Stationary combustion is part of the Fuel Combustion sector that is a sub-sector to the Energy sector. Stationary combustion includes power plants, combined heat and power production plants, industrial combustion plants and district heating plants as well as small plants e.g. stoves and residential boilers.

Stationary combustion plants consist of the emission source sub-categories;

• Energy Industries, Public Electricity and Heat Production that includes large power plants, combined heat and power production plants and plants producing district heating. Public electricity and heat production is the largest source category regarding both fuel consumption and greenhouse gas emissions for stationary combustion.
• Energy Industries, Petroleum refining that includes combustion activities in the two Danish refineries. Fugitive emissions from refineries are not included here.
• Energy Industries, Oil and gas extraction that includes the offshore gas turbines combusting natural gas.
• Manufacturing Industries and Construction that includes several industrial sub-sectors.
• Other sectors, Commercial/Institutional that includes stationary combustion plants, mainly boilers, in e.g. schools, shops and office buildings. 
• Other sectors, Residential. This sector includes residential boilers, stoves etc. The sector includes both single-family houses and apartment blocks.
• Other sectors, Agriculture/Forestry that includes stationary combustion plants in e.g. horticulture.

The stationary combustion sector is a large emission source for CO₂, SO₂, NO_x, CO, particulate matter (PM), heavy metals, PAH, dioxin, HCB, PCB and black carbon (BC). The CO₂ emission from stationary combustion in 2022 adds up to 46 % of the national emission whereas the emission share for SO₂ and NO_x is 70 % and 28% respectively. Stationary combustion accounts for 61 % of the emission of particulate matter < 2.5 µm (PM_2.5) and 79 % of the dioxin emission.

Public electricity and Heat Production is the largest emission source for CO₂ and NO_x. Residential plants are the main emission source for particulate matter and dioxin. Industrial plants and Public electricity and Heat Production are the main emission sources for SO₂ emission.
 
Figure 1   Distribution of the emissions from stationary combustion plants, 2022. 

Despite a decrease in fuel consumption of 31% since 1990, CO₂ emission from stationary combustion has decreased by 67% because of the change of fuel type used. The fluctuations in total CO₂ emission follow the fluctuations in CO₂ emission from Public Electricity and Heat Production and in coal consumption. The fluctuations are a result of electricity import/export.

SO₂ emission from stationary combustion plants has decreased 96 % since 1990. The large emission decrease is mainly a result of the reduced emission from Public Electricity and Heat Production, made possible due to installation of desulphurisation plants and due to the use of fuels with lower sulphur content. These improvements are a result of both sulphur tax laws and legislation concerning sulphur content of fuels, emission ceilings for large power plants and emission limits for several plant categories.

NO_x emission from stationary combustion plants has decreased 79 % since 1990. The reduced emission is largely a result of the reduced emission from Public Electricity and Heat Production due to installation of low NO_x burners, selective catalytic reduction (SCR) units and selective non-catalytic reduction (SNCR) units. These improvements are a result of both emission ceilings for large power plants and lower emission limits for several plant categories. The fluctuations in the time series follow the fluctuations in electricity and heat production, which, in turn, result from electricity trade fluctuations.

The emission of PM_2.5 has decreased 42 % since year 1990. The PM emissions increased until 2007 and decreased after 2007. The increase was caused by the increased wood combustion in residential plants until 2007. The decrease since 2007 is related to the decrease of the PM emission factors for residential wood combustion due to installation of modern stoves and boilers.

The dioxin emission has decreased 53 % since 1990 mainly due to installation of dioxin filters in waste incineration plants that was needed to meet the lower emission limit value in Danish legislation valid for most waste incineration plants since 2005. The emission from residential plants has increased due to increased wood consumption in this source category.
 

Figure 2   Time-series for emissions from stationary combustion, 1990-2022. Click on the figures to enlarge.

The emission inventory for stationary combustion is based on activity rates from the Danish energy statistics. The energy statistics are aggregated according to the reporting requirements for the emission inventories.

For each fuel, sector and plant category a set of general area source emission factors has been determined. The emission factors are either nationally referenced or based on the international guidebooks including the EMEP/EEA Guidebook and the IPCC Guidelines.

Some large plants, such as power plants, are registered individually and plant-specific emission data are applied. These emission data include data from the EU Emission Trading Scheme (EU ETS), data from annual environmental reports of the plants, PRTR data etc.    

Emission factors that are not plant-specific are available on the emission inventory home-page.

For a more detailed description of the data and methodology for the inventory of stationary combustion see the emission report to UNFCCC and UNECE.