Is Natural Gas Cleaner Than Coal? It Depends on Leaks—and There's a Huge One in the North Sea

By Sarah Zhang | April 11, 2012 5:52 pm

A news report from the first week of the leak. 

Since March 25, the Elgin gas platform off the coast of Scotland has been leaking 7 million cubic feet of gas a day. The natural gas, mostly methane, doesn’t have the dark stain of oil and it hasn’t inspired the news coverage of Deepwater Horizon. But that doesn’t mean it can be ignored.

Like carbon dioxide, methane is a greenhouse gas that traps heat in the Earth’s atmosphere. But methane is much worse: the same amount of methane will have 25 times the warming effect of carbon dioxide over a 100-year period. In the six months that it will take to stop the leak, enough methane would have escaped into the atmosphere to equal the annual global warning impact as 300,000 new cars, according to a recent TIME article.

The Elgin gas leakage is an extreme example of how natural gas exploration and processing is always beset by leaks. After all, the stuff is gas that wants to float away. The TIME piece dissects a recent paper in the Proceedings of the National Academy of Sciences evaluating whether natural gas really is more environmentally friendly than coal. Their answer? It depends, and it partially depends on leaks.

The redline for power plants seems to be a leakage rate of 3.2%. As long as the share of methane that escapes remains below that level, natural gas beats coal. And since a 2009 estimate from the Environmental Protection Agency (EPA) pegs the average leakage rate at 2.4%, natural gas does seem to come out comfortably ahead — especially when you factor in the much lower levels of mercury and other traditional air pollutants emitted when power plants burn gas as compared with coal.

But if we replace gasoline cars with ones powered by natural gas in an effort to reduce oil consumption — as some like natural-gas tycoon T. Boone Pickens have urged — methane leakage would need to be kept below 1.6% to provide a meaningful climate benefit. For heavy-duty trucks run on diesel — a fuel that has a smaller carbon footprint than gasoline — methane leakage would have to be reduced by two-thirds below the EPA estimate of 2.4% to provide a climate benefit. “It’s a much steeper hill to climb,” says Hamburg.

The full TIME article goes through a more detailed explanation and possible caveats for some of these numbers. Indeed it is frustrating that we don’t have better information about natural gas, and one reason to use caution in ramping up domestic natural gas exploration with fracking. Natural gas may or may not be a solution, but it’s almost certainly not a permanent, one-size-fits-all solution.

CATEGORIZED UNDER: Environment
  • Yacko

    CO2 ->> CH4 ->> CH3OH. Have all coal, gas, and liquid petroleum energy users/producers recapture carbon, and that includes vehicles, either directly or via a power plant. Fuel vehicles with methanol or electricity. It’s a closed loop system with limited losses. New methane can be injected into the loop. It doesn’t alter the energy infrastructure much. Use petroleum mostly for plastics and modern materials.

  • Paul

    Released chlorine into the troposphere. Photolyzed to Cl radicals, it will oxidize methane to methyl radicals and HCl. If cycles with NOx can recycle HCl back to atomic chlorine then it might be even more effective.

  • jeff

    Did you just suggest making copious amounts of hydrochloric acid in the atmosphere? As if wet acid deposition wasn’t already a big enough problem.

  • Tim

    The turnover rate of soluble components (like HCl and H2SO4) is much slower in the upper atmosphere. At least a few scientists have suggested injecting sulfate aerosols into the upper atmosphere to radically combat global warming; HCl probably has the same effect (ever open a bottle of muriatic acid on a humid day?). It certainly isn’t an ideal solution: rain acidity and haze will rise. But it’s not nearly as bad as terrestrial smog, which is what most people are familiar with. If such treatment works, it would provide an additional benefit offsetting natural gas leakage, simultaneously reducing the impact of atmospheric methane, reducing direct petroleum and coal consumption, and reducing insolation.

  • Paul

    #3: Done globally, it shouldn’t be a big problem. The manufacture of chlorine produces a base, sodium hydroxide, as a byproduct, so the net acidification would ultimately cancel out.

  • Jonathan

    Chlorine can be added but may affect the ozone level.

  • http://n/a RICHARD D. STACY

    If, as is reported, methane is worse than carbon dioxide with regard to its “greenhouse gas” effect, then someone should just toss a lighted match in the North Sea and convert all of those millions of cubic feet of methane to carbon dioxide and water.

  • http://CurlewKeep.name Bryan Bremner

    Wonderful Idea!!! Inject Chlorine => HCL into the atmosphere! I worked at the Bunker Hill Mine in N. Idaho for ONE YEAR – that’s how long it took me to get another job. What they shipped out was Lead, Zink and Sulfuric Acid, but not all of the sulfur was converted to SO4, the rest went out the smokestack to create H2SO4 in the air. That worked out well, the whole valley is now a Superfund site. You know; kills horses, kids, trees, whatever. The company was good about it though, they would pay for the horse but then put a lein on your property to prevent you from claiming any more horses. My kids were tested for lead. I really had this big warm, comfy feeling after that.

    I have 2 comments.

    1. Make sure you know all the reactions before you make a suggestion, the cure may be worse than the problem.

    2. Efficiency, wind turbines, photovoltaics, geothermal, perhaps even some hydro but those are mostly used up, are much safer ways of reducing our dependency on fossil fuels. If you have to get a bicycle, walk, or take mass transit, OK, maybe we could all pay $15 per gallon for gas.

    Update, we fed our horses trucked in hay and moved before our kids had any ill effects – or at least not very serious ones, they both have doctor after their names now.

  • http://CurlewKeep.name Bryan Bremner

    Wonderful Idea!!! Inject Chlorine => HCL into the atmosphere! I worked at the Bunker Hill Mine in N. Idaho for ONE YEAR – that’s how long it took me to get another job. What they shipped out was Lead, Zink and Sulfuric Acid, but not all of the sulfur was converted to SO4, the rest went out the smokestack to create H2SO4 in the air. That worked out well, the whole valley is now a Superfund site. You know; kills horses, kids, trees, whatever. The company was good about it though, they would pay for the horse but then put a lien on your property to prevent you from claiming any more horses. My kids were tested for lead. I really had this big warm, comfy feeling after that.

    I have 2 comments.

    1. Make sure you know all the reactions before you make a suggestion, the cure may be worse than the problem.

    2. Efficiency, wind turbines, photovoltaics, geothermal, perhaps even some hydro but those are mostly used up, are much safer ways of reducing our dependency on fossil fuels. If you have to get a bicycle, walk, or take mass transit, OK, maybe we could all pay $15 per gallon for gas.

    Update, we fed our horses trucked in hay and moved before our kids had any ill effects – or at least not very serious ones, they both have doctor after their names now.

  • Paul

    Bryan: heavy metals are a whole different matter. That valley isn’t a superfund site because of sulfur.

  • gene

    Even if the CO2 output is the same, using natural gas still creates less soot, grime, carcinogens and other pollutants than petroleum based fuels, so its still worth switching over. At least our cities will be cleaner and brighter. We are TOO focused on only the CO2. Lets not get distracted. Plus natural gas can be produced from biofuels, avoiding the need for problem causing foreign policies.

  • http://discovermagazine.com Iain

    As long as we burn fossil fuels all we are doing is kidding ourselves. About a year ago I read an article about fracking and natural gas leakage and apparently 7% of the natural gas leaks away. So that would be like 2 1/3% each at production, transportation and end user sites.

    By the way, on a geological scale, stretching oil out to last an extra 500 or 1000 years is meaningless. All that CO2 will still be around and global temperatures will be rising. Back to the Jurassic for planet Earth.

  • Rick

    #1. Isn’t there an entropy problem with capturing CO2 from burning methane and turning it back into methane or methanol?

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

80beats

80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles covering the day's most compelling topics.
ADVERTISEMENT

See More

ADVERTISEMENT
Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »