Overview of the average coal seam gas composition by country and region

• N.V Popov

  Yu. A. Israel Institute of Global Climate and Ecology, 20B, Glebovskaya st., 107258, Moscow, Russian Federation

  Автор

• A.A. Mironov

  Autonomous Non-Сommercial Organization “International Sustainable Energy Development Centre” under the auspices of UNESCO, 3rd floor, build. 2, 8, Kedrova str., 117292, Moscow, Russian Federation

  Автор

• A.K. Singh

  Indian Technology Institute in Bombay (IIT Bombay), Bombay, India

  Автор

By 2027, the IPCC plans to develop a Methodological Report on the
inventory of short-lived climate forcers that are not greenhouse gases (non-methane
volatile organic compounds and black carbon). This guidance is expected to provide a
methodological basis for accounting for these substances in national inventories and
to include recommended emission factors for their estimation across various sectors
of human activity, including the coal mining industry. The development of these
methodological guidelines is currently being carried out by lead authors – experts
invited by the IPCC from different countries, including Russia.
In this context, a database on the compositional characteristics of coal seam
gases from major coal deposits worldwide was compiled and systematized. Based
on the analysis of open scientific and industry sources, average coal seam gas
compositions were derived for individual countries and global regions across three
depth intervals recommended by the IPCC.
The average methane content in coal seam gas predominantly ranges from 52%
to 95%. The maximum average concentrations of other components were 4.55% for
ethane (C2H6), 1.8% for propylene (C3H6), 1.9% for propane (C3H8), 0.48% for
butane (C4H10), and 0.63% for hydrogen (H2). Summary NMVOC – 2.53%.
Hydrogen sulfide (H2S) was not detected in the reviewed open-source publications,
and carbon monoxide (CO) was not analyzed due to its limited occurrence.  The relationship between gas composition and depth was evaluated for CH4,
NMVOC (Non-Methane Volatile Organic Compounds), and H2. The results
indicate that methane concentration generally increases with depth, reaching
maximum values within the 750-1500 m interval, followed by a nonlinear decrease
at greater depths. In contrast, NMVOC content exhibits an exponential increase
with depth, with a steeper trend observed beyond 1000 m. Overall, the highest
concentrations of hydrocarbon components are observed at depths of 1000-1500 m,
while deeper intervals show divergent trends among individual components.
The compiled database can serve as a basis for further estimation of emission
factors for short-lived climate forcers from coal mining. The results have practical
significance for the further development of IPCC methodological approaches and
can be used in the preparation of international guidelines for emission inventory in
the coal mining sector.

• PDF (Russian)