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Cost curve analysis for SO2 and NOx emission control in Finland
Environmental Science & Policy 6 (2003) 329–340
Cost curve analysis for SO2 and NOx emission control in Finland Niko Karvosenoja∗ , Matti Johansson Finnish Environment Institute, P.O. Box 140, FIN-00251 Helsinki, Finland
Abstract The development of air pollution policies requires information on emission control effectiveness, application potential and costs. In this study Finnish cost-effectiveness data were calculated for sulphur and nitrogen oxides emissions in 1990 using technical and cost parameters from national operation experience in power plants and industry. Both derived cost curves depicting abated amount of emissions and related annualised costs were comparable with those in the Europe-wide Regional Air Pollution Information and Simulation (RAINS) model data for Finland using more aggregated input data, part of which were the same for all European countries. The ranking of abatement measures to combat acidifying emissions was explored by combining the controls of both SO2 and NOx based on their acidifying potential. The most cost-efficient controls, related mainly to SO2 , were already in use in 1995. A sensitivity analysis for SO2 indicated that the uncertainty in annual operating hours of combustion plants (±1000 h per annum) has the largest effect on total abatement costs (−7 to −6%), whereas the presumed uncertainties of ±10% in removal efficiencies have the greatest effect of ±11% on total emissions. The national assessment of emission controls was important in describing the country-specific conditions in detail and highlighting the major differences from the RAINS model data and methodology. The results have facilitated the composition of further national reduction measures. © 2003 Elsevier Science Ltd. All rights reserved. Keywords: Air emissions; Cost curve; Reduction costs; Integrated models
1. Introduction The detrimental effects caused by atmospheric pollution have been recognised to be among the major environmental problems in many countries. The long-range transport of pollutants across country borders have made air pollution a truly international problem, which has resulted in intensive and extensive international cooperation in both scientific research and policy-making. The harmful impacts are generally difficult to mitigate with means other than emission controls at source. Successful planning and implementation of concrete policies to reduce air pollution impacts need information on applicable abatement measures. One means to this is to rank emission reduction amounts and related costs of individual control techniques within a country according to their cost-effectiveness. These illustrative cost curves give an overview on possible measures to be taken and their respective costs. They can also be used in mathematical models to find cost-effective solutions to, e.g. minimise ecosystem area at risk for acidification. The development of effects-oriented cost-effective emission reduction strategies in Europe has long been supported by integrated assessment models (Hordijk, 1995). Recent ∗ Corresponding author. Tel.: +358-9-40300371; fax: +358-9-40300390. E-mail address: [email protected] (N. Karvosenoja).
emission reduction agreements have addressed several air pollution problems simultaneously: acidification, eutrophication and ground-level ozone, and the reduction requirements are allotted to the emissions of sulphur and nitrogen oxides, ammonia and volatile organic compounds (VOC) (UNECE, 1999; EC, 2001a). Environmental protection targets are based on long-term ecosystem tolerance against harmful air pollutants, critical loads, or human health indicators, and targets have been set for allowable excess deposition or exposure. Emission reduction requirements are allocated to those countries where emission reductions both have low costs and effectively reduce excess deposition or exposure of sensitive receptors. Calculations are carried out with integrated assessment models, such as the Regional Air Pollution Information and Simulation (RAINS) model of International Institute for Applied Systems Analysis (IIASA) (Schöpp et al., 1999) covering the whole of Europe and with national model systems (e.g. Johansson et al., 2001). Following these guidelines the convention on long-range transboundary air pollution under the auspices of United Nations Economic Commission for Europe (UNECE/CLRTAP) has adopted a new agreement, the protocol to abate acidification, eutrophication and ground-level ozone, in December 1999 (UNECE, 1999), and the work in the European Union has led to the realisation of the national emission ceilings directive (EC, 2001a) and the launching of the clean air for Europe (CAFE)-programme, a thematic strategy of
1462-9011/$ – see front matter © 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S1462-9011(03)00060-1
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technical analysis and policy development in the European Union. 1.1. Finnish integrated assessment modelling In Finland, three integrated model systems have been widely used in assessing acidification and supporting decision-making at national and international levels (Johansson, 1999; Johansson et al., 2000). These were the Finnish integrated acidification model HAKOMA (Johansson et al., 1990), the critical load integrated model (CLIM) system (e.g. Sverdrup et al., 1992) and the dynamic integrated model system (e.g. Forsius et al., 1997) mainly connected with site-specific applications. All model systems are deterministic and mainly process-oriented, which has enabled adequate information detail with appropriate regional applicability (De Vries, 1990), and they partly share common methods, models and input data. The critical load integrated model system includes modules for emissions, deposition and impacts (Johansson, 1999; Johansson et al., 2000). The emission inventories and scenarios were based on national and international official emission inventories and reduction plans. The descriptions of atmospheric dispersion and transport, and the source–receptor transfer coefficients, were derived from detailed atmospheric models on long-range transboundary pollution and national mesoscale dispersion. The modelled deposition levels were used to estimate current and future exceedances of critical loads. The maps of critical loads for lakes and forest soils as environmental protection targets were calculated using best available input data, methods and effects criteria harmonised among European countries (Posch et al., 2001). The current model system is presented in Fig. 1.
1.2. The RAINS model The RAINS model has been developed at IIASA as an integrated tool for the assessment of air pollution control strategies in Europe (e.g. Alcamo et al., 1990; Schöpp et al., 1999; Amann et al., 1999). RAINS includes the country total emissions contributing to acidification, eutrophication and formation of tropospheric ozone. It then calculates the resulting deposition and exposure levels, which are compared with the critical thresholds for ecosystems and human health. The optimisation analysis enables identification of the cost-minimal allocation of emission controls necessary to achieve the target levels. The RAINS model includes data on sulphur dioxide (SO2 ), nitrogen oxides (NOx ), ammonia (NH3 ), volatile organic compounds and the various technical abatement options and related costs. These data are used to generate cost curves for each pollutant, ranking the measures in terms of cost-effectiveness. 1.3. Aims of the study This study assesses the measures to control emissions of sulphur and nitrogen oxides in Finland. The method is based on cost curves, which provide aggregated information on the control potential and related costs of individual control options for selected activity sector and fuel type combinations. First, cost curves based on national studies were calculated separately for SO2 and NOx emission abatement. They were compared with the corresponding curves in the RAINS model for Finland. Second, both acidifying emissions were presented in one cost curve in order to make the emission reduction potentials and relating costs for sulphur and nitrogen commensurate. Here SO2 and NOx emissions were considered as SO2 equivalents on the basis of their respective potential acidifying impact as acid equivalents. The acidifying impact for sulphur is 1 g S = 62.5 meq. and for sulphur dioxide 1 g SO2 = 31.3 meq. For nitrogen, the potential is 1 g N = 71.4 meq. and 1 g NOx = 21.7 meq. Thus, NOx emissions equal to SO2 as 1 g NOx = 0.693 g SO2eq . Third, a sensitivity analysis was carried out for the national SO2 cost curve in order to identify the most important calculation parameters affecting the cost curve.
2. Methodology 2.1. Emissions and control costs in the RAINS model
Fig. 1. Model diagram for the critical load integrated model system (CLIM) in Finland.
The RAINS model calculates emissions in a country emi,j,k,l,m (t) from activity data aj ,k,l (t) (e.g. fuel consumption) and unabated emission factors efi,j,k,l . Several emission control technologies with removal efficiencies ηi,k,l,m can be applied to each economic sector and fuel type combination with defined penetration percentages xi,j,k,l,m (t).
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The emissions are: emi,j,k,l,m (t) = (1 − ηi,k,l,m )xi,j,k,l,m (t) aj,k,l (t) ef i,j,k,l k
l
(1)
m
where t is the time; i the pollutant; j the country; k the fuel type; l the economic sector and m the abatement technology. For each emission control technology, in each sector–fuel combination, the unit cost uci,j,k,l,m (e.g. kg−1 SO2 −1 ) is calculated from technical and cost parameters of control technologies (emission reduction efficiencies, investment costs, operation and maintenance costs), and parameters characterising a typical production plant in the sector (unabated emission factors, boiler sizes, annual operating hours). Investment cost and technical parameters of the emission control technologies are general for the whole Europe, while the parameters defining production plants, as well as the prices of labour, sorbent materials and electricity are country-specific. Total emission control costs ci,j,k,l,m (t) are calculated from reduced emission quantities and unit costs: ci,j,k,l,m (t) = uci,j,k,l,m ηi,k,l,m xi,j,k,l,m (t) aj,k,l (t) ef i,j,k,l k
l
m
(2) The execution of emission reduction options in different countries is ranked based on the cost-effectiveness of individual options in the cost curves. A cost curve illustrates how to achieve a certain emission reduction with least cost using the optimal cost-abatement combination. Technologies are ranked according to their unit costs for removing the last unit of emissions, i.e. the marginal cost. A cost curve is usually compiled starting from a hypothetical “no-control” situation or an actual emission level of a chosen year. The composed curve is piece-wise linear, with individual segments determined by both the costs of applying the various technologies and the reduction potentials of the technologies in various sector–fuel combinations.
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in the national study. The costs given in the national literature (Ministry of the Environment, 1998, 1995) are in Finnish marks (FIM) from the years 1994–1995, and in this study they were converted to euros as 1 = 5.9FIM. Since there were no national cost data available on NOx emissions from the traffic sector, the RAINS traffic cost curves for Finland were used as such. The cost curves based on national experiences were constructed for the 1990 “no-control” situation. 3. Data sources 3.1. Activity data for 1990 The activity data in the RAINS model contain primary energy consumption and production levels of process industry. This study employed the RAINS model version from 1998 (Cofala and Syri, 1998a,b) which includes some national comments on the cost curve review carried out in early 1997. In this study, the activity data for 1990 were re-checked against national statistics (Statistics Finland, 2002). They matched with the statistics and were used in the national cost curve study for the construction of the cost curves. Total primary energy consumption of fuels in Finland was roughly 830PJ in 1990 excluding non-energy use of fuels. Nearly 60% of this was combusted in power plants and industry. The most important fuels for these sectors were hard coal (28% of the fuel use in power plants and industry) and natural gas (26%). Specific features for the Finnish energy production system are the combustion of peat (11%) and biomass (8%), with an extensive use of fluidised bed boilers, and large pulp and paper industry, where considerable amounts of black liquor are combusted in recovery boilers (18%). The most important sectors of process industry, in terms of sulphur and nitrogen emissions, are pulp and paper industry (SO2 and NOx emissions constituting 12 and 2.6%, respectively, of the country total emissions in 1992), metal industry (7.2 and 1.1%) and oil refining (6.0 and 0.7%) (Statistics Finland, 2002). 3.2. Data on production plants
2.2. Cost curves based on Finnish experiences In the national cost curve study, the same methodology as in the RAINS model was used to construct cost curves. The same sector and fuel classification and cost calculation approach were employed. The RAINS model data for Finland on activity levels, emission factors, sets of applicable emission control technologies and technical and cost parameters were reviewed using national data based on national statistics (e.g. Statistics Finland, 2002) and actual operation experiences from Finnish power plants and industry (e.g. Ministry of the Environment, 1998, 1995). The clearly differing parameters were refined for the national calculation. In addition, the restrictions in the maximum applicabilities of the end-of-pipe technologies were re-estimated and used
The parameters characterising industrial and energy production plants in the RAINS model, i.e. emission factors, boiler sizes, annual operating hours and applicability potentials of emission controls, were revised. The unabated emission factors for SO2 were estimated using data on sulphur contents of fuels used in Finland in the 1990s (Acidification Committee, 1998; Statistics Finland, 2002). The emission factors for NOx were reviewed using national estimates (Boström et al., 1992). The average boiler sizes and annual operating hours during 1990s were estimated using data from the Finnish VAHTI register on air pollution permits (Korkia-Aho et al., 1995), which contains information on all point sources exceeding 5 MWth . The calculation values on operating hours and NOx emission factors were refined with
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Table 1 Annual operating hours and NOx emission factors in the national study and in the RAINS model data for Finland for the sectors where the RAINS values were refined with national data National data
RAINS data
Operating hours per annum Industrial peat boilers Heavy fuel oil power plants Industrial heavy fuel oil boilers
5000 500 1000
7500 3000 6000
NOx emission factors (mg MJ−1 ) Coal power plants Wood power plants Industrial wood boilers Black liquor recovery boilers Gas power plants Industrial gas boilers/turbines
335 100 80 50 200 130
290 130 130 130 150 70
national data on some sectors (Table 1). The boiler sizes and emission factors for sulphur in the RAINS model matched with the latest national data and they were applied as such in the national calculations. The potential economically feasible applicabilities of end-of-pipe technologies in various sectors were also estimated using the VAHTI register. Restrictions in applicability play a significant role in sectors with diverse characteristics, e.g. plant sizes or annual operating hours. Specific investment costs (i.e. MWth −1 ) of end-of-pipe equipment, such as flue gas desulphurisation (FGD) or selective NOx reduction techniques, in combustion plants are typically considerably higher for small plants than large ones. In addition, small plants are often used only for peak-load supply with low annual operating hours. This would increase the fraction of the emission reduction costs from the total energy production costs and lead to a more costly use of the plant. In the RAINS model the unit cost of a control option in a sector–fuel combination is calculated for a plant with typical characteristics for this sector. If some of the plants in the sector have considerably different characteristics, the cost estimates would be misrepresented for this part of the sector. For such sectors with diverse characteristics it was assumed in this study that the end-of-pipe technologies can
be utilised only in boilers with thermal capacity higher than 50 MWth . This is also the definition for a large combustion plant in the Large Combustion Plant Directive (EC, 2001b). Most heavy fuel oil boilers in Finland are small in capacity and used for peak-load supply, and the applicability of the end-of-pipe technologies was estimated 10% in power plant sector and 5% in industrial sector. The RAINS model version used in this study estimates full applicability for heavy fuel oil boilers in Finland. 3.3. Data on control options for sulphur emissions The applicable control options for sulphur emissions in Finnish power plants and industry were estimated using national data (Table 2) (Ministry of the Environment, 1998; Acidification Committee, 1998). Specific national features, e.g. combustion of domestic fuels in fluidised bed boilers or combustion of black liquor in pulp and paper industry, were calculated in more detail than in the RAINS model. Measures taken to reduce non-combustion process emissions differ from straightforward end-of-pipe controls. An integrated set of measures in this sector often applies to improve overall process efficiency and reduction of waste material and emissions to air and water. National experiences of air pollution prevention expenditure available from a limited number of sectors were used to allocate costs directly related to air emission reductions from these measures. The cost efficiencies were highly variable (Table 3) (Acidification Committee, 1998; Sulphur Committee II, 1993). However, the national experiences were mainly reasonably consistent with the RAINS values, which are aggregated to three different efficiency and unit cost levels equal to all process industry sectors, and the RAINS estimates were also used in the national study. The use of low sulphur coal was not included in the national study as an abatement option, contrary to the RAINS model data for Finland. Coals used in Finnish boilers have a relatively low sulphur content, mainly below 0.8%, and currently almost all coal boilers are equipped with flue gas desulphurisation (Ministry of the Environment, 1998).
Table 2 SO2 control options applicable in the national study and in the RAINS model data for Finland SO2 control options in the national study
SO2 control options in RAINS
Emissions control in process industry
Emissions control in process industry
Low sulphur fuels • Heavy fuel oil • Medium distillates
Low sulphur fuels • Hard coal • Heavy fuel oil • Medium distillates
Flue gas desulphurisation (FGD) • Limestone injection in fluidised bed boilers • Wet FGD in boilers over 400 MWth • Spray dry scrubbers in boilers over 50 MWth • NaOH-based scrubbers in black liquor recovery boilers
Flue gas desulphurisation (FGD) • Limestone injection in all the boilers • Wet FGD in all the boilers
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Table 3 Removal efficiency levels and unit costs of SO2 process emission control based on national experiences (Acidification Committee, 1998; Sulphur Committee II, 1993) and in the RAINS model data general for all European countries National parameters
RAINS parameters
Industrial sector
Removal efficiency level (%)
Unit cost ( t(SO2 )−1 )
Industrial sector
Removal efficiency level (%)
Unit cost ( t(SO2 )−1 )
Cu and Ni production Oil refining TiO2 production Paper pulp production Coke production
50 70 80 80 80
3500 100 600 950 510
All industrial sectors All industrial sectors All industrial sectors
50 70 80
350 407 513
The Finnish Acidification Committee (1998) has estimated the unit cost of low sulphur heavy fuel oil (1.0%S) to be 508 t(SO2 )−1 based on the costs of changes needed in the oil refining processes. This value was used in the national study. The RAINS estimate for the unit cost for 0.6% S heavy fuel oil is 425 t(SO2 )−1 . For low sulphur medium distillates the same unit cost for abatement as in the RAINS model was employed. The RAINS model calculates unit costs for FGD technologies from a set of parameters characterising control technologies and production plants. The control technology
parameters were refined with national data based on actual operation experiences of control technologies used in the 1990s in Finnish power plants and industry (Ministry of the Environment, 1998) (Table 4). The national operation experiences for sulphur reductions were comprehensive with national cost and technical data available from all relevant sector-control technology combinations, since much of the sulphur emissions were abated during the 1990s. For example, sulphur removal by FGD technologies in Finland in 1995 was roughly 70 kt SO2 and total emissions then were 96 kt SO2 (Karvosenoja et al., 2001). Fig. 2 shows an
Table 4 Cost parameters of flue gas desulphurisation (FGD) according to national (Ministry of the Environment, 1998) and the RAINS model data for Finland National parameters
RAINS parameters
Investment ( kW−1 )
43–58: WFGD 1.7–3.4: LI 29–39: SD, Na
69–108: WFGD 30–46: LI
Fixed operation and maintenance (% from total investment per annum)
2.5
4
Removal efficiency (%)
85: WFGD, Na 30–65: LI 65–80: SD
85–95: WFGD 50 LI
Labour price ( man-year−1 ) Electricity price ( MWh−1 )
29050a 34
29050 40
Sorbent material price ( t−1 )
42: WFGD, LI (CaCO3 ) 85: SD (CaO) 220: Na
18
By-product disposal cost ( t−1 )
8.5
0: WFGD 35: LI
Labour demand (man-years GW−1 )
10.8a
10.8
Electricity demand (GWh PJ−1 )
1.5: WFGD 0.5: LI 0.75: SD, Na
1.0: WFGD 0.5: LI
Sorbent material demand (t t(SO2 )−1 )
1.56: 4.68: 1.05: 0.63:
1.56: WFGD 4.68: LI
By-product production (t t(SO2 )−1 )
2.6: 7.8: 2.1: 1.3:
WFGD: wet FGD; SD: spray dry FGD; LI: limestone injection; Na: NaOH-scrubber. a RAINS estimates used in the national study.
WFGD (molar ratio 1) LI (molar ratio 3) SD (molar ratio 1.2) Na (molar ratio 1)
WFGD LI SD Na
2.6: WFGD 7.8: LI
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Fig. 2. Comparison between the RAINS model data for Finland and national study of (a) total annual costs and (b) unit costs of flue gas desulphurisation in Finnish coal power plants. WFGD: wet flue gas desulphurisation.
example of comparisons between the RAINS model and the national study on total annual costs and unit costs of FGD in coal power plants, which constitute the most important sector contributing to sulphur emissions. 3.4. Data on control options for nitrogen emissions The options for nitrogen emission control in the RAINS model and in the national study are presented in Table 5. No national cost data were available for the NOx control technologies of mobile sources or the process industry. Therefore, the same reduction potentials and costs as in the RAINS model were used in the national study. The data available
on national operation experiences from power plants and industry were not as comprehensive as for sulphur controls, because only a small part of the total NOx emissions from stationary sources are abated to date. The nitrogen reduction in power plants and industry in 1995 was only about 20 kt NOx , while the total emission after abatement was 86 kt NOx (Karvosenoja et al., 2001). Combustion modification (CM) techniques or primary measures in stationary sources relate to modifications in the boiler design. The objective is to reach combustion conditions where the formation of NO from the nitrogen contained in combustion air (thermal NOx ) is decreased, or where the already formed NO can be reduced back to
Table 5 NOx control options applicable in the national study and in the RAINS model data for Finland NOx control options in the national study
NOx control options in RAINS
Technologies for mobile sources • Combustion modifications • Catalytic converters
Technologies for mobile sources • Combustion modifications • Catalytic converters
Emissions control in process industry
Emissions control in process industry
Technologies for stationary sources • Combustion modifications in all the boilers • SCR in coal power plants • SNCR in boilers over 50 MWth
Technologies for stationary sources • Combustion modifications in all the boilers • SCR in all the boilers • SNCR in industrial boilers
SCR: selective catalytic reduction; SNCR: selective non-catalytic reduction.
N. Karvosenoja, M. Johansson / Environmental Science & Policy 6 (2003) 329–340 Table 6 Cost parameters of NOx control options in stationary sources according to national (Ministry of the Environment, 1995) and in the RAINS model data for Finland National parameters
RAINS parameters
Investment ( kW−1 )
30: SCR 15–23: SNCR 0.90–9.9: CM
22: SCR 10–11: SNCR 3.2–8.5: CM
Total operation and maintenance ( MWh−1 )
0.49: SCR 0.15–0.58: SNCR 0–0.059: CM
0.58: SCR 0.08–0.20: SNCR (–): CM
Removal efficiency (%)
80: SCR 50–70: SNCR 20–50: CM
80: SCR 70: SNCR 50–65: CM
SCR: selective catalytic reduction; SNCR: selective non-catalytic reduction; CM: combustion modifications.
molecular nitrogen. Commonly used primary measures in pulverised combustion coal boilers are low-NOx burners, staging of combustion air, staging of fuel injection and flue gas recirculation. NOx reduction efficiencies of these measures vary from 10 to 70%, depending on fuel type, combustion technique, boiler type and boiler size. Furthermore, several of these measures can be simultaneously applied in one single boiler (Kilpinen, 1995). The reduction efficiencies and related costs of control technologies used in the national study are based on actual operation experiences in Finnish power plants (Ministry of the Environment, 1995). In the RAINS model, combustion modifications relate
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to the use of an “efficient” set of these techniques with reduction efficiencies from 50 to 65% (Table 6). Therefore, the CM techniques in the national study and in the RAINS model are not identical for most sectors, thus the costs or reduction efficiencies are not fully comparable. In those sectors where the national data were comparable to the RAINS model estimates for Finland, e.g. in coal power plants, RAINS tended to underestimate the reduction costs (Fig. 3a). Selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) technologies are not widely used in Finland. Currently there is only one SCR equipment in use in one Finnish coal power plant. The costs of SCR used in the national study were based on calculations with catalyst dimensioning application by Ekono Energy Ltd. (Ministry of the Environment, 1995), and they were comparable with the RAINS model estimates for Finland (Fig. 3b). SCR technologies were estimated to be applicable only in the coal power plants sector, since other sectors consist of boilers too small and emission factors too low for the cost-effective use of SCR (Ministry of the Environment, 1995). The costs of SNCR technologies in the national study were based on Swedish experiences (Ministry of the Environment, 1995). 3.5. Value ranges for calculation parameters In the sensitivity analysis, the SO2 cost curve based on the national data was calculated with minimum, maximum and the best estimate values of each parameter. The range of
Fig. 3. Comparison between the RAINS model data for Finland and national study of annual costs of (a) combustion modifications (CM) and (b) combined combustion modifications and selective catalytic reduction (CM + SCR) of NOx emissions in Finnish coal power plants.
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Fig. 4. Comparison of national and RAINS cost curves for SO2 in 1990 starting from the “no-control” situation. The segments and related texts illustrate the rough sequence of the most important emission abatement options. The text on the right relates to the national curve and on the left to the RAINS model curve. The first segment of both curves is explained on the right hand side. FGD: flue gas desulphurisation.
the values was estimated using values from national literature (Ministry of the Environment, 1998, 1995; Acidification Committee, 1998; Sulphur Committee II, 1993), the Finnish VAHTI register on air pollution permits (Korkia-Aho et al., 1995) and expert estimates.
4. Results 4.1. RAINS and national cost curves for SO2 Fig. 4 presents the comparison of SO2 cost curves based on our detailed national study and RAINS model data for Finland in 1990 starting from the “no-control” situation. The national estimates on both reduction potentials and costs are convergent with the estimates of the RAINS model for Finland. RAINS estimates the maximum technically feasible emission reduction potential to be 38 kt SO2 per annum higher than the national study suggests. This is mainly due to the RAINS model assumption on the full applicability of the end-of-pipe technologies for small peak-load heavy fuel oil boilers. If the full applicability of flue gas desulphurisation were assumed also in the national study, the national estimate for the maximum feasible emission reduction potential would be 16 kt SO2 per annum lower than the RAINS estimate.
On the one hand, the RAINS model slightly underestimates the costs of low sulphur heavy fuel oil for specific measures. On the other hand, RAINS tends to overestimate the costs of flue gas desulphurisation technologies because of the investment cost overestimation in most of the sectors. In the RAINS model, the removal efficiencies of FGD technologies are fixed and independent of the sulphur contents of fuels, which is not the case in reality. Therefore it overestimates the removal efficiencies and consequently the reduction potentials for those FGD technologies applied on low sulphur content fuels, such as peat. 4.2. RAINS and national cost curves for NOx Fig. 5 presents the comparison of NOx cost curves based on the national study and the RAINS model for Finland in 1990 starting from the “no-control” situation. The cost curves are convergent as was the case for SO2 . However, there were no national cost data available on NOx emission control for many sectors. For the traffic sector, where the greatest emission reduction potential resides, the same reduction potentials and costs as in the RAINS model were used in the national cost curve. Therefore, the parts of the national NOx cost curve which refer to emission reductions from traffic do not represent national experiences. For the control technologies of stationary sources, where there were national experiences available, the RAINS model
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Fig. 5. Comparison of national and RAINS cost curves for NOx in 1990 starting from the “no-control” situation. The segments and related texts illustrate the rough sequence of the most important emission abatement options. The text on the right relates to the national curve and on the left to the RAINS model curve. The first segment of both curves is explained on the right hand side. SCR: selective catalytic reduction; SNCR: selective non-catalytic reduction.
Fig. 6. The combined SO2 and NOx cost curve in 1990 starting from the “no-control” situation calculated with national data. FGD: flue gas desulphurisation; SCR: selective catalytic reduction; SNCR: selective non-catalytic reduction.
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tends to underestimate the costs of both combustion modifications and selective non-catalytic reduction. Removal efficiencies of CM are mainly higher in RAINS than according to the nationally prevailing set of techniques implemented in the Finnish plants. They do not, in many cases, represent the maximum technically feasible reduction potentials as described in RAINS (see Section 3.4). Therefore, the costs or reduction potentials are not fully comparable. 4.3. Combined SO2 and NOx cost curve In Fig. 6 emissions and reduction measures for both SO2 and NOx are presented in the same combined cost curve. The emissions are considered as SO2 equivalents on the basis of their acidifying impact. This simplified approach comparing the overall acidifying potential of different emission substances, used, e.g. in life cycle impact analyses, does not take into account the location and height of the emissions contributing to ecosystem-specific acidifying loading. When starting from the “no-control” situation, the most cost-efficient methods are mainly for sulphur emission reduction. Only combustion modifications in boilers of the NOx control technologies are in the same cost range as most of the SO2 reduction methods. SCR and SNCR technologies are considerably less cost-efficient, and low sulphur medium distillates and spray dry technique in peat and heavy fuel oil boilers are in the same cost range. Since the reductions of NOx can have side benefits also on the diminishing amounts of VOC and CO emissions and their effects, which are difficult to quantitatively compare with the acidifying potential, the advantages for NOx are an underestimate in this comparison. 4.4. Sensitivity analysis for the national SO2 cost curve Table 7 presents the summary of the effects of parameter uncertainties on total costs and emissions in the SO2 cost curve of the national study with maximum technically feasible reduction scenario (MFR). The interest rate and the payback time for annualising of investment costs have a significant impact on the total annual abatement cost. However, international assessment aiming at good comparability
usually assumes same lifetime and discount rates for all countries under study. This is a reasonable assumption also in view of the free market situation for Europe. Investment cost and annual operating hours have the second greatest effect on total costs. The variation of annual operating hours in heavy fuel oil boilers used for peak-load supply have a particularly strong effect on costs. The range of ±10% removal efficiencies of FGD technologies greatly affect total emissions. The sequence of abatement options in the cost curve did not change significantly in any of the uncertainty calculations.
5. Discussion and conclusions The cost curve approach is a useful method to illustrate emission reduction potentials and related costs in an aggregated and comprehensible manner. The number of activity sectors and fuels assessed in the national study was chosen to be the same as in the RAINS model. For some sector–fuel combination parameters, more detailed national data was available and the results were then aggregated to the RAINS classification. The RAINS model data on cost curves has been assessed by European countries through a general review process in 1997, planned again for 2003. National detailed studies on these data have been carried out in, e.g. United Kingdom, Finland, Germany and Norway, but the results in general have not been published in scientific fora. The RAINS model has also been compared with other emission calculation and integrated assessment models, and some of its versions have been partly adapted to national purposes, e.g. in Finland and in Poland. The most cost-efficient sulphur emission reductions in Finland can be achieved mainly in power plants and industry according to the cost curve constructed for the 1990 “no-control” situation. The comparison of specific technologies for sulphur emission abatement illustrates the need for careful interpretation and explanation of individual segments in the cost curves. The two curves derived from the national data and in the RAINS model may have same measures in different segments due to different data and parameter
Table 7 Effect of variation of cost parameters on total costs and emissions with maximum technically feasible reductions (MFR) Total cost with MFR (%) Interest rate and pay-back time (from 4%, 20 years to 8%, 15 years)
+17 Maximum
Investment ± 20% Other fixed costs ± 20% Variable costs ± 20% Annual operating hours ± 1000 h per annum Removal efficiencies of FGD (%) ± 10 Unabated emission factor of coal ± 20% Lower limit of applicability of FGDs 100/30 MWth
+7.6 +2.8 +2.5 −6.9 +0.6 +0.6 −3.1
Total emission with MFR (%) –
Minimum
Maximum
Minimum
−7.6 −2.7 −2.9 +16 −0.5 −0.5 +3.8
– – – – −11 +2.3 +5.2
– – – – +11 −2.7 −2.7
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values and aggregation, although the overall shape and location are almost the same. According to the combined SO2 and NOx cost curve the most cost-efficient methods to reduce acidifying emissions are mainly for sulphur emission reductions. However, most of the cost-efficient reduction methods of sulphur emissions are already in use in Finland. The sensitivity analysis for the SO2 cost curve indicated that variations in annual operating hours of the combustion plants have the greatest effect on abatement costs. Both the interest rate and the payback time may have a significant effect on total annual abatement cost. However, using same values of interest rate and payback time for all the countries is desirable to further ensure comparability in international assessment. The approach used in the RAINS model aims to compile and use data relevant to emission controls and costs in a consistent way for all European countries. Therefore, compromises are unavoidable on the level of details, e.g. the removal efficiencies. The more detailed national results on reduction potentials and costs were coherent with the estimates of the RAINS model for Finland as a whole. However, some measures lay in different positions in the cost curve, which is of importance in the planning of national implementation. This study was carried out for the year 1990, which also was the base year for international emission reduction negotiations (UNECE, 1999; EC, 2001a). The implementation of emission control technologies, especially FGD retrofitting to large energy and industrial plants, has been intensive during the early 1990s in Finland. In 1995 most of the cost-efficient sulphur control potential by technical measures were already utilised (Karvosenoja et al., 2001). Furthermore, a switch from the use of coal to sulphur-free natural gas has taken place, driven mainly by the aspiration to decrease carbon dioxide emissions. The total SO2 emissions have decreased from 260 to 86 kt SO2 per annum, or 67%, in 1990–2001 (Statistics Finland, 2002). The decrease has not been as intensive for NOx . Combustion modification retrofitting has taken place to some extent in stationary combustion, but plenty of cost-efficient control potential was still left in 1995 (Karvosenoja et al., 2001). The decrease of traffic NOx emissions follows the renewal of the vehicle fleet and the possibilities to accelerate this development at national level are limited. The NOx emissions have decreased from 290 to 211 kt NOx per annum, or 27%, in 1990–2001 (Statistics Finland, 2002). The national calculation system can also be used to assess future reduction potential for given energy and activity scenarios. The cost curves are constructed separately for each target year. They can be split in two parts; the first shows the measures in use by the time point and the second the remaining reduction potential. The second part can be used in ranking further cost-effective measures either nationally or between different countries. The latter approach has been used in the RAINS model in finding optimal solution alternatives to European emission reduction strategies in the preparation of international protocols (UNECE, 1999; EC,
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2001a). In these emission ceiling negotiations such national cost curves, starting at expected fulfilment of legislation and committed reduction plans, were calculated for each country to form the basic reference scenario (REF) for 2010 (Amann et al., 1999). The final emission ceilings for Finland, 110 kt SO2 per annum and 170 kt NOx per annum, were close to the REF scenario values. It was estimated in another scenario study that these goals can be achieved without measures additional to adopted legislation (Syri et al., 2002). The remaining reduction potentials above the agreed emission ceiling levels are relatively expensive (Cofala and Syri, 1998a,b). This study suggested that the aggregation level of cost and emission estimates in international integrated modelling is practical. In the cost curves of the national study the country-specific conditions were considered better than in the RAINS model and the major differences were explained. The national study helped to assure that international estimates on the emission reduction potential and costs correspond to national conditions as closely as possible. Thus the results of this study increase the credibility of policy-supporting modelling tools in international negotiations for emissions reductions.
Acknowledgements The authors wish to acknowledge the whole Transboundary Air Pollution (TAP) Project team at IIASA, especially J. Cofala for helpful discussions and supplementary data. We thank S. Syri at the Technical Research Centre of Finland and A. Heikkinen at Fortum Power and Heat Ltd. for their comments during the study. We thank also K. Grönfors, L. Timonen, K. Hietikko and K. Aalto at the Statistics Finland for information about national emissions and air pollution prevention expenditures. This study was funded by the LIFE financing instrument of the Directorate General—Environment of the European Union through project LIFE97/ENV/FIN/336.
References Acidification Committee, 1998. Happamoitumistoimikunnan mietintö (Report of the Acidification Committee). The Finnish Environment 219. Ministry of the Environment, Helsinki, Finland. (In Finnish with English summary.) Alcamo, J., Shaw, R., Hordijk, L. (Eds.), 1990. The RAINS Model of Acidification. Science and Strategies in Europe. Kluwer Academic Publishers, Dordrecht, The Netherlands. Amann, M., Bertok, I., Cofala, J., Gyarfas, F., Heyes, C., Klimont, Z., Makowski, M., Schöpp, W., Syri, S., 1999. Cost-Effective Control of Acidification and Ground-Level Ozone. Seventh Interim Report to the European Commission, DG-XI. International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria. Boström, S., Backman, R., Hupa, M., 1992. Greenhouse Gas Emissions in Finland 1988 and 1990 Energy, Industrial and Transport Activities. Insinööritoimisto Prosessikemia Ky, Turku, Finland.
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Cofala, J., Syri, S., 1998a. Sulfur Emissions, Abatement Technologies and Related Costs for Europe in the RAINS Model Database. IIASA Interim Report IR-98-035. International Institute for Applied Systems Analysis, Laxenburg, Austria. Cofala, J., Syri, S., 1998b. Nitrogen Oxides Emissions, Abatement Technologies and Related Costs for Europe in the RAINS Model Database. IIASA Interim Report IR-98-88. International Institute for Applied Systems Analysis, Laxenburg, Austria. De Vries, W., 1990. Philosophy, structure, and application methodology of a soil acidification model for The Netherlands. In: Kämäri, J. (Ed.), Impact Models to Assess Regional Acidification. International Institute for Applied Systems Analysis. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 3–21. EC (European Commission), 2001a. Directive 2001/81/EC of the European Parliament and of the Council of 23 October 2001 on National Emission Ceilings for Certain Atmospheric Pollutants. Official Journal of the European Communities L 309 EN, Brussels, Belgium, 27 November 2001, pp. 22–30. EC (European Commission), 2001b. Directive 2001/80/EC of the European Parliament and of the Council on the Limitation of Emissions of Certain Pollutants into the Air from Large Combustion Plants. Official Journal of the European Communities L 309/1, Brussels, 27 November 2001, Belgium. Forsius, M., Johansson, M., Posch, M., Holmberg, M., Kämäri, J., Lepistö, A., Roos, J., Syri, S., Starr, M., 1997. Modelling the effects of climate change, acidic deposition and forest harvesting on the biogeochemistry of a boreal forested catchment in Finland. Boreal Environ. Res. 2, 129–143. Hordijk, L., 1995. Integrated assessment models as a basis for air pollution negotiations. Water, Air, Soil Pollut. 85, 249–260. Johansson, M., 1999. Integrated models for the assessment of air pollution control requirements. Doctoral dissertation. Monographs Boreal Environ. Res. 13, 73. Johansson, M., Kämäri, J., Pipatti, R., Savolainen, I., Tuovinen, J.-P., Tähtinen, M., 1990. Development of an integrated model for the assessment of acidification in Finland. In: Kauppi, P., Anttila, P., Kenttämies, K. (Eds.), Acidification in Finland. Springer, Berlin, pp. 1171–1193. Johansson, M., Ahonen, J., Amann, M., Bartnicki, J., Ekqvist, M., Forsius, M., Karvosenoja, N., Lindström, M., Posch, P., Suutari, R., Syri, S., 2000. Integrated Environmental Assessment Modelling. Final Report of the Finnish Subproject, EU/LIFE Project. The Finnish Environment 387. Finnish Environment Institute, Helsinki, Finland. Johansson, M., Alveteg, M., Amann, M., Bak, J., Bartnicki, J., Ekqvist, M., Forsius, M., Frohn, L., Geernaert, G., Gimeno, B., Guardans, R., Karvosenoja, N., Mart´ın, F., Posch, M., Suutari, R., Syri, S., 2001. Inte-
grated assessment modeling of air pollution in four European countries. Water, Air, Soil Pollut. 130 (1–4), 175–186. Karvosenoja, N., Hillukkala, P., Johansson, M., Syri, S., 2001. Cost-effective abatement of acidifying emissions with flue gas cleaning vs. fuel switching in Finland. Water, Air, Soil Pollut. 130, 1619–1624. Kilpinen, P., 1995. Typen oksidien muodostuminen ja hajoaminen (formation and decomposition of nitrogen oxides). In: Raiko, R., KurkiSuonio, I., Saastamoinen, J., Hupa, M. (Eds.), Poltto ja palaminen (Burning and Combustion). International Flame Research Foundation (IFRF). Finnish National Department, Jyväskylä, Finland, pp. 239–276. Korkia-Aho, S., Koski, O., Meriläinen, T., Nurmio, M., 1995. VAHTIkäsiteanalyysi (VAHTI description). Memorandum, West Finland Regional Environmental Centre. (In Finnish.) Ministry of the Environment 1995. Energiantuotannon typenoksidipäästöjen vähentäminen (Reduction of nitrogen oxide emissions in energy production). Report 1/1995. Ministry of the Environment, Helsinki, Finland. (In Finnish with English summary.) Ministry of the Environment, 1998. Rikkidioksidi-ja typenoksidipäästöjen vähentämismahdollisuudet (Possibilities to reduce sulphur and nitrogen oxide emissions). The Finnish Environment 251. Ministry of the Environment, Helsinki, Finland. (In Finnish with English summary.) Posch, M., Smet, P.A.M., Hettelingh, J.-P., Downing, R.J. (Eds.), 2001. Modelling and mapping of critical thresholds in Europe: Status report 2001. RIVM Report No. 259101010, Coordination Center for Effects. National Institute for Public Health and the Environment, Bilthoven, The Netherlands. Schöpp, W., Amann, M., Cofala, J., Heyes, C., Klimont, Z., 1999. Integrated assessment of European air pollution emission control strategies. Environ. Modell. Software 14 (1), 1–9. Statistics Finland 2002. Energy Statistics 2001. Energy 2002:2, Statistics Finland, Helsinki, Finland. Sulphur Committee II, 1993. Rikkitoimikunta II:n mietintö (Report of the Sulphur committee II). Committee Report 1993:6, Ministry of the Environment, Helsinki, Finland. (In Finnish with English summary.) Sverdrup, H., Warfvinge, P., Frogner, T., Håøya, A.O., Johansson, M., Andersen, B., 1992. Critical loads for forest soils in the Nordic countries. Ambio 21 (5), 348–355. Syri, S., Karvosenoja, N., Lehtilä, A., Laurila, T., Lindfors, V., Tuovinen, J.-P., 2002. Modeling the impacts of the Finnish climate strategy on air pollution. Atmos. Environ. 36, 3059–3069. UNECE, 1999. Protocol to the Convention on Long-range Transboundary Air Pollution to Abate Acidification, Eutrophication and Ground-Level Ozone. EB.AIR/1999/1, United Nations, Economic Commission for Europe, Geneva, Switzerland.
Cost curve analysis for SO2 and NOx emission control in Finland Niko Karvosenoja∗ , Matti Johansson Finnish Environment Institute, P.O. Box 140, FIN-00251 Helsinki, Finland
Abstract The development of air pollution policies requires information on emission control effectiveness, application potential and costs. In this study Finnish cost-effectiveness data were calculated for sulphur and nitrogen oxides emissions in 1990 using technical and cost parameters from national operation experience in power plants and industry. Both derived cost curves depicting abated amount of emissions and related annualised costs were comparable with those in the Europe-wide Regional Air Pollution Information and Simulation (RAINS) model data for Finland using more aggregated input data, part of which were the same for all European countries. The ranking of abatement measures to combat acidifying emissions was explored by combining the controls of both SO2 and NOx based on their acidifying potential. The most cost-efficient controls, related mainly to SO2 , were already in use in 1995. A sensitivity analysis for SO2 indicated that the uncertainty in annual operating hours of combustion plants (±1000 h per annum) has the largest effect on total abatement costs (−7 to −6%), whereas the presumed uncertainties of ±10% in removal efficiencies have the greatest effect of ±11% on total emissions. The national assessment of emission controls was important in describing the country-specific conditions in detail and highlighting the major differences from the RAINS model data and methodology. The results have facilitated the composition of further national reduction measures. © 2003 Elsevier Science Ltd. All rights reserved. Keywords: Air emissions; Cost curve; Reduction costs; Integrated models
1. Introduction The detrimental effects caused by atmospheric pollution have been recognised to be among the major environmental problems in many countries. The long-range transport of pollutants across country borders have made air pollution a truly international problem, which has resulted in intensive and extensive international cooperation in both scientific research and policy-making. The harmful impacts are generally difficult to mitigate with means other than emission controls at source. Successful planning and implementation of concrete policies to reduce air pollution impacts need information on applicable abatement measures. One means to this is to rank emission reduction amounts and related costs of individual control techniques within a country according to their cost-effectiveness. These illustrative cost curves give an overview on possible measures to be taken and their respective costs. They can also be used in mathematical models to find cost-effective solutions to, e.g. minimise ecosystem area at risk for acidification. The development of effects-oriented cost-effective emission reduction strategies in Europe has long been supported by integrated assessment models (Hordijk, 1995). Recent ∗ Corresponding author. Tel.: +358-9-40300371; fax: +358-9-40300390. E-mail address: [email protected] (N. Karvosenoja).
emission reduction agreements have addressed several air pollution problems simultaneously: acidification, eutrophication and ground-level ozone, and the reduction requirements are allotted to the emissions of sulphur and nitrogen oxides, ammonia and volatile organic compounds (VOC) (UNECE, 1999; EC, 2001a). Environmental protection targets are based on long-term ecosystem tolerance against harmful air pollutants, critical loads, or human health indicators, and targets have been set for allowable excess deposition or exposure. Emission reduction requirements are allocated to those countries where emission reductions both have low costs and effectively reduce excess deposition or exposure of sensitive receptors. Calculations are carried out with integrated assessment models, such as the Regional Air Pollution Information and Simulation (RAINS) model of International Institute for Applied Systems Analysis (IIASA) (Schöpp et al., 1999) covering the whole of Europe and with national model systems (e.g. Johansson et al., 2001). Following these guidelines the convention on long-range transboundary air pollution under the auspices of United Nations Economic Commission for Europe (UNECE/CLRTAP) has adopted a new agreement, the protocol to abate acidification, eutrophication and ground-level ozone, in December 1999 (UNECE, 1999), and the work in the European Union has led to the realisation of the national emission ceilings directive (EC, 2001a) and the launching of the clean air for Europe (CAFE)-programme, a thematic strategy of
1462-9011/$ – see front matter © 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S1462-9011(03)00060-1
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technical analysis and policy development in the European Union. 1.1. Finnish integrated assessment modelling In Finland, three integrated model systems have been widely used in assessing acidification and supporting decision-making at national and international levels (Johansson, 1999; Johansson et al., 2000). These were the Finnish integrated acidification model HAKOMA (Johansson et al., 1990), the critical load integrated model (CLIM) system (e.g. Sverdrup et al., 1992) and the dynamic integrated model system (e.g. Forsius et al., 1997) mainly connected with site-specific applications. All model systems are deterministic and mainly process-oriented, which has enabled adequate information detail with appropriate regional applicability (De Vries, 1990), and they partly share common methods, models and input data. The critical load integrated model system includes modules for emissions, deposition and impacts (Johansson, 1999; Johansson et al., 2000). The emission inventories and scenarios were based on national and international official emission inventories and reduction plans. The descriptions of atmospheric dispersion and transport, and the source–receptor transfer coefficients, were derived from detailed atmospheric models on long-range transboundary pollution and national mesoscale dispersion. The modelled deposition levels were used to estimate current and future exceedances of critical loads. The maps of critical loads for lakes and forest soils as environmental protection targets were calculated using best available input data, methods and effects criteria harmonised among European countries (Posch et al., 2001). The current model system is presented in Fig. 1.
1.2. The RAINS model The RAINS model has been developed at IIASA as an integrated tool for the assessment of air pollution control strategies in Europe (e.g. Alcamo et al., 1990; Schöpp et al., 1999; Amann et al., 1999). RAINS includes the country total emissions contributing to acidification, eutrophication and formation of tropospheric ozone. It then calculates the resulting deposition and exposure levels, which are compared with the critical thresholds for ecosystems and human health. The optimisation analysis enables identification of the cost-minimal allocation of emission controls necessary to achieve the target levels. The RAINS model includes data on sulphur dioxide (SO2 ), nitrogen oxides (NOx ), ammonia (NH3 ), volatile organic compounds and the various technical abatement options and related costs. These data are used to generate cost curves for each pollutant, ranking the measures in terms of cost-effectiveness. 1.3. Aims of the study This study assesses the measures to control emissions of sulphur and nitrogen oxides in Finland. The method is based on cost curves, which provide aggregated information on the control potential and related costs of individual control options for selected activity sector and fuel type combinations. First, cost curves based on national studies were calculated separately for SO2 and NOx emission abatement. They were compared with the corresponding curves in the RAINS model for Finland. Second, both acidifying emissions were presented in one cost curve in order to make the emission reduction potentials and relating costs for sulphur and nitrogen commensurate. Here SO2 and NOx emissions were considered as SO2 equivalents on the basis of their respective potential acidifying impact as acid equivalents. The acidifying impact for sulphur is 1 g S = 62.5 meq. and for sulphur dioxide 1 g SO2 = 31.3 meq. For nitrogen, the potential is 1 g N = 71.4 meq. and 1 g NOx = 21.7 meq. Thus, NOx emissions equal to SO2 as 1 g NOx = 0.693 g SO2eq . Third, a sensitivity analysis was carried out for the national SO2 cost curve in order to identify the most important calculation parameters affecting the cost curve.
2. Methodology 2.1. Emissions and control costs in the RAINS model
Fig. 1. Model diagram for the critical load integrated model system (CLIM) in Finland.
The RAINS model calculates emissions in a country emi,j,k,l,m (t) from activity data aj ,k,l (t) (e.g. fuel consumption) and unabated emission factors efi,j,k,l . Several emission control technologies with removal efficiencies ηi,k,l,m can be applied to each economic sector and fuel type combination with defined penetration percentages xi,j,k,l,m (t).
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The emissions are: emi,j,k,l,m (t) = (1 − ηi,k,l,m )xi,j,k,l,m (t) aj,k,l (t) ef i,j,k,l k
l
(1)
m
where t is the time; i the pollutant; j the country; k the fuel type; l the economic sector and m the abatement technology. For each emission control technology, in each sector–fuel combination, the unit cost uci,j,k,l,m (e.g. kg−1 SO2 −1 ) is calculated from technical and cost parameters of control technologies (emission reduction efficiencies, investment costs, operation and maintenance costs), and parameters characterising a typical production plant in the sector (unabated emission factors, boiler sizes, annual operating hours). Investment cost and technical parameters of the emission control technologies are general for the whole Europe, while the parameters defining production plants, as well as the prices of labour, sorbent materials and electricity are country-specific. Total emission control costs ci,j,k,l,m (t) are calculated from reduced emission quantities and unit costs: ci,j,k,l,m (t) = uci,j,k,l,m ηi,k,l,m xi,j,k,l,m (t) aj,k,l (t) ef i,j,k,l k
l
m
(2) The execution of emission reduction options in different countries is ranked based on the cost-effectiveness of individual options in the cost curves. A cost curve illustrates how to achieve a certain emission reduction with least cost using the optimal cost-abatement combination. Technologies are ranked according to their unit costs for removing the last unit of emissions, i.e. the marginal cost. A cost curve is usually compiled starting from a hypothetical “no-control” situation or an actual emission level of a chosen year. The composed curve is piece-wise linear, with individual segments determined by both the costs of applying the various technologies and the reduction potentials of the technologies in various sector–fuel combinations.
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in the national study. The costs given in the national literature (Ministry of the Environment, 1998, 1995) are in Finnish marks (FIM) from the years 1994–1995, and in this study they were converted to euros as 1 = 5.9FIM. Since there were no national cost data available on NOx emissions from the traffic sector, the RAINS traffic cost curves for Finland were used as such. The cost curves based on national experiences were constructed for the 1990 “no-control” situation. 3. Data sources 3.1. Activity data for 1990 The activity data in the RAINS model contain primary energy consumption and production levels of process industry. This study employed the RAINS model version from 1998 (Cofala and Syri, 1998a,b) which includes some national comments on the cost curve review carried out in early 1997. In this study, the activity data for 1990 were re-checked against national statistics (Statistics Finland, 2002). They matched with the statistics and were used in the national cost curve study for the construction of the cost curves. Total primary energy consumption of fuels in Finland was roughly 830PJ in 1990 excluding non-energy use of fuels. Nearly 60% of this was combusted in power plants and industry. The most important fuels for these sectors were hard coal (28% of the fuel use in power plants and industry) and natural gas (26%). Specific features for the Finnish energy production system are the combustion of peat (11%) and biomass (8%), with an extensive use of fluidised bed boilers, and large pulp and paper industry, where considerable amounts of black liquor are combusted in recovery boilers (18%). The most important sectors of process industry, in terms of sulphur and nitrogen emissions, are pulp and paper industry (SO2 and NOx emissions constituting 12 and 2.6%, respectively, of the country total emissions in 1992), metal industry (7.2 and 1.1%) and oil refining (6.0 and 0.7%) (Statistics Finland, 2002). 3.2. Data on production plants
2.2. Cost curves based on Finnish experiences In the national cost curve study, the same methodology as in the RAINS model was used to construct cost curves. The same sector and fuel classification and cost calculation approach were employed. The RAINS model data for Finland on activity levels, emission factors, sets of applicable emission control technologies and technical and cost parameters were reviewed using national data based on national statistics (e.g. Statistics Finland, 2002) and actual operation experiences from Finnish power plants and industry (e.g. Ministry of the Environment, 1998, 1995). The clearly differing parameters were refined for the national calculation. In addition, the restrictions in the maximum applicabilities of the end-of-pipe technologies were re-estimated and used
The parameters characterising industrial and energy production plants in the RAINS model, i.e. emission factors, boiler sizes, annual operating hours and applicability potentials of emission controls, were revised. The unabated emission factors for SO2 were estimated using data on sulphur contents of fuels used in Finland in the 1990s (Acidification Committee, 1998; Statistics Finland, 2002). The emission factors for NOx were reviewed using national estimates (Boström et al., 1992). The average boiler sizes and annual operating hours during 1990s were estimated using data from the Finnish VAHTI register on air pollution permits (Korkia-Aho et al., 1995), which contains information on all point sources exceeding 5 MWth . The calculation values on operating hours and NOx emission factors were refined with
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Table 1 Annual operating hours and NOx emission factors in the national study and in the RAINS model data for Finland for the sectors where the RAINS values were refined with national data National data
RAINS data
Operating hours per annum Industrial peat boilers Heavy fuel oil power plants Industrial heavy fuel oil boilers
5000 500 1000
7500 3000 6000
NOx emission factors (mg MJ−1 ) Coal power plants Wood power plants Industrial wood boilers Black liquor recovery boilers Gas power plants Industrial gas boilers/turbines
335 100 80 50 200 130
290 130 130 130 150 70
national data on some sectors (Table 1). The boiler sizes and emission factors for sulphur in the RAINS model matched with the latest national data and they were applied as such in the national calculations. The potential economically feasible applicabilities of end-of-pipe technologies in various sectors were also estimated using the VAHTI register. Restrictions in applicability play a significant role in sectors with diverse characteristics, e.g. plant sizes or annual operating hours. Specific investment costs (i.e. MWth −1 ) of end-of-pipe equipment, such as flue gas desulphurisation (FGD) or selective NOx reduction techniques, in combustion plants are typically considerably higher for small plants than large ones. In addition, small plants are often used only for peak-load supply with low annual operating hours. This would increase the fraction of the emission reduction costs from the total energy production costs and lead to a more costly use of the plant. In the RAINS model the unit cost of a control option in a sector–fuel combination is calculated for a plant with typical characteristics for this sector. If some of the plants in the sector have considerably different characteristics, the cost estimates would be misrepresented for this part of the sector. For such sectors with diverse characteristics it was assumed in this study that the end-of-pipe technologies can
be utilised only in boilers with thermal capacity higher than 50 MWth . This is also the definition for a large combustion plant in the Large Combustion Plant Directive (EC, 2001b). Most heavy fuel oil boilers in Finland are small in capacity and used for peak-load supply, and the applicability of the end-of-pipe technologies was estimated 10% in power plant sector and 5% in industrial sector. The RAINS model version used in this study estimates full applicability for heavy fuel oil boilers in Finland. 3.3. Data on control options for sulphur emissions The applicable control options for sulphur emissions in Finnish power plants and industry were estimated using national data (Table 2) (Ministry of the Environment, 1998; Acidification Committee, 1998). Specific national features, e.g. combustion of domestic fuels in fluidised bed boilers or combustion of black liquor in pulp and paper industry, were calculated in more detail than in the RAINS model. Measures taken to reduce non-combustion process emissions differ from straightforward end-of-pipe controls. An integrated set of measures in this sector often applies to improve overall process efficiency and reduction of waste material and emissions to air and water. National experiences of air pollution prevention expenditure available from a limited number of sectors were used to allocate costs directly related to air emission reductions from these measures. The cost efficiencies were highly variable (Table 3) (Acidification Committee, 1998; Sulphur Committee II, 1993). However, the national experiences were mainly reasonably consistent with the RAINS values, which are aggregated to three different efficiency and unit cost levels equal to all process industry sectors, and the RAINS estimates were also used in the national study. The use of low sulphur coal was not included in the national study as an abatement option, contrary to the RAINS model data for Finland. Coals used in Finnish boilers have a relatively low sulphur content, mainly below 0.8%, and currently almost all coal boilers are equipped with flue gas desulphurisation (Ministry of the Environment, 1998).
Table 2 SO2 control options applicable in the national study and in the RAINS model data for Finland SO2 control options in the national study
SO2 control options in RAINS
Emissions control in process industry
Emissions control in process industry
Low sulphur fuels • Heavy fuel oil • Medium distillates
Low sulphur fuels • Hard coal • Heavy fuel oil • Medium distillates
Flue gas desulphurisation (FGD) • Limestone injection in fluidised bed boilers • Wet FGD in boilers over 400 MWth • Spray dry scrubbers in boilers over 50 MWth • NaOH-based scrubbers in black liquor recovery boilers
Flue gas desulphurisation (FGD) • Limestone injection in all the boilers • Wet FGD in all the boilers
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Table 3 Removal efficiency levels and unit costs of SO2 process emission control based on national experiences (Acidification Committee, 1998; Sulphur Committee II, 1993) and in the RAINS model data general for all European countries National parameters
RAINS parameters
Industrial sector
Removal efficiency level (%)
Unit cost ( t(SO2 )−1 )
Industrial sector
Removal efficiency level (%)
Unit cost ( t(SO2 )−1 )
Cu and Ni production Oil refining TiO2 production Paper pulp production Coke production
50 70 80 80 80
3500 100 600 950 510
All industrial sectors All industrial sectors All industrial sectors
50 70 80
350 407 513
The Finnish Acidification Committee (1998) has estimated the unit cost of low sulphur heavy fuel oil (1.0%S) to be 508 t(SO2 )−1 based on the costs of changes needed in the oil refining processes. This value was used in the national study. The RAINS estimate for the unit cost for 0.6% S heavy fuel oil is 425 t(SO2 )−1 . For low sulphur medium distillates the same unit cost for abatement as in the RAINS model was employed. The RAINS model calculates unit costs for FGD technologies from a set of parameters characterising control technologies and production plants. The control technology
parameters were refined with national data based on actual operation experiences of control technologies used in the 1990s in Finnish power plants and industry (Ministry of the Environment, 1998) (Table 4). The national operation experiences for sulphur reductions were comprehensive with national cost and technical data available from all relevant sector-control technology combinations, since much of the sulphur emissions were abated during the 1990s. For example, sulphur removal by FGD technologies in Finland in 1995 was roughly 70 kt SO2 and total emissions then were 96 kt SO2 (Karvosenoja et al., 2001). Fig. 2 shows an
Table 4 Cost parameters of flue gas desulphurisation (FGD) according to national (Ministry of the Environment, 1998) and the RAINS model data for Finland National parameters
RAINS parameters
Investment ( kW−1 )
43–58: WFGD 1.7–3.4: LI 29–39: SD, Na
69–108: WFGD 30–46: LI
Fixed operation and maintenance (% from total investment per annum)
2.5
4
Removal efficiency (%)
85: WFGD, Na 30–65: LI 65–80: SD
85–95: WFGD 50 LI
Labour price ( man-year−1 ) Electricity price ( MWh−1 )
29050a 34
29050 40
Sorbent material price ( t−1 )
42: WFGD, LI (CaCO3 ) 85: SD (CaO) 220: Na
18
By-product disposal cost ( t−1 )
8.5
0: WFGD 35: LI
Labour demand (man-years GW−1 )
10.8a
10.8
Electricity demand (GWh PJ−1 )
1.5: WFGD 0.5: LI 0.75: SD, Na
1.0: WFGD 0.5: LI
Sorbent material demand (t t(SO2 )−1 )
1.56: 4.68: 1.05: 0.63:
1.56: WFGD 4.68: LI
By-product production (t t(SO2 )−1 )
2.6: 7.8: 2.1: 1.3:
WFGD: wet FGD; SD: spray dry FGD; LI: limestone injection; Na: NaOH-scrubber. a RAINS estimates used in the national study.
WFGD (molar ratio 1) LI (molar ratio 3) SD (molar ratio 1.2) Na (molar ratio 1)
WFGD LI SD Na
2.6: WFGD 7.8: LI
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Fig. 2. Comparison between the RAINS model data for Finland and national study of (a) total annual costs and (b) unit costs of flue gas desulphurisation in Finnish coal power plants. WFGD: wet flue gas desulphurisation.
example of comparisons between the RAINS model and the national study on total annual costs and unit costs of FGD in coal power plants, which constitute the most important sector contributing to sulphur emissions. 3.4. Data on control options for nitrogen emissions The options for nitrogen emission control in the RAINS model and in the national study are presented in Table 5. No national cost data were available for the NOx control technologies of mobile sources or the process industry. Therefore, the same reduction potentials and costs as in the RAINS model were used in the national study. The data available
on national operation experiences from power plants and industry were not as comprehensive as for sulphur controls, because only a small part of the total NOx emissions from stationary sources are abated to date. The nitrogen reduction in power plants and industry in 1995 was only about 20 kt NOx , while the total emission after abatement was 86 kt NOx (Karvosenoja et al., 2001). Combustion modification (CM) techniques or primary measures in stationary sources relate to modifications in the boiler design. The objective is to reach combustion conditions where the formation of NO from the nitrogen contained in combustion air (thermal NOx ) is decreased, or where the already formed NO can be reduced back to
Table 5 NOx control options applicable in the national study and in the RAINS model data for Finland NOx control options in the national study
NOx control options in RAINS
Technologies for mobile sources • Combustion modifications • Catalytic converters
Technologies for mobile sources • Combustion modifications • Catalytic converters
Emissions control in process industry
Emissions control in process industry
Technologies for stationary sources • Combustion modifications in all the boilers • SCR in coal power plants • SNCR in boilers over 50 MWth
Technologies for stationary sources • Combustion modifications in all the boilers • SCR in all the boilers • SNCR in industrial boilers
SCR: selective catalytic reduction; SNCR: selective non-catalytic reduction.
N. Karvosenoja, M. Johansson / Environmental Science & Policy 6 (2003) 329–340 Table 6 Cost parameters of NOx control options in stationary sources according to national (Ministry of the Environment, 1995) and in the RAINS model data for Finland National parameters
RAINS parameters
Investment ( kW−1 )
30: SCR 15–23: SNCR 0.90–9.9: CM
22: SCR 10–11: SNCR 3.2–8.5: CM
Total operation and maintenance ( MWh−1 )
0.49: SCR 0.15–0.58: SNCR 0–0.059: CM
0.58: SCR 0.08–0.20: SNCR (–): CM
Removal efficiency (%)
80: SCR 50–70: SNCR 20–50: CM
80: SCR 70: SNCR 50–65: CM
SCR: selective catalytic reduction; SNCR: selective non-catalytic reduction; CM: combustion modifications.
molecular nitrogen. Commonly used primary measures in pulverised combustion coal boilers are low-NOx burners, staging of combustion air, staging of fuel injection and flue gas recirculation. NOx reduction efficiencies of these measures vary from 10 to 70%, depending on fuel type, combustion technique, boiler type and boiler size. Furthermore, several of these measures can be simultaneously applied in one single boiler (Kilpinen, 1995). The reduction efficiencies and related costs of control technologies used in the national study are based on actual operation experiences in Finnish power plants (Ministry of the Environment, 1995). In the RAINS model, combustion modifications relate
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to the use of an “efficient” set of these techniques with reduction efficiencies from 50 to 65% (Table 6). Therefore, the CM techniques in the national study and in the RAINS model are not identical for most sectors, thus the costs or reduction efficiencies are not fully comparable. In those sectors where the national data were comparable to the RAINS model estimates for Finland, e.g. in coal power plants, RAINS tended to underestimate the reduction costs (Fig. 3a). Selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) technologies are not widely used in Finland. Currently there is only one SCR equipment in use in one Finnish coal power plant. The costs of SCR used in the national study were based on calculations with catalyst dimensioning application by Ekono Energy Ltd. (Ministry of the Environment, 1995), and they were comparable with the RAINS model estimates for Finland (Fig. 3b). SCR technologies were estimated to be applicable only in the coal power plants sector, since other sectors consist of boilers too small and emission factors too low for the cost-effective use of SCR (Ministry of the Environment, 1995). The costs of SNCR technologies in the national study were based on Swedish experiences (Ministry of the Environment, 1995). 3.5. Value ranges for calculation parameters In the sensitivity analysis, the SO2 cost curve based on the national data was calculated with minimum, maximum and the best estimate values of each parameter. The range of
Fig. 3. Comparison between the RAINS model data for Finland and national study of annual costs of (a) combustion modifications (CM) and (b) combined combustion modifications and selective catalytic reduction (CM + SCR) of NOx emissions in Finnish coal power plants.
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Fig. 4. Comparison of national and RAINS cost curves for SO2 in 1990 starting from the “no-control” situation. The segments and related texts illustrate the rough sequence of the most important emission abatement options. The text on the right relates to the national curve and on the left to the RAINS model curve. The first segment of both curves is explained on the right hand side. FGD: flue gas desulphurisation.
the values was estimated using values from national literature (Ministry of the Environment, 1998, 1995; Acidification Committee, 1998; Sulphur Committee II, 1993), the Finnish VAHTI register on air pollution permits (Korkia-Aho et al., 1995) and expert estimates.
4. Results 4.1. RAINS and national cost curves for SO2 Fig. 4 presents the comparison of SO2 cost curves based on our detailed national study and RAINS model data for Finland in 1990 starting from the “no-control” situation. The national estimates on both reduction potentials and costs are convergent with the estimates of the RAINS model for Finland. RAINS estimates the maximum technically feasible emission reduction potential to be 38 kt SO2 per annum higher than the national study suggests. This is mainly due to the RAINS model assumption on the full applicability of the end-of-pipe technologies for small peak-load heavy fuel oil boilers. If the full applicability of flue gas desulphurisation were assumed also in the national study, the national estimate for the maximum feasible emission reduction potential would be 16 kt SO2 per annum lower than the RAINS estimate.
On the one hand, the RAINS model slightly underestimates the costs of low sulphur heavy fuel oil for specific measures. On the other hand, RAINS tends to overestimate the costs of flue gas desulphurisation technologies because of the investment cost overestimation in most of the sectors. In the RAINS model, the removal efficiencies of FGD technologies are fixed and independent of the sulphur contents of fuels, which is not the case in reality. Therefore it overestimates the removal efficiencies and consequently the reduction potentials for those FGD technologies applied on low sulphur content fuels, such as peat. 4.2. RAINS and national cost curves for NOx Fig. 5 presents the comparison of NOx cost curves based on the national study and the RAINS model for Finland in 1990 starting from the “no-control” situation. The cost curves are convergent as was the case for SO2 . However, there were no national cost data available on NOx emission control for many sectors. For the traffic sector, where the greatest emission reduction potential resides, the same reduction potentials and costs as in the RAINS model were used in the national cost curve. Therefore, the parts of the national NOx cost curve which refer to emission reductions from traffic do not represent national experiences. For the control technologies of stationary sources, where there were national experiences available, the RAINS model
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Fig. 5. Comparison of national and RAINS cost curves for NOx in 1990 starting from the “no-control” situation. The segments and related texts illustrate the rough sequence of the most important emission abatement options. The text on the right relates to the national curve and on the left to the RAINS model curve. The first segment of both curves is explained on the right hand side. SCR: selective catalytic reduction; SNCR: selective non-catalytic reduction.
Fig. 6. The combined SO2 and NOx cost curve in 1990 starting from the “no-control” situation calculated with national data. FGD: flue gas desulphurisation; SCR: selective catalytic reduction; SNCR: selective non-catalytic reduction.
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tends to underestimate the costs of both combustion modifications and selective non-catalytic reduction. Removal efficiencies of CM are mainly higher in RAINS than according to the nationally prevailing set of techniques implemented in the Finnish plants. They do not, in many cases, represent the maximum technically feasible reduction potentials as described in RAINS (see Section 3.4). Therefore, the costs or reduction potentials are not fully comparable. 4.3. Combined SO2 and NOx cost curve In Fig. 6 emissions and reduction measures for both SO2 and NOx are presented in the same combined cost curve. The emissions are considered as SO2 equivalents on the basis of their acidifying impact. This simplified approach comparing the overall acidifying potential of different emission substances, used, e.g. in life cycle impact analyses, does not take into account the location and height of the emissions contributing to ecosystem-specific acidifying loading. When starting from the “no-control” situation, the most cost-efficient methods are mainly for sulphur emission reduction. Only combustion modifications in boilers of the NOx control technologies are in the same cost range as most of the SO2 reduction methods. SCR and SNCR technologies are considerably less cost-efficient, and low sulphur medium distillates and spray dry technique in peat and heavy fuel oil boilers are in the same cost range. Since the reductions of NOx can have side benefits also on the diminishing amounts of VOC and CO emissions and their effects, which are difficult to quantitatively compare with the acidifying potential, the advantages for NOx are an underestimate in this comparison. 4.4. Sensitivity analysis for the national SO2 cost curve Table 7 presents the summary of the effects of parameter uncertainties on total costs and emissions in the SO2 cost curve of the national study with maximum technically feasible reduction scenario (MFR). The interest rate and the payback time for annualising of investment costs have a significant impact on the total annual abatement cost. However, international assessment aiming at good comparability
usually assumes same lifetime and discount rates for all countries under study. This is a reasonable assumption also in view of the free market situation for Europe. Investment cost and annual operating hours have the second greatest effect on total costs. The variation of annual operating hours in heavy fuel oil boilers used for peak-load supply have a particularly strong effect on costs. The range of ±10% removal efficiencies of FGD technologies greatly affect total emissions. The sequence of abatement options in the cost curve did not change significantly in any of the uncertainty calculations.
5. Discussion and conclusions The cost curve approach is a useful method to illustrate emission reduction potentials and related costs in an aggregated and comprehensible manner. The number of activity sectors and fuels assessed in the national study was chosen to be the same as in the RAINS model. For some sector–fuel combination parameters, more detailed national data was available and the results were then aggregated to the RAINS classification. The RAINS model data on cost curves has been assessed by European countries through a general review process in 1997, planned again for 2003. National detailed studies on these data have been carried out in, e.g. United Kingdom, Finland, Germany and Norway, but the results in general have not been published in scientific fora. The RAINS model has also been compared with other emission calculation and integrated assessment models, and some of its versions have been partly adapted to national purposes, e.g. in Finland and in Poland. The most cost-efficient sulphur emission reductions in Finland can be achieved mainly in power plants and industry according to the cost curve constructed for the 1990 “no-control” situation. The comparison of specific technologies for sulphur emission abatement illustrates the need for careful interpretation and explanation of individual segments in the cost curves. The two curves derived from the national data and in the RAINS model may have same measures in different segments due to different data and parameter
Table 7 Effect of variation of cost parameters on total costs and emissions with maximum technically feasible reductions (MFR) Total cost with MFR (%) Interest rate and pay-back time (from 4%, 20 years to 8%, 15 years)
+17 Maximum
Investment ± 20% Other fixed costs ± 20% Variable costs ± 20% Annual operating hours ± 1000 h per annum Removal efficiencies of FGD (%) ± 10 Unabated emission factor of coal ± 20% Lower limit of applicability of FGDs 100/30 MWth
+7.6 +2.8 +2.5 −6.9 +0.6 +0.6 −3.1
Total emission with MFR (%) –
Minimum
Maximum
Minimum
−7.6 −2.7 −2.9 +16 −0.5 −0.5 +3.8
– – – – −11 +2.3 +5.2
– – – – +11 −2.7 −2.7
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values and aggregation, although the overall shape and location are almost the same. According to the combined SO2 and NOx cost curve the most cost-efficient methods to reduce acidifying emissions are mainly for sulphur emission reductions. However, most of the cost-efficient reduction methods of sulphur emissions are already in use in Finland. The sensitivity analysis for the SO2 cost curve indicated that variations in annual operating hours of the combustion plants have the greatest effect on abatement costs. Both the interest rate and the payback time may have a significant effect on total annual abatement cost. However, using same values of interest rate and payback time for all the countries is desirable to further ensure comparability in international assessment. The approach used in the RAINS model aims to compile and use data relevant to emission controls and costs in a consistent way for all European countries. Therefore, compromises are unavoidable on the level of details, e.g. the removal efficiencies. The more detailed national results on reduction potentials and costs were coherent with the estimates of the RAINS model for Finland as a whole. However, some measures lay in different positions in the cost curve, which is of importance in the planning of national implementation. This study was carried out for the year 1990, which also was the base year for international emission reduction negotiations (UNECE, 1999; EC, 2001a). The implementation of emission control technologies, especially FGD retrofitting to large energy and industrial plants, has been intensive during the early 1990s in Finland. In 1995 most of the cost-efficient sulphur control potential by technical measures were already utilised (Karvosenoja et al., 2001). Furthermore, a switch from the use of coal to sulphur-free natural gas has taken place, driven mainly by the aspiration to decrease carbon dioxide emissions. The total SO2 emissions have decreased from 260 to 86 kt SO2 per annum, or 67%, in 1990–2001 (Statistics Finland, 2002). The decrease has not been as intensive for NOx . Combustion modification retrofitting has taken place to some extent in stationary combustion, but plenty of cost-efficient control potential was still left in 1995 (Karvosenoja et al., 2001). The decrease of traffic NOx emissions follows the renewal of the vehicle fleet and the possibilities to accelerate this development at national level are limited. The NOx emissions have decreased from 290 to 211 kt NOx per annum, or 27%, in 1990–2001 (Statistics Finland, 2002). The national calculation system can also be used to assess future reduction potential for given energy and activity scenarios. The cost curves are constructed separately for each target year. They can be split in two parts; the first shows the measures in use by the time point and the second the remaining reduction potential. The second part can be used in ranking further cost-effective measures either nationally or between different countries. The latter approach has been used in the RAINS model in finding optimal solution alternatives to European emission reduction strategies in the preparation of international protocols (UNECE, 1999; EC,
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2001a). In these emission ceiling negotiations such national cost curves, starting at expected fulfilment of legislation and committed reduction plans, were calculated for each country to form the basic reference scenario (REF) for 2010 (Amann et al., 1999). The final emission ceilings for Finland, 110 kt SO2 per annum and 170 kt NOx per annum, were close to the REF scenario values. It was estimated in another scenario study that these goals can be achieved without measures additional to adopted legislation (Syri et al., 2002). The remaining reduction potentials above the agreed emission ceiling levels are relatively expensive (Cofala and Syri, 1998a,b). This study suggested that the aggregation level of cost and emission estimates in international integrated modelling is practical. In the cost curves of the national study the country-specific conditions were considered better than in the RAINS model and the major differences were explained. The national study helped to assure that international estimates on the emission reduction potential and costs correspond to national conditions as closely as possible. Thus the results of this study increase the credibility of policy-supporting modelling tools in international negotiations for emissions reductions.
Acknowledgements The authors wish to acknowledge the whole Transboundary Air Pollution (TAP) Project team at IIASA, especially J. Cofala for helpful discussions and supplementary data. We thank S. Syri at the Technical Research Centre of Finland and A. Heikkinen at Fortum Power and Heat Ltd. for their comments during the study. We thank also K. Grönfors, L. Timonen, K. Hietikko and K. Aalto at the Statistics Finland for information about national emissions and air pollution prevention expenditures. This study was funded by the LIFE financing instrument of the Directorate General—Environment of the European Union through project LIFE97/ENV/FIN/336.
References Acidification Committee, 1998. Happamoitumistoimikunnan mietintö (Report of the Acidification Committee). The Finnish Environment 219. Ministry of the Environment, Helsinki, Finland. (In Finnish with English summary.) Alcamo, J., Shaw, R., Hordijk, L. (Eds.), 1990. The RAINS Model of Acidification. Science and Strategies in Europe. Kluwer Academic Publishers, Dordrecht, The Netherlands. Amann, M., Bertok, I., Cofala, J., Gyarfas, F., Heyes, C., Klimont, Z., Makowski, M., Schöpp, W., Syri, S., 1999. Cost-Effective Control of Acidification and Ground-Level Ozone. Seventh Interim Report to the European Commission, DG-XI. International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria. Boström, S., Backman, R., Hupa, M., 1992. Greenhouse Gas Emissions in Finland 1988 and 1990 Energy, Industrial and Transport Activities. Insinööritoimisto Prosessikemia Ky, Turku, Finland.
340
N. Karvosenoja, M. Johansson / Environmental Science & Policy 6 (2003) 329–340
Cofala, J., Syri, S., 1998a. Sulfur Emissions, Abatement Technologies and Related Costs for Europe in the RAINS Model Database. IIASA Interim Report IR-98-035. International Institute for Applied Systems Analysis, Laxenburg, Austria. Cofala, J., Syri, S., 1998b. Nitrogen Oxides Emissions, Abatement Technologies and Related Costs for Europe in the RAINS Model Database. IIASA Interim Report IR-98-88. International Institute for Applied Systems Analysis, Laxenburg, Austria. De Vries, W., 1990. Philosophy, structure, and application methodology of a soil acidification model for The Netherlands. In: Kämäri, J. (Ed.), Impact Models to Assess Regional Acidification. International Institute for Applied Systems Analysis. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 3–21. EC (European Commission), 2001a. Directive 2001/81/EC of the European Parliament and of the Council of 23 October 2001 on National Emission Ceilings for Certain Atmospheric Pollutants. Official Journal of the European Communities L 309 EN, Brussels, Belgium, 27 November 2001, pp. 22–30. EC (European Commission), 2001b. Directive 2001/80/EC of the European Parliament and of the Council on the Limitation of Emissions of Certain Pollutants into the Air from Large Combustion Plants. Official Journal of the European Communities L 309/1, Brussels, 27 November 2001, Belgium. Forsius, M., Johansson, M., Posch, M., Holmberg, M., Kämäri, J., Lepistö, A., Roos, J., Syri, S., Starr, M., 1997. Modelling the effects of climate change, acidic deposition and forest harvesting on the biogeochemistry of a boreal forested catchment in Finland. Boreal Environ. Res. 2, 129–143. Hordijk, L., 1995. Integrated assessment models as a basis for air pollution negotiations. Water, Air, Soil Pollut. 85, 249–260. Johansson, M., 1999. Integrated models for the assessment of air pollution control requirements. Doctoral dissertation. Monographs Boreal Environ. Res. 13, 73. Johansson, M., Kämäri, J., Pipatti, R., Savolainen, I., Tuovinen, J.-P., Tähtinen, M., 1990. Development of an integrated model for the assessment of acidification in Finland. In: Kauppi, P., Anttila, P., Kenttämies, K. (Eds.), Acidification in Finland. Springer, Berlin, pp. 1171–1193. Johansson, M., Ahonen, J., Amann, M., Bartnicki, J., Ekqvist, M., Forsius, M., Karvosenoja, N., Lindström, M., Posch, P., Suutari, R., Syri, S., 2000. Integrated Environmental Assessment Modelling. Final Report of the Finnish Subproject, EU/LIFE Project. The Finnish Environment 387. Finnish Environment Institute, Helsinki, Finland. Johansson, M., Alveteg, M., Amann, M., Bak, J., Bartnicki, J., Ekqvist, M., Forsius, M., Frohn, L., Geernaert, G., Gimeno, B., Guardans, R., Karvosenoja, N., Mart´ın, F., Posch, M., Suutari, R., Syri, S., 2001. Inte-
grated assessment modeling of air pollution in four European countries. Water, Air, Soil Pollut. 130 (1–4), 175–186. Karvosenoja, N., Hillukkala, P., Johansson, M., Syri, S., 2001. Cost-effective abatement of acidifying emissions with flue gas cleaning vs. fuel switching in Finland. Water, Air, Soil Pollut. 130, 1619–1624. Kilpinen, P., 1995. Typen oksidien muodostuminen ja hajoaminen (formation and decomposition of nitrogen oxides). In: Raiko, R., KurkiSuonio, I., Saastamoinen, J., Hupa, M. (Eds.), Poltto ja palaminen (Burning and Combustion). International Flame Research Foundation (IFRF). Finnish National Department, Jyväskylä, Finland, pp. 239–276. Korkia-Aho, S., Koski, O., Meriläinen, T., Nurmio, M., 1995. VAHTIkäsiteanalyysi (VAHTI description). Memorandum, West Finland Regional Environmental Centre. (In Finnish.) Ministry of the Environment 1995. Energiantuotannon typenoksidipäästöjen vähentäminen (Reduction of nitrogen oxide emissions in energy production). Report 1/1995. Ministry of the Environment, Helsinki, Finland. (In Finnish with English summary.) Ministry of the Environment, 1998. Rikkidioksidi-ja typenoksidipäästöjen vähentämismahdollisuudet (Possibilities to reduce sulphur and nitrogen oxide emissions). The Finnish Environment 251. Ministry of the Environment, Helsinki, Finland. (In Finnish with English summary.) Posch, M., Smet, P.A.M., Hettelingh, J.-P., Downing, R.J. (Eds.), 2001. Modelling and mapping of critical thresholds in Europe: Status report 2001. RIVM Report No. 259101010, Coordination Center for Effects. National Institute for Public Health and the Environment, Bilthoven, The Netherlands. Schöpp, W., Amann, M., Cofala, J., Heyes, C., Klimont, Z., 1999. Integrated assessment of European air pollution emission control strategies. Environ. Modell. Software 14 (1), 1–9. Statistics Finland 2002. Energy Statistics 2001. Energy 2002:2, Statistics Finland, Helsinki, Finland. Sulphur Committee II, 1993. Rikkitoimikunta II:n mietintö (Report of the Sulphur committee II). Committee Report 1993:6, Ministry of the Environment, Helsinki, Finland. (In Finnish with English summary.) Sverdrup, H., Warfvinge, P., Frogner, T., Håøya, A.O., Johansson, M., Andersen, B., 1992. Critical loads for forest soils in the Nordic countries. Ambio 21 (5), 348–355. Syri, S., Karvosenoja, N., Lehtilä, A., Laurila, T., Lindfors, V., Tuovinen, J.-P., 2002. Modeling the impacts of the Finnish climate strategy on air pollution. Atmos. Environ. 36, 3059–3069. UNECE, 1999. Protocol to the Convention on Long-range Transboundary Air Pollution to Abate Acidification, Eutrophication and Ground-Level Ozone. EB.AIR/1999/1, United Nations, Economic Commission for Europe, Geneva, Switzerland.