PM2.5 emission from the coal combustion in the Polish residential sector. State and outlooks
Published Online: Dec 31, 2023
Page range: 21 - 29
DOI: https://doi.org/10.2478/oszn-2023-0019
Keywords
© 2023 Damian Zasina et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Fossil fuels are the major energy resource in the world. According to the data provided by the [World Bank 2020], the contribution of energy derived from fossil fuels was nearly 80% in 2015. The [EIA 2020] data indicates that the contribution of fossil fuels in total energy production was close to 85% in 2016, with coal as the second most important energy resource.
According to statistics provided by [British Petroleum 2019], Poland had the 10th biggest coal production in the world in 2018, and according to the official statistics [GUS 2019a–b], a significant part of produced coal (15.7%) was used for residential heating and cooking.
The coal combustion in households matters a lot for the air quality and occurrence of the low emission phenomenon in Poland [Adamczyk et al. 2017; Bogacz 2018; Dzikuć et al. 2019], especially during the winter [Juda–Rezler et al. 2020; Reizer and Juda–Rezler 2016; Rogula–Kozłowska et al. 2013]. [EEA 2019a] clearly stated that, taking into account the annual limit values for PM2.5 particulates in European countries, bad air quality occurs primarily in Poland, northern Italy and the Balkan countries. Moreover, the Polish National Health Fund presented bad air quality as a cause of the increased number of deaths in 2017 [NFZ 2018]. The harmful effects of bad air quality are also emphasized by medical environments [Zieliński et al. 2018; FPS 2019] and the Polish Anti–Smog Movement [Burchard–Dziubińska 2019]. The reliable quantitative assessment of the PM2.5 emissions is also very important in the context of the introduced emission–reducing policies [European Commission 2020].
Taking into account the environmental impact, the specificity of the residential sector in comparison to other sectors of the economy is its spatial dispersion (scatteredness), characteristic temporal variability (noticeably stronger during fall and winter), as well as problems with a precise estimation of the amount of particular pollutant released into the air.
This paper presents the current state of estimated PM2.5 emissions released into the air from coal combustion in individually heated Polish households, which corresponds to the sector 1A4bi in the international NFR (or IPCC) nomenclature [EEA 2019b; IPCC 2006] as well as the projected PM2.5 emission from the sector taking into account various data (including official) about anticipated consumption of coal in the 1A4bi sector till 2040.
The emission is defined as the particular mass of the air pollutant released into the air. Estimating the PM2.5 emission, we can consider only the primary emission, which means PM2.5 is emitted directly into the atmosphere [Klimont et al. 2017; US EPA 2019]. Methodology of emission estimation is presented widely in [EEA 2019b; Quoc Bang et al. 2019], and can be mathematically expressed as follows:
The emission factor is defined as the average mass of air pollutants being produced in a particular process (including combustion). Emission factors can be obtained using various approaches: in laboratory experiments, field studies and as a result of mathematical modelling or statistical analysis e.g. [Czaplicka et al. 2019; Shen 2014; Stala–Szlugaj 2011; Shen 2015; Tian et al. 2018]. The example of the emission factors' official classification is ‘Tier’, presented in [EEA 2019b; IPCC 2006]. The following list details the Tiers of emission factors:
Tier 1: default methodology using the international average values for the emission factors, Tier 2: using the ‘country specific’ emission factors (derived from the country's own studies and analysis), and Tier 3: based on mathematical modelling.
The presented classification of emission factors is also associated with the qualitative uncertainty class corresponding with the typical error range describing the statistical properties of considered emission factors [EEA 2019b, Chapter 5].
Activity data for the current state emission estimations (years: 1990–2018) is derived from the [EUROSTAT 2020] database. The data about projected coal consumption for 2015–2030 is given in [Stala–Szlugaj 2017, p. 178]. There are elaborated 3 scenarios at national and regional levels: ‘high’ (HIGH, [Sc_WYS_GD]), ‘reference’ (REF, [Sc_REF_GD]), and ‘low’ (LOW, [Sc_NIS_GD]). For the HIGH scenario, detailed assumptions are elaborated:
smooth changes in coal consumption, adjusted to the economic condition of Polish households, gradually increasing share of households using other (non–coal) energy carriers or renovated heating appliances (boilers and furnaces), and the decreasing consumption trend driven by the energy efficiency index for heating of the living area.
Mathematical assumptions for the elaborated HIGH scenario are given below:
2016–2023: −3.2% 2027–2030: decline of decreasing to −0.25%
The LOW scenario assumes that:
in 2030, the use of coal will be limited only to rural areas, from 2016, the use of coal in cities will constantly decrease, in the case of Polish voivodeships (provinces) that entered into force antismog resolutions is assumed the time necessary to change old boilers and furnaces, and newly built houses will not consume coal for heating.
The REF scenario is assumed to average between the HIGH and LOW scenarios. The original data derived from [Stala–Szlugaj 2017] are presented in Tab. 1.
Projected coal consumption in Polish households for 2015–2030 [109 kg]
| 9.8* | 8.5 | 7.8 | 7.7 | |
| 9.8* | 8.4 | 7.4 | 7.0 | |
| 9.8* | 8.2 | 7.0 | 6.3 |
Data derived from Statistics Poland [GUS 2016] (round from 9.75).
The base year for enumerated scenarios is taken from Statistics Poland [GUS 2016].
To express the data in energy units, the average heating value for 2015 is used (25.932 MJ/kg). The time series of the energy produced from the coal combustion in the Polish households is shown in the Fig 1.
Figure 1.
Coal consumption in Polish households 1990–2018. Time series: EUROSTAT – derived from [EUROSTAT 2020], HIGH, REF, LOW – based on [Stala–Szlugaj 2017]
Currently used emission factors are derived from analysis by [Kubica, Kubica 2014] and by [Kubica, Dębski 2016], which is included in the official Polish emission inventory [NCEM 2020]. The time series for the emission factor used for the current submission is presented in Fig 2.
Figure 2.
The time series of the PM2.5 emission factor from coal combustion in Polish households 1990–2018 [NCEM 2020]
The time series for the emission factor is modelled using the assumptions on the coal qualitative parameters (heating value and ash content primarily) and the structure of combustion devices (furnaces and boilers) used in the buildings of the particular age.
The data collected at the CEIP official repository [NCEM 2020] can also be obtained from the [EEA 2020] repository. Apart from the officially submitted historical emissions trend, the projected PM2.5 emissions are derived from the official ‘National Energy and Climate Plan for the years 2021–2030’ (NECP) [MSA 2019, Annex 2, Tab. 26, p. 30].
In the NECP report, two scenarios are taken into account: reference (REF) and introducing dedicated energy and climate policy (PEK). However, the official projections include emissions from the combustion of all fuels, including coal, wood, natural gas, fuel oils, and others (Fig. 3 (a)); the PM2.5 emission is generated mainly by the combustion of coal and wood (Fig. 3 (b)).
Figure 3.
Data for 2018 [NCEM 2020]. (a) ‘energy mix’ – structure of energy obtained due to combustion of fuels in Polish households (b) ‘fuel mix’ – structure of the PM2.5 emission generated by particular fuels
The time series of the PM2.5 emissions from coal combustion in Polish households (1990–2018) is presented in Fig. 4.
Figure 4.
PM2.5 emissions from coal combustion in Polish households 1990–2018. Time series: LRTAP [NCEM 2020], NECP REF, NECP PEK [MSA 2019]
Taking into account the emission data is derived from the newest submission [NCEM 2020], and the official projections [MSA 2019] (Fig. 4), a vertical gap (
The model is based on the equation given in [Radović 1997], [Lorenz 1999], and [Stala–Szlugaj 2011]:
Detailed assumptions are presented in Tab. 2.
Parameters used for the estimation of the PM2.5 emission factor from hard coal combustion in Polish households
| – | 0.9 | [Huang et al. 2014] | |
| [2.6; 11.0] | [Wierzchowski, Pyka 2015; GIG 2016] | ||
| [21,000; 31,000] | * | ||
| [23,000; 29,000] | ** | ||
| [10; 20] | [Stala–Szlugaj 2011] | ||
| – | 1 | [Stala–Szlugaj 2011] |
Data on coal from Polish mines. Range basing on [Stala–Szlugaj 2011], contribution – 86.7% [GUS 2017].
Data on imported coal. Range basing on [Stala–Szlugaj 2011], contribution – 13.3% [GUS 2017].
The simulation is carried out for 10,000 iterations and performed in
Figure 5.
The PM2.5 emission factor from coal combustion in Polish households obtained performing Monte Carlo simulation [kg/TJ]: 2.5th percentile – 138.6 (blue), median – 291.5 (green), 97.5th percentile – 469.3 (red)
The selected statistics of the simulated PM2.5 emission factor from the coal combustion in Polish households [kg/TJ]
|
|
||||||||
|---|---|---|---|---|---|---|---|---|
| 295.1 | 84.6 | 138.6 | 190.6 | 236.4 | 291.5 | 349.8 | 406.3 | 469.3 |
The Tier 1 methodology for the emission estimation in European countries [EEA 2019b] suggests the mean PM2.5 emission factor of 398 [kg/TJ] (95%CI: 72–480), which is very close to the model using the Monte Carlo simulation 294.5 (95%CI: 138.7–470.4) [kg/TJ]. The new study by [Czaplicka et al. 2019] proposes that the particulate matter emission factor (bituminous coal) equals 10.20 [g/kg], which corresponds to 378.5 [kg/TJ] (recalculated using the lower heating value – 26.95 MJ/kg given by [Czaplicka et al. 2019]). The range for emission factor given by [Shen 2014, p. 169] – 3.2–8.5 [g/kg] corresponds with 118.7–315.4 [kg/TJ] (recalculated using the average heating value for hard coals – 26.95 MJ/kg given by [Shen 2014, p. 48]).
On this background, the emission factors used in the currently submitted national emission inventory [NCEM 2020] (range: 115.2–151.3 kg/TJ, see Fig. 2) are very low. Assuming that the decreasing trend of the currently applied emission factor (Fig. 2) continues, representing the gradual displacement of the older boilers and furnaces, the new trend emission factor is proposed. Because the emission factors given in [Czaplicka et al. 2019; Shen 2014] are close to the upper quartile of the simulated emission factor (349.8 kg/TJ, Tab. 3), the upper quartile is used as the basic value. The new trend of the emission factor is presented in Fig. 6. It is obtained by rescaling the trend of the old emission factor (shown in Fig. 2) along with the identical trend over time.
Figure 6.
The recalculated time series of the PM2.5 emission factor from coal combustion in Polish households 1990–2018
The difference between the time series (1990–2018) is presented in Fig. 7, together with the official PM2.5 emission projections [MSA 2019]. The PM2.5 emissions derived from the current submission [NCEM 2020] are marked as ‘OLD’. The ‘NEW’ time series is elaborated using the upper quartile of the new, simulated emission factor (Tab. 3). The projected emissions are shown in Fig. 7.
Figure 7.
PM2.5 emissions and projections from coal combustion in Polish households 1990–2040. Time series: NEW EF – New estimation calculated simulated emission factor, OLD EF – old emission factor – official submission [NCEM 2020], NECP REF – official PM2.5 emission projection – reference scenario, and NECP PEK – official PM2.5 emission projection – climate policy scenario
Analysis of Fig. 7 gives important information about potential inconsistency due to changes in the emission factor.
The consistency between the data obtained from the measurements [Czaplicka et al. 2019; Shen 2019] and simulated using the model [Stala–Szlugaj 2011] is observed. In this context, the assumptions given in [Kubica, Dębski 2016; Kubica, Kubica 2014; NCEM 2020] are worth deeper investigation to better reflect the PM2.5 emissions estimated for 1990–2018. The actual PM2.5 emission factor from coal combustion in the residential sector may be higher than given in [NCEM 2020]. Moreover, the emission factor provided in the newest available national emission inventory [MCAE 2023] (219.45 kg/TJ) is almost 30% lower than the calculated in this paper (average value 291.5 kg/TJ). This finding is particularly important for PM2.5 emission estimation in areas where old combustion appliances are in use. The emissions of PM2.5 estimated particularly for years before 2000 still need more insight. The PM2.5 emission factor obtained using the Monte Carlo simulation will be useful for the retropolation, which means reconstruction of the emission trends for previous years.
The results of laboratory studies [Czaplicka et al. 2019; Shen 2019] suggests that the currently used PM2.5 emission factors in official reports [NCEM 2020; MCAE 2023] could be underestimated. It may suggest providing a status quo analysis using the newest available data, including those obtained from the necessary literature review. Apart from using the newest available data on the fuel quality, scientists and policymakers should also pay attention to the historical trends. Using statistically simulated emission factors, and information about the gradual technical development of domestic combustion appliances, combined with the Monte Carlo techniques can be used for deep analysis of both: historical and projected data.
The question of the approximate real trend of the PM2.5 emission factor for coal combustion in Polish households is still unsolved. It might be possible that the trend that ‘better’ reflects the gradual renewal of domestic furnaces, and then – the PM2.5 emission should be investigated using more advanced methods such as dedicated backward analysis prepared from the perspective of the current state (retropolation).
The findings, interpretations, and conclusions expressed in this paper are those of the authors, and not necessarily of the organization with which the authors are affiliated or official position of the Polish Government.
The condensable fraction in particulate matter is not taken into consideration in the analysis.
The article does not include data after the recalculation of statistical household balances carried out in 2022 (covering the period since 2018). This is because the data from the recalculation are not consistent with previous historical data and with available projected data. Furthermore, the process of recalculation of data is still ongoing and will take into account other source material, i.e. the results of the National Population and Housing Census 2021. An update of the official national energy projections is also planned, as the current official data in this regard is the data from the National Energy and Climate Plan for the years 2021–2030 submitted to the European Commission in 2019. After the indicated updates, the data will be available (expected no sooner than the end of 2024) that can be used to update the analyses in the article and publish an update of the article, based on the new available data.