A new study by Western Virginia University has found the amount of carbon dioxide released from 140 coal mines throughout Pennsylvania, USA, is equal to that of a small power plant.
Department of Geology and Geography associate professor, Dorothy Vesper, and her team, used a meter designed for measuring carbon dioxide levels in beverages to more accurately measure the gas in mine drainage water.
They used measurements from a number of sites and estimated values from United States Geological Survey data for 140 mines to calculate the amount of carbon dioxide released from abandoned coal mines.
They measured the water’s carbon dioxide levels at two mine sites, comparing the results to estimated gas levels for a limited set of inactive mines across the region. The findings that the amount of gas is equivalent to a small power plant has paved the way for larger studies identifying the impact carbon dioxide from mine drainage has on the environment.
Vesper said there is a bias in the way carbon dioxide concentrations are estimated in water but they were able to quantify them.
“Many people calculate carbon dioxide from alkalinity, or the capability of water to neutralise acid, so the pH has to be above five, but if you have a lot of carbon dioxide dissolved in the water, it forces the pH to fall below five and people just dismiss it and ignore it,” she said.
“A lot of those very low pH waters have plenty of carbon dioxide in them.”
Mine water rich in sulphates can dissolve surrounding limestone, enabling carbon dioxide gas to be present in the water, and, when the water reaches the land’s surface, some of the carbon dioxide enters the atmosphere.
Vesper went on to say that carbon dioxide is “really high” in mine waters and no one has been able to measure it in great detail due, in part, to its difficulty.