Reference · the terms, precisely

Glossary

Every load-bearing term on this site, defined once. Where a term has a regulatory meaning, the article of Regulation (EU) 2024/1787 is cited.

Closed mine

A mine where coal operations have ceased but a responsible operator, owner or licensee can still be identified, or closure followed a regulated procedure. Under Regulation (EU) 2024/1787 the operator or the member state carries its methane obligations (Art. 25(7)).

Abandoned mine

A mine where no operator, owner or licensee can be identified as responsible, or which was not closed in a regulated manner (Arts. 2(53)–(54)). Obligations fall to the member state.

Underground mine

A mine worked by shafts and galleries rather than open excavation. Only underground hard-coal mines are modelled in the study inventory; surface mines are counted but not modelled.

AMM — abandoned-mine methane

Methane continuing to desorb from coal seams and workings after a mine stops operating, escaping through shafts, vents, fractures and connected workings.

Flooded / dry

Whether rising groundwater has substantially submerged the workings. A substantially flooded mine is expected to emit far less methane; a dry one keeps venting for decades. In reality flooding is partial and dynamic — the model's binary toggle is a simplified bounding scenario, not a site prediction.

Dry path

The non-flooded mine scenario in the decline model (hyperbolic decline, Kholod et al. 2020). It does not refer to dry-gas volume conditions.

MCM / yr

Million cubic metres of methane per year — a volume rate. 1 MCM CH₄ ≈ 0.67 kt CH₄ (IPCC 2006 density convention at 0 °C, 1 atm).

kt CH₄ / yr

Kilotonnes (thousand tonnes) of methane per year — a mass rate. Multiply by 82.5 (20-year lens) or 29.8 (100-year lens) for CO₂-equivalents.

GWP — global warming potential

How much warming a gas causes relative to CO₂ over a stated horizon. Fossil methane: 82.5× over 20 years, 29.8× over 100 (IPCC AR6). Both lenses are always shown together on this site.

Source-level measurement

An instrument reading taken at the emission point itself (a shaft, vent or borehole), with a stated method and date — the only thing this site labels Field-measured. Inventory records and constants are labelled Reported or Reference instead.

Venting

Releasing methane to the atmosphere uncombusted. Prohibited for in-scope equipment from 1 January 2030 (Art. 26(2)).

Flaring

Burning methane without using the energy. Also prohibited from 2030, with narrow exceptions for infeasibility or safety. An enclosed flare destroys methane at ≈90–99.5% efficiency.

Recovery / use

Capturing methane rich enough (≳35% CH₄) to run a gas engine or feed a network — turning the liability into energy.

Oxidation (thermal or biological)

Destroying dilute methane by controlled reaction: regenerative thermal oxidisers below a ≈1.5% feed ceiling, or methanotrophic biofilters at research scale. The 5–15% explosive band is never handled raw.

MRV

Measurement, reporting and verification — the regulatory discipline of continuous instrumented evidence behind every claimed tonne.

Digital twin

A model of a specific mine — geometry, gas, water, interventions — kept honest by displaying model-versus-measurement gaps rather than smoothing them.

Modelled vs estimated

Modelled figures come from a published model with stated inputs; estimated figures come from analogues or expert ranges where no model exists. Both are distinct from Reported (published records) and Field-measured (instrument readings).

Deeper detail: the methodology · the evidence labels on Proof