Substantial quantities of methane-rich gas become trapped and adsorbed within coal formations and are inevitably desorbed in association with coal mining. In some cases of underground mining, a formation is permeabilized with perforations before and/or during extraction work and so-called firedamp gases are allowed to vent as a safety measure. In addition, during work, methane enters the air ventilation system in concentrations of up to 1% and is usually freely expelled from the mine mouth. Ventilation air methane (VAM) is the largest source of methane in operating and decommissioned coal mines worldwide. Methane also continues to be desorbed in considerable quantities from stored coal and abandoned mines. [12]​.

The US Environmental Protection Agency projects that by 2020, global methane releases from coal mines worldwide will exceed 35 million tons or 800 million tons of CO equivalent emissions and will account for 9% of all global methane emissions. China contributes more than 50% of the total, followed by the United States (10%), Russia (7%), Australia, Ukraine, Kazakhstan and India (3-4% each). By 2015, some 200 mines in a wide range of countries had implemented technology to capture around 3 million tonnes of methane, either for economic use or for reduction in gas flares or thermal oxidizers. [12]​.

Outcrops, veins or near-surface formations are also often permeated by wells to extract and capture methane, in which case it is classified as an unconventional form of gas. [12]​ This capture of methane in coalfields can reduce the volume of gas seepage that would otherwise occur naturally, while in turn adding carbon dioxide emissions once the fuel is used elsewhere. [12][13]​.

IEA global monitoring estimates during 2019 suggest that around 40 million tonnes of methane were released from all coal mining-related activities. This amount includes vented, fugitive and leak emissions. [14]​.

In gas fields, obtaining non-associated petroleum gas – a form of crude natural gas – represents the main financial objective. Unlike gas extracted from oil fields or coal mines, this type of gas usually has a lower proportion of unwanted components. Most ventilation emissions occur instead during pipeline transport to trade and distribution centers, refineries and consumer markets. [7]​.

The U.S. Department of Energy reports that the majority of leaks in U.S. gas industry operations in 2017 occurred at compressor stations, from pneumatically operated controllers and regulators.[15] Improved maintenance strategies and advanced equipment technologies exist or are being developed to reduce such venting. [16]​.

IEA global monitoring estimates indicate that by 2019 around 23 million tonnes of methane were released from all segments of the gas industry, including onshore conventional gas, offshore gas, unconventional gas and downstream gas activities. If the amount released by fugitive emissions is included, the estimated total is approximately 43 million tons. [17]​.

The gases associated with oil and coal mining used to be considered problematic, dangerous and low value, perceived as a 'free' by-product derived from the extraction of coal or liquid hydrocarbons, more financially profitable activities. However, the growth of international gas markets, along with the development of infrastructure and supply chains, has transformed this perception. It is also becoming an increasingly common practice:.

• - Capture and use the associated gas to provide local energy.

• - Reinject recompressed gas for oil reservoir pressure maintenance, secondary recovery and possible subsequent reservoir depressurization once hydrocarbon liquids recovery has been maximized and gas export infrastructure and market access has been established.

In recent years, some industry advocates and policymakers have promoted fossil gas as a 'bridge fuel', arguing that its use generates less waste, and therefore reduces both environmental impact and associated economic losses, during the transition from finite fossil fuels to more sustainable energy sources. [18]​ However, the actual volumes of methane released cumulatively along the supply chain have an impact on short-term climate warming that already rivals, and may exceed, that of coal and oil use. [19]​.

Venting and other releases of gaseous hydrocarbons have increased steadily throughout the industrial era, coupled with rapid growth in fossil fuel production and consumption. [20]​ The International Energy Agency estimates that total annual methane emissions from the oil and gas industry increased from approximately 63 to 82 million tonnes between 2000 and 2019, an average increase of around 1.4% annually. [21]​ [22]​ Globally, the IEA estimates that the geological extraction of coal, crude oil and natural gas is responsible for approximately 20% of all methane emissions. [7] Other researchers have found evidence that their contribution may be substantially greater: 30% or more. [23]​ [24]​.

The atmospheric concentration of methane has almost doubled in the last century and is currently 2.5 times higher than in any other period of the last 800,000 years. [25]​ Methane is a powerful gas that causes global warming despite its lower abundance compared to atmospheric carbon dioxide. Atmospheric methane is responsible for at least a quarter and up to a third of the changes in radiative forcing that drive near-term climate warming. [26]​ [27]​ [28]​.

Natural gas components, such as ethane, propane and butane, have a significantly shorter atmospheric life (one week to two months) compared to methane (one to two decades) and carbon dioxide (one to two centuries). Because of this, they are not dispersed uniformly in the atmosphere and their concentration is considerably lower. [29] However, their oxidation ultimately leads to the creation of longer-lived carbon compounds that also disrupt the atmosphere and the planetary carbon cycle through a variety of complex pathways. [30]​.

• - Methane emissions.

• - Flare and vent removal systems on PetroWiki.

• - Coal methane at PetroWiki.

Substantial quantities of methane-rich gas become trapped and adsorbed within coal formations and are inevitably desorbed in association with coal mining. In some cases of underground mining, a formation is permeabilized with perforations before and/or during extraction work and so-called firedamp gases are allowed to vent as a safety measure. In addition, during work, methane enters the air ventilation system in concentrations of up to 1% and is usually freely expelled from the mine mouth. Ventilation air methane (VAM) is the largest source of methane in operating and decommissioned coal mines worldwide. Methane also continues to be desorbed in considerable quantities from stored coal and abandoned mines. [12]​.

The US Environmental Protection Agency projects that by 2020, global methane releases from coal mines worldwide will exceed 35 million tons or 800 million tons of CO equivalent emissions and will account for 9% of all global methane emissions. China contributes more than 50% of the total, followed by the United States (10%), Russia (7%), Australia, Ukraine, Kazakhstan and India (3-4% each). By 2015, some 200 mines in a wide range of countries had implemented technology to capture around 3 million tonnes of methane, either for economic use or for reduction in gas flares or thermal oxidizers. [12]​.

Outcrops, veins or near-surface formations are also often permeated by wells to extract and capture methane, in which case it is classified as an unconventional form of gas. [12]​ This capture of methane in coalfields can reduce the volume of gas seepage that would otherwise occur naturally, while in turn adding carbon dioxide emissions once the fuel is used elsewhere. [12][13]​.

IEA global monitoring estimates during 2019 suggest that around 40 million tonnes of methane were released from all coal mining-related activities. This amount includes vented, fugitive and leak emissions. [14]​.

In gas fields, obtaining non-associated petroleum gas – a form of crude natural gas – represents the main financial objective. Unlike gas extracted from oil fields or coal mines, this type of gas usually has a lower proportion of unwanted components. Most ventilation emissions occur instead during pipeline transport to trade and distribution centers, refineries and consumer markets. [7]​.

The U.S. Department of Energy reports that the majority of leaks in U.S. gas industry operations in 2017 occurred at compressor stations, from pneumatically operated controllers and regulators.[15] Improved maintenance strategies and advanced equipment technologies exist or are being developed to reduce such venting. [16]​.

IEA global monitoring estimates indicate that by 2019 around 23 million tonnes of methane were released from all segments of the gas industry, including onshore conventional gas, offshore gas, unconventional gas and downstream gas activities. If the amount released by fugitive emissions is included, the estimated total is approximately 43 million tons. [17]​.

The gases associated with oil and coal mining used to be considered problematic, dangerous and low value, perceived as a 'free' by-product derived from the extraction of coal or liquid hydrocarbons, more financially profitable activities. However, the growth of international gas markets, along with the development of infrastructure and supply chains, has transformed this perception. It is also becoming an increasingly common practice:.

• - Capture and use the associated gas to provide local energy.

• - Reinject recompressed gas for oil reservoir pressure maintenance, secondary recovery and possible subsequent reservoir depressurization once hydrocarbon liquids recovery has been maximized and gas export infrastructure and market access has been established.

In recent years, some industry advocates and policymakers have promoted fossil gas as a 'bridge fuel', arguing that its use generates less waste, and therefore reduces both environmental impact and associated economic losses, during the transition from finite fossil fuels to more sustainable energy sources. [18]​ However, the actual volumes of methane released cumulatively along the supply chain have an impact on short-term climate warming that already rivals, and may exceed, that of coal and oil use. [19]​.

Venting and other releases of gaseous hydrocarbons have increased steadily throughout the industrial era, coupled with rapid growth in fossil fuel production and consumption. [20]​ The International Energy Agency estimates that total annual methane emissions from the oil and gas industry increased from approximately 63 to 82 million tonnes between 2000 and 2019, an average increase of around 1.4% annually. [21]​ [22]​ Globally, the IEA estimates that the geological extraction of coal, crude oil and natural gas is responsible for approximately 20% of all methane emissions. [7] Other researchers have found evidence that their contribution may be substantially greater: 30% or more. [23]​ [24]​.

The atmospheric concentration of methane has almost doubled in the last century and is currently 2.5 times higher than in any other period of the last 800,000 years. [25]​ Methane is a powerful gas that causes global warming despite its lower abundance compared to atmospheric carbon dioxide. Atmospheric methane is responsible for at least a quarter and up to a third of the changes in radiative forcing that drive near-term climate warming. [26]​ [27]​ [28]​.

Natural gas components, such as ethane, propane and butane, have a significantly shorter atmospheric life (one week to two months) compared to methane (one to two decades) and carbon dioxide (one to two centuries). Because of this, they are not dispersed uniformly in the atmosphere and their concentration is considerably lower. [29] However, their oxidation ultimately leads to the creation of longer-lived carbon compounds that also disrupt the atmosphere and the planetary carbon cycle through a variety of complex pathways. [30]​.

• - Methane emissions.

• - Flare and vent removal systems on PetroWiki.

• - Coal methane at PetroWiki.