IEA (2023), Global Methane Tracker 2023, IEA, Paris https://www.iea.org/reports/global-methane-tracker-2023, License: CC BY 4.0
Strategies to reduce emissions from coal supply
Coal operations are a major source of methane emissions. There are many low-hanging opportunities available to cut down on these, but in general wholesale reductions are more challenging than is the case for oil and gas operations. One of the most effective ways to cut down on coal mine methane is likely to be to cut coal consumption itself. Nonetheless, widespread deployment of abatement measures should still be a priority, especially given the risk that coal demand remains high in the coming years. Here we look at the sources of coal mine methane emissions, the potential and costs of abatement measures, and – drawing on the IEA’s new Regulatory Roadmap and Toolkit for coal mine methane – the policy, regulation and co-operation that can help drive reductions.
Coal seams naturally contain methane, which can be released during or after mining operations, and which is referred to as coal mine methane (CMM). Sources of emissions include seepage from coal seams exposed in surface or open pit mines; drainage systems used to reduce the methane content of coal deposits; ventilation systems (where methane is extracted and vented from underground coal mines as a safety measure); post‐mining activities such as processing, storage and transport when methane still trapped in the matrix of the coal seeps out; and from abandoned mines. Ventilation air methane is the largest source of CMM at underground coal mines. Drainage systems are a major source of emissions at surface mines.
Methane emissions tend to be higher from underground mines than from surface mines, as deeper coal seams tend to contain more methane than shallower seams. Coal type also affects its methane content: lignite tends to have the lowest methane content, followed by steam coal and coking coal. More than 80% of all coal produced today is steam coal, which is mainly used for heat and electricity generation, 15% is coking coal, mainly used in steel making, and the remainder is lignite.
Just over 40 Mt of CMM were released to the atmosphere in 2022, representing more than 10% of total methane emissions from human activity. Steam coal and lignite accounted for around 75% of CMM emissions and coking coal for the remaining 25%. Underground mines were responsible for around 70% of emissions and surface mines for the remainder. Emissions from abandoned coal mines are not included in these estimates, but could represent a significant source of emissions.
Coal production and related methane emissions are concentrated in a handful of countries. The world’s top eight largest emitters account for more than 90% of total CMM emissions. China is the world’s largest coal producer and is responsible for around half of global CMM emissions.
CMM abatement technologies have already been implemented at a number of sites around the world, but they are still far from being standard industry practice. Projects are often hindered by lack of potential users of power or natural gas, economic barriers, and legal and regulatory challenges around the ownership of the methane.
We estimate that it is technically possible to avoid over half of global CMM emissions with existing technologies. Mitigation measures and their costs vary depending on mine characteristics, including methane concentrations, emissions volumes, and the scale of operations. CMM concentrations can be very low and fluctuate significantly over the lifetime of a project. For example, ventilation air methane from underground mines generally contains less than 1% methane. The lower the concentration of methane, the more technically and economically difficult it is to abate.
High concentration sources of methane can be captured through degasification systems if abatement measures are planned prior to the start of mining operations. For example, degasification wells and drainage boreholes can capture methane from coal deposits, which reduces emissions during production. These systems can also be applied to working mines before operations migrate to new areas of coal exploration or after operations have ceased in an area. While underground mines hold the greatest potential for abatement through these systems, degasification programmes have also been successfully applied to surface mines (e.g., at the North Antelope Rochelle Mine). Recovered CMM can often be used to generate heat and electricity or sold to industrial customers. We estimate that widespread CMM utilisation could provide around 40 TWh of electricity globally.
If utilisation is not an option, it is better to use flares or other combustion technologies given methane’s potency as a GHG. Because of the variations in the volume and concentration of CMM over the lifetime of a mine, utilisation technologies may need to be complemented by destruction systems, such as flares, to ensure methane abatement at all times.
Abating methane from ventilation systems is the single most important measure the coal industry can take to reduce its emissions. It would reduce CMM on a global level by almost 30%. Tapping into this opportunity requires firm policy action and stronger economic incentives, as the potential for energy recovery is marginal. Integrating CMM into emissions trading schemes could provide an avenue for methane mitigation.
In underground coal mines, on-site recovery and use of ventilation air methane can provide heat to mine facilities or be used for coal drying. Alternatively, thermal oxidation can destroy ventilation air methane. Oxidation projects can be relatively expensive and technically challenging but enable methane destruction even at very low concentrations.
Other CMM sources include losses from utilisation equipment, coal processing, storage and transport. Measures to reduce these emissions include efficiency improvements, such as maintaining a high combustion efficiency at flares, gas engines and related equipment through process control systems. Measures to capture fugitive emissions and route to abatement systems help to reduce losses by monitoring, capturing and sealing fugitive sources (e.g., closing unused mine entries or boreholes) and directing CMM to drainage or ventilation air methane abatement systems.
There is wide variation in the abatement costs and potential for different types of mines. The abatement potential is higher for large, porous underground coal mines and lower for surface mines, where methane emissions are more diffuse. Globally, we estimate that around 70% of CMM from underground mines can be abated while only 20% of CMM from surface mines can be abated. There are also differences in the abatement potential for steam coal and lignite (about 50% of CMM can be avoided) and coking coal (about 60% of CMM can be avoided).
This has important implications for abatement potentials across different countries. For example, we estimate that China – where around 90% of coal production comes from underground mines – could reduce its CMM emissions by close to 65% with existing technologies. In Indonesia – where around 90% of coal production comes from surface mines – measures are available to reduce its CMM by only about 25%. The Global Methane Initiative has developed country profiles for most coal producers, assessing their unique CMM abatement challenges and opportunities.
In many countries, a few mines are responsible for an outsized volume of emissions. Emissions at these sites are often the most cost effective to abate due to their high methane concentrations and economies of scale. Implementing abatement technologies at these sites could also improve prospects for developing CMM abatement elsewhere. They could help develop new infrastructure to use captured gas, including new grid connections, gas processing equipment or pipelines, boost understanding by the industry of the abatement measures, and lower institutional barriers. It would also encourage new companies, including service providers, project developers and technical specialists, to develop, deploy and maintain CMM technologies.
The coal industry does not usually have the right incentives to undertake voluntary action to address CMM emissions. There are a few instances where methane capture and use is economically worthwhile for coal operators, but this is the exception rather than the rule and most mitigation measures are not cost-effective without pricing externalities. In such cases, policy and regulation are needed to change company incentives. This includes promoting best industry practice to monitor and manage emissions, facilitating access to energy markets and establishing the right mix of carrots and sticks to drive CMM mitigation.
The IEA has developed a Regulatory Roadmap and Toolkit for coal mine methane, a step-by-step guide for countries seeking to drive down these methane emissions. This report shares experience on CMM regulation, highlighting lessons learned in different jurisdictions to support the development of new and functional regulations. It provides a comprehensive guide for the process for establishing new policies and regulations and the potential content of these policies.
Regulators should implement policies sooner rather than later. It is easier to incorporate abatement technologies into coal developments if they are considered from the outset. Abandoned underground coal mines continue to emit methane, especially in the first few years after the end of operations, making this an important window for mitigation action.
International co-operation – through the Clean Development Mechanism, for example – has already contributed to CMM mitigation. New initiatives, including the Joint Declaration from Energy Importers and Exporters on Reducing Greenhouse Gas Emissions from Fossil Fuels, call on fossil fuel importers to reduce the methane emissions associated with their energy consumption – thereby supporting emissions reductions across the value chain. Some countries have clarified the status of CMM as an alternative resource to facilitate its use as an energy source. Others have introduced feed-in tariffs to encourage CMM utilisation for power generation. Some jurisdictions are also using prescriptive requirements to curtail CMM emissions.
International initiatives, such as the Just Energy Transition Partnership launched by Indonesia and a group of leading economies, could support the adoption of CMM abatement technologies by some major steam coal producers. Just transition policies can incorporate methane abatement to minimise climate impacts and to generate energy and jobs. Large coking coal producers may also need support and some of the largest users of coking coal, such as the steel industry, could help in this regard.
Clarification around resource rights to methane emitted from active and abandoned coal mines is necessary to lay the foundation for the beneficial use of the gas. Incentives can take the form of grants or subsidies for project implementation, feed-in tariffs for electricity produced, or the inclusion of projects in carbon offset crediting schemes. The German Renewable Energy Sources Act provides a guaranteed fixed payback tariff for 20 years through feed-in tariffs or fees paid for electricity produced from approved CMM or abandoned mine methane projects.
Abatement measures can be very costly for small facilities. The best option to reduce CMM in a country may therefore be to focus on closing older, smaller mines.