Methane

{{#badges: Climate change |CoalSwarm | WaterEnergy}} Methane (CH₄) is a potent greenhouse gas with a high global warming potential 72 times that of carbon dioxide (averaged over 20 years) or 25 times that of carbon dioxide (averaged over 100 years), according to the Intergovernmental Panel on Climate Change (IPCC)'s Third Assessment Report. Methane in the atmosphere is eventually oxidized, producing carbon dioxide and water. This breakdown accounts for the decline in the global warming potential of methane over longer periods of time.

The global warming potential of methane was estimated at 21 times that of carbon dioxide, averaged over 100 years, in the IPCC Second Assessment Report, and the 21 figure is currently used for regulatory purposes in the United States.

Methane time bomb

In September 2008, The Independent newspaper reported how preliminary scientific findings suggested that massive deposits of sub-sea methane were bubbling to the surface as the Arctic region becomes warmer and its ice retreats. This methane time-bomb is seen as extremely worrying, because it could be a positive feedback mechanism, where the more the Arctic melts the more methane is released, which could put us on the path to runaway global warming.

Coal mining and methane

Coal mining accounts for about 10 percent of US releases of methane. It is the fourth largest source of methane, following landfills, natural gas systems, and enteric fermentation.

Methane released by coal mining includes:

• Underground Mining: In the United States, methane from underground mining operations is typically vented. In some other countries it is also flared.
• Surface Mining: During surface mining, methane is released directly to the atmosphere.
• Post-Mining Activities: Some methane remains in the coal after mining and is released during subsequent processing and transportation.
• Abandoned Mines: Methane emissions from abandoned mines are not quantified and included in U.S. inventory estimates, but may be significant.

Methane and coal mining explosions

When coal is mined, fissures and pores in the coal bed in which methane is lying are exposed, releasing methane into the confined area. This can be dangerous because methane is not only highly flammable, with the potential to violently explode in a ball of flame, but is also an asphyxiant, capable of driving out oxygen and causing death by suffocation. A build up of hazardous gas in a mine is known as a damp, with methane build-ups called “fire damps”. Carbon monoxide accumulation, called “white damp,” adds to these dangers. When methane combusts, this highly toxic and flammable gas is generated as a by-product and spreads through a mine’s tunnels and shafts. Coal dust also reacts badly to a methane explosion. As part of a violent chain reaction, it can burst into flames in a series of secondary explosions throughout a mine.

The properties of methane make it difficult to detect without equipment. It is colorless and odorless, so there are no obvious physical signs such as coughing or watering eyes to warn of its proximity, although it will cause suffocation if it builds up in a badly ventilated space. It is also difficult to assess how much methane is likely to be freed from a particular coal bed – factors such as coal type, the depth of the mine, and the geologic age of the coal strata all play a part.

Once present in the atmosphere of the mine, methane can be easily ignited. Modern mining equipment includes electric arcs, hammers, and cutters that can all generate sparks and open flames that can detonate a pocket of methane gas. U.S. federal standards stipulate that if there is 1.0 percent or more of methane in the working area, miners must immediately shut down all electrically powered tools and other mechanized equipment.

The 1907 Monongah Mine Disaster of West Virginia, which claimed the lives of 362 men and boys and is known as the worst mining disaster in American History, is thought to have been caused by the ignition of methane, which in turn ignited highly flammable coal dust.

Methane and the Upper Big Branch Mine Disaster

In July 2010, an electrician at the Upper Big Branch Mine, site of the Upper Big Branch Mine Disaster in April 2010, confirmed that he was ordered to bypass the methane detector on a piece of mining equipment. Such detectors are designed to automatically turn off a machine once methane reaches a certain level; with the detector bypassed, the machine would continue operating regardless of methane levels. The detector was on a continuous mining machine four miles from the origins of the explosion and was not thought to have played a role in the explosion. Investigators, however, are now looking to see if the practice of bypassing the detectors had happened in other areas of the mine, something that could point to wider questions about safety practices at the mine. Micah Ragland, spokesman for Massey Energy, confirmed that someone had bridged the methane monitor.

Federal investigators first learned of the monitor bridging from Ricky Lee Campbell, a former Upper Big Branch miner who was fired from his job at another Massey mine after he publicly criticized safety practices at Upper Big Branch. Massey lawyers said Mr. Campbell was fired for violating a safety rule at the company's Marfork Coal Co., but in June 2010, Department of Labor officials won temporary reinstatement of Mr. Campbell after an administrative law judge ruled that he had actually been fired in retaliation for speaking out. According to Campbell, he and two other miners at Upper Big Branch saw a supervisor instruct Mr. Holtzapfel to run a wire that would bypass a methane detector on a continuous mining machine on Feb. 13 -- seven weeks before the blast. Campbell said Holtzapfel had protested the order, calling it improper, but was forced to make the bridge. When told of Mr. Campbell's account, Mr. Holtzapfel said, "That's how it went."

Resources

Related SourceWatch Articles

• Coal dust
• Fracking
• Marcellus Shale
• Methane released by coal mining
• The methane time-bomb
• Natural gas as an alternative to coal
• Natural gas transmission leakage rates
• Powder River Basin
• Upper Big Branch Mine Disaster

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