The Methane Calculation

The old mining term for explosive gases in coal mines is “firedamp”. It seems illogical – I mean, a damp fire? – until you realize that it comes from the German word “dampf” for vapors.

There are other “damps” in mining terminology – “afterdamp”, for instance, refers to the poisonous gas carbon monoxide, which tends to build up in mines after an explosion. But firedamp explicitly refers to a gas mixture rich in the flammable gas methane, which – as the recent mining disaster in New Zealand reminds us – is ever available to act as a fuse for an underground denotation.

As of this morning, following a Friday explosion, 29 miners remain trapped in in the Pike River coal mine, which is located on the forested west coast of New Zealand’s South Island. There has been no contact with miners since then and observers report no evidence of human activity. Officials say the miners were working in a section of a shaft drilled horizontally more than two kilometers into the surrounding hillside.

AP Photo - Smoke drifts out following an explosion at New Zealand's Pike River mine

We don’t need to be down there to know what happened. We’ve played this scenario over countless times. The word firedamp is old because methane-fed mine explosions are old, old, old news. One of the most famous was almost 200 years ago in a coal mine in England; methane gas ignited by a lantern set off an explosion that killed 92 miners. The explosion in the Felling mine in 1812 was so powerful that flames roared out of the mine-shaft entrance into the open air.

The disaster prompted the  British scientist, Sir Humphrey Davy, to design a “safety lamp” with an enclosed flame – which burned brighter if methane seeped into the lamp – for use in mines. Davie’s lamp greatly reduced but, obviously, didn’t eliminate methane explosions in mines. In the year, 1907, for one instance, 362 American miners were killed in a methane explosion.

In an excellent look at methane in coal mines, Thomas Maugh of The Los Angeles Times, points out that the gas is always found in coal mines. It’s produced by the same buried organic material, heat, and underground pressure that creates coal itself. In other words, methane is just another hydrocarbon. It’s chemical formula is CH4, another way of saying one atom of carbon to every four of hydrogen, another way of saying a wonderfully flammable kind of fuel.

A chemical model of methane

The gas methane is usually found in the same seams that contain coal itself. As miners drill into those seems out it seeps, an airy invisible kind of kindling, the primary component in the natural gas we burn in our furnaces. If we wonder why explosion occur in coal mines over and over, century after century,  it’s because we create an astonishingly volatile environment down below – methane poised to ignite, explosive materials all around, and only a single spark needed to trigger an event.

That awareness demands a high standard of safety precautions. Mine operators have responded with a safety systems including methane detectors (high-tech versions of the 19th century Davy safety lamp) and ventilation systems that remove methane from underground tunnels and also blow fresh air into the system to dilute methane levels.

But it’s not enough to just put in monitors and air shafts because what history tells us is that here’s – in how we ourselves maintain those shafts, listening to those warning flickers – it’s here where it tends to break down.  Reports have been circulating of ventilation problems at the New Zealand mine, that may have allowed a methane buildup in the tunnels. The Sydney Morning Herald quoted a mining expert today who insisted modern safety systems do guarantee against explosive accidents. ”If they had all the [safety] systems in place it shouldn’t have happened.”

I believe that was pretty much what people said when the Upper Branch  mine in  West Virginia (coal mining country, United States of America) went up in a methane-fed fireball last April, killing 29 miners as it went. They undoubtedly said that when a Russian mine explosion about a month later, killed 60-some miners there.

We’ve learned a lot about methane for the past two centuries and a lot about safety equipment. We just haven’t learned yet to be meticulous with it, to step away when the first hint of danger drifts by. The technology has come to us far more quickly than the best solution – remembering that the people who go down into the mine are actually more valuable than the coal coming up.

Here’s hoping the New Zealand miners, despite all fears, survive this latest evidence that we remain very slow learners.

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11 Responses to The Methane Calculation

  1. Grant says:

    Thank you so much for putting this up.

    You write of the 1812 explosion “flames roared out of the mine-shaft entrance into the open air”. Tree around the vent you show appear burnt, as you may have seen from other photographs or video footage. (There’s some on the sciblogs website that my blog is hosted on. Those interested in following local reportage may find the stuff.co.nz one useful source.)

  2. Happy says:

    remembering that the people who go down into the mine are actually more valuable than the coal coming up

    Well, that would seem to be the crux of the problem really.

    Obviously the price of shutting mines, installing safety equipment, emergency escape shafts etc is a burden on day to day profitability.

    NZ is just across the water from me, I’m not suggesting anything untoward going on there because I haven’t really seen much in-depth about it.

    However, China isn’t all that far away and they have _lots_ of mining accidents… so regular that it’s almost a footnote in the news… I don’t see a lot of western media camped out at those mines doing expert analysis live on tv.

    Here we have lots of “open cut” coal – I don’t particularly like that solution either; maybe if we could just walk away from coal altogether it would be a good thing and a truer weighing of the value of human life versus the utility of burning the stuff.

  3. Deborah Blum says:

    It’s just one of those issues I find really compelling – and important, all those people going down dark tunnels to supply the rest of us with fuel. I really hope this one turns out well. And I encourage any readers to follow Grant’s tips on further information.

  4. Deborah Blum says:

    You make some great points here. We really don’t get a good job of making people understand the real costs of fossil fuels, do we? And I’d include global climate change in that dilemma.

  5. Grant says:

    There is also a little information from experts interviewed by the Science Media Centre (who act to link media and scientists, they also host sciblogs.co.nz):

    http://www.sciencemediacentre.co.nz/2010/11/22/pike-river-experts-on-explosion-conditions-in-the-mine-rescue-efforts/

    Someone familiar features at the very end ;-)

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  9. Warren Young says:

    Tragically a second explosion occurred this afternoon (1427 local time) at Pike River. Its said that there is no possibility of the miners having survived the second blast which was perhaps bigger than the blast Friday. Another 29 miners lost.

  10. Curtis Jones says:

    Look you write well but not from an operational standpoint of having worked in the industry. You fail to mention directional gas drainage drilling, which has vastly improved issues related to outgassing. Not all coal mines make explosive gas – quite a number have their issues aligned more with carbon dioxide, which is not explosive and not particularly (compared to carbon monoxide) poisionous, but can cause a hell of a mess if you mine into a pocket and have a outburst & heave. You photo of the exhaust fan evase is incorrectly labeled as showing smoke issuing from the mine. It’s not smoke – it’s water vapour.

  11. Deborah Blum says:

    Thanks so much for writing. I appreciate your insight into mine operations. You’re right that I oversimplified the picture; certainly all coal mines are not alike. We heard after the Upper Big Branch explosion that the area of West Virginia in question was a fairly gaseous coal mining area, for instance. I really was trying to just make a simple point: that coal mines of this type need to be managed extremely carefully, that they contain all the right ingredients for an explosion if this isn’t done. I’ll definitely mention directional gas drilling if I list good management tips again. As to window of rescue opportunity – agreed, maybe. But a very small maybe based on the carbon monoxide and methane readings. On whether the operations at the mine were handled in an ideal way – again, agreed – they were obviously and very sadly not.