1.B.1 - Solid Fuels

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The source category Solid fuels (1.B.1) consists of two sub-source subcategories – the source subcategory Coal mining (1.B.1.a) and the source subcategory Coal transformation (1.B.1.b). This chapter discusses fugitive emissions from coal mining, coal handling, including door leakages from coke ovens and quenching (emissions from the furnace are covered by category 1.A.1.c), and emissions from the beneficiation of solid fuels. In the mining sector, a distinction is made between open-pit mines, in which raw materials are extracted from pits open to the surface, and closed-pit mines, in which seams are mined underground. In Germany, hard coal used to be mined in closed-pits only (until 2018), while lignite is mined in four coal fields since 2003 with the open-pit method only.

Activity data for lignite production have been taken from the Statistik der Kohlenwirtschaft’s website (in German only) ¹⁾. Extracted coal is moved directly to processing and to power stations.

The emission factors used for calculating emissions from lignite production (TSP, PM₁₀ and PM_2.5) already include possible emissions from transport and storage. The PM₁₀ factor is taken from a 2021 research project ²⁾. TSP and PM_2.5 have been reduced the same way on the basis of the previous values³⁾.

Table 1: Annual amounts of extracted raw lignite, in [Mt]

Table 2: Emission factors applied for lignite extraction, in [kg/t]

Table 3: Annual amounts of lignite coke produced, in [Mt]

Emissions from lignite production other than listed below are reported by plant operator. Particle emission factors were verified in a research project (Emissionen und Maßnahmenanalyse Feinstaub 2000-2020) ⁴⁾ .

Table 4: Emission factors applied for lignite-coke production

The activity rates for hard coal coke production have been taken from the Statistik der Kohlenwirtschafts’s website (in German only) ⁵⁾.

Table 5: Annual amounts of hard coal coke produced, in [Mt]

The emission factors for hard coal coke production have been obtained from the research project “Emission factors for the iron and steel industry, for purposes of emissions reporting” (“Emissionsfaktoren zur Eisen- und Stahlindustrie für die Emissionsberichterstattung”) ⁶⁾.

Table 6: Emission factors for hard coal coke production

There are many potential sources of PAH emissions from coking plants. The dominant emission sources are leakages from coke oven doors and from charging operations. As there is limited data available on PAH emissions, the uncertainties of the estimated emission factors are very high. It should also be taken into account that emissions from coke production greatly vary between different coke production plants. The emission factors for benzo[a]pyrene and mixed PAH have been revised by research projects in 2010 ⁷⁾⁸⁾. Split factors for Black Carbon (BC) are based on the EMEP Guidebook 2016 ⁹⁾.

NMVOC Emissions from decommissioned hard-coal mines play a role in this sub- source category. When a hard-coal mine is decommissioned, mine gas can escape from neighbouring rock, and from coal remaining in the mine, into the mine's network of shafts and passageways. Since the mine is no longer artificially ventilated, the mine gas collects and can then reach the surface via gas pathways in the overlying rock or via the mine's own shafts and passageways. Such mine gas was long seen primarily as a negative environmental factor. Recently, increasing attention has been given to the gas' positive characteristics as a fuel (due to its high methane content, it is used for energy recovery). In the past, use of mine gas was rarely cost-effective. This situation changed fundamentally in 2000 with the Renewable Energy Sources Act (EEG). Although mine gas is a fossil fuel in finite supply, its use supports climate protection, and thus the gas was included in the EEG. The Act requires network operators to accept, and provide specified compensation for, electricity generated with mine gas and fed into the grid.

The NMVOC emissions from decommissioned hard-coal mines have been calculated in the research project “Potential for release and utilisation of mine gas” (“Potential zur Freisetzung und Verwertung von Grubengas”) ¹⁰⁾. The relevant calculations were carried out for all mining-relevant deposits in Germany.

Table 7: NMVOC emission factor for decommissioned hard-coal mines, in [kg/m¹³]

No further improvements are planned.