Coal Mine Gas-Level Rating Methodology
| This article is part of the Global Coal Mine Tracker, a project of Global Energy Monitor. |
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This page describes the methodology used by GEM's Global Coal Mine Tracker to identify the gas levels of coal mines with known appraisal results from reported sources.
Gas-level rating is a safety classification system used in coal mining to assess the risk level of methane (CH₄) emissions in coal mines , particularly underground operations. It helps determine the potential hazard of gas explosions, suffocation, or sudden outbursts (violent releases of gas and coal).
In 2025, the Global Coal Mine Tracker began monitoring gas-level ratings in Chinese coal mines as part of its effort to identify potential super emitters and their locations. The tracker plans to expand this coverage to additional countries as more data becomes available.
Gas-Level Classification Method in China
According to the 2018 “Measures for the Classification and Identification of Coal Mine Gas” (煤矿瓦斯等级鉴定办法),[1] issued by the State Administration of Coal Mine Safety and the National Energy Administration, underground coal mines, including newly constructed mines, expanded or retrofitted operations, resource-integrated mines, and production mines, are required to be classified based on gas levels.
Coal mines are categorized into three levels:
Low-gas mines
- Relative gas emission rate ≤ 10 m³ per ton of coal mined.
- Absolute gas emission rate ≤ 40 m³/min (entire mine).
- No high-gas zones detected.
High-gas mines
- Relative gas emission rate > 10 m³/t.
- Absolute gas emission rate > 40 m³/min.
- Any mining face emitting at a rate > 5 m³/min, or tunneling face emitting at a rate > 3 m³/min.
Coal and gas outburst mines (or CO₂ outburst mines, abbreviated as “outburst mines”)
- History of coal/gas outbursts (sudden ejections of coal and gas).
- Geological signs of high gas pressure/flow.
Low-gas mines are required to undergo a high-gas classification appraisal every two years. High-gas and outburst mines must measure and calculate gas emissions (including carbon dioxide) annually at the mine, mining area, and working face levels.
Data sources
Coal mine gas-level data is collected from:
- central and provincial government records on individual mines’ gas levels;
- company reports on mine development and environmental appraisals;
- News and media reports on coal mine development.
References
- ↑ 国家煤矿安监局国家能源局关于印发《煤矿瓦斯等级鉴定办法》的通知, April, 2018.
