Aarhus Universitets segl

No. 454: Projection of greenhouse gases 2020-2040

Nielsen, O.-K., Plejdrup, M.S., Winther, M., Hjelgaard, K., Nielsen, M., Mikkelsen, M.H., Albrektsen, R., Gyldenkærne, S. & Thomsen, M.. 2021. Projection of greenhouse gases 2020-2040. Aarhus University, DCE – Danish Centre for Environment and Energy, 132 pp. Scientific Report No.454.  https://dce2.au.dk/pub/SR454.pdf 


This report contains a description of the models, background data and projections of the greenhouse gases (GHG) carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6) for Denmark. The latest historic year that has formed the basis of the projection is 2019. The emissions are projected to 2040 using a scenario, which includes the estimated effects of policies and measures implemented on Denmark’s greenhouse gas (GHG) emissions based on ‘frozen policy‘ (or ‘with existing measures’ projection) – meaning that the policies and measures are implemented or decided by December 2020. The official Danish energy projection, e.g. the latest official projection from the Danish Energy Agency (DEA), is used to provide activity rates (2020-2040) in the models for those sectors for which these projections are available. The emission factors refer to international guidelines or are country-specific and refer to Danish legislation, Danish research reports or calculations based on emission data from a considerable number of industrial plants in Denmark. The projection models are generally based on the same structure and methodology as the Danish emission inventories in order to ensure consistency. The numbers presented in this report are based on the global warming potentials (GWPs) from the IPCC 4th Assessment Report (AR4). In the data file published with the projections, the results are presented using GWPs from both AR4 and IPCC’s 5th Assessment Report.

The main emitting sectors in 2019 are Energy industries (19 %), Transport (28 %), Agriculture (23 %) and Other sectors (9 %). For the latter sector, the most important sources are fuel combustion in the residential sector. GHG emissions show a decreasing trend in the projection period. The total emissions in 2019 are estimated to be 46.7 million tonnes CO2 equivalents including LULUCF and indirect CO2 and the corresponding total in 2040 is projected to be 31.8 million tonnes CO2 equivalents. From 1990 to 2019 the emissions decreased by 40 %. From 2019 to 2040, the emission is projected to decrease by approximately 32 %.

The total greenhouse gas emissions in 1990 including LULUCF and indirect CO2 is estimated at 77.4 million tonnes of CO2 equivalents and the emission in 2030 is projected to be 35.9 million tonnes of CO2 equivalents including LULUCF and indirect CO2. This corresponds to a reduction of 54 % between 1990 and 2030. The effect of carbon capture and storage (CCS) in the projection is not attributable to any sector and not included in this figure.

In 2005, the emissions including LULUCF and indirect CO2 is calculated to 71.1 million tonnes of CO2 equivalents. It decreased by 34 % from 2005 to 2019 and estimated to be reduced by 50 % from 2005 to 2030.

Stationary combustion

Stationary combustion includes Energy industries, Manufacturing industries and construction and Other sectors. Other sectors include combustion in commercial/institutional, residential and agricultural plants. The GHG emissions in 2019 from the main source, which is public power and heat production (45 %), are estimated to decrease in the period from 2019 to 2040 (91 %) due to a significant decrease in the fossil fuel consumption for electricity production in the later part of the time series. For residential combustion plants, a significant decrease in emissions is also projected; the emissions are expected to decrease by 84 % from 2019 to 2040, due to a lower consumption of fossil fuels. Emissions from manufacturing industries on the other hand only decreases by 55 %, due to a much smaller decrease in fossil fuel combustion.

Fugitive emissions from fuels

The greenhouse gas emissions from the sector "Fugitive emissions from fuels" show large fluctuations in the historical years 1990-2019, due to emissions from exploration, which occur only in some years with varying amounts of oil and gas flared. Emissions from exploration are not included in the projection, as no projected activity data are available. Emissions are estimated to decrease in the projection period 2019-2040 by 35 %. The decrease mainly owe to expected decrease of offshore flaring in the oil and natural gas extraction. Emissions from extraction of oil and natural gas are estimated to decline over the projection period due to the expectation of a decrease of extracted amounts of natural gas. Emissions of greenhouse gases from other sources are estimated to be constant or nearly constant over the projection period.

Industrial processes and product use

The GHG emission from industrial processes and product use increased during the nineties, reaching a maximum in 2000. Closure of a nitric acid/fertiliser plant in 2004 has resulted in a considerable decrease in the GHG emission. The most significant sources of GHG emission in 2019 are mineral industry (mainly cement production) with 68 % and use of substitutes (f-gases) for ozone depleting substances (ODS) (18 %). The corresponding shares in 2040 are expected to be 82 % and 4 %, respectively. Consumption of limestone and the emission of CO2 from flue gas cleaning are assumed to follow the consumption of coal and waste for generation of heat and power. The GHG emission from this sector will continue to be strongly dependent on the cement production at Denmark’s only cement plant.

Transport and other mobile sources

Road transport is the main source of GHG emissions from transport and other mobile sources in 2019 (80 %) and emissions from this source are expected to decrease in the projection period 2019 to 2040, but with the largest reduction happening after 2030. The emission shares for the remaining mobile sources (e.g. domestic aviation, national navigation, railways and non-road machinery in industry, households and agriculture) are small compared with road transport. Non-road machinery in agriculture, forestry and fishing contributes 9 % of the sectoral GHG emission in 2019.


The main sources in 2019 are agricultural soils (39 %), enteric fermentation (34 %) and manure management (25 %). The corresponding shares in 2040 are expected to be 37 %, 39 % and 22 %, respectively. From 1990 to 2019, the emission of GHGs in the agricultural sector decreased by 17 %. In the projection years 2019 to 2040, the emissions are expected to remain almost constant with only a small reduction of about 4 %. The reduction in the historical years can mainly be explained by improved utilisation of nitrogen in manure, a significant reduction in the use of fertiliser and a reduced emission from N-leaching. Measures in the form of technologies to reduce ammonia emissions in stables and expansion of biogas production are considered in the projections, but emissions from enteric fermentation are estimated to increase due to an expected increase in the number of animals.


The total GHG emission from the waste sector has been decreasing in the years 1990 to 2019 by 35 %. The decreasing trend is expected to continue with a decrease of 25 % from 2019 to 2040. In 2019, the GHG emission from solid waste disposal contributed with 43 % of the emission from the sector as a whole. A decrease of 40 % is expected for this source in the years 2019 to 2040, due to less waste deposition on landfills. An almost constant level for emissions from wastewater is expected for the projection period. GHG emissions from wastewater handling in 2019 contribute with 16 %. Emissions from biological treatment of solid waste contribute with 39 % in 2019 and 40 % in 2040.


The LULUCF sector includes emissions from Afforestation, Deforestation, Forest land remaining forest land, Cropland, Grassland, Wetlands, Settlement and Other land. This projection include only Cropland, Grassland, Wetland, Settlement and Other land. Forestry and Harvested wood products (HWP) is reported separately in Johannsen et al. (2019) although the emission estimates has been included here. The overall picture of the LULUCF sector excl. Forestry and HWP is a net source of 7762 kt CO2 equivalents in 1990. In 2019, the emission has been reduced to a net source of 5304 kt CO2 and estimated to be a net source of 4076 kt CO2 equivalents in 2021-2030 (average of 2021-2030). A small decrease is expected in years 2031-2040 compared to 2021-2030. This decrease may very likely be attributed to an expected increase in crop yield and a slightly lower area with agricultural organic soils. However, it should be noted that the overall emission from this sector is very variable as it is very difficult to predict climate related emission/stock development in the agricultural soils. Agricultural mineral soils are expected to store more carbon in the near future. Agricultural regulations will reduce the area with cultivated agricultural organic soils further in the future, but there will still be a large net emission from these soils.