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No. 219: Projection of SO2, NOx, NMVOC, particulate matter and black carbon emissions - 2015-2030

Nielsen, O.-K., Plejdrup, M., Hjelgaard, K., Nielsen, M., Winter, M., Mikkelsen, M.H., Albrektsen, R., Fauser, P. & Gyldenkærne, S. 2017. Projection of SO2, NOx, NMVOC, particulate matter and black carbon emissions - 2015-2030. Aarhus University, DCE – Danish Centre for Environment and Energy, 145 pp. Scientific Report from DCE – Danish Centre for Environment and Energy No. 219 http://dce2.au.dk/pub/SR219.pdf

Summary

Introduction

This report contains a description of the models and background data used for the emission projection of the pollutants sulphur dioxide (SO2), nitrogen oxides (NOX), non-methane volatile organic compounds (NMVOC), particulate matter with diameter less than 2.5 µm (PM2.5) and black carbon (BC) for Denmark. The emissions are projected to 2030 using basic scenarios which include the estimated effects at implementation on emissions of policies and measures implemented until January 2016 (‘with measures’ projections). Official Danish projections, e.g. the official energy projection from the Danish Energy Agency, are used to provide activity rates in the models for those sectors for which these projections are available. The emission factors refer to international guidelines or are country-specific, referring to Danish legislation, Danish research reports or calculations based on emission data from a considerable number of plants in Denmark. The projection models are based on the same structure and methodology as the Danish emission inventories in order to ensure consistency.

In Europe, regional air pollution is regulated by a number of protocols under the UNECE Convention on Long-Range Transboundary Air Pollution (CLRTAP). The objectives of the Gothenburg Protocol are to control and reduce the emissions of SO2, NOX, NMVOC and NH3. In addition to the UN regulation there is also EU legislation addressing the emissions of air pollution (National Emission Ceiling Directive – NECD).

In 2012 the Gothenburg Protocol was amended to establish emission reduction commitments for 2020 and beyond. Furthermore, reduction commitments for particulate matter (PM2.5) were introduced for the first time. In the amended Gothenburg Protocol, the reduction commitments are given as a percentage reduction compared to the emission level in 2005. The emission ceilings for Denmark in 2010 according to the Gothenburg Protocol are shown in Table S.1 together with the reduction percentages for 2020 recalculated to a “ceiling” value. 

Trend by Pollutant

The historical emissions in the latest historical year, 2014, are shown in Table S.2 together with the projected emissions for 2020, 2025 and 2030. The results of the projection indicate that emissions of SO2, NOx, NMVOC, PM2.5 and BC decrease from the latest historical inventory year (2014) to the projection year 2020. From 2020 to 2030 the projection indicates a further decrease of emissions of the same pollutants, except SO2, which is expected to show a slight increase. 

Nitrogen oxides, NOX

The largest sources are road transport, other mobile sources, and energy industries, accounting for 44 %, 20 % and 15 % of the NOx emission in 2014, respectively.

The NOx emission is expected to decrease 22 % (40 %) from 2014 to 2020 (2030). The decrease is mainly related to road transport and other mobile sources due to the introduction of stricter demands at EU level (new EURO norms).

It is not possible to quantify the effect of the change in NOx tax. In the 2013 projection the possible effect of the increased tax was not estimated and likewise in this projection the effect of the lowering of the tax has not been estimated.

NOx emissions from manure management and agricultural soils will not be part of the reduction commitment for 2030. This is due to the fact that methodologies were only recently included in the EMEP/EEA Guidebook, that the emissions from mineral fertiliser are very high and that this source was not included at the time when the reduction commitments were established.

Sulphur dioxide, SO2

The largest sources of SO2 emissions are manufacturing industries and energy industries both accounting for 24 % of the national SO2 emission in 2014.

The SO2 emission is expected to decrease 12 % (10 %) from 2014 to 2020 (2030). The emissions from other mobile sources and manufacturing industries are expected to show a marked decrease, while emissions from combustion in public power and district heating plants are expected to increase due to increasing fuel consumption in this sector.

Non methane volatile organic compounds, NMVOC

The largest sources of emissions of NMVOC are agriculture followed by industrial processes, residential plants, extraction/storage/refining of oil and gas, and road transport. These sources account for 36 %, 26 %, 10 %, 9 % and 8 %, respectively, of the total NMVOC emission in 2014.

The NMVOC emission is expected to decrease 3 % (6 %) from 2014 to 2020 (2030). The largest decrease is expected for residential plants but pronounced decreases are also expected for road transport and other mobile sources.

NMVOC emissions from manure management and agricultural soils will not be part of the reduction commitment for 2030. This is due to the fact that methodologies were only recently included in the EMEP/EEA Guidebook, that the emissions from mineral fertiliser are very high and that this source was not included at the time when the reduction commitments were established.

Particulate matter with diameter less than 2.5 µm - PM2.5

The single major source of the PM2.5 emission is non-industrial combustion, mainly wood combustion in residential plants, which accounted for 62 % of the national PM2.5 emission in 2014. Other important sources are road transport, other mobile sources and agriculture with 10 %, 9 % and 6 %, respectively.

The PM2.5 emission is expected to decrease by 12 % (30 %) from 2014 to 2020 (2030) mainly due to a decreasing emission from residential plants caused by the introduction of new technologies with lower emissions and other mobile sources.

Black carbon, BC

The single major source of the BC emission is non-industrial combustion, mainly wood combustion in residential plants, which accounted for 43 % of the national BC emission in 2014. Other important sources are transport, other mobile sources and fugitive emissions from fuels with 23 %, 21 % and 11 %, respectively.

The BC emission is expected to decrease by 28 % (46 %) from 2014 to 2020 (2030) mainly due to a decreasing emissions from transport and other mobile sources, due to lower emission limit values for particulate matter.

Trend by sector

Stationary combustion

The trend in emissions from stationary combustion is mainly a result of the trend in the use of different fuels. The consumption of wood in heat and electricity production is expected to increase. Due to higher emission factors, this means that emissions from this sector are expected to show a slight increase. Also, the consumption of coal is projected to be at the same level in 2030 as in 2015. However, the time-series shows a dip around 2020 that can also be seen in the emission trends.

Since the latest official energy projection only covered the years until 2025, the same fuel consumption has been assumed from 2025 to 2030. This means that emissions for the most part are constant in this period. The exception being when there are changes in emission factors, which is the case for residential wood combustion due to the assumption of replacement of older appliances.

The total NOx emission increases from 2015 to 2025 due to increasing wood consumption. The emission factor for wood is larger than for both natural gas and coal, which are the other largest fuel categories. Also, the increasing use of biogas leads to an increase in emissions due to the high emission factors for biogas. NOx emissions from gas turbines used in the offshore sector are projected to increase significantly. From 2015 to 2025 the emission increases by 15 % due to increasing fuel consumption.

The total SO2 emission decreases slightly from 2015 to 2025 due to a decrease in oil consumption. This mainly occurs in the industrial plants, while the emissions from the other sectors remain relatively constant.

From 2015 to 2030 the NMVOC emission is projected to decrease due to a lower emission factor for wood combustion in residential plants. This is due to the replacement of old wood stoves and boilers with new technologies that have considerably lower emissions. The residential sector will account for between 68 % and 81 % of the total NMVOC emission from stationary combustion plants, with the higher share being in the early part of the projection period.

The PM2.5 emission has increased in the historic years due to increasing wood combustion in residential plants. However, from 2015 to 2030 the PM2.5 emission is expected to decrease due to a lower emission factor for wood combustion in residential plants. This is due to the replacement of old wood stoves and boilers with new technologies that have considerably lower emissions. The residential sector will account for between 81 % and 89 % of the total PM2.5 emission from stationary combustion plants in the period 2015-2030 with the share being highest in the beginning of the period.

The BC emission has increased in the historic years due to increasing wood combustion in residential plants. However, from 2015 to 2030 the BC emission is expected to decrease due to a lower emission factor for wood combustion in residential plants. This is due to the replacement of old wood stoves and boilers with new technologies that have considerably lower emissions. The residential sector will account for between 83 % and 87 % of the total BC emission from stationary combustion plants in the period 2015-2030 with the share being highest in the beginning of the period.

Road transport

Total fuel consumption and SO2 emissions for road traffic are kept at a constant level during the 2015-2030 period. Passenger cars have the largest fuel consumption share, followed by heavy duty vehicles, light duty vehicles, buses and two-wheelers in decreasing order. The SO2 emission development relies on the fuel consumption in the forecast period given that road transport fuel has a sulphur content of 10 ppm.

The NMVOC emissions from road transport are expected to decrease by
27 % from 2015 to 2030. The majority of the NMVOC emissions comes from gasoline passenger cars, and for this vehicle category the projected emissions decrease by 28 % from 2015 to 2024, explained by the gradually phasing out of less efficient catalytic converters. From 2024 onwards the emissions increase proportionally with the total mileage for gasoline cars.

In terms of PM2.5 and BC the total emission is expected to decline by 81 % and 94 %, respectively, from 2015 to 2030, in particular due to the introduction of diesel particulate filters (DPF) for Euro 5 cars/vans, and Euro VI trucks/buses. The largest emission source is passenger cars, followed by light duty vehicles, heavy duty vehicles and buses. Emission reductions are generally higher for BC than for PM2.5 due to the very efficient removal of BC by the DPF technology.

The NOX emission for road transport declines by 72 % from 2015 to 2030. For trucks and buses high relative emission declines of 83 % and 86 %, respectively, are expected during the forecast period, due to the fleet turnover towards newer EU emission standards that in practice reduce the emission factors from Euro III onwards. For cars and vans the emission reductions (64 % and 72 %, respectively) are less favourable mainly due to the well-known problems for diesel cars (and vans) to comply with the EU emission legislation standards.

The fact that diesel cars and vans emit more NOx in real driving than during type approval tests, is accounted for in the present forecast based on COPERT IV baseline factors. However, recently published measurements of high NOx emissions from Euro 6 diesel cars foster the need for assessing the emission consequences in two cases where NOx emission factors for the present Euro 6 diesel vehicles are even higher than suggested by COPERT IV.

·       2016 forecast: The present forecast using baseline emission factors from the COPERT IV model.

·       Euro 6 = Euro 5: This scenario describes the situation if no emission factor improvements are gained with the introduction of the Euro 6 emission standard.

·       Euro 6 RDE (Real Driving Emission): In this scenario Euro 6 emission factors are kept at Euro 5 levels until the emission factors are step wise reduced for diesel cars (in 2018/2020) and diesel vans (in 2019/2021) to comply with the RDE emission legislation limits (Euro 6 RDE).

 

In the Euro 6 = Euro 5 scenario the NOx emission increases for diesel cars[diesel vans] become 31 %[36 %] in 2020 and 224 %[256 %] in 2030 compared with the present forecast. In total, the road transport emissions increase by 20 % and 131 %, respectively, in 2020 and 2030. In the Euro 6 RDE model case the calculated NOx emissions for diesel cars[diesel vans] increase by 20 %[31 %] in 2020 and 39 %[45 %] in 2030 compared with the present forecast. In total the road transport emissions increase by 15 % and 23 %, respectively, in 2020 and 2030.

Other mobile sources

Other mobile sources are divided into the sub-sectors: National navigation, fishery, domestic air traffic, railways, working machinery and equipment in the sectors agriculture/forestry, industry, commercial/institutional and residential, and other (military activities and recreational craft).

From 2015-2030, the total fuel consumption decrease by 5 % for other mobile sources. The emissions of SO2 increase by 8 %, due to an increase in fuel consumption for fishery, which uses marine diesel with relatively high sulphur content. For other mobile sources the emissions of NOx, NMVOC, PM2.5 and BC decrease by 55 %, 16 %, 64 % and 79 %, respectively.

The SO2 emissions for other mobile sources are insignificant except for sea-going vessels. However, for navigation, the reduction of the sulphur content in heavy fuel oil used in the Baltic and North Sea SOx emission control areas (SECAs) has had a major emission impact from 2015.

By far the most of the NMVOC emission comes from gasoline gardening machinery in commercial/institutional. The same gasoline equipment types also give considerable contributions for residential. The projected NMVOC emission reductions for commercial/institutional and residential are due to the introduction of the cleaner gasoline stage II and stage V emission technology for some types of equipment. For agriculture/forestry and industry, the gradually stricter emission standards for diesel engines and the decrease in fuel consumption will cause the NMVOC emission to decrease during the forecast period.

For PM2.5, industrial non road machinery is the largest emission source for other mobile sources in the beginning of the forecast period followed by agriculture/forestry, fisheries and navigation. By the end of the forecast period, fisheries and navigation become the largest emission sources. Due to the penetration of cleaner engine technologies, in compliance with future emission standards, the emissions from agriculture/forestry and industry decrease substantially throughout the forecast period.

The PM2.5 emissions from fishing vessels increase proportional with fuel consumption throughout the forecast period, whereas the SECA reduction in the sulphur content for heavy fuel oil has significantly reduced the PM2.5 emissions for navigation in 2015.

Being a sub part of total PM, the decline in BC emissions throughout the forecast period is driven by the general decrease in PM emissions for diesel fuelled agriculture/forestry and industry machinery and the step-wise introduction of Stage V machinery from 2019/2020. In order to meet the Stage V PM emission standards for engines >= 19 kW particulate filters are needed which in addition are very efficient removers of BC.

For agriculture/forestry, industry, navigation, fisheries and railways, substantial NOx emission improvements are expected during the course of the forecast period due to the penetration of cleaner engine technologies, in compliance with future emission standards.

Fugitive emissions from fuels

This sector includes emissions from exploration, extraction, refining, storage, handling, and transport of fuels, the major sources being SO2 and NMVOC from oil and BC emissions from solid fuels.

SO2 mainly stem from refining of oil, and fluctuates annually in the historical years due to unpredictable circumstances at the refineries, e.g. the performance of the sulphur recovery units. The mean of the latest five historical years are applied for all projection years. SO2 from the fugitive sector contribute 7-8 % to the national SO2 emission in the years 2015-2030.

The major NMVOC sources are refinery processes, onshore and offshore activities in oil and gas production, and service stations, refinery processes being by far the major single source in the projection years. Fugitive emissions from refineries are highly unpredictable and only very few measurements are available. As for SO2 the average of the latest five historical years are applied for the projection years to take the annual fluctuations into account. Emissions from onshore and offshore activities and from service stations follow the prognosis for oil- and gas production and gasoline consumption for transport, respectively. NMVOC from the fugitive sector contribute 9 % to the national NMVOC emission in the years 2015-2030 (Table S3).

The major BC source is storage of coal. BC from the fugitive sector contributes 7 % to the national BC emission in 2015, increasing to 13 % in 2030 (Table S4). The increasing share of the national total owe to decreasing emissions from other sectors (mainly transport and small combustion), as BC emissions from coal storage are at the same level for the projection years, variations only depend on the coal consumption in the energy prognosis.

Industrial processes and product use

The projections of emissions from the industrial processes and product use (IPPU) sector are generally based on projection of activity data for the individual source categories and implied emission factors (IEF) for 2014. Activity data can be projected in four ways all of which has been used as described in the following chapters;

·       By extrapolation of representative historical years using the projected production values for glass, steel and cement/construction industries available from the DEA (Danish Energy Agency, 2015).

·       By estimating an expected future activity level and the number of years for the given source category to reach this level.

·       By using an average of representative historical years.

·       By linear regression of a significant trend in the historical data.

 

The increasing trend of the projected SO2 emissions is caused by increasing emission from the production of ceramics (bricks, tiles and expanded clay products), see Table S5. Ceramics are projected using the projected production values from the DEA. Only the very small contribution to SO2 emissions from the use of tobacco has a decreasing trend, the remaining four source categories are estimated as constant in the projection.

Only three small source categories in the IPPU sector lead to NOx emissions and only the smallest of the three (use of tobacco) is expected to decrease, the remaining two source categories are projected as constant.

The predominant source of NMVOC emissions are from diffuse solvent use constituting highly diverse activities and product uses, each comprising a large number of chemicals. Emissions from industrial sectors are typically attributed relatively low emission factors. All projected solvent use categories show a decrease in NMVOC emissions, however, there is stagnation in the latest eight years of the historic emissions; i.e. the four solvent use categories show approximately constant emissions during the period (2007 to 2014).

The most realistic projection from 2015 to 2030 is assumed to represent 25 % of an exponential fit and 75 % of the, approximately constant, historic 2007 - 2014 estimates. However, if the emissions in the coming years continue the constant trend, a possible change in the coming projection will be to assign a higher weight of the constant 2007 to present emissions compared to the exponential fit of historic 1995 – present emissions. This is in agreement with new information and data on production, sale and import/export within and outside the EU supplied by the European Solvents Industry Group (ESIG), which predict a stabilized growth in Europe and probably also in Denmark.

Between 52 % (2015) and 61 % (2030) of the projected PM2.5 emissions from IPPU are projected using the projected production values from the DEA. The largest of these sources, and the primary reason for the increasing trend in PM2.5 emissions, is quarrying and mining of other minerals than coal. Around 25 % of the PM2.5 emissions from IPPU are expected to remain constant, the largest of these is wood processing.

There are seven source categories emitting BC in the IPPU sector, the largest of which is stone wool production, see Table S5. The 33 % increase in BC emissions expected from 2015-2030 is calculated based on the projection values from DEA. An additional four (of the seven) source categories are projected in the same way adding up to around 95 % of the total BC emission from IPPU.

Agriculture

In 2014 agriculture contributed with 36 % of the NMVOC emission, 12 % of the NOx emission and 11 % of the PM2.5 emission.

The total emission of NMVOC is expected to be nearly unaltered from 2014 to 2030. The emission from manure management increases mainly due to increase in emission from swine and dairy cattle. The emission of NMVOC from cultivated crops and field burning of agricultural residue is expected to decrease due to decrease in agricultural area.

The total emission of NOx is expected to decrease with 2 % from 2014 to 2030. The emission from manure management decrease mainly for swine and dairy cattle due to change in housings with slurry which have a lower emission of NOx compared to solid manure. The emission of NOx from inorganic N-fertiliser, sewage sludge and field burning decreases due to decrease in agricultural area. Emission of NOx from manure applied to soil increase due to increase in amount of manure applied.

The total emission of PM2.5 is expected to increase slightly from 2014 to 2030 due to increase in the emission from manure management. The increase in PM2.5 emission from manure management is mainly due to increase in emission from swine. The emission of PM2.5 from field operations and field burning of agricultural residue is expected to decrease due to decrease in agricultural area.

Waste

Since all municipal, industrial and hazardous waste incineration in Denmark occur with energy recovery, emissions from these activities are included in the stationary combustion part of the inventory and projection. The sources reported in the waste sector are human and animal cremations, accidental fires and composting. The pollutants covered by this projection are not applicable to composting, where e.g. NH3 and CH4 emissions are estimated. Therefore, composting is not mentioned further in this report.

During the years 2015-2030, the waste categories are projected to emit 5-6 % of the national SO2 emission. For the remaining pollutants the contribution from the waste sector are all around or under 1 % of the national emission.

The emissions for all pollutants are projected to remain relatively stable during the time-series.