Nielsen, O.-K., Illerup, J.B., Kindbom, K., Saarinen, K., Aasestad, K., Hallsdottir, B., Winther, M., Sjodin, Å., Makela, K. & Mikkola-Pusa, J. 2010: Review, improvement and harmonisation of the Nordic particulate matter air emission inventories. National Environmental Research Institute, Aarhus University. 77 pp. – NERI Technical report No. 809.
This project has conducted a study of the particulate matter (PM) inventories in the Nordic countries. The focus has been on the two major sources road transport and residential combustion.
For road transport both exhaust emissions and non-exhaust emissions such as tyre and brake wear and road abrasion have been included. For residential combustion the work has focussed on wood burning in stoves and small scale boilers, since this is the predominant source of PM emission from the residential sector.
The main goal of this project was to asses the quality and completeness of the PM emission inventories in the Nordic countries. The basis for the evaluation was the countries submissions to the Convention on Long-Range Transboundary Air Pollution (CLRTAP) under the United Nations Economic Commission for Europe (UNECE) in 2007, where the latest reported year was 2005.
The emission inventories for PM in the Nordic countries have somewhat different key sources compared to other parts of Europe; this is caused by different climatic conditions and other structural differences.
An overview of the PM emissions for the Nordic countries are provided in Chapter 2 showing the overall emissions of PM from the Nordic countries distributed on source sectors. A key source analysis is made for the overall Nordic inventory for both PM10 and PM2.5. For both PM10 and PM2.5 residential plants, exhaust emissions from road transport and non-exhaust emissions from road transport are in the top five. The other two categories finishing the top five for PM10 are agriculture and manufacturing industries and construction. For PM2.5 the two other sources included in the top five are manufacturing industries and construction and non-road machinery. Residential plants account for 39 % of the PM10 emission and 50 % of the PM2.5 emission. However, there are considerable differences between the four countries, where PM inventories are available. For example, in Sweden the PM emission from residential plants comprise a very low share of total emissions compared to Denmark, Finland and Norway. Detailed accounts of the key sources for each of the four countries are included in Chapter 2.
The ratio between the reported emissions of PM10 and PM2.5 was calculated for each country. Norway has the largest share of PM2.5 compared to PM10 (88 %), whereas Finland has the lowest (66 %). Denmark and Sweden are right in the middle with 73 and 76 %, respectively.
The completeness of the inventories was assessed with particular emphasis on the categories where emissions were reported by one or more countries, while the other categories reported notation keys. It is found that the PM emission inventories generally are complete and that the sources reported as not estimated only are expected to have minor contributions to the total PM emissions. The completeness of the 2007 submission was compared with the status of completeness in the 2010 submission in Chapter 5. The recalculations for the year 2005 between the 2007 submission and the 2010 submission are also presented and discussed.
The methodologies used by the countries to estimate PM emissions from residential wood combustion and road transport are described for the Nordic countries, and the differences between them are discussed. For road transport different models are used in the Nordic countries. The differences include different classifications of vehicles, different age classes, different driving condition and different driving modes. Due to the different models there are also differences in emission factors. This is described in-depth in Chapter 3.2.
For residential wood combustion the differences concern the emission factors used and also the level of disaggregation in the emission calculations. The emission factors used in Sweden are lower compared to the other three countries. This can probably be attributed to a different sampling method in the measurements upon which the Swedish emission factors are based. The importance of sampling method, operating conditions and other variables is discussed in Chapter 4.
In Chapter 4 the variability of emission factors for residential wood combustion is discussed and it is illustrated that the emission factors can vary by several orders of magnitude. The importance of the sampling method used to perform the measurements is clearly of great significance. It is shown that measurements performed in a dilution tunnel can result in emission factors that are 2.5-10 times higher compared to in-stack measurements in the hot flue gas.
Several studies have also shown great variations in emission factors depending on variables such as wood species, water content of the wood, log size, batch size and the general operating conditions such as the air flow etc. It is also clear that the emissions vary between different types of appliances. Stoves and boilers have different emission characteristics depending on age and whether the boiler is with or without an accumulation tank. Pellet stoves and boilers have very low emission factors compared to traditional stoves and boilers fired with wood logs. The different emission factor studies carried out for pellet stoves and boilers also show very similar low results for PM emissions.
Chapter 5 provides an overview of the current status of PM emission inventories in the Nordic countries. The basis for this is the countries 2010 submission to the UNECE Convention on Long-Range Transboundary Air Pollution. Additionally the recalculations of emission between the 2007 and the 2010 submission are quantified and the improvements in completeness are presented. The recalculations performed between the 2007 and 2010 submissions are minor.
Full report in PDF-format (1,71 MB).
