page_title: Gas venting
section_title: Coal mining and coalbed methane activity
hierarchical_section_title: Gas venting / Coal mining and coalbed methane activity
context_page_description: Gas venting, more specifically known as natural-gas venting or methane venting, is the intentional and controlled release of gases containing alkane hydrocarbons - predominately methane - into earth's atmosphere.
  It is a widely used method for disposal of unwanted gases which are produced during the extraction of coal and crude oil.
  Such gases may lack value when they are not recyclable into the production process, have no export route to consumer markets, or are surplus to near-term demand.
  In cases where the gases have value to the producer, substantial amounts may also be vented from the equipment used for gas collection, transport, and distribution.
  Gas venting contributes strongly to climate change, nevertheless many individual cases are sufficiently small and dispersed to be deemed "safe" with regard to immediate health hazards.
  Large and concentrated releases are usually abated with gas flares to produce relatively less-harmful carbon dioxide gas.
  Gas venting and flaring that are performed as routine practices are especially wasteful, and may be eliminated in many modern industrial operations where other low-cost options are available to utilize the gas.
context_section_description: Substantial amounts of methane-rich gas are trapped and adsorbed within coal formations,  and are unavoidably desorbed in association with coal mining.
  In some cases of sub-surface mining,  a formation is permeated with boreholes prior to and/or during extraction work, and the so-called firedamp gases allowed to vent as a safety measure.
  Also during work, methane enters the ventilation air system at concentrations as high as 1%,  and is usually freely exhausted from the mine opening.
  Such ventilation air methane (VAM) is the largest source of methane from all operating and decommissioned coal mines worldwide.  
  Substantial methane also continues to desorb from coal placed into storage and from abandoned mines. 
  The U.S. Environmental Protection Agency projects that by year 2020, global methane releases from coal mines throughout the world will exceed 35 million tons or 800 million tons of CO₂-equivalent emissions, and account for 9% of all global methane emissions. China contributes over 50% of the total, followed by the United States (10%) and Russia (7%), and then by Australia, Ukraine, Kazakhstan, and India (3-4% each).   About 200 mines across a broad scope countries had implemented technology by year 2015 to capture about 3 million tons of methane; either for economic use or for abatement in gas flares or thermal oxidizers.
  Outcroppings, seams, or formations near the surface are also sometimes permeated with wells to extract and capture the methane, in which event it is classified as a form of unconventional gas.
  Such coalbed methane capture can reduce the volume of gas seepage that would otherwise occur naturally; while in-turn adding emissions of carbon dioxide once the fuel is utilized elsewhere.
  Global tracking estimates from the IEA during year 2019 suggest that about 40 millions tons of methane were released from all activities related to coal mining.  This total amount includes all vented,  fugitive,  and seepage emissions.
caption: A large fan supplying fresh air to a mine ventilation shaft.  Methane and coal dust are removed by exhaust air.
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