From coal boom to methane boom

Indonesia’s coal industry has experienced remarkable growth over the past two decades, with production increasing by more than 11% per year on average between 2000 and 2024. However, this massive expansion has led to a corresponding surge in coal mine methane emissions. 

Methane from coal mining is now a major but overlooked climate risk. As coal extraction intensifies, methane released during mining operations has quietly grown into a major, yet largely unmonitored, source of greenhouse gas emissions. Ember estimated that CMM emissions in 2024 reached 722 kt CH4, more than four times the government reported emissions of 168 CH4. Other organisations, such as IEA and GEM, showed even higher estimates. 

CMM underreporting reflects deeper structural issues across government, industry, and existing reporting systems. Limited institutional capacity, low corporate awareness, and ineffective MRV frameworks have left methane emissions from coal mining largely overlooked and unaccounted for.

The official report still understates the true scale of CMM emissions. The government has made limited progress in improving monitoring, reporting, and verification (MRV) systems in the recently published Biennial Transparency Report (BTR). Specific emission factors for open-cut coal mines have yet to be developed, despite earlier commitments in the Third Biennial Update Report (BUR). 

The government continues to rely on IPCC’s low emissions factors for open cut coal mines, without clarifying assumptions such as overburden depth. 

Evidence points to higher emissions than reported. Ember’s analysis on five big coal mining companies revealed higher emissions intensity, which correlates with calorific values. Furthermore, an initial assessment by Tekmira also clearly indicates higher emissions factors.

Furthermore, emissions from underground mines, which have far higher emissions per ton of coal, remain excluded in the CMM estimation. Whereas, Ember’s previous assessment showed that underground coal mines could contribute one third of national CMM emissions. 

As BTR is intended to establish baseline emissions, the use of inaccurate emission factors and incomplete emissions sources could distort Indonesia’s national greenhouse gas inventory. This, in turn, risks setting misleading baselines and reduction targets under both the second Nationally Determined Contribution (NDC) and the Global Methane Pledge. 

Even though CMM emissions inventory and companies’ reporting are already regulated under the MEMR Regulation No. 22/2019, the detailed guidance has yet to be issued. Therefore, existing emissions reporting applies only to publicly-listed companies as part of sustainability reports. 

Ember’s analysis revealed that five companies, representing 17.7% of national coal production, reported combined emissions of 90 kt CH4. This accounts for more than half of officially reported CMM emissions, highlighting the persistent and significant underreporting across the sector. 

A big underground coal mine in South Kalimantan that recently began operations has also not reported its emissions. With 2.6 million tonnes of coal production in 2024, we estimated that CMM emissions from this mine alone could reach 35 kt CH4. Once it operates at full capacity, producing around 20 million tonnes per year, CMM emissions could increase nearly tenfold.

There are currently 15 companies engaged in underground coal mining at various development stages. However, due to limited information, we only analyse an underground coal mine in South Kalimantan with production capacity of 2 x 10 million tonnes per year. 

This underground coal mine is expected to become a major source of CMM emissions. With last year’s production of only 2.6 million tonnes, its output and associated methane emissions could increase sharply in coming years. Ember estimates this coal mine will reach full capacity by 2030, given the planned operation of the second coal mine next year and the end of mining permits in 2034.  

Accordingly, CMM emissions from this underground coal mine are projected to increase from 35 kt CH4 in 2024 to 332 kt CH4 in 2030. Even with a projected 14% decline in national coal production, total CMM emissions are expected to increase by around 25% by the end of the decade, driven by the growing emissions from this underground mine.

Given this trajectory, early implementation of mitigation measures is crucial. Technologies to mitigate CMM exist but are not being applied. Underground coal mine mitigation measures, such as pre-mine drainage and ventilation air methane (VAM) oxidation are commercially viable and have been implemented in other countries. 

Furthermore, methane leakage continues after mines close. Unlike open-cut mines, underground mines can continue releasing gas for decades after closure. Abandoned mine methane (AMM) must therefore be treated as an integral part of mine closure, similar to reclamation obligations. Companies could be required to provide financial guarantees or bonds to ensure post-closure methane control through measures such as controlled flooding, sealing, or active gas recovery.