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Environmental Project no. 764, 2003

Denmark's Greenhouse Gas Projections until 2012, an update including a preliminary projection until 2017

Contents

1 Introduction

This report presents the results of a project financed by the Danish Environmental Protection Agency. The purpose of the project is to make "with measures"- projections of the emissions from Danish sources of the greenhouse gases CO₂, CH₄, N₂O, HFCs, PFCs and SF₆. The ‘with measures’ projection encompasses currently implemented and adopted policies and measures.

The time period covered is from 1972, the first year detailed Danish energy statistics were produced, until the first commitment period (2008-2012) under the Kyoto Protocol to the Climate Convention. A preliminary projection is also made for the second commitment period (2013-2017), but here no projections are available for the agricultural sector and the emissions from this sector have therefore been kept equal to the emissions in the first commitment period.

Estimations of HFCs, PFCs and SF₆-emissions and projections have are base upon a new report [20]. These estimations cover only the period from 1993 until 2020.

Only emissions caused by human activities are included in the calculations. However, it can sometimes be difficult to draw the borderline between emissions from nature and anthropogenic emissions.

Due to small differences between the methodology used in this project and the methodology (CORINAIR) used by the National Environmental Research Institute for the purpose of annual reporting the estimated emissions presented for the period 1990-2000 may deviate a little from the official emission estimates reported to the EU and the Climate Convention (UNFCCC). Therefore the GHG emission estimates presented in this report for the period until 2000 should only be seen as an illustration of the order of magnitude. This is also the case for the parts of the trend analysis in Chapter 2, which are based on the historic data coming from this project.

The description of the emissions in the report is structured according to the IPCC sectors:

Energy (chapter 3)
Industrial processes (chapter 4)
Agriculture (chapter 5)
Land use change & forestry (chapter 6)
Waste (chapter 7)

The NMVOC emission from solvent use is included as a source of CO₂ emission.

A separate chapter is dedicated to each of these sectors. However, the report starts with a summary (chapter 2) of the emissions with a section for each of the pollutants treated. At the end of each of these sections the main differences between the present calculation and the values in Denmark’s Second National Communication on Climate Change [1] are described shortly. For each of the pollutants the development of the emissions in the period 1972-2012 and the various emission targets in Danish sector plans or international conventions are shown on a figure. Below the figures the emissions for the main emitting sectors are shown in a table. The years shown in these tables are not the same for all pollutants. When a column is marked with "2010" it means that the values in the columns are averaged over the first commitment period 2008-2012. "2015" means similarly the average for the second commitment period 2013-2017.

It is not possible in this report to present all the data from the emission calculations. The data is contained in an EXCEL notebook model. The Appendix 1 contains a table with time-series for 1975-2017 for the greenhouse gases CO₂, CH₄ and N₂O for all emitting sectors (see table 28 to table 30). In Appendix 2 the results of the projections 2000-2017 are shown in the IPCC/CRF Sectoral Tables format in CO₂ equivalents for each greenhouse gas and in total (only source and sink categories with greenhouse gas emissions or removals are shown). If the reader needs additional information, please ask the author.

The model is structured as a set of worksheets for the primary energy consuming sectors and the model contains similar sets for each of the pollutants. Additional sheets have been included for the relevant pollutants, where emissions originate from non-combustion processes. Each of these spreadsheets contains time-series for the emissions from each of the primary fuels consumed in the sector.

2 Summary of emissions

The following sections give a summary of the emissions of each of the gases covered. Detailed time-series for the gases CO₂, CH₄ and N₂O can be found in table 28 to table 30 in Appendix 1. In these tables the time-series are disaggregated in the emitting sectors and a total is shown. For CO₂ from fossil fuel combustion both totals without and with corrections for electricity import/export and inter-annual temperature variations are shown. The aggregate anthropogenic carbon dioxide equivalent (CO₂-eq.) emission of the greenhouse gases CO₂, CH₄, N₂O, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF₆) are calculated by multiplying the emissions of each of the greenhouse gases with the 100 years global warming potentials (GWP) shown in Table 1 [2]. These GWPs are recommended by IPCC in the Second Assessment Report and shall be used under the Kyoto Protocol. The GWP of 310 for N₂O means e.g. that the global warming caused by 1 tonne of N₂O is the same as the global warming caused by 310 tonnes of CO₂.

Table 1.
Global warming potentials

In the Kyoto Protocol to the Climate Convention, the parties to the Convention in Kyoto in 1997 agreed, as a first step, to reduce the greenhouse gas emissions of the industrialized countries in 2008 to 2012 by at least 5 per cent in comparison to the 1990 level. According to the agreement, the EU is to contribute a total reduction of 8 per cent. Since then, the EU Member States have agreed to an internal burden sharing that commits Denmark to a reduction of 21 per cent.

With the latest updated GHG emission inventory from the National Environmental Research Institute (NERI), Denmark’s commitment to reducing emissions of greenhouse gases by 21 per cent in the first commitment period means that emissions are to be reduced from 69.7 Mt CO₂-eq. in the base year to an average of 55.0 Mt CO₂-eq. in the first commitment period 2008 and 2012. The result of the updated projections for emissions of greenhouse gases until 2012 carried out in this project shows that Denmark is expected to emit an average of 80.1 Mt CO₂-eq. in the first commitment period.

The results are summarized in Table 2, which shows that the emission of CH₄ decreases from 5.8 Mt CO₂-eq. in 1990 to 5.0 Mt CO₂-eq. in "2010". The emissions of N₂O also decrease, from 10.8 Mt CO₂-eq. in 1990 to 8.7 Mt CO₂-eq. in "2010". For the industry gasses HFCs, PFCs and SF₆ there is an increase from 0.3 Mt CO₂-eq. in the base year to 0.7 Mt CO₂-eq. in "2010".

Table 2.
Denmark's expected GHG emissions in 2008-2012 and the deficit when comparing with the Kyoto target for the first commitment period in the Kyoto Protocol.

The base year estimation in this project is 0.5 Mt CO₂-eq. lower than the estimate shown in Table 2 coming from the use of the CORINAIR methodology as mentioned in Chapter 1. Similarly is our estimate for the year 2000 a bit higher (0.2 Mt CO₂-eq.) than the CORINAIR value shown in Table 2.

As show in Table 2 the total emissions depend strongly on the CO₂ emissions from the fuel used for electricity export. Of the total emission of 80.1 Mt CO₂-eq. in the first commitment period 9.9 Mt CO₂-eq. originates from electricity export. The calculation in the model of the emissions from electricity export is based on the amount of fuel used on the power plants producing for export. The updated energy projection described in [4] expects an electricity export gradually increasing to about 12 TWh in 2010 corresponding to an emission of 9.9 Mt CO₂-eq.

According to Table 2 the Danish deficit is now 25 Mt CO₂-eq.when the projection is compared to the Danish Kyoto target in the first commitment period. This deficit has increased compared to the former projection [58] where the deficit was 1.8 Mt CO₂-eq. when the base year emission was corrected for net-electricity exports (i.e. electricity import in 1990) and measures to exclude the effect of the electricity export 2008-12 were included. A recalculation of the base year emissions by NERI in April 2002 gave a 0.4 Mt CO₂ -eq. raise to the deficit. The increase in the deficit of 22.8 Mt CO₂-eq. shown in this report is composed of 5.0 Mt CO₂-eq. from not correcting the emissions in the base year 1990 and 9.9 Mt CO₂-eq. from not including measures to exclude the effect of the electricity export 2008-12. The main reason for the remaining increase of 7.9 Mt CO₂-eq. is changes in the energy projection. The main changes in the energy baseline compared to the one used in the 2001 projection is the following:

Primary energy consumption in industry, manufacturing and construction in 2012 is projected to be 114 PJ compared to 95 PJ in the former projection. This has caused the deficit to increase about 1.1 Mt CO2. Increased use of diesel in agriculture in the new projection will cause an increase of 0.5 Mt CO2, whereas an expected decrease in the fuel consumption in domestic and service sector will reduce emissions with 0.2 Mt CO2. That total increase in the deficit from these contributions is then 1.4 Mt CO2.

Changed assumptions for electricity and heat production have increased the deficit with 2.0 Mt CO2. This increase in the sum of an increase of 1.6 Mt CO2 on large power plants, 0.3 Mt CO2 on decentral power plants, and 0.1 Mt CO2 on district heating plants. The reduction in the expected number of wind turbines is one of the explanations for this increase.

The expected electricity export in 2012 has now been reduced to 12 TWh from the 17 TWh in the former projection [58]. The emissions caused by the production of electricity for export has therefore decreased from 12.9 Mt CO2 to 9.9 Mt CO2 in the first commitment period. This decrease of 3.0 Mt CO2 is part of the increased deficit. With the same fuel consumption for electricity production and reduced exports the old deficit would have been these 3.0 Mt CO2 larger.

The primary energy consumption for road transport in 2012 is projected to be 180 PJ compared to 165 PJ in the former projection [58]. This causes an increase in the deficit of 0.8 Mt CO2-eq. This includes an increase of 0.3 Mt CO2 from extra diesel bought in Denmark by foreign drivers and 0.1 Mt CO2-eq. from the increase in nitrous oxide emissions related to fuel consumption in cars with catalytic converters.

The CO2 emission from the use of natural gas on the platforms in the North Sea has increased about 0.7 Mt CO2 compared to the former projection. The reason for this increase is primarily new extraction methods, which increase the amount of resources that it is possible to extract from the fields.

In the calculation of the emissions in Figure 1 and Table 2, the emissions from flaring, emissions of CO₂ from plastics in waste incinerated and the reduction of emissions due to the growth of new forest planted after 1990 are included. The sequestration in forest existing before 1990 is not included. The emissions from international air transport and international bunkers are not included. The emissions from road transport are based on gasoline and diesel sold in Denmark, and therefore not corrected for border trade.

Figure 1.
2000-2017: Total emissions of CO₂ equivalents from Denmark if no new measures are introduced.

2.1 Emissions of CO₂

The main source of CO₂ emissions from Denmark is the combustion of fossil fuels. The only other source contributing is the mineral sector and CO₂ from the decomposition of NMVOCs emitted from the use of solvents. It is shown in section 4.1 that the total emission from the mineral sector increases from 1 Mt CO₂ in 1990 to 1.5 Mt CO₂ in 2010. The emission increased already to 1.5 Mt CO₂ in 2000 and is expected to be constant until 2010, since the cement producing capacity, emitting 1 Mt CO₂ in 1990 and 1.4 Mt CO₂ in 2000, is running at maximum capacity. The emission from the production of yellow bricks and lime is only about 0.1 Mt CO₂.

The CO₂ emission from the solvent sector declines from 0.124 Mt CO₂ in 1990 to 0.069 Mt CO₂ in 2010. This is based on the assumption that 85% of the weight of the NMVOCs emitted from solvents results in an emission factor of 3.12 kg CO₂ /kg NMVOC. The emission projection for NMVOC from 2001 until 2012 now uses the updated projection in [64], whereas the historical values are the same as in the former projection [58], since these numbers are still used in the Danish CORINAIR reporting.

In the Danish energy plan "Energi21", the goal is to reduce the emissions of CO₂ corrected for net electricity export and temperature with 20% of the 1988 level in 2005. This total is calculated in a different way than done for the Kyoto Protocol above. The national CO₂-target includes emissions from international air transport but excludes emissions from cement, lime and yellow bricks production and from flaring and plastics in waste incinerated as well as removals by sinks. The emissions from road transport are based on gasoline and diesel consumed in Denmark, and therefore corrected for border trade (according to Table 3, cars from other countries bought fuel equivalent to an emission of 0.2 Mt CO₂ in 1988). The category other in Table 3 covers fuel use for transport in the military and the use of gasoline for off-roaders at power plants, railways and in the household sector. Done in this way, the total emission in 1988 was 61.1 Mt CO₂. The emission target for 2005 is therefore 48.8 Mt CO₂ (shown on Figure 2 as the upper horizontal line).

As shown on Table 3, the total emission in 2005 will be 52.3 Mt CO₂ calculated using the energy projection in the latest energy projection from the Danish Energy Agency [4]. This is 3.5 Mt CO₂ or 7.2% above the Energy21 target. Figure 2 shows that the total emission in 2002 is closer to the Energy21 target; this year the emissions is expected to be 51.3 Mt CO₂ or 5.1% above the target.

The sector with the largest increase in CO₂ emission is road transport, increasing from 8.8 Mt CO₂ in 1988 to 13.0 in "2010". International air transport, which as mentioned above is also included in the total in Figure 2, increases from 2.4 Mt CO₂ in 2000 to 3.2 Mt CO₂ in "2010". The emission from central power plants in Table 3 is the actual uncorrected emission. According to the next line in the table, the corrected CO₂ emission in "2010" will be 9.9 Mt CO₂ lower.

In 1998 the CO₂ emission factor regarding waste incineration was revised to take into account CO₂ emissions from plastic in the waste. Assuming 6.4% of plastic in the waste (see section 3.2) the emission from the combustion of waste was rising from 0.29 Mt CO₂ in 1990 to 0.60 Mt CO₂ in 2000, and is expected to be 0.72 Mt CO₂ in 2010 (see Table 3).

Figure 2.
Corrected CO₂ emissions compared to Danish Energy21 Plan

Table 3.
Emission of CO₂ by sectors

2.2 Emissions of CH₄

The main part of the CH₄ emissions originates from the animals in the agricultural sector (see chapter 5). The decrease in the CH₄ emissions from enteric fermentation in the period 1980 to 2000 continuing until 2012 as shown on Figure 3 is caused by the decrease in the number of cattle. For the same reason the CH₄ emissions from manure management also decreases n this period, but are offset by the increased emissions from the increased number of pigs. As mentioned in section 5.1.2 the emission factors for manure management for Denmark has been changed since Denmark’s Second National Communication from using emission factors for temperate to cool areas. This change has reduced the CH₄ emission from manure management considerably, by more than a factor of three.

The second largest CH₄ emitter is the landfills (see section 7.1). The emissions from landfills had a maximum in 1992. Since then the emission has declined, due to the stop for landfilling of combustible waste in 1996, the decrease due to the ageing of the landfills and the increasing number of landfill gas collection plants.

Figure 3.
Emissions of CH₄ from Denmark

The CH₄ emission from energy combustion has increased since the introduction of decentralised power plants using gas engines, where some of the natural gas is not combusted (see section 3.2). The CH₄ emission in Table 4 from residential & service is from the use of wood and straw in small individual combustion units.

The calculation of the CH₄ emission has changed since the Second Danish Communication [1]. The total CH₄ emission in 1990 was then calculated to be 424 kt CH₄ (the value is now 270.9 kt CH₄ for 1990). The main reason is the change for animal manure, where the emission has dropped with a factor of three, as described in section 5.1.2. New figures for the amount of waste landfilled have also decreased the emission in 1990 from 71 kt CH₄ to 64.0 kt CH₄. The emissions of CH₄ are not corrected for electricity import/export. Table 4 shows the CH₄ emissions both from the energy sectors and the non-energy sector.

Table 4.
Emissions of CH₄ by sectors

2.3 Emissions of N₂O

As shown on Figure 4 the major part of the N₂O emissions originate from agricultural soils (se section 5.2). The main reason for the decrease on the figure from 1990 to 2003 is the combined action of the Danish Action Plan for Sustainable Agriculture and "Vandmiljøplan II". The projection has been updated to take into account the impacts of the midterm evaluation of vandmiljøplan II and the Danish action plan to reduce the evaporation of ammonia from agriculture.

Figure 4.
Emissions of N₂O from Denmark

Table 5 shows the increase of the N₂O emission from road transport from 0.4 kt N₂O in 1990 to 2.0 kt N₂O in 2010 due to the introduction of 3-way catalytic converters on the gasoline cars. Table 8 shows that the emission factor for N₂O increases with a factor of five from 1991 to 2010.

Table 5.
Emissions of N₂O by sectors

The procedure for the calculation of the N₂O emission has changed since the Denmark’s Second Communication [1]. However the totals have changed very little. In [1] the emission in 1990 was 34 kt N₂O and the emission in 2000 and 2010 was 28 kt N₂O. The emissions of N₂O are not corrected for electricity import/export.

2.4 Emissions of HFCs, PFCs and SF₆

Section 4.1.3 contains a projection of the emissions of three groups of greenhouse gases, perfluorocarbons (PFCs), sulphur hexafluoride (SF₆), and hydrofluorocarbons (HFCs) through to the year 2020.

The emission levels have decreased compared to former reports [58] for several reasons:

1. Because the actual emissions have been corrected for the greenhouse gases contained in the exported and imported appliances.
2. A tax has been introduced on these three groups of gases amounting to 1/10^th of their GWP in Table 1 up to a maximum of 400 kr/kg.
3. New Danish legislation containing dates for outphasing import, production and use of these industrial greenhouse gasses.
4. New rules for decommissioning, where the GHG in refrigerators, foam etc. are destroyed instead of emitted to the atmosphere. This is a mayor reason for the decrease in the present projection compared to the last one in [58]. The difference with the old calculation is especially large in the second commitment period, 2013-17 (marked as "2015").
5. Further there have been changes in the leak-rates for commercial and mobile refrigerants.

Table 6.
Emissions of HFCs, PFCs and SF₆

As shown in Table 6 the total emissions in 1995 of these gases have changed to 0.35 Mt CO₂ eq. since Denmark’s Second National Communication [1], where the emission in 1995 was 0.42 Mt CO₂ equivalents. No emission projection was made for HFCs, PFCs and SF₆ in [1]. The calculations are now done according to the 1996 IPCC Revised Guidelines for National Greenhouse Gas Inventories. The emissions are corrected for the greenhouse gas contained in the exported (and imported) appliances.

3 Energy

According to the 1996 IPCC Revised Guidelines for National Greenhouse Gas Inventories this chapter is divided into two parts: the emission from combustion of fuels and the fugitive emissions from fossil fuels.

There is a change in the assumptions on the composition of the electricity production in the present projection and in the former projection [58]. The total capacity of Danish wind turbines is now not expected to increase above the 3000 MW reached in 2003. The reason is that the on-shore capacity will stay constant and that no off-shore wind parks after Horns rev and Rødsand in 2003 are included in the baseline, due to that economic condition for the future off-shore wind parks are not yet resolved. Some other subsidies have also been cancelled: One example is biogas where the production biogas from animal manure therefore only will increase about 50% from 2000 until 2012 since no new biogas plants are expected after 2004.

3.1 Fuel Combustion Activities

The emissions from the combustion of energy are based on the data for energy consumption in Denmark for the period 1972-2017 (there is a minor inconsistency in the historical use of fossil energy of less than 0.3 PJ). The Danish Energy Agency produced an EXCEL pivot-table, in a standard format, containing the historic energy data until 2001 and the latest projection of the future primary energy consumption, according to the follow-up on the Danish energy plan "Energi21" [4]. The emission model at Risø is automatically updated, when the Danish Energy Agency produces a new pivot-table.

The projection of the energy consumption is based on the projection of the production until 2010 in the report from the Danish Ministry of Finance: Økonomisk Oversigt, januar 2002 supplemented with a longer projection from the Danish Ministry of Finance: Finansredegørelse 2001. The latest price projections for crude oil and coal are based on IEA: World Energy outlook 2002, September 2002. The economic projection is transformed into a projection of the energy consumption using a number of models in the Danish Energy Agency such as the EMMA-model. The RAMSES model is then used to transform the demand for electricity and district heat into fuel demand at the power plants.

According to Table 2 the Danish deficit is now 25 Mt CO₂-eq. when the projection is compared to the Danish Kyoto target in the first commitment period. This deficit has increased compared to the former projection [58] where the deficit was 1.8 Mt CO₂-eq. when the base year emission was corrected for net electricity exports and measures to exclude the effect of the electricity export 2008-12 were included. A recalculation of the base year emissions by NERI in April 2002 gave a 0.4 Mt CO₂ -eq. raise to the deficit. The increase in the deficit of 22.8 Mt CO₂-eq. shown in this report is composed of 5.0 Mt CO₂-eq. from not correcting the emissions in the base year 1990 and 9.9 Mt CO₂-eq. from not including measures to exclude the effect of the electricity export 2008-12. The main reason for the remaining increase of 7.9 Mt CO₂-eq. is changes in the energy projection. The main changes in the energy baseline compared to the one used in the 2001 projection is the following:

Primary energy consumption in industry, manufacturing and construction in 2012 is projected to be 114 PJ compared to 95 PJ in the former projection. This has caused the deficit to increase about 1.1 Mt CO2. Increased use of diesel in agriculture in the new projection will cause an increase of 0.5 Mt CO2, whereas an expected decrease in the fuel consumption in domestic and service sector will reduce emissions with 0.2 Mt CO2. That total increase in the deficit from these contributions is then 1.4 Mt CO2.

Changed assumptions for electricity and heat production have increased the deficit with 2.0 Mt CO2. This increase in the sum of an increase of 1.6 Mt CO2 on large power plants, 0.3 Mt CO2 on decentral power plants, and 0.1 Mt CO2 on district heating plants. The reduction in the expected number of wind turbines is one of the explanations for this increase.

The expected electricity export in 2012 has now been reduced to 12 TWh from the 17 TWh in the former projection [58]. The emissions caused by the production of electricity for export has therefore decreased from 12.9 Mt CO2 to 9.9 Mt CO2 in the first commitment period. This decrease of 3.0 Mt CO2 is part of the increased deficit. With the same fuel consumption for electricity production and reduced exports the old deficit would have been these 3.0 Mt CO2 larger.

The primary energy consumption for road transport in 2012 is projected to be 180 PJ compared to 165 PJ in the former projection [58]. This causes an increase in the deficit of 0.8 Mt CO2-eq. This includes an increase of 0.3 Mt CO2 from extra diesel bought in Denmark by foreign drivers and 0.1 Mt CO2-eq. from the increase in nitrous oxide emissions related to fuel consumption in cars with catalytic converters.

The CO2 emission from the use of natural gas on the platforms in the North Sea has increased about 0.7 Mt CO2 compared to the former projection. The reason for this increase is primarily new extraction methods, which increase the amount of resources that it is possible to extract from the fields.

The energy consuming sectors used in the calculation of the emissions from the energy sector is shown in Table 7. The energy consumption and the emissions from power plants are disaggregated into two groups, one above 25 MW electric capacity and one below 25 MW. The reason for this is that the Danish Ministry for Economy and Business Affairs restricts the total emissions of SO₂ and NO_x from the power plants above 25 MW to be below a certain value each year [16].

Table 7 shows the fuel type used in the emission calculations. Minor amounts of brown coal were included in the category "coal". Woodchips, fuelwood, wood pellets and wood waste were added and called "wood". The fuel type "energy crops" consist of fish oil, elephant grass and willow. The fuel types based on biomass do not contribute to the CO₂ emission due to the recirculation of the carbon - but other pollutants are emitted from the combustion of biomass as shown in Table 8.

Table 7.
Energy sectors and fuel types used in the calculation

3.2 Emission factors

All emission factors for fuel combustion used in the calculations are shown in Table 8. The table is organised with a set of emission factors for each group of energy consuming sectors. The units for the emission factors are always in kg of emission per GJ of fuel combusted. When tonnes are converted to joules in Danish energy statistics, net calorific values are applied as recommended by IPCC. In each sector there are individual emission factors for all fuels used in the sector. Table 8 also shows the decrease over time for some emission factors. If a cell in the table is blank it means that the emission factor has not changed and the value above is used. The emission factors have been updated so that the emission factors in the CORINAIR database are in agreement with the emission factors used in the projections.

Since not all the combustible waste is of biomass origin a CO₂ emission factor for the combustion of waste is estimated in order to take the plastic content of the waste into account. It is assumed that 6.4% of the waste is plastic [9], that the calorific value of plastic is 42.4 GJ/t and that the carbon content is 20 kg C/GJ. The resulting emission factor is then 18.95 kg CO₂ /GJ.

The high CH₄ emission factor for decentralised power plants is based on the assumption that 3% of the natural gas in the gas engines is not combusted [10]. Table 8 also contains separate emission factors for natural gas turbines and for natural gas engines.

The historic emission factors for road transport are calculated with the COPERT II model [11,12]. The output from COPERT II for the total emission of each pollutant for each year were divided with the total fuel consumed for each of the road vehicles categories: gasoline cars, diesel cars, light duty diesel vehicles, heavy duty diesel vehicles, and LPG cars.

For the future emission factors in 2005 and 2010 the information on deterioration factors, future cold start emission levels and updated emission factors for EURO I-IV vehicles in the background material for the COPERT III model was used [13]. The implementation of this emission information especially affects the catalyst car emissions.

The emission factors used for railways are the factors from COPERT II for heavy duty vehicles above 16 tonnes at highway driving conditions.

Combining relevant air traffic statistics, energy use and emission factors, an energy and emission calculation model for the Danish air traffic was developed at the National Environmental Research Institute [12] following the CORINAIR methodology. In this model, energy use and emissions from both the domestic and international air traffic for LTO (Landing and Take Off) and the cruise activity are covered in four sub categories. The Danish part of the total air traffic energy use is defined by the UNECE convention as the LTO energy use. At the same time the cruise activity covering all air transport activity above 1000 m is defined as international transport. This allocation procedure is made for all pollutants except for CO₂. In the latter case the Danish emission part is defined as the CO₂ contribution from all domestics flights during both LTO and cruise.

To end up with the final aggregated air traffic emission factors, the energy use and the emissions are estimated for the four sub-categories mentioned above.

As a start all take-off’s from Danish airports are divided into the number of LTO’s carried out by different representative aircraft types. The next step is to multiply the fuel consumption factor for each aircraft type with the corresponding number of LTO’s, giving the energy use totals for domestic and international LTO’s, respectively. The total energy use by domestic and international cruise is then calculated as the difference between the total fuel sold for aviation in Denmark and the total calculated fuel used for LTO.

The LTO emissions are calculated by combining LTO emission factors and -numbers for all representative aircraft. For cruise the emissions are estimated as the fuel use times fuel related emission factors. The aggregated emission factors in Table 8 are finally found as the total emissions divided with the total energy use for LTO and cruise, respectively.

Emissions from other mobile sources and machinery in agriculture, forestry, industry and household & gardening using diesel oil, gasoline and LPG are estimated following the guidelines in CORINAIR. Information on the stock of different machine types and their respective load factors, engine sizes, annual working hours and emission factors is combined in a computer model [12] in order to calculate the total emissions.

Table 8.
Emission factors used for fuel combustion

3.3 Fugitive emissions from fossil fuels

This section covers all emissions from production, processing, handling and transport of fossil fuels, which are not the result of combustion. For greenhouse gas emissions from Denmark this means emissions from the flaring of natural gas, CH₄ emissions from coal storage, CH₄ escaping from the gas networks, and CH₄ from refineries.

3.3.1 Flaring

The energy content of the natural gas flared is not included in the Danish energy balance. According to the Energy Agency the 0.8 PJ was flared in 1972 increasing to an expected maximum of 15.4 PJ in the year 2000, and thereafter decreasing to 10.0 PJ in 2010. The resulting CO₂ emission, following the same oil extraction curve, is shown in Figure 5. At the maximum in 1999 it is 0.88 Mt CO₂, falling to 0.57 Mt CO₂ in 2012. The CO₂ emission from flaring is not included in the Danish Energi21 target for 2005, but it is included in the United Nations Framework Convention on Climate Change and the Kyoto Protocol. In the IPCC guideline for Emission Inventories [36] the emissions from flaring is found in the category "fugitive emissions from fuels".

Figure 5.
CO₂ emissions from flaring in the Danish North Sea

In the production process at the refineries a part of the volatile hydrocarbons (VOC) is emitted to the atmosphere. It is assumed that CH₄ account for 1 % of the emission or 505g VOC/tonne of crude [7]. In table 10.5 the emissions are calculated to be only about 0.05 kt CH₄, based on the historic information and the projection for the processing of crude on Danish refineries. The calorific value used for crude oil is 42.7 GJ/t.

Table 9.
Emissions CH₄ from refineries

3.3.3 Gas networks

The emission from leakage of CH₄ from the gas networks was estimated in the report "Danish Budget for Greenhouse Gases" [8] to be 7.9 kt CH₄ and from the town gas network in Copenhagen 0.6 kt CH₄. Thus the total CH₄ emission from gas networks were 8.5 kt CH₄. These values is being updated at the moment but since the work is not yet finished the result from [8] is therefore used here for the whole period.

3.3.4 Emissions from storage of coal in Denmark

As in [8,15] it is assumed that 50 % of the emissions under transport and storage are emitted in Denmark. As shown in Table 10 the CH₄ emission factors for coal and coal post mining is more than 20 times lower for surface mined coal than for underground mined coal [36]. In the calculation here the midpoint in this interval is used. It is therefore important to know the fraction of the coal imported by Denmark, which originates from underground mines. Table 11 shows the origin of the coal imported by Denmark. The table shows e.g. that the coal import from South Africa was stopped in the period 1987-1991. At the bottom of Table 11 the fraction of the coal mined underground in each country [14] is shown. Table 12 shows the time series of the total coal import and its disaggregation into surface and underground mined coal, based on the information in Table 11. It is assumed that the coal import in the future will originate from the same countries as it does in the last year covered by the statistics - 2001. The coal import is not corrected for electricity import/export.

The CH₄ emission had a maximum in 1997, where the emission was about 6.1 kt CH₄ falling to about 4 kt CH₄ in 2010 with some fluctuation over time.

Table 10.
CH₄ emission factors for coal storage

Table 11.
Origin of the coal imported by Denmark (Unit: % of total import)

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Table 12.
Total coal import and the resulting emissions of CH₄

4 Industrial Processes

Greenhouse gases are produced from a variety of industrial activities, which are not related to energy. This section covers the emissions from industrial production processes, which chemically or physically transform materials. For Denmark this means CO₂ emissions from the production of cement, lime and yellow bricks, and emissions of HFCs, PFCs and SF₆.

4.1 Mineral Products

4.1.1 Cement, lime and yellow bricks production

Only the mineral products sector is contributing to the emission of CO₂. In 2000 a total of 1.46 million tonnes of CO₂ originated from production of cement, lime and yellow bricks. According to Table 3 this is an increase of about 50% from the 1.0 MtCO₂ in 1990. However, the present level of emissions are not expected to increase in the period until 2012.

The CO₂ emissions from cement production are shown in Figure 6. In 2000 the emission was 1.35 million tonnes of CO₂. Since 1990 the emission has been increasing due to the increase in building activity. The Ålborg Portland plant is now running at its full capacity, it is therefore assumed that the Danish CO₂ emission form cement production will not increase in the period to 2010, since it will take 5-10 years for a new cement plant to be operational after the decision to build it.

Figure 6.
CO₂ emission from cement production

The curve in Figure 6 is based on information from Ålborg Portland [17]. The total CO₂ emissions in the figure consist of two parts: The emissions from white cement calculated the amount of white cement produced multiplied by an emission factor of 0.669 t CO₂/t cement. The CO₂ emission from grey cement is calculated as the amount of grey cement weighted by the relative fractions of the three types of clinker multiplied by the three respective emission factors shown in Table 13 [17].

Table 13.
CO₂ emission factors for grey cement

The source of information for the production of bricks and lime is the Industrial Sales Statistics [18]. Assuming that half of the bricks are yellow bricks, their production gives rise to an emission of 0.158 kg CO₂/brick [19]. This emission factor is calculated the following way. When limestone (CaCO₃) is heated it decomposes into lime (CaO) and CO₂. Using the molecular weights, 44 kg of CO₂ is emitted for every 100 kg CaCO₃ decomposed. Since clay used to produce yellow bricks contains 18% limestone and the average weight of a brick is 2 kg, the emission factor is 2*0.18*0.44= 0.158. With the annual production of yellow bricks shown in Table 14, the emissions from brick production was in the range 0.02-0.03 million tonnes of CO₂ in the period 1988-2000.

If the amount of yellow bricks used in Denmark is projected with the long range annual increase of 1.5% p.a. used in the ADAM projections for the supplier of building materials made by Denmark's Statistics, the CO₂ emissions from yellow bricks will increase to 0.04 Mt CO₂ in 2010.

Table 14.
CO₂ emissions from production of yellow bricks

The production of lime emits 0.785 t CO₂/t burned lime (standard IPCC value), since 44.01 kg of CO₂ is emitted for every 56.08 kg of CaO produced, according to the molecular weights in the two products in the disintegration of CaCO₃. According to Table 15 the annual emission from lime production was in the range 0.07-0.10 million tonnes of CO₂ in the period 1988-2000.

Table 15.
CO₂ emissions from production of burned lime.

4.1.2 HFCs, PFCs and SF₆

This section contains a projection of the emissions of three groups of greenhouse gases, perfluorocarbons (PFCs), sulphur hexafluoride (SF₆), and hydrofluorocarbons (HFCs) through to the year 2020. These gases were added to the gases CO₂, CH₄ and N₂O under the 1997 Kyoto Protocol to the United Nations Framework Convention on Climate Change. The GWPs of the gases are shown in Table 1.

The information in Table 16 is from a report made by COWIconsult [20]. The emission levels have decreased compared to former reports for several reasons:

1. Because the actual emissions have been corrected for the greenhouse gases contained in the exported and imported appliances.
2. A tax has been introduced on these three groups of gases amounting to 1/10^th of their GWP in Table 1 up to a maximum of 400 kr/kg.
3. New Danish legislation containing dates for outphasing import, production and use of these industrial greenhouse gasses.
4. New rules for decommissioning, where the GHG in refrigerators, foam etc. are destroyed instead of emitted to the atmosphere. This is a mayor reason for the decrease in the present projection compared to the last one in [58]. The difference with the old calculation is especially large in the second commitment period, 2013-17 (marked as "2015").
5. Further there have been changes in the leak-rates for commercial and mobile refrigerants. The reduction in leak-rates decreases the emission form those sources with a smaller amount.

In agreement with Article 3.8 of the Kyoto Protocol, the Denmark has chosen 1995 as the base year for HFCs, PFCs and SF₆ [57]. The total emission of the three groups of gases increase from 0.35 Mt CO₂ in 1995 to the peak of 0.81 Mt CO₂ in 2000. Thereafter the emission decrease gradually to 0.71 Mt CO₂ in "2010" and further to 0.50 Mt CO₂ in "2015".

The emissions are calculated using the IPCC method for actual emission, taking into account the time lag between consumption and emission, which may be considerable in some application areas, e.g. closed cell foams and refrigeration.

Hydrofluorocarbons (HFCs)

HFCs are used as replacements for chloro-fluorocarbons (CFCs) and hydrochloro-fluorocarbons (HCFCs). Unlike the CFCs and the HCFCs, HFCs do not convey chlorine to the stratosphere and thus do not contribute to ozone depletion. According to the 1987 Montreal Protocol and its subsequent amendments, CFCs were largely banned for developed countries after January 1996 (and developing countries after 2010), although some countries have failed to meet the deadline. Furthermore, according to global rules, HCFC usage will be subject to a gradual phase-out with cuts of 35%, 65% and 90% in 2004, 2010 and 2015, respectively. Final HCFC consumption phase-out will occur in 2020 (2040 for developing countries). The main sources of emissions of HFCs are from the uses as refrigerant in cooling and as a blowing agent for insulation foams. The most used HFC is HFC-134a. The mixtures with the names R-401a to R-507a contains various amounts of different HFCs sometimes mixed with HCFCs and hydrocarbons. The weight in tonnes of the emissions of these R-mixtures are therefore not only HFCs. However, in order to calculate the total emissions in CO₂ equivalents, the GWPs shown at the top of the table were used. The GWPs for the mixtures are calculated from the GWP of the individual HFCs in the mixture.

The main emission is from HFC-134a and HFC-404a (containing 44% HFC-125, 4% HFC-134a and 52% HFC-143a). The total emission reaches 0.64 Mt CO₂ in "2010" and only 0.37 Mt CO₂ in "2015".

Perfluorocarbons (PFCs)

PFCs are fully fluorinated hydrocarbons. Because of their extreme long atmospheric lifetimes (2,600 - 50,000 years), they have particularly high GWPs.

The production of aluminum is thought to be the largest source of emissions of the CF₄ and C₂F₆. These emissions are produced primary by the anode effect, which occurs during the reduction of alumina (aluminum oxide) in the primary smelting process, when alumina concentrations become too low in the smelter. Under these conditions, the electrolysis cell voltage increases sharply to a level sufficient for bath electrolysis to replace alumina electrolysis. This causes a high energy loss and a release of fluorine, which combines with the carbon to form CF₄ as well as C₂F₆ in lower quantities. However, there is no primary aluminum production in Denmark. The only source of PFC emission is the use of a small amount of Perflouropropane (C₃F₈) as a component in a cooling liquid in some older cooling installations. Table 1 shows that the emission of PFC (C₃F₈) from Denmark had a maximum of 28 kt CO₂-eq. in 2000 and decreases to 18 kt CO₂ -eq. in "2010" .

Sulphur hexafluoride is an extremely stable atmospheric trace gas. Its unique physico-chemical properties make this gas ideally suited for many specialised industrial applications. Its GWP of 23,900 is the highest of any atmospheric trace gas.

The emissions of SF₆ from Denmark are from three main applications. The largest consumer (60%) is the glass industry, using SF₆ as a sound insulating gas. The second largest consumer is the power plants using SF₆ as an electrical insulation gas. Additionally there is a small consumption (6%) in magnesium foundries, where SF₆ is used to prevent oxidation of molten magnesium and laboratories using the gas.

The time-serie for the emission on SF₆ in Table 16 declines from 107 kt CO₂-eq. in 1995 to 28 kt CO₂ -eq. in 2008 but increases to 107 kt CO₂-eq. in 2012 due to end of life emissions.

Table 16.
Actual emission of HFCs, PFCs and SF₆ from Denmark

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5 Agriculture

The emission calculations in this section was done together with a working group with participants from, the Ministry of Food, Agriculture and Fisheries, Danish Institute of Agriculture and Fisheries Economics, Danish Institute of Agricultural Sciences and the National Environmental Research Institute, as reported in [47,48].

5.1 CH₄ from Enteric Fermentation & Manure Management

Methane is produced as a by-product during the digestive processes in animals. All domestic animals emit CH₄, but the largest contribution comes from ruminants, due to their ability to breakdown cellulose. The number of domestic livestock in Denmark is shown in Table 17 and Figure 7. The data sources are the Danish ten-year statistical review [21] for all the types of domestic animals except for dairy cows, and turkey-ducks-geese, which are taken from a series of Danish annual statistics [22]. In the Second Communication to the UNFCCC [1] cows kept for suckling were included in "dairy cows". They are now included in "other cattle", since they have an emission factor similar to that category. Fur animals are not included since no emissions factors exist for this category. The number of cows is assumed to decrease 1.8% per year [46]. The amount of pigs slaughtered annually is assumed to increase 1.5% p.a. from 2000 until 2012; this number is then driving the future amount of sows [46]. As shown below, the total emissions in 2000 of CH₄ from agriculture was 170.3 kt, consisting of 134.2 kt from enteric fermentation and 36.1 kt from manure management.

Table 17.
Domestic livestock in Denmark

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Figure 7.
Development of the main livestock categories

5.1.1 CH₄ emissions from enteric fermentation

IPCC gives two alternative ways to estimate CH₄ emissions. Tier 1, which just uses the IPCC default emission factors for the region, and Tier 2, in which emission factors are calculated based on local conditions. The CH₄ emission per animal is here calculated based on weight, weight gain, frequency of pregnancy, fat % of the milk, and the energy efficiency of the animal. In the Second Danish Communication [1], Tier 1 was used for all animal categories. However, due to new information [23], Tier 2 is now used for cattle, which by far is the largest CH₄ emitter from enteric fermentation.

Table 18 shows that the emission factor for dairy cows in Tier 2 is expected to increase from the present 101 kg CH₄/yr/head to 119 kg CH₄/yr/head in 2012 [23], due to the expected higher productivity per head..

Table 18.
CH₄ emission factors for enteric fermentation

Figure 8 shows that the CH₄ emission has been decreasing from about 200 kt in the seventies to 134 kt in 2000 due to the decreasing number of cattle. Since the enteric emission factor for pigs are much lower, the increasing number of pigs only result in a small increase in the emissions. Emissions for chickens, fowls and fur animals are not included since no emission factors are available. The emissions in 2000 from horses (0.7 kt) and sheep (1.2 kt) are too small to be seen on Figure 8. The above-mentioned decrease in the number of cattle outweighs the increase in the emission factor for cattle and the increase in the number of pigs.

Figure 8.
CH₄ emissions from enteric fermentation in domestic livestock

5.1.2 CH₄ emissions from manure management

Two changes have been made in the present emission calculations for CH₄ from manure management compare to the one presented in the Second Danish Communication [1], where Tier 1 was used for all animal categories. Based on the information in [23], Tier 2 is now used for all animal categories. The second change is that the emission factors for a cool climate, having an average temperature below 15 degrees, are now used (see definition in the IPCC Revised Guidelines [36], footnote to table 4-6). In the Second Danish Communication [1] the Tier 1 emission factors for temperate climate, with average annual temperatures in the range 15-25 degrees were used.

The resulting total CH₄ emissions from manure management are very sensitive to which set of emission factors that are use for Denmark. Figure 9 shows that the total CH₄ emission decreases from 38,6 kt CH₄ in 2000 to 36.5 kt. CH₄ in 2012.

Table 19.
CH₄ emission factors for manure management.

The Tier 2 CH₄ emission factors for "other cattle", "other pigs", "other fowls", and "Turkeys-ducks-geese" are weighted averages of emission factors calculated in [23].

Figure 9.
CH₄ emissions from manure management (excl. biogas plants).

Figure 9 shows that the CH₄ emission has been decreasing from about 42 kt in the seventies to 38,6 kt in 2000. The increase in the emission from the manure from the increasing number of pigs has almost balanced the drop due to the decreasing number of dairy cattle. The total CH₄ emission from horses, sheep and fowls is so small (0.8 kt) that it is almost impossible to see it on Figure 9. The CH₄ emission projection for manure management is based on the animal projection in Table 17 and the emission factors in Table 19.

However, the emissions shown on Figure 9 are not the actual emissions of CH₄ from manure management. The reductions caused by the biogas plants have to be subtracted. The production of biogas at sewage gas plants, industrial biogas plants and landfill biogas plants is subtracted from the total production of biogas according to the Danish Energy Agency. The rest is then the production at agricultural biogas plants as shown in Figure 10. The main part of the production is on joint biogas plants the rest on smaller plants on single farms. Of the total production in 2000 of 2.92 PJ, 0.58 came from landfill gas plants, 0.86 PJ from sewage gas plants, 0,07 from industrial biogas plants. From agricultural biogas plants the production was therefore 1.42 PJ. The data before 1995 is from [29] combined with information from landfill biogas production. The production from agricultural biogas plants is expected to increase 46% from the 1.4 PJ in 2000 to around 2 PJ in 2004. The production values are from [28], which however is lower than the former projection in the Danish Energy Plan "Energi21". There is thus not included any new biogas plants after 2004 in the projection.

Figure 10.
Total biogas production

Assuming a calorific value for biogas of 24 MJ/m³ biogas, a content of 60% CH₄ in biogas [29], a CH₄ density of 0.72 kg/ m³, the 2000 production e.g. equals 25.5 kt CH₄. However, the emissions of 38.6 kt CH₄ from manure management in 2000 shown on Figure 9 are not reduced by this value but only with 9.7% of 22.5 or 2.5 kt CH₄. This is because the manure produces much more CH₄ in a biogas plant than under normal storage conditions. The 9.7 % were calculated based on the new information in [63], where the reduction in CH₄ emission from biogas plants has been calculated. If 1 kg average volatile solid (VS) containing 30% cattle manure, 26% pig manure and 44% industrial organic waste is processed in a biogas plant it will produce 0.314 m³ CH₄. Combining this with the information in the report [63] that the emission reduction by the treatment of 1 kg VS is 0.0218 kg CH₄ = 0.030 m³ CH₄ the result is a reduction of 9.7%. With the projected biogas production in Figure 10, the emission of 36.5 kt CH₄ in 2012 on Figure 9 will be reduced by 3.5 kt CH₄ to 33.0 kt CH_4.

5.2 N₂O from agriculture

Production of N₂O in soils is a result of nitrification (an aerobic microbial oxidation of ammonium to nitrate) and denitrification (an anaerobic microbial reduction of nitrate to nitrogen gas). Nitrous oxide (N₂O) is a gaseous intermediate in the reaction sequence of both processes. Formation of N₂O is enhanced by an increase of available nitrogen. Only anthropogenic emissions are included, defined as emissions from cultivated land. Emissions from unfertilised fields are considered as background emission.

The total N₂O emission in 2000 from Danish agriculture was 27.3 kt N₂O expected to decrease to 24.3 kt N₂O in 2010 (see Table 21, part 2). The N₂O emissions were calculated for the sources listed in Table 20 by multiplying the emission factors with the respective activity data for the N-inputs after subtraction of the NH₃ evaporation (except for manure management, where the emission factor is use before subtraction of evaporation). The emission factors are the IPCC default values [36].

Table 20.
N₂O emission factors for agriculture

Table 20 shows that the largest N₂O emissions originates from Nitrogen leaching & runoff (7.2) and from crop residues (6.2 kt). The third largest source is the synthetic fertilisers (4.7 kt). As a new thing a line has been introduced to account for the reduction of N₂O due to the treatment of manure at biogas plants, the emission reduction increases from 0.01 kt N₂O in 1990 to 0.05 kt N₂O in 2010. This reduction is based on the projection for biogas production in section 5.1.2., using the information in [63] that if 1 kg of the average volatile solid (VS) is treated in a biogas plants it will produce 0.314 m³ CH₄ and will reduce emission by 0.325 kg N₂O from the manure. Combining this with the information in section 5.1.2 of the total biogas production gives the N₂O emission reduction mentioned.

Table 20 do not include the emission of 0.11 kt N₂O from the use of 5.8 kt N in synthetic fertilisers used on parks and lawns.

Table 21 (part 1 and part 2) shows how these N₂O emissions from the above-mentioned sources were calculated for the period 1985-2010. The source of the synthetic fertiliser user is [53]. Here the 1997/98 value is used for 1998 and the 5.8 kt N in synthetic fertilisers used on parks and lawns subtracted. According to table 4.12 in the midterm evaluation of "Vandmiljøplan II" a reduction in synthetic fertiliser use of 19.7 kt N had been reached in 1999 of goals in the plan and 59.8 kt plus 13.5 (Agenda 2000) is expected to be reached in 2003. The 2003 value for fertiliser used in the projection is therefore the 1999 value of 256.9 kt minus the extra 53.5 to be reached in the period 1999-2003 plus the impact of the extra initiatives in the Danish government’s plans for "Vandmiljøplan II" [51] and NH₃ emission reductions [52]. These initiatives are expected to reduce the use of synthetic fertiliser with 24.3 kt before 2003. The value for 2003 is therefore 179.1 kt N. Before the N₂O emission is calculated by multiplying with the emission factor of 1.25% from Table 20, the N content of NH₃ emission in Table 21, part 3 from the fertiliser use (close to 2%) is subtracted.

Concerning animal manure, the historical data is from [25] (1998/99 values are used for 1999 etc.) and the future data for 2003 and 2010 are from [26], this historical report [25] contain information for the years 1984, 1989, 1995, 1996, 1997, 1998 and 1999. Linear interpolation is used for the years in-between. For the years in-between values are interpolated linearly. In the column in Table 21, part 1 showing N-input from animal grazing, the NH₃ emission shown in Table 21, part 3 is subtracted. The values in Table 21, part 1 for N-input from animal fertiliser on soils is also after subtraction of NH₃ evaporation. However the N content in manure management in Table 21, part 3 is according to the IPCC rules before any NH₃ evaporation has taken place. The fractions of the total amount of manure, which are solid (21.5%) and liquid (71.5%) [24] are kept constant in the time series.

The N-input from nitrogen fixation in Table 21, part 2 is lower than in former inventories, because now only the symbiotic N-fixation is included (about 90% of the total N-fixation). The data is from Appendix A in [26], where 1998/99 data is used for 1999 and also for all future years.

The activity data for the historic N-inputs from industrial waste and sewage sludge used as fertilisers are from the field-N-balance appendix 3.1 in [27]. The future N-input from industrial waste has been put equal to the 1999 value. According to [23] the N-input from sewage sludge is expected to decrease in the period 1999-2003.

The combined action of "Vandmiljøplan I" (called The Action Plan on the Aquatic Environment), the Danish Action Plan for Sustainable Agriculture and the "Vandmiljøplan II" was expected to result in a decrease in the N-input from leaching & runoff (="udvaskning") from 230 mill. kg to 130 mill. kg in 2003. With the new initiatives in the Governments plan after the midterm evaluation of "Vandmiljøplan II"[51] the 100 mill. kg N reduction in the leaching & runoff is expected to be reached in 2003. However, one of the initiatives in this plan is to speed up the increase in the wetland area in such a way that it will absorb 3.6 kt N in 2003. This is the reason for the expected 2003 value in Table 21, part 2 for leaching & runoff to be 133.6 kt N instead of 130.0 kt N. No change is expected after 2003.

The IPCC method [36] for the calculation of N₂O emissions from crop residues was used in the calculations. Here it is assumed that the amount of Nitrogen in the crop residues is equal to the N-content in the crops. The values in the "N- in crops" column in Table 21, part 2 is from the appendices in [25], except that the historical amounts of cereal straw and rape/pea straw has been subtracted and shown in two separate columns. The amount of rape/pea straw is from [54] and has an N-content of 1%, the double of the N-content in cereal straw. The values for cereal straw are from [25]. The future projection for the N-content in cereal straw is expected to be proportional to the increase in the amount of straw used in the energy sector. According to the midterm evaluation of "Vandmiljøplan II" the N-content in catch crops will increase to 3 kt N in 2003.

The total area in Denmark covered with histosols, defined as colour-code 7/JB 11 in the Danish soil classification, is 237,700 ha. Histosols are cultivated organic soils originating from old N-rich organic matter. However, only 184,400 ha are used for agricultural purposes. Of this area again 90% is used for grassland, which is in a stable situation, without N₂O emissions. This means that only 10%, or 18,400 ha of histosols area [23] is included in Table 21, with an annual emission of 0.14 kt N₂O using the emission factor of 5 kg N₂O-N/ha shown in Table 20. When these soils are cultivated, their surface gradually sinks. However, emission of CO₂ from this process in histosols has not been included.

The only source of N₂O in Table 21 not yet mentioned is the N₂O release after deposition of NH_3. According to Table 20 an emission factor of 1% should be used for the NH₃ deposited in Denmark. However, IPCC recommend that the deposition = evaporation of NH₃ - N from Denmark (import/export are not taken into account). Time series for all the sources of NH₃ emission are shown in Table 21, part 3. These data for NH₃ from synthetic fertiliser, animal manure, straw leaching and evaporation from sludge is from the new projection of NH₃ emissions to be published in [64]. Here the emission of NH₃ has increased primary due to a change in the estimation of the way the manure is being spread on the fields. There exist no statistics on the practice used by the farmers and an estimate has to be used. The total evaporation from agriculture in e.g. 2010 has with this change increased from 61.2 kt NH₃-N to 75.6 kt NH₃-N and thereby increasing the N₂O emission by 0.2 kt N₂O.

The NH₃ emission from straw leaching is expected to drop to zero in 2003 according to the expected ban on this activity [52].

Table 21.
N-input and N₂O emissions from agriculture

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6 Land-use Change & Forestry

The total area of Denmark is 43000 km². About 10% or 4170 km² (417,000 ha) of the area was forest in 1990, this includes 60 km² not covered at the moment of counting [30]. The forest area is defined as the area covered with trees. This means that open woodland and open areas within the forests are not included.

At the moment there is a discussion in IPCC whether sequestration in forest can be included in the Danish totals. In this report it is assumed that CO₂ sequestration in new forests planted after 1. January 1990 can be included. The sequestration in forests existing prior to 1990 is not included in the totals in the projections in this report.

Table 22 shows the conversion factors used for the calculations. In the Danish literature an expansion factor of 2.0 is used both for broadleaves and conifers [33]. This value also includes roots and some carbon in the undergrowth and soil (IPCC default expansion factors [36] are 1.75 for undisturbed forests and 1.90 for logged forests). In order to estimate the stored amount of CO₂, the stem wood volume is first multiplied with the expansion factor to include the additional biomass apart from commercial stem wood: branches, leaves/needles, stumps and roots. This is finally multiplied with the carbon content (as CO₂ equivalents) per cubic meter.

In the default IPCC methodology the last multiplication is separated into three steps: first the roundwood volumes are converted to tons of dry biomass by multiplying with 0.65 for broadleaf trees and 0.45 for conifers, next converted to tons of carbon (by multiplying with 0.5) and finally converted to CO₂ (by multiplying with 44/12). Combining these three factors gives 1.19 t CO₂/m³ and 0.83 t CO₂/m³. Comparison with Table 22 shows that the Danish calculations use a lower carbon content than default IPCC values for both broadleaves and conifers. This is due to lower conversion factors for dry mass per volume of wood.

Table 22.
Conversion factors

6.1 CO₂ Sequestration in Existing Forests

Two hundred years ago, the forests of Denmark were exploited to such a degree that only about 2-3% of the land was covered by forest [31]. One of the consequences was a serious threat of sand drift. The trend was successfully changed and the forest area has increased until the present 10% forest cover. During the last decade, the stock of existing forests has also been increasing on a per hectare basis. The reasons for this are a distorted age distribution because of wind-throw and a diminished harvest due to current low prices.

The CO₂ uptake by existing forests has not been calculated with a model. It is based on the forest statistics. According to the Forest Act of 1989, a forest census must be produced every 10 years. The latest census [59] of the total standing volume over bark (stem wood) in 2000 showed a much higher CO₂ sequestration than for the former 10-year period. For the period 1980 to 1989 0.916 Mt CO₂ per year was sequestered in Danish forests. According to the new count it is now estimated that the average annual uptake in the period 1990-99 was four times higher, or about 3.9 Mt CO₂/year. This large increase is partly caused by the large areas regenerating from the massive fall of conifers in the storm in 1981. However, the sequestration in forest existing before 1990 is not included in the projections in the present report.

6.2 CO₂ Sequestration in New Forests

Since 1987 it has been a strategy of the Danish Government to double the forested area within the next 80-100 years, that is within about a forest generation. Using the forest model mentioned in the following it was calculated that the permanent storage in mature Danish forest is between 500 and 850 tCO₂/ha [33]. The current prognosis of afforestation is that about 200,000 ha will be afforested within the period. This would result in about 125 million tons CO₂ being stored in the first 125 years or about 1 million tons CO₂/year as an average annual sequestration over the period (see Table 24)

The CO₂ sequestration in new forests has been calculated using a model developed in Denmark [33,35,37]. As opposed to the IPCC guidelines [36], the model calculates the annual changes in the carbon stored over the whole tree generation. It does not only take into account the growth rates of the forests. It also attempts to bring into the calculation the "fate" of the stored carbon, thus recognising the "delay" in the release of carbon stored in (1) commercial wood products: fuel wood, paper and wood products with short and long lifetimes and (2) roots, leaves/needles and branches/stumps. The model uses constant five-year decomposition rates in the calculations. However, in our projections we assume that the carbon stored in the commercial wood products just replace similar wood products on the marked, which are burned after the replacement, thus resulting in no net increase of carbon stored in wood products.

The model consists of an EXCEL file with three parts: The model calculates the carbon stored annually in the 100 year period 1990-2089.

The first input to the main module of the forest model is the annual area afforested according to the Danish Afforestation Plan (see Table 23). The model operates with the two major species used for afforestation, oak (Quercus robur) representing broadleaves and Norway spruce (Picea abies) representing conifers.

Table 23.
Annual area afforested.

The total afforestation area for the period 1990-1999 is based on table 1 in the recent evaluation of the afforestation in the period 1989-1998 [56]. Distribution between broadleaves and conifers are based on the estimate, that 2/3 is broadleaves and 1/3 is conifers [34]. However, based on the new forest census [59] the historic distribution for 1990-1999 has been changed to 48% broadleaves and 52% conifers. Also the total afforested area has been reduced compared to the former projection [58], since it has been recognised that a large part of the afforested area has been planted with Normanns fir. These stands are more representative of short-rotation forestry, as trees are cut about 10 years for Christmas trees and greenery. Furthermore, the land-use change is not permanent, as changes in the market for Christmas trees may force land owners to revert the land use to agriculture after a few years.

The present prognosis for the years 1999-2003 do not satisfy the parliamentary agreement on the aquatic environment (Vandmiljøplan II), that 20000 ha shall be afforested during the period 1998-2003 (6 years). Only about 16000 ha is expected to be afforested. The projection for the areas afforested in the period 2004-2012 is based on information in the report from "Wilhelmudvalget" [38]. After 2012 it is assumed that the rate of afforestation is going to be equal to the level before the parliamentary decision, i.e. in average a total of 2000 hectares [38]. However, this means that we will only reach an afforestation of about 200,000 ha in 2089, e.g. a 50% increase in the forest area. In order to reach the 100% increase of the forest areas additional measures have to be implemented.

The next input to the main module of the forest model is how fast one hectare of new broad-leaved or coniferous forest sequesters CO₂ over its lifetime. This information is calculated in the two other modules "broadleaves" and "conifers". "Broadleaves" represents the broad-leaved forest and contains empirically based yield tables for annual increment (5-year steps), thinning harvests every 10 years, and the final harvest after a rotation time of 140 years (in m³ roundwood). "Conifers" represents the conifers and contains similar yield tables for a rotation time of 70 years. These key values are based on the experience of Danish foresters documented in [39]. The "Broadleaves" module contains yield tables for 4 different site qualities ("boniteter") and "Conifers" includes only for 3 site qualities, since afforestation sites for conifers are assumed to be among the three best site quality classes. So far, the model only uses the values for site quality 2, since this site quality is assumed to be average.

The annual increment and thinning harvests in m³ in "Broadleaves" and "Conifers" are then converted to CO₂ stored in the trees and the products by using the conversion factors in Table 22 and assumptions about the percentage composition of the wood product categories.

Based on these inputs the main module of the forest model separately calculates the CO₂ stored in the forest area planted each year over the next 100 years. Finally, for each of the next 100 years, the respective amounts of CO₂ stored in plantations of different age are added. The final result (without products) for the two tree types is shown in Table 24. In the first commitment period 2008-12 under the Kyoto Protocol the total absorption in new forest is 1416 kt CO₂ or equal to an average annual absorption in these five years of 283.2 kt CO₂. Table 24 also shows that the average annual sequestration until 2090 is about 0.8 Mt CO₂.

Table 24.
CO₂ sequestration in new forest.

6.3  CO₂ Sequestration in forest soils

According to IPCC [36] carbon stock estimates should include the total organic carbon content to a depth of 30 cm in the mineral soils as well as the carbon content of the organic layer accumulated on top of the mineral soil. A recent Danish study quantified the amounts of carbon in well-drained Danish forest soils and found an average of 125 t C/ha in the forest floor and to 1 meter depth for 140 forest sites [61]. For the forest floor and to 30 cm in the mineral soil, the carbon storage was 93 t C/ha.

The development in carbon storage over time since afforestation is currently being studied in detail, but the knowledge of differences in carbon content between agricultural soils and forest soils is still scarce for Danish conditions. However, a current Danish study aims [62] aims at quantifying the carbon pools in former agricultural soils following afforestation with oak and Norway spruce. This study could provide important input to the model calculations of carbon storage due to afforestation activities. There are a few results available for nutrient rich soils as yet, but for the organic layer alone, about 8-10 ton C/ha may be sequestered in Norway spruce stands and about 2 ton C/ha may be sequestered in oak stands after 30 years in the upper 5 centimetre of the soil [60]. There was no evidence of increased carbon content in the mineral soil 30 years after afforestation, but a similar study on nutrient-poor soil showed an increase in the upper 25 cm of the mineral soil of 23 t C/ha over 40 years [34].

However, this CO₂ sequestration in forest soil is not included in the values in Table 24, because it is still not possible to generalize for the whole country. It is assumed that the rather large expansion factor in Table 22 includes some forest soil carbon.

7 Waste

7.1 Solid Waste Disposal on Land

The former Danish Government published the last waste disposal plan "Waste 21: The Government's Waste Management Plan for the period 1998 to 2004", in May 1999 [45]. "Waste 21" puts the future waste disposal on the agenda and the plan set as a goal to stabilise the amount of waste and to improve the quality of waste treatment. This shall be obtained by reducing the influence from environmental pollutants by a higher degree of recycling of the resources in the waste. The plan has the target that 64% of the waste should be recycled in 2004, 24% incinerated and 12% landfilled (see Table 25). However, "Waste 21" does not project the production of waste in the year 2004, but with the optimistic assumption of constant total amounts from 1997, the result is that 1.5 million tonnes will be landfilled in 2004 [42] (see Table 25).

Table 25.
Treatment of solid waste in Denmark 1985-2004.

The amount of solid waste being landfilled in Denmark according to source is shown in Table 27, the information is from the following sources: The first complete estimate of the solid waste was made for the year 1985 by the Danish Municipalities and Counties [40]. In 1993, the new ISAG-data system started to operate in the Ministry of Environment. According to public regulations, waste management facilities have to report the amount of waste received to the Danish Environmental Protection Agency. The data in ISAG includes the amount of waste grouped according to sources, types (like domestic waste, garden waste, industrial waste etc.), and waste management. However, only ISAG data from 1994 to 2000 [41] is used in the calculation, due to the incompleteness of the 1993 data.

From January 1, 1997 the Danish Government introduced a stop for landfilling of combustible waste [45]. Due to lack of incineration capacity part of the combustible waste will be stored temporarily before it is treated. However, it is assumed that no methane is emitted from these interim storages due to the dry conditions prevailing there.

The source of the historical data-point for the amount of waste landfilled in 1970 in Table 27, is Figure 2.16 in [43], which shows that the total amount of waste being landfilled in 1970 was 42% of the 1994 value, increasing linearly in the period 1970-1985 with the same disaggregation on source categories. A linear interpolation is also used in the periods 1985-1994 and 2000-2003 for each source category.

The disaggregation of the total amount of waste in 2004 on source categories were done using the following assumptions [42]: the amount of domestic-, bulky-, garden- and commercial waste in 2004 were assumed to be 50% of the 1997 values, the amount of industrial waste and building & construction waste in 2004 were assumed to be 75% of the 1997 values [42], the amount of sludge waste were assumed to be constant after 1999, and the small amount of ash & slag to disappear after 2004. For the period 2004-2012 the amounts of waste landfilled are kept constant for all source categories.

Since the carbon content in different fractions in the landfilled waste varies, it is necessary to make assumptions about the composition of the waste in the source categories. The assumptions are shown in Table 26 (the sum of all the fractions in each line of the table is one). All these fractions are from reference [40] except for the composition of sludge. The weight of the landfilled sludge in Table 27 includes 71% water [42], so only 29% of the sludge landfilled is in the category "other combustible".

The assumptions of the carbon content in the different fractions are shown at the bottom of Table 26. The carbon content of the fraction "other combustible" varies among the source categories from 20% in domestic waste to 57% in sludge [42]. The resulting CH₄ emission factors are also shown. They are based on the following assumption: 50% of the carbon in the landfill is emitted as a gas containing 45% CH₄, 10% of the CH₄ is oxidised in the topsoil layer [44]. The calorific value used for biogas is therefore 18 MJ/ m³ (45% of the calorific value of CH₄, which is 40 MJ/m³).

Table 26.
Composition of landfilled waste

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To the right in Table 27 the calculated CH₄ emissions from Danish landfilled are shown in the column " Potential emissions". Here the emissions in a given year are calculated, using the IPCC tier 2 method, as a sum of the emissions from the waste landfilled the years before, based on the assumption of a half-life of the carbon of 10 years (e.g. ten years later always half of the carbon is converted to CH₄). Due to this calculation method there is a time-delay between the year with maximum waste landfilled (1985) and the year with the maximum potential CH₄ emissions of 68.8 kt CH₄ (1996).

In order to calculate the "actual emission" of CH₄ from landfills in Table 27, the CH₄ collection by landfill gas plants must be subtracted from then "potential emission". According to Willumsen [44] the first landfill gas plant started operating in the end of 1985. The data from this source were used until the year 1994. In the period from 1994 until 1999 the production increases from 0.333 PJ to 0.58 PJ (10.3 kt CH₄) according to the Danish Energy Agency [28]. It increases to 0.66 in 2004 and thereafter no new plants are included. From 2004 the production decreases slowly due to ageing of the plants. Table 27 shows that due to the decrease in the potential emissions and the increase in the CH₄ collected the actual emissions in 2012 will have decreased to 38.5 kt CH₄ from the 62.4 kt CH₄ in 1990.

Table 27.
Time-series for the amount of landfilled waste and annual CH₄ emissions

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7.2 Wastewater Handling

Since all wastewater in Denmark is treated aerobically, there are no emissions of CH₄ from this source.

8 References

Appendix 1

Table 1.
CO₂ emissions from all sectors in Denmark

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Table 2.
CH₄ emissions from all sectors in Denmark

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Table 3.
N₂O emissions from all sectors in Denmark

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Appendix 2

Table 31:
CO₂ projections 2000-2017 in the IPCC/CRF format

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Table 32:
CH₄ projections 2000-2017 in the IPCC/CRF format

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Table 33:
N₂O projections 2000-2017 in the IPCC/CRF format

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Table 34:
HFCs projections 2000-2017 in the IPCC/CRF format

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Table 35:
PFCs projections 2000-2017 in the IPCC/CRF format

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Table 36:
SF₆ projections 2000-2017 in the IPCC/CRF format

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Table 37:
Total GHGs projections 2000-2017 in the IPCC/CRF format

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