Indicator Assessment

Emissions of air pollutants from large combustion plants in Europe

Indicator Assessment
Prod-ID: IND-427-en
  Also known as: INDP 002
Created 03 Dec 2019 Published 06 Jan 2020 Last modified 06 Jan 2020
8 min read

Large combustion plants are responsible for a significant proportion of anthropogenic pollutant emissions.

Since 2004, emissions from large combustion plants in the 28 EU Member States have decreased, by 86 % for sulphur dioxide, 59 % for nitrogen oxides and 84 % for dust.

In 2017, from a total of 3 664 large combustion plants, 50 % of all emissions came from just 68, 141 and 58 plants for sulphur dioxide, nitrogen oxides and dust, respectively. However, the performances of these largest plants have improved greatly over time.

One indicator of the environmental performance of large combustion plants is the ratio between emissions and fuel consumption (i.e. the implied emission factor). The implied emission factors for all three pollutants decreased significantly between 2004 and 2017 for all sizes of large combustion plants.


Indexed emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants in the European Union


Emissions from large combustion plants in the European Union, by capacity class

Sulfur dioxide
Nitrogen oxides

Large combustion plants (LCPs) have been regulated in the EU through:

  • the LCP Directive (Directive 2001/80/EC; fully repealed by the Industrial Emissions Directive (IED) (2010/75/EU) by 1 January 2016), which imposed minimum requirements for emissions of nitrogen oxides (NOx), sulphur dioxide (SO2) and dust;

  • the Integrated Pollution Prevention and Control (IPPC) Directive (Directive 2008/1/EC; repealed by the IED (2010/75/EU) by 7 January 2013) and the related Reference Document on Best Available Techniques (BREF) for Large Combustion Plants (updated in 2017); the IPPC Directive required the establishment of integrated permits taking into account the principle of best available techniques (BATs) and local considerations;

  • the IED, Directive 2010/75/EU (see Indicator specification and metadata for details); from 7 January 2013, minimum requirements have been set by this directive for new LCPs and as from 2016 for all LCPs.


    The collective aim of these policies was to reduce the environmental impacts of LCPs and in particular the emissions of acidifying pollutants, particulate matter and ozone precursors, to which NOx, SO2 and dust contribute.

    Emission reductions occur not only as a result of implementing policies, but also because of other factors including broader economic and societal changes, e.g. economic conditions, international fuel prices and industry initiatives.

    LCPs vary significantly in size. Four capacity classes have been established for this indicator:

  • small LCPs, with a thermal input of between 50 and 100 megawatts thermal (MWth);
  • medium-sized LCPs, with a thermal input of between 101 and 300 MWth;
  • large LCPs, with a thermal input of between 301 and 500 MWth;
  • very large LCPs, with a thermal input greater than 500 MWth.


Large combustion plant emissions

Emissions from LCPs constitute a significant proportion of total anthropogenic emissions.

Between 2004 and 2017, emissions of SO2 from LCPs reduced by 86 %, NOx by 59 % and dust by 84 % (Fig. 2). Emissions have decreased for LCPs in all capacity classes; however, the majority of emission reductions in absolute terms has been achieved through environmental improvements in very large LCPs, with a rated thermal input above 500 MW (21 % of all LCPs by number, representing 70 % of the installed capacity).

Between 2007 and 2009, emissions of SO2, NOx and dust declined very significantly. Although the entry into force (on 1 January 2008) of emission limit values for existing plants under the LCP Directive occurred in this period, a potentially more significant factor was the general economic downturn in Europe that commenced during 2008. A corresponding decrease in fuel consumption between 2007 and 2009 (9 %) suggests that the decrease in emissions may have been due to a decrease in the activity of LCPs, rather than to a substantial improvement in environmental performance. This significant reduction in emissions was followed by a period of more stable but nonetheless decreasing emissions until 2017.

Very large LCPs account for only 21 % of all LCPs but are responsible for the vast majority of LCP SO2, NOx and dust emissions. In 2017, these largest plants emitted 71 % of all LCP SO2 emissions, 64 % of NOx emissions and 67 % of dust emissions.

In fact, only a small number of very large LCPs are responsible for the majority of emissions. In 2017, from a total of 3 664 LCPs, 50 % of all emissions came from just 68, 141 and 58 plants for SO2, NOx and dust, respectively. Conversely, the 1 216 smallest LCPs emitted only 5 % of SO2, 7 % of NOx and 8 % of dust.


Evolution of the environmental performance of large combustion plants in the EU-28, expressed as implied emission factors for sulphur dioxide, nitrogen oxides and dust, by capacity class

Sulphur dioxide
Nitrogen oxides

Evolution of the environmental performance of large combustion plants in the EU-28, expressed as implied emission factors for sulphur dioxide, nitrogen oxide and dust, by fuel type

Sulphur dioxide
Nitrogen oxide

The ratio of emissions to fuel consumed (also referred to as the implied emission factor (IEF)) can be used as an indicator for assessing the environmental performance of a combustion plant.

Environmental performance of different capacity classes

The environmental performance of LCPs in all capacity classes has improved significantly (Fig. 3). The largest decline in IEFs can be observed for the period 2006-2010. One possible reason for this is the introduction of improved abatement measures to comply with the LCP Directive (which entered into force in January 2008) and the IPPC permit (taking into account the LCP BREF from 2006).

In January 2016, the IED entered into force. It covers some additional installations compared with the IPPC Directive, which explains part of the increase in the number of installations covered (+7 % between 2015 and 2016, stable in 2017). For instance, the IED now covers gas turbines licensed before 27 November 2002 and diesel engines. This explains the break in the trend of previous years observed in 2016 in environmental performance, i.e. the trend in IEFs, especially for NOx, for users of liquid fuels.

Between 2004 and 2017, IEFs decreased most for large LCPs (301 to 500 MWth capacity) and very large LCPs (> 500 MWth capacity), namely by 80 % and 83 % for SO2, 36 % and 55 % for NOx, and 82 % and 82 % for dust, respectively.

Fossil fuels are a concern because of their contribution to climate change. Coal and lignite are considered the worst fuel options in terms of climate change and air pollution impacts. While natural gas is considered a “cleaner option” (because less SO2 and dust are emitted), there are still concerns from a climate change perspective. A higher proportion of small LCPs use less-polluting natural gas as their main fuel rather than solid fuels (i.e. coal and lignite). In 2017, solid fuels represented 1 % of fuel consumption in small LCPs, compared with 88 % for very large plants. This results in small LCPs having overall lower operating IEFs (Fig. 3). However, when calculated for each fuel and capacity class, small LCPs have consistently higher IEFs. For example, the SOIEF for the combustion of solid fuels in 2017 was 0.44 tonnes per terajoule (t/TJ) for small LCPs and 0.10 t/TJ for very large LCPs. This difference is likely to be caused by the higher operating efficiencies possible in larger plants.


Environmental performance for different fuel types

Overall, the environmental performance of LCPs improved for all fuel types between 2004 and 2017 (Fig. 4) for single-fuel plants, i.e. those with at least 95 % of fuel consumption from one fuel type (see Indicator specification and metadata for further methodological details). Solid fuels showed the largest improvements in environmental performance. The solid fuel IEF decreased by 81 % for SO2, by 49 % for NOx and by 81% for dust across the time series.

The environmental performances of liquid fuels and solid fuels are consistently worse than for the other fuels across the three pollutants. Natural gas has the lowest IEF for all three pollutants, most notably for SO2 (0.0004 t/TJ for natural gas compared with 0.186 t/TJ for liquid fuels and 0.090 t/TJ for solid fuels, in 2017). At the beginning of the time series, the NOx IEF for other gases was similar to that of natural gas, but the environmental performance did not improve over time as much as it did for natural gas.

Supporting information

Indicator definition

This indicator tracks trends since 2004 in emissions of SO2, NOx and dust, as well as the environmental performance of LCPs. LCPs comprise combustion plants with a total rated thermal input equal to or greater than 50 MW.


The geographical coverage comprises the 28 EU Member States (EU-28) (Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden and the United Kingdom).


The temporal coverage is 2004-2017 (most recent year with officially reported LCP emissions and fuel use; obtained from the EEA LCP database v5.2 — see Data sources).


SO2, NOx and dust emissions — kilotonnes (kt)/year

Total fuel consumption — terajoules (TJ)/year

Implied emission factor — tonnes (t)/terajoules (TJ)

Rated thermal input — megawatt thermal (MWth)


Policy context and targets

Context description


The EU has had policies on emissions from combustion plants since the 1980s. Between 2004 and 2015, two pieces of EU law were in place: the LCP Directive and the IPPC Directive (EC, 2010). This EU legislation imposed specific limit values on emissions of NOx, SO2 and dust from plants with a thermal rated input equal to or greater than 50 MW. Since 1 January 2016, this legislation has been replaced by the IED (EC, 2010).

The aim of EU policy on LCPs is to reduce emissions to air, water and land, including measures related to waste, to achieve a high level of protection of the environment as a whole. The focus with regard to LCPs is to reduce emissions of acidifying pollutants, particles and ozone precursors while also covering other environmental concerns (e.g. mercury emissions). 

The Large Combustion Plant Directive

The EU (then the European Economic Community (EEC)) started to regulate combustion plants by means of Directive 84/360/EEC. This directive established a framework for the permitting of installations and the criteria to do so, but did not establish specific limitations that were applicable across Member States. During the 1980s, the European Communities became party to the Convention on Long-range Transboundary Air Pollution which requires more harmonised action and the establishment of clearer operational criteria and emission limit values.

These directives were replaced by Directive 2001/80/EC, known as the LCP Directive, which imposed limits on emissions of NOx, SO2 and dust from plants with a rated thermal input equal to or greater than 50 MW. The aim of the LCP Directive was to reduce the emissions of acidifying pollutants, particles and ozone precursors.

The Integrated Pollution Prevention and Control Directive and the 2006 Reference Document on Best Available Techniques for Large Combustion Plants

Combustion plants were also regulated by the so-called IPPC Directive, a piece of EU law that tackled LCPs in an integrated way and not only with regard to their emissions to air. Under the IPPC Directive, a BREF on LCPs was agreed on to establish a reference for the permits of LCPs.

The Industrial Emissions Directive (EC, 2010)

IED permits are based on an integrated approach to overall environmental performance. For LCPs, and several other activities, the IED sets emission limit values for SO2, NOx and dust. Permit conditions, including emission limit values, are based on BATs. The BAT reference document (BREF) and BAT conclusions on LCPs were published in 2017.

Permit conditions including emission limit values must be based on BATs. The term ‘best available techniques’ refers to the most effective, and economically and technically viable methods of operation that reduce emissions and the impact on the environment.

To define BATs, the European Commission organises an exchange of information between Member State experts, industry and environmental organisations. This process results in the production of BREFs. Each BREF contains information on the techniques and processes used in a specific industrial sector in the EU, current emission and fuel consumption trends, and techniques for the determination of BATs, as well as emerging techniques.

The European Pollutant Release and Transfer Register

An additional EU regulation is the Regulation on the European Pollutant Release and Transfer Register (E-PRTR) (Regulation (EC) No 166/2006): plants with activities over certain thresholds must report to the E-PRTR on releases of pollutants and off-site transfers of waste and pollutants in waste water.


No targets have been specified

Related policy documents



Methodology for indicator calculation

Queries are applied to the LCP database v5.2 for the calculations necessary in this analysis. For each plant, total fuel consumption (a sum of fuel consumption from all fuel types) and capacity class (based on a plant's rated thermal input (MWth)) are calculated. Plants are grouped into five capacity classes: > 500 MWth, 301-500 MWth, 101-300 MWth, 50-100 MWth and < 50 MWth. The last of these (< 50 MWth) is excluded from calculations involving capacities in this indicator.


Fig. 1: to create an index graph of the pollutants, disaggregated by capacity class, an index for each pollutant and capacity class is calculated for 2004-2017 as follows: (emissions in the capacity class for the current year/emissions for all capacity classes in the base year) × 100. The base year is 2004.


Fig. 2: for each capacity class and year, emissions and total fuel consumption are summed, and an IEF is calculated as follows: emissions (t)/fuel consumption (TJ).


Figs 3 and 4: IEFs are calculated for each pollutant separated by capacity class (Fig. 3) and fuel type (Fig. 4) at the EU level. The sum of emissions for a given pollutant in a given year is divided by the total fuel consumption, for each capacity class and fuel type.


LCP emissions are reported at plant level if a plant can use different fuels. For the calculation of fuel-specific IEFs, only single-fuel plants (i.e. plants for which one fuel represents more than 95 % of the total fuel input in TJ) are included. All emissions of the plant are attributed to the single fuel, resulting in a coverage of 77 % of plants, 74 % of SOemissions, 81% of NOx emissions and 72 % of dust emissions. 


Methodology for gap filling

For the earlier years in the time series, some plants had missing MWth capacity data. Where possible, the MWth data from an adjacent year’s reporting for that plant were used to gap fill.

Methodology references

No methodology references available.



Methodology uncertainty

This indicator covers the EU-28 countries. However, there are no data for Croatia for 2004-2009. The data for Croatia have not been gap filled, and in the years of reporting Croatia contributed less than 1 % of emissions and fuel consumption to the EU-28 total. This lack of data is thus considered a minor distortion of the overall trend.


Data sets uncertainty

Although reporting requirements began in 2004, it is possible that the data for the first reported period (2004-2006) contain some gaps.

Rationale uncertainty

No uncertainty has been specified.

Data sources

Other info

DPSIR: Pressure
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • INDP 002
Frequency of updates
Updates are scheduled once per year
EEA Contact Info


Geographic coverage

Temporal coverage


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