CO2 Emissions

Published on April 19th, 2014 | by Guest Contributor


Methane Emissions Questions Gas Being ‘Bridge’ Fuel

April 19th, 2014 by  

Originally published on Climate Central.
By Bobby Magill

Natural gas as a means to produce electricity is being hailed by the Intergovernmental Panel on Climate Change as the fuel that can act as a “bridge” between carbon-heavy coal and zero-carbon renewables, helping to reduce humans’ impact on the climate.

The idea is that burning natural gas involves fewer greenhouse gas emissions than burning coal. The IPCC in its Working Group III report says natural gas as a bridge fuel will only be effective if few gases escape into the atmosphere during natural gas production and distribution.


Flares burn off excess methane at an oil and gas field.
Credit: Pacific Northwest National Laboratory

But a study published Monday adds to the growing evidence those escaping gases, called “fugitive” emissions, are numerous, especially methane emissions while a well is being drilled, a phase of well development previously thought to emit little if any methane. Over a 100-year timeframe, methane is about 35 times as potent as a climate change-driving greenhouse gas than carbon dioxide, and over 20 years, it’s 84 times more potent.

Natural gas drilling could emit up to 1,000 times the methane previously thought, possibly significantly increasing the greenhouse gas footprint of the production of natural gas, the study shows.

The study, conducted by researchers at Purdue and Cornell universities and other institutions, is one of numerous studies conducted over the past several years that have discovered methane leaking from oil and natural gas wells, pipelines and hydraulic fracturing operations. The studies generally agree that methane leakage is significant in many areas, but some question the overall impact to the climate.

University of Texas study found last year that natural gas wells leak methane at about the rate reported in U.S. Environmental Protection Agency methane emission inventories, and the leaks can be contained with emissions control technology. The author of that study, University of Texas-Austin chemical engineering professor David T. Allen, could not be reached for comment Tuesday.

EPA inventories are compiled using the industry’s own measurements of emissions at well sites. Using those numbers, the EPA extrapolates to estimate total methane emissions for an entire region without actually measuring emissions throughout the area.

The EPA estimated in 2011 that natural gas drilling accounts for about 1,200 gigagrams, or 2.6 billion pounds, of methane emissions each year from well completions, equipment leaks and pneumatic controllers. “Flowback,” one of the final stages in well development after fracking, is estimated to emit an average of 81 megagrams of methane per operation. The EPA’s most recent geenhouse gas inventories show that natural gas production and distribution is the second largest source of methane emissions nationwide, just behind methane emissions from livestock.

But the new Purdue study suggests the EPA’s inventories may not be quantifying all the methane emissions from wells being drilled because few people have measured methane leaking from wells in the earliest stage of well development — the actual drilling itself.

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“Some inventories leave emissions from drilling out entirely because it is assumed to be negligible,” study co-author Dana Caulton, a Purdue Ph.D. candidate, said Tuesday.

The study shows that during drilling, as much as 34 grams of methane per second were spewing into the air from seven natural gas well pads in southwest Pennsylvania — up to 1,000 times the EPA estimate for methane emissions during drilling, Purdue atmospheric chemistry professor and study lead author Paul Shepson said in a statement.

“This indicates that there are processes occurring — e.g. emissions from coal seams during the drilling process — that are not captured in the inventory development process,” he said.

To determine emissions rates at natural gas fields in Pennsylvania’s Marcellus shale gas fields, the researchers used emissions data gathered from an airplane that flew over natural gas wells in southwest Pennsylvania in June 2012, some of which were in the process of being drilled.

None of the wells in the area were being fracked at the time, and none were in the “flowback” stage, according to the study.

“There were a large number of wells being drilled,” study co-author and Cornell University civil and environmental engineering professor Anthony Ingraffea told Climate Central on Tuesday. “No one goes out and measures methane emissions while they’re drilling.”

He said regulators have always thought that there are few emissions during the drilling process, but when drilling rigs drill through shale layers containing a lot of natural gas, a pressure pulse will send gas out of the well and into the atmosphere.


A typical natural gas drilling rig.
Credit: EPA

“We need to develop a way to objectively measure emissions from shale gas development that includes the full range of operator types, equipment states and engineering approaches,” Shepson said. “A whole-systems approach to measurement is needed to understand exactly what is occuring.”

The methane leak rates found in Pennsylvania were similar to those found in the atmosphere near natural gas fields in Utah’s Uintah Basin and Colorado’s Denver-Julesberg Basin, showing that methane leaks are widespread in natural gas fields across the country, the study says.

“From a climate point of view, when you’ve got thousands of wells all emitting (methane) during drilling, it’s not inconsequential anymore,”  Ingraffea said. “To say we get a pass on natural gas is not faring up to current science. It is not a bridge fuel, there’s too much leakage.”

The study says there is an urgent need to identify and plug methane leaks in shale gas production nationwide.

But identifying and shutting off all the leaks in the natural gas production and distribution system in the U.S. could be costly.

“The same IPCC report that says (natural gas) is a bridge fuel says we only have 15 to 20 years to do something,” Ingraffea said, referring to the IPCC’s call to reduce greenhouse gas emissions globally. “How long would it take to go and fix thousands of leaks throughout the pipeline system?”

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  • Bob_Wallace

    This article makes the too common mistake of using “bridge” but actually talking about “coal replacement”.

    A 1:1 coal to natural gas transformation doesn’t necessarily get us much. If we tightly control methane leaks we could make some gain on GHG problems. But that is not what “bridge” is all about.

    The Sun doesn’t shine all the time. The wind doesn’t blow all the time. But when the Sun shines and the wind blows we can fill our grids with clean, carbon-free electricity. And that might be as high as 80% of the time.

    So what do we do for the other 20% of the time? Storage is one option, dispatchable generation is another. Storage (except for PuHS) isn’t ready for prime time. Natural gas gives us very responsive dispatchable generation at a reasonably low price right now.

    If GHG emission problems are equal for coal and NG the using 20% NG along with wind and solar cuts our GHG problem to 20% of what it would be with 100% coal.

    Natural gas is a bridge between what we can do right now and the future which is likely to be once we sort out the storage issue.

    And if we never develop storage, we could live with 20% fossil fuel on our grid (based on the latest IPCC analysis).

    • Bob_Wallace

      Now, let’s look at what the utility companies are doing.

      1) They are switching to NG in order to save money.

      2) They are faced with replacing coal plants that are being forced to close by the EPA and NG is relatively cheap and quick to install. It’s also controllable which is is valuable to the industry which is tasked to keep the lights on 24/365. And they are familiar with burning stuff to make electricity. NG is in their comfort zone.

      3) I suspect they realize that these new NG plants will pay for themselves fairly quickly (low capex and short install times which means low finex).

      Once paid off they can sit largely unused as deep backup. As the grid becomes more and more solar/wind those gas plants will be available for emergency use/extended low wind/sunshine events.

      Remember, in the Budischak, et al. paper they found it best (cheapest) to have NG generation on hand to cover a few hours (about 7) each year rather than covering those hours with more storage.

    • Michael Berndtson

      Not disagreeing with anything here. Makes perfect sense. One problems is how we continue to finance oil and gas production. Get at it and how. So lots of money is spent to drill lots of wells to start producing lots of gas, gas liquids and oil. More drilling and production is needed to pay off capital investment. And the cycle continues. What we can’t use is being sent overseas including oil and LNG. The goal is to make both as expensive as possible and make customers as dependent as possible, for as long as possible.

      No producer wants to throttle or close a well. That’s why intermittent, periodic or seasonal sales suck to oil and gas producer. They want a constant stream of oil and gas flowing. And that’s why LNG overseas sales are being pushed so hard.

      In a perfect world we would have begun hydraulic fracking of shale oil and gas slowly, with a better understanding of impacts to groundwater and the atmosphere. This didn’t happen. Oil and gas went at it like gangbusters and will continue to until there’ is absolutely no reason to produce a well field, i.e. more money is put into production than what comes back from oil/gas sales.

      You really can’t separate oil and gas. There’s simply two phases of hydrocarbons. Every producer would love to have a Bakken well rather than a Marcellus well.

      Most important – natural gas in general will become expensive as overseas LNG sales and electric generation continue. At some point coal seam methane and coal to gas will raise its ugly head and not just in Wyoming, but in Illinois. Yuck!

      • Bob_Wallace

        I think the odds of a carbon tax/price getting passed on a federal level is very low. Even if Democrats were to regain control of both houses of Congress there are some reps/senators from “fossil fuel” states that wouldn’t be able to vote for the bill without committing political suicide.

        The only route I see is to make oil obsolete. That will happen (IMHO) when batteries become gain capacity and become cheaper.

        Give us ~200 mile EVs selling for about the same price (or a few thou more) than a same-model gasmobile and we’ll turn away from oil.

        In the meantime, since we (mere mortals) can’t produce the batteries what we can do to help is reduce our personal oil use as much as we reasonably can.

        Buy a new car? Put MPG high on the list. Drive efficiently (minimize back-tracking, car pool, make fewer “one item” trips, etc.). Walk, bike, use public transportation when reasonable.

        In terms of NG, it looks like batteries are becoming competitive for short term load-matching and frequency regulation. Batteries are not full of tooexpensivetoconsiderium. As production volume grows prices will fall. Batteries will first eat up the “15 minute” market, then the “1 hour” market and continue taking market away from NG.

        And don’t count out pump-up hyro. PuHS is an affordable, viable way to replace large amounts of NG.

        • Rick Kargaard

          Reducing our personal use is by far the best strategy both in travel and housing. The problem is convincing the public to actually make an effort. Gas mileage of cars has increased tremendously in recent years but the response by the public seems to be, drive faster, further and bigger. If the number of SUVs and large pickups seen on the road are any indication, we are losing the battle for overall reduction in use.

          • Bob_Wallace

            US fuel efficiency continues to rise. We hit a record high last August at 24.9 MPG. (Haven’t found more recent data.) And President Obama recently instituted mileage requirements for large trucks.

            Miles driven are down from the 2008 peak. There’s a small recent uptick but it’s too early to tell if it’s a real increase or just noise.

            And every EV/PHEV sold is one less ICEV on the road.

          • Rick Kargaard

            Miles driven were down less than would be expected, given the severity of the recession. I suspect that the recent uptick is Just the start of a much larger increase in response to more disposable income. My opinion only. Also, we are considering U.S. stats only. My observations are personal and more relevant to Canada where the recession had less impact.
            Electric is having an impact but it is pretty tiny to this point, at least on the international stage. Total electric sales seem to be less than the yearly increase in global auto sales. I would love to be proven wrong on this point and the future is likely much different. As for miles by electric compared to miles for gasoline, I have not seen any data.

          • Bob_Wallace

            In the US we’re seeing what looks like a change in driving patterns with younger people. Young people are driving less, waiting longer to get their drivers licenses, and not buying cars like was happening. There’s some feeling that this is not recession driven but a lifestyle change.

      • Rick Kargaard

        Burning natural gas produces CO2 but it is much cleaner, in other respects, than coal. Natural gas plants can also be regulated quickly for output and reduce overgeneration.

        • Bob_Wallace

          If we don’t deal with methane leaks then we end up no better than if we continue to burn coal.

          The dispatchability of NG plants means that we can more easily push gas off the grid as we add wind and solar. So there’s that.

          Heavy regulation and inspection at the well is necessary. But very difficult to accomplish in an atmosphere in which the government is being starved. (Perhaps we should return to the 19th Century and offer bounties to anyone who discovers leaky wells. Quadcopters would be all over that.)
          Then we badly need to repair our distribution system. That needs to happen whether we use NG for electricity or not.

          • Rick Kargaard

            Alberta regulates flaring and venting of gas quite stringently and I believe B.C. has similiar regulations. Substantial reductions have been accomplished in recent years.

            Leaks from facilities are probably pretty minimal since a lot of gas is sour and therefore very dangerous and easily detectable at low concentrations. The link is for information. I am not familiar with American practices or regulation.

          • Bob_Wallace

            “Leaks from facilities are probably pretty minimal” is not good enough.
            We need ‘sniffers’ that constantly feed data back to central monitoring agencies/made public and very heavy fines for excessive leakage. With “excessive” set low.

            We cannot allow the industry to police itself.

          • Rick Kargaard

            That would require considerable infrastructure. Similiar to putting webcam on every corner to combat crime. A good idea in principle, but is it practical?

          • Bob_Wallace

            Say four sniffers per well? Pretty minimal amount of infrastructure.

            Solar power them if needed. Let them send data back via the cell phone system.

            It looks like portable industrial grade methane leak detectors run about $500. A couple thou per well is nothing.

          • Rick Kargaard

            According to the EIA there were nearly 483.000 producing gas wells in the U, 2012. There are over 1.1 million active oil and gas wells. Oil wells need to be included as they may release more methane than gas wells (through tank vents and such.) There is little financial incentive to reduce losses from an oil well. That makes an investment of over 2 billion dollars, if that many sniffers were even available.
            Wouldn’t it be better to invest that money in renewable technology?
            It is wrong to assume that all or most petroleum producers are irresponsible. Regulation is necessary, but most producers would comply without close monitoring if the fines are sufficiently high to provide a financial incentive.
            Regulations help to assure that there is less possibility of gaining a competitive advantage through irresponsible venting.
            Once again we are using U.S. figures and the global picture is much bigger.

          • Bob_Wallace

            “483.000 producing gas wells in the U,S”

            Take a look at revenues per well. Calculate a “$2k” percentage.

            “As reported by the Wheeling Intelligencer, natural gas drillers are earning substantially more revenue – up to three times more – for every “wet gas” well they complete compared to every dry well, according to Chesapeake Energy. Company information shows that for a typical dry gas well, the company makes an average of $13,000 in revenue per day.”

            $4k per day for a wet gas well. $1,460,000 per year. $2k is 0.1% of that first year earnings.

            Then ~ a half a million wells with 4 sniffer per well yells “Economy of scale!!!”. Something made in small quantities for $500 would probably cost less than $100 if built in the millions of units.

          • Rick Kargaard

            Clearly, you have never lost money on a petroleum stock. Things are not nearly as rosy as total cash flows would suggest. You are still considering gas wells to be the biggest offenders The Bakken tight oil feilds likely vent and flare far more methane than the average gas field.

          • Bob_Wallace

            I’m sure I’ve lost money on fossil fuel stocks. But they are deeply hidden in the index funds I hold.

            I put the cost of monitoring in perspective of the revenue of NG wells I found on line.

            Monitor and control all methane leaks. Is that clear enough?

  • Will E

    Putin Gas, Gas Pipeline, Methane Gas, Mercury Gas, Gas Explosion,
    Gas Earthquake , Liquefied Natural Gas, Gas Flare, Black Smoke Gas, Gas Price, Gas Rotonde Holland,
    and so on

    Replace Gas by
    Wind and Solar and there is a clean safe story to make billions
    with clean energy.

  • Michael Berndtson

    That picture of a flare could be considered actionable, i.e. take action to improve performance. Eyeballing isn’t considered monitoring. You need a sampling and analysis plan and actual data. The picture could be a stock photo of any gas flare. Maybe even from a landfill gas collection system. Nonetheless, it sure doesn’t look like the presumed 90+ percent combustion efficiency is happening. And another thing, the heavier hydrocarbons entrained along with the vapours light ends (methane through propane) probably are causing all that black smoke. That could be butane through aromatics like benzene (C6) and toluene (C7).

    Is there any public data on mercury in US shale gas? I cannot find any. Here’s my concern. Natural gas typically contains mercury. As does oil and coal. Some subsurface petroleum source formations contain a bunch of mercury. Some hardly any. Either way mercury removal is an essential step in natural gas processing. Especially for processing natural gas into LNG for overseas sales. Some concerns are geared towards health and safety and the environment. Some concerns focus on mercury’s impact on vessel metallurgy and natural gas catalyst poisoning.

    If natural gas gets burned and vented before mercury processing, how much mercury is escaping into the atmosphere? Again, I’ve only read broad statements from DoE that gas is better than coal because there’s less mercury. NRDC has a report on mercury in natural gas, but only cites vague amounts, based on data collected before the shale oil and gas boom started.

    Well field flaring will do little to control mercury emissions. In some instances this may not be an issue. In some areas like North Dakota and Texas, where the money hydrocarbon is liquid (oil) and gas is flared copiously, this could be an issue. Again, there’s no public data, that I can find.

    • Rick Kargaard

      The black smoke in the picture is most likely from the presence of oil droplets in the gas stream, Not too unusual when flaring waste gas from an oil well. One more reason flaring should be controlled

      • Michael Berndtson

        You probably are right. Well field vapor/liquid separators (knockout pots) aren’t always the most highly efficient things.The “mist” carryover is probably the source of the smoke. This is one thing for oil and gas to put its technical knowhow on, and fast. Nonetheless, the liquid particles are bigger hydrocarbons, that are difficult to mineralize.

  • jburt56

    They forgot to tell you the bridge was over the river Styx.

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