 5 (4) Feb 11, 2014
It's all a conspiracy, the global powers just want control, humans cant change the climate, it was cold yesterday, etc. etc.
4.5 / 5 (4) Feb 11, 2014
Sigh! Reducing losses of natural gas from distribution is a worthy goal. (I think though that further study will find losses from LNG tanks and backyard barbecues as a major source.*)

However, the big picture on using natural gas today is using it to generate electricity. It used to be that burning coal was the primary source of electricity in the US. For a time oil looked to replace coal, but then 50 years ago oil prices started rising. However today not only is natural gas replacing coal, it makes sense to use combined cycle plants which use natural gas to fuel a gas turbine then use the heat from the exhaust to generate more electricity. These CCGT plants have efficiencies (around 60%) almost twice that of older coal plants.

* Propane may be the fuel of choice for most outdoor gas grills, but incomplete combustion can and does create methane and ethane, along with ethylene which also comes from ripening fruit, including tomatoes. ;-)
The Shootist
2 / 5 (8) Feb 11, 2014
NO. Natural gas is a way to power our communities so we don't sit in the dark and freeze.

Stupid, evil, watermelons.
5 / 5 (2) Feb 11, 2014
All fossil fuels contribute to the problem.
3.7 / 5 (3) Feb 11, 2014
Natural gas is not a solution of anything - it just complements the oil, when its price becomes competitive due to rising price of oil. Nobody is mining the tons of gas or oil for saving of world, but for money. It's a simple as that.
3 / 5 (4) Feb 11, 2014
Huh. Here is another major factor in global warming that hasnt been included in models. And I thought they had this stuff all worked out. Silly me.

Have I said this before? (lots)
5 / 5 (1) Feb 11, 2014
Huh. Here is another major factor in global warming that hasnt been included in models. And I thought they had this stuff all worked out. Silly me.

Have I said this before? (lots)

Nah -it is included in the models.

What they are trying to identify here is the origin of the methane.

Is that really you, Otto --or has someone coopted your identity?

5 / 5 (1) Feb 11, 2014
Well I can't imagine *additional* greenhouse gasses are likely to change the models much in denialists' favor.
1 / 5 (1) Feb 11, 2014
The IPCC modelers grossly overestimate atmospheric methane levels the growth rate of which which appear to have been dropping since 1985
5 / 5 (2) Feb 11, 2014
Very good science article for the public btw. From the article;
natural gas may be less of a panacea in the search for a "green" fuel.
It's all blamed on leaks and gas delivery for increasing the methane levels. That makes sense, but in addition, natural gas production won't last forever. At best it's a stop-gap measure while we transition and build a solar and renewables based electric society. Peak oil has passed and now it's natural gas.
not rated yet Feb 11, 2014
...At best it's a stop-gap measure while we transition and build a solar and renewables based electric society...

It's a stop-gap measure while we transition and build cheap reliable and virtually unlimited fusion energy source. ITER is almost there, followed by DEMO. Your vision of picturesque landscape littered with propellers and black shingles is never going to materialize.
not rated yet Feb 15, 2014
Clean coal is the best option. Since climate change is inevitable and global warming doesn't really exist under the desperate left wing definition. The geological warming trend we were in, is pretty much ending and the ice packs at the poles are expanding and the lakes are freezing over so global warming is non-existent as a result of jobs and progress. Coal of which we have a 900 year supply is our hope for mitigating political climate change propaganda and becoming energy independent of the dangerous and evil muslim hoards..
not rated yet Feb 15, 2014
It's a stop-gap measure while we transition and build cheap reliable and virtually unlimited fusion energy source.

And if that never happens, the natural gas infrastructure becomes the key factor in making renewable energy possible, because we have to use the intermittent and seasonal surplus power to produce synthetic methane.

It's the only practical energy storage method that can be reasonably built anywhere and at any scale to meet the demand of both energy and further synthetic hydrocarbons that we'd need to produce anyways - like plastics and fertilizers.

Every other method runs up against non-scalability and lack of suitable locations, or lack of materials, or extremely poor efficiencies.

not rated yet Feb 25, 2014
It's a stop-gap measure while we transition and build cheap reliable and virtually unlimited fusion energy source.

Sigh! Who has been spreading the fairy tale that fusion is a panacea? Yes, it would be nice if ITER and successors are successful, but if so they will produce at least 50 times as many neutrons as a fission plant. In fact, one of the best ideas for what to do once fusion is practical is to combine it with a (subcritical) fission reactor. Most of the power would come from fission, but the fuel could be mostly what is now considered high-level radioactive waste.

Messy, but better than generating fifty times the current amount of nuclear waste.

If you really want to get rid of CO2 emissions, the best way available is to build thorium fueled reactors. Not all fission reactors are alike, and thorium/molten salt reactors are inherently much safer than current reactors. (And fifty years of evolution in control systems won't hurt.)

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