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

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

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