Just over a month ago, the Grosvenor coal mine in Queensland exploded, causing a massive methane plume and doing more damage in an hour than 10,000 tree saplings could offset in 10 years.
  • Dave.@aussie.zoneEnglish
    9·
    3 months ago

    The horse has well and truly bolted on this one.

    About 30 years ago, I used to do coal seam sampling around those parts. There are thousands of boreholes going down to the coal seams there. We would drill down to the seam and then take about a 6 metre cross section of the seam.

    You’d pull up the core samples, place them in sealed tubes made out of metre long, 100mm diameter plastic pipe and take them back to the lab to see how much gas came out.

    Over the course of about 48 hours, about 30 litres of gas would come from about 10kg of coal.

    Oh, those boreholes? They were just left uncapped. Sometimes if it was particularly gassy, they’d put a burner on top, sometimes they wouldn’t, and if a bushfire went through the area those boreholes would never go out and you’d see hundreds of them burning away into the distance. There’s thousands of square kilometres with boreholes in them in that area.

    Every kilogram of coal that they take to the surface will vent the same amount of methane as my samples did 30 years ago and the aggregate amount of coal they mine in the Bowen Basin is about 50 million tons a year.

    So when they finally close all the coal mines, and seal all the shafts and fill in all the pits, they’re also going to have to go and cap the thousands upon thousands of boreholes because they’re a direct line to the remaining seams below, and they’ll basically vent forever.

    • No1@aussie.zoneEnglish
      1·
      3 months ago

      So when they finally close all the coal mines,

      OK

      and seal all the shafts and fill in all the pits, they’re also going to have to

      Hmmm. Will they really? That’s a cost with no revenue. I’d go bankrupt if I were a company.

      go and cap the thousands upon thousands of boreholes because they’re a direct line to the remaining seams below, and they’ll basically vent forever.

      I gas that seems more likely…

      • Dave.@aussie.zoneEnglish
        2·
        3 months ago

        They are forced by the state government to put aside money for future rehabilitation.

        Something else to point out is that “huge methane plume” is actually methane that is always there. It’s just that normally there is a huge amount of forced ventilation into (and subsequently out of) underground mines and while that is working this methane plume is diluted to much lower levels.

        • No1@aussie.zoneEnglish
          1·
          3 months ago

          They are forced by the state government to put aside money for future rehabilitation. Piles of money set aside frequently have a way of disappearing…

          Something else to point out is that “huge methane plume” is actually methane that is always there. It’s just that normally there is a huge amount of forced ventilation into (and subsequently out of) underground mines and while that is working this methane plume is diluted to much lower levels.

          Oh, my bad. I thought that the methane was kinda trapped underground with the coal and was released by mining/boring.