W O R K I N G P A P E R
OPTIMAL SO2 A B A W POLICIES
IN
EUROPE :SCME EXAMF'LES
Stuart Batterman Markus Amann
Jean-Paul Hettelingh Leen Hordijk
Gabor Kornai
August 1986 I@-86-042
I n t e r n a t i o n a l I n s t i t u t e for Applied Systems Analysis
NOT FOR QUOTATION WITHOC'T PERMISSION OF THE AUTHORS
OPTIWIAI, S O ABATEMENT POIJCIES &UROPE:
SOME EXAMPLES
S t u a r t B a t t e r m a n M a r k u s Amann
J e a n - P a u l H e t t e l i n g h L e e n H o r d i jk
G a b o r K o r n a i
August 1 9 8 6 TVP-86-42
Working P a p e r s a r e i n t e r i m r e p o r t s o n w o r k of t h e I n t e r n a t i o n a l I n s t i t u t e f o r A p p l i e d S y s t e m s A n a l y s i s a n d h a v e r e c e i v e d o n l y lim- i t e d r e v i e w . Views o r o p i n i o n s e x p r e s s e d h e r e i n d o n o t n e c e s - s a r i l y r e p r e s e n t t h o s e of t h e I n s t i t u t e o r of i t s N a t i o n a l M e m b e r O r g a n i z a t i o n s .
INTERNATIONAL INSTITUTE FOR APPLIED SYSTEMS ANALYSIS 2361 L a x e n b u r g , A u s t r i a
PREFACE
IIASA's Acid Rain p r o j e c t h a s developed a n i n t e r a c t i v e c o m p u t e r model f o r t h e evaluation of acidification abatement policies. Two i m p o r t a n t addi- tions t o t h e RAINS model h a v e been p r o d u c e d r e c e n t l y : a cost-of-control submodel a n d a n optimization mode. Combination of t h e s e two new f e a t u r e s and existing submodels allows a completely new a p p r o a c h t o t h e E u r o p e a n acidification problem. In addition t o s c e n a r i o evaluation, cost-effective emission r e d u c t i o n policies and environmentally t a r g e t t e d policies c a n now b e c o n s t r u c t e d . The r e s e a r c h r e p o r t e d in t h i s p a p e r i l l u s t r a t e s t h e u s e of t h e new submodels. In a s e p a r a t e p a p e r t h e cost-of-control submodel will b e d e s c r i b e d in detail.
This p a p e r h a s b e e n p r e p a r e d a t t h e r e q u e s t of t h e s e c r e t a r i a t of t h e Convention on Long-range Transboundary Air Pollution, a n d h a s been p r e s e n t e d at a meeting of designated e x p e r t s on c o s t s and b e n e f i t s , 19-21 August 1 9 8 6 , Geneva.
Leen Hordijk
L e a d e r , Acid Rain P r o j e c t
ACKNOWLEDGEMENTS
The a u t h o r s are g r a t e f u l t o B. L u b k e r t (OECD), B. S c h a r e r (Umweltbun- desamt, FRG), D. S t r e e t s (Argonne National L a b o r a t o r y , USA) and B.
Tangena (National I n s t i t u t e f o r Public Health a n d Environmental Hygiene, Netherlands), who were involved in discussions a b o u t t h e c o s t of c o n t r o l submodel. W e are a l s o indebted t o t h e many individuals who worked a n d h a v e been working in t h e Acid Rain P r o j e c t . Vicky Hsiung skillfully typed t h e s e v e r a l d r a f t s of t h i s p a p e r . The World Meteorological Organization and t h e U N Economic Commission f o r E u r o p e h a v e given permission to use r e s u l t s from t h e EMEP programme. The Norwegian Meteorological I n s t i t u t e p r o - vided t h e a t m o s p h e r i c t r a n s f e r m a t r i c e s used in t h i s p a p e r . S u p p o r t from t h e Nordic Council of Ministers, t h e Umweltbundesamt, FRG, t h e Dutch P r i o r i t y Programme on Acidification and t h e US Department of E n e r g y , i s g r a t e f u l l y acknowledged.
The a u t h o r s assume s o l e responsibility f o r t h e c o n t e n t s of t h i s p a p e r .
TABLE OF CONTENTS
1. INTRODUCTION
2. THE RAINS MODEL
3. CURRENT REDUCTION PLANS
4. EXTENSION OF RAINS
4 . 1 Control costs
4.1.1 Overview a n d limitations of t h e a p p r o a c h 4.1.2 Emission c o n t r o l s t r a t e g i e s
4.1.3 Technology-specif i c cost functions 4.1.4 National cost c u r v e s
4.2 Optimization
4.2.1 T a r g e t t e d emission c o n t r o l s t r a t e g i e s 4.2.2 C u r r e n t s t a t u s of t h e optimization submodel 4.2.3 Limitations
5 . OPTIMIZED REDUCTION OF SO2 EMISSIONS: SOME EXAMPLES
Introduction
1)evelopment of E u r o p e a n c o n t r o l cost c u r v e s Reduction of p e a k s u l f u r deposition
Reduction functions
Flat rate deposition r e d u c t i o n
Reduction of s u l f u r deposition in s o u t h e r n Fenno-Scandia Reduction of t r a n s b o u n d a r y f l u x e s
Comparison of policies
6. CONCLUSION
REFERENCES
- vii -
OPTIMAL SO ABATEMENT POLICIES &UROPE:
SOME EXAMPLES
S t u a r t Batterman, Markus Amann, J?an-Paul Hettelingh, Leen Hordijk and G a b o r Kornai
1. INTRODUCTION
Governments of E u r o p e a n d North America are u n d e r i n c r e a s i n g p r e s - s u r e t o t a k e remedial a c t i o n a g a i n s t acidification of t h e environment. Also i n c r e a s i n g i s t h e amount a n d d i v e r s i t y of s c i e n t i f i c a n d engineering r e s e a r c h devoted t o t h i s s u b j e c t . The link between political decisions and s c i e n t i f i c evidence c o n c e r n i n g acidification h a s n o t b e e n v e r y s t r o n g , although a number of c o u n t r i e s h a v e s t a r t e d r e s e a r c h programmes on aci- dif ication.
In a n a t t e m p t t o link s c i e n c e a n d policy making on t h e E u r o p e a n level, t h e I n t e r n a t i o n a l I n s t i t u t e f o r Applied Systems Analysis s t a r t e d a n Acid Rain P r o j e c t in 1983. The p r i n c i p a l goal of t h i s p r o j e c t i s t h e development of a policy-support system of models t h a t could b e used at i n t e r n a t i o n a l a n d national l e v e l s in t h e e f f o r t t o develop c o o r d i n a t e d s t r a t e g i e s f o r r e d u c t i o n of emissions. To d a t e t h e work h a s c o n c e n t r a t e d on emissions a n d e f f e c t s of SO2.
This p a p e r f o c u s e s on two r e c e n t additions t o t h e RAINS model (Regional Acidification Information and Simulation). In C h a p t e r 2 t h e model i s d e s c r i b e d b r i e f l y , w h e r e a s in C h a p t e r 3 a n overview of c u r r e n t SO r e d u c t i o n plans in E u r o p e i s p r e s e n t e d t o g e t h e r with examples of
graphics?
o u t p u t options of RAINS. C h a p t e r 4 p r e s e n t s t h e new c o s t s and optimization submodels. Examples of v a r i o u s optimal r e d u c t i o n s t r a t e g i e s f o r E u r o p e are shown in C h a p t e r 5.
2. THE RAINS MODEL
IIASA's model of a c i d deposition i s a n i n t e r a c t i v e s e t of submodels with g r a p h i c a l output. The model h a s been developed in c o l l a b o r a t i o n with t h e UN Economic Commission f o r E u r o p e a n d in t h e c o n t e x t of t h e Convention on Long Range T r a n s b o u n d a r y Air Pollution. The framework of t h e RAINS model consists of t h r e e compartments: P o l l u t i o n G e n e r a t i o n , Atmospheric Processes a n d E n v i r o n m e n t a l Impacts. Each of t h e s e compartments c a n b e filled by d i f f e r e n t a n d s u b s t i t u t a b l e submodels. The submodels c u r r e n t l y a v a i l a b l e a r e S u l f u r E m i s s i o n s , EMEP Long Range T r a n s p o r t , Forest Soil A c i d i t y a n d Lake A c i d i t y . The RAINS model h a s been p r e s e n t e d in more d e t a i l in Alcamo e t a l . (1985) a n d Hordijk (1985).
F i g u r e 1 d e p i c t s t h e c u r r e n t s t a t u s of t h e RAINS model including t h e e x t e n s i o n s discussed in t h i s p a p e r . S t a r t i n g from t h e t o p of t h e f i g u r e t h e RAINS d a t a bank c o n t a i n s a number of d i f f e r e n t e n e r g y pathways f o r E u r o p e . These e n e r g y pathways h a v e b e e n d e r i v e d from publications by t h e Economic Commission f o r E u r o p e (1983) a n d t h e I n t e r n a t i o n a l E n e r g y Agency (1985) f o r e a c h of t h e 27 l a r g e r E u r o p e a n c o u n t r i e s . The e n e r g y u s e p e r c o u n t r y i s b r o k e n down i n t o 8 c a t e g o r i e s of fuel: h a r d c o a l , brown c o a l , d e r i v e d coal, l i g h t oil, heavy oil, c r u d e oil, g a s a n d o t h e r s ( h y d r o , n u c l e a r , biomass). The emission producing s e c t o r s a r e conversion ( r e f i n e r i e s ) , power p l a n t s , i n d u s t r y , domestic, t r a n s p o r t a n d o t h e r . The emissions of SO2 p e r f u e l a n d s e c t o r h a v e been c a l c u l a t e d f o r combustion p r o c e s s e s using s u l f u r c o n t e n t and h e a t values of t h e fuels. These numbers were c o l l e c t e d from many d i f f e r e n t s o u r c e s , both i n t e r n a t i o n a l (UN, OECD) and national.
The model u s e r h a s many ways t o influence model r u n s , beginning with t h e c h o i c e of a n e n e r g y pathway. S i n c e w e c o n s i d e r t h e e n e r g y f u t u r e t o b e o n e of t h e l a r g e s t u n c e r t a i n t i e s , w e h a v e l e f t t h e c h o i c e of a p a r t i c u l a r e n e r g y pathway t o t h e u s e r . The n e x t submodel of RAINS, which c a l c u l a t e s SO2 emissions, can a l s o b e influenced by t h e u s e r . A menu p r e s e n t s options f o r a b a t e m e n t s t r a t e g i e s : fuel switching, physical o r chemical f u e l cleaning, desulfurization units, a n d combustion modifications. The u s e r c a n s e l e c t a combination of s t r a t e g i e s f o r any c o u n t r y o r combination of c o u n t r i e s and t h e y e a r of implementation. The c o s t s of t h e c o n t r o l policy c o n s t r u c t e d by t h e u s e r will t h e n b e p r e s e n t e d .
The SO emissions p r o v i d e inputs t o t h e a t m o s p h e r i c t r a n s p o r t submo- del. c u r r e n t l y RAINS u s e s t r a n s f e r m a t r i c e s d e r i v e d from t h e a t m o s p h e r i c t r a n s p o r t model developed at t h e Meteorologic Synthesizing Center-West of t h e Co-operative Programme f o r Monitoring a n d Evaluation of t h e Long- Range Transmission of Air P o l l u t a n t s in E u r o p e (EMEP) in Oslo. This model h a s been d e s c r i b e d i n t e r a l i a in Eliassen a n d S a l t b o n e s (1983) a n d WMO (1984). The t r a n s f e r m a t r i c e s are used t o c a l c u l a t e s u l f u r depositions a n d SO2 c o n c e n t r a t i o n s in g r i d s q u a r e s of 1 5 0 x 1 5 0 km o v e r a l l of E u r o p e . A u s e r of RAINS may o b t a i n deposition o u t p u t in t h e form of isolines, c o l o r e d maps o r t h r e e dimensional p i c t u r e s .
I Energy Pathways
IPollution Generation
Atmospheric Processes
Environmental l mpact s Groundwater Direct Forest
Evaluation Optimizetion
F i g u r e 1. S t r u c t u r e of t h e RAINS model and i t s submodels.
T h e o u t p u t s of t h e a t m o s p h e r i c t r a n s p o r t submodel a r e u s e d in t h e f o r e s t s o i l a n d l a k e a c i d j t y submodels. Soil a c i d i f i c a t i o n h a s b e e n d e s c r i b e d as a d e c r e a s e in t h e a c i d n e u t r a l i z i n g c a p a c i t y of t h e s o i l ( v a n Breemen et.
a ) . , 1 9 0 4 ) , which may c o i n c i d e with a d e c r e a s e in soil pH. T h e r e a c t i o n of t h e s o i l t o t h e incoming a c i d stress d e p e n d s o n t h e s o i l ' s b u f f e r i n g p r o p e r - t i e s . T h e s e p r o p e r t i e s a r e d e s c r i b e d using two v a r i a b l e s , o n e f o r t h e g r o s s p o t e n t i a l ( b u f f e r c a p a c i t y ) a n d t h e o t h e r f o r t h e rate of t h e r e a c t i o n ( b u f f e r r a t e ) . B u f f e r i n g i s assumed t o b e g o v e r n e d b y s e v e r a l r e a c t i o n s : c a r b o n a t e , s i l i c a t e w e a t h e r i n g , c a t i o n e x c h a n g e a n d aluminum b u f f e r i n g . T h e d a t a b z n k f o r t h e f o r e s t soil submodel c o n t a i n s t h e s p a t i a l d i s t r i b u t i o n of 88 s o i l t y p e s i n g r i d s of lo lo n g i t u d e b y 0 . 5 ~ l a t i t u d e . Model o u t p u t i s p r o v i d e d in m a p s a n d g r a p h s f o r soil pH, c o n c e n t r a t i o n ,
ca2+
/ A I ~ + r a t i o s a n d b a s e s a t . u r a t i o n l e v e l s . The f o r e s t soil submodel h a s Deen d e s c r i b e d in d e t a i l i n Kauppi et a l . (1905), K a m a r i et a l . (1985a) a n d P o s c h et a l . (1985).The l a k e a c i d i f i c a t i o n submodel c o n s i s t s of s e v e r a l c o m p o n e n t s f o r m e t e o r o l o g y , h y d r o l o g y , soil c h e m i s t r y a n d water q u a l i t y of l a k e s . T h e m e t e o r o l o g i c submodel r e g u l a t e s i n p u t flows of w a t e r a n d d e p o s i t i o n t o t h e s o i l a n d d i r e c t l y t o t h e l a k e . T h e h y d r o l o g i c a n d s o i l c h e m i s t r y submodels t o g e t h e r d e t e r m i n e t h e flow of i o n s l e a c h i n g f r o m t h e t e r r e s t r i a l c a t c h m e n t t o t h e l a k e . New e q u i l i b r i u m c o n c e n t r a t i o n s in t h e l a k e water are t h e n com- p u t e d in t h e l a k e submodel. C u r r e n t l y t h i s snbmodel h a s b e e n implemented f o r Finland a n d Sweden. Model o u t p u t i s i n t h e f o r m of m a p s showing s p r i n g o r summer pH of l a k e areas. Documentation of t h e submodel i s p r o v i d e d in K a m a r i et a l . (3 9 8 5 b , c , 1986).
C u r r e n t a n d f u t u r e work on t h e RAINS model c o n c e r n s t h e following t o p i c s . In c o l l a b o r a t i o n with OECD, a model f o r e s t i m a t i n g NOx emissions i s u n d e r d e v e l o p m e n t . T h e n u m b e r of e n e r g y p a t h w a y s will b e e x t e n d e d t o i n c l u d e o p t i o n s which maximize t h e u s e of n a t u r a l g a s a n d which r e f l e c t i n c r e a s e d e f f o r t s in e n e r g y c o n s e r v a t i o n t h r o u g h o u t E u r o p e . T h e s t r u c t u r e of t h e e n e r g y a n d emissions submodel i s b e i n g c h a n g e d t o allow f o r i n c r e a s e d u s e r i n t e r a c t i o n . T h e E n v i r o n m e n t a l I m p a c t s c o m p a r t m e n t will c o n t a i n two m o r e submodels: Direct I m p a c t s o n Forests (Makela, 1 9 8 6 ) a n d G r o u n d w a t e r A c i d i f i c a t i o n (Holmberg, 1986). Q u a n t i f i c a t i o n of t h e s e n s i - t i v i t y a n d t h e u n c e r t a i n t y of t h e submodels f o r m s a s u b s t a n t i a l p a r t of t h e work p r o g r a m . A method f o r u n c e r t a i n t y a n a l y s i s h a s b e e n d e v e l o p e d a n d a p p l i e d t o t h e EMEP model ( c f . Alcamo a n d B a r t n i c k i , 1 9 8 5 a n d Alcamo et a l . 1 9 8 6 ) a n d i s b e i n g a p p l i e d t o t h e s u l f u r emissions submodel. R e s u l t s of a n a l o g o u s s t u d i e s f o r t h e f o r e s t soil a n d l a k e s u b m o d e l s are r e p o r t e d in P o s c h et a l . (1985) a n d Kamari et a l . (1986) r e s p e c t i v e l y . To i m p r o v e t h e t r a n s p o r t a b i l i t y of RAINS t h e c o m p u t e r c o d e f o r u s e o n a m i c r o c o m p u t e r will b e a v a i l a b l e s h o r t l y . O t h e r a d d i t i o n s t o RAINS i n c l u d e t h e c o s t of con- t r o l of SO emissions a n d a n optimization mode. T h e s e a d d i t i o n s are d i s - c u s s e d in & a p t e r 4.
3. CURRENT REDUCTION
PLANS
I n t e r n a t i o n a l negotiations focus on t h e y e a r 1980 as a basis f o r SO2 emission r e d u c t i o n s . The P r o t o c o l t o t h e Convention o n Long-Range Transboundary Air Pollution states in Article 2: "The P a r t i e s s h a l l r e d u c e t h e i r national annual s u l p h u r emissions o r t h e i r t r a n s b o u n d a r y f l u x e s by at l e a s t 30% as soon as possible a n d at t h e l a t e s t by 1993, using 1980 levels as t h e b a s i s f o r calculation of reductions" (ECE, 1985, Annex I). I t i s t h e r e f o r e important t o h a v e a good estimate of t h e 1 9 8 0 emission l e v e l s of SO
.
Table 1 l i s t s 1980 emissions of SO2 (measured as kilotonnes s u l f u r ) . In t%e f i r s t column of t h e t a b l e emissions c u r r e n t l y used in t h e EMEP programme are given ( s e e Dovland a n d S a l t b o n e s , 1986). The second column p r o v i d e s r e s u l t s from t h e RAINS submodel f o r e n e r g y a n d emissions. F o r most coun- t r i e s t h e d i f f e r e n c e s a r e small. The RAINS emissions are used in s u b s e q u e n t c h a p t e r s of t h i s p a p e r .The 2 1 p a r t i e s t o t h e Convention t h a t signed t h e P r o t o c o l are a l s o indi- c a t e d in Table 1. In t h e t h i r d column we p r e s e n t p e r c e n t a g e r e d u c t i o n s f o r t h e s e c o u n t r i e s , which r e f l e c t o u r c u r r e n t understanding of t h e r e d u c t i o n plans. The numbers a r e t a k e n from s e v e r a l p r e s e n t a t i o n s by c o u n t r y r e p r e s e n t a t i v e s . A final column of Table 1 p r o v i d e s a n e s t i m a t e of 1993/5 emissions of SO2 b a s e d on t h e 1 9 8 0 emissions as estimated in RAINS a n d t h e r e d u c t i o n p e r c e n t a g e s given in t h e t h i r d column.
The g r a p h i c a l o u t p u t modes of RAINS allow quick inspection a n d com- p a r i s o n of deposition isolines emerging from d i f f e r e n t emission p a t t e r n s . F i g u r e 2 d e p i c t s s u l f u r deposition isolines f o r t h e 1980 emissions a n d t h e 1993/5 emissions. A f o u r - y e a r a v e r a g e d t r a n s f e r matrix w a s used f o r t h e calculations. Another mode of g r a p h i c a l o u t p u t of RAINS viz. a t h r e e - dimensional p i c t u r e of depositions i s shown in Figure 3.
Table 1. Emissions of SO2 in E u r o p e a n c o u n t r i e s in 1 9 8 0 (Kilotonnes s u l f u r ) .
Country From EMEP Estimated Current Emlalons
data wlthln RAINS reduction plans a f t e r reductions (percentages) uslng
RAlNS estimates Albanla
Austria Belglum Bulgaria Czechoslovakia Denmark Flnland France
German Dem.Rep.
Federal Rep. of Germany Greece
Hungary Ireland Italy Luxembourg Netherlands Norway Poland Portugal Romanla Spain Sweden Switzerland Turkey USSR
Unlted Klngdom Yugoslavia Europe Total
F i g u r e 2. S u l f u r d e p o s i t i o n i s o l i n e s f o r 1980 (a) and a f t e r implernenta- t i o n of c u r r e n reduct.ion p l a n s (1995) (b). I s o p l e t h s f o r 2.5, 5 , 7.5 a n d 10 g/rn - y r a r e shown.
5
F i g u r e 3. Calculated d e p o s i t i o n (gram S/m 2 /yr) in E u r o p e , 1980. The t e n h i g h e s t d e p o s i t i o n areas are i n d i c a t e d o n t h e map.
4.
EXTENSION OF RAINS
This c h a p t e r c o n t a i n s t w o p a r t s d e s c r i b i n g t h e new submodels being i n c o r p o r a t e d into t h e RAINS model. In s e c t i o n 4.1 t h e cost-of-control sub- model, which is u n d e r development, i s p r e s e n t e d . Section 4.2 d i s c u s s e s t h e formulation a n d use of t h e optimization submodel.
4.1. Control costs
This s e c t i o n d i s c u s s e s t h e p r e s e n t preliminary s t a t u s of t h e c o s t sub- model of RAINS. F i r s t , a n overview of t h e a p p r o a c h a n d i t s limitations a r e provided. Then t h e c o n t r o l options are discussed. Lastly t h e national c o s t functions are d e s c r i b e d .
4.1.1. Overview and limitations of the approach
Within t h e c o n t e x t of t h e o v e r a l l goals of RAINS ( s e e C h a p t e r 2 ) , t h e c o s t submodel e s t i m a t e s pollution c o n t r o l c o s t s in a n internationally com- p a r a b l e way. R a t h e r t h a n a s t a t i s t i c a l o r economic analysis, a n engineering a p p r o a c h w a s used to estimate c o n t r o l costs. In b r i e f , t h e a p p r o a c h c o m p r i s e s t h e following s t e p s :
S p e c i f i c a t i o n of emission c o n t r o l options f o r e a c h s e c t o r a n d f u e l t y p e . Specification of technology-specific c o s t functions by means of a c t i v i t y analysis.
Derivation of country-specific national cost c u r v e s b a s e d o n t h e technology-specific c o s t functions.
To avoid t h e misuse of t h i s politically sensitive submodel, i t i s impor- t a n t t o specify t h e limitations of t h e model. The p r e s e n t c o s t submodel is limited t o t h e c o n t r o l of s u l f u r emissions. Of t h e many social c o s t s a n d bene- f i t s of c o n t r o l policies w e d e a l almost exclusively with t h e d i r e c t c o s t s r e l a t e d t o c e r t a i n emission a b a t e m e n t options in combustion p r o c e s s e s . W e d o n o t c o n s i d e r o t h e r pollutants, t h e c o s t s of mitigation of environmental e f f e c t s and second a n d h i g h e r o r d e r i n t e r a c t i o n s between pollution c o n t r o l a n d economic growth, s e c t o r a l composition, supply a n d demand i s s u e s , i n t e r n a t i o n a l t r a d e , etc.
Due t o t h e lack of detailed d a t a , c o n t r o l of s u l f u r emissions from non- combustion processes, i s not y e t included in o u r model. F u r t h e r limitations are c a u s e d by t h e l a c k of internationally c o m p a r a b l e emission c o n t r o l d a t a f o r t h e 27 c o u n t r i e s modeled.
During t h e development of RAINS i t w a s decided t h a t a number of e n e r g y pathways would b e a v a i l a b l e t o t h e u s e r . Consequently, p r i m a r y f u e l switching and e n e r g y c o n s e r v a t i o n are n o t y e t c o n s i d e r e d as emission r e d u c i n g options. However, t h e c o s t s of t h e s e s t r a t e g i e s c a n b e o b t a i n e d indirectly by comparing a b a t e m e n t c o s t s of d i f f e r e n t e n e r g y pathways.
4.1.2. Emission control strategies
In g e n e r a l , f o u r major s t r a t e g i e s t o r e d u c e s u l f u r emissions from t h e energy-use s e c t o r s exist:
1. E m i s s i o n control technologies applied b e f o r e , during o r a f t e r t h e combustion p r o c e s s e s .
2. Use of low s u l f u r coal a n d oil
3. Fuel s w i t c h i n g s u b s t i t u t e s n a t u r a l g a s , hydro- o r n u c l e a r power fc:
high sulfur coal and oil without substantially changing t h e final e n e r g y demand. Fuel switches may a l s o b e motivated by economic and political considerations.
4. E n e r g y c o n s e r v a t i o n uses l e s s primary e n e r g y by e i t h e r reducing t h e e n e r g y demand o r increasing t h e efficiency of combustion p r o c e s s e s . Associated c o s t s and benefits may b e r e l a t e d largely t o economic and e n e r g y policies.
The f i r s t two c o n t r o l s t r a t e g i e s are c u r r e n t l y i n c o r p o r a t e d into RAINS. Work i s underway t o include fuel switching. Energy conservation s t r a t e g i e s may b e evaluated by modifying t h e e n e r g y pathway.
4.1.3. T e c h n o l o g y - s p e c i f i c cost f u n c t i o n s
The sulfur abatement technologies f o r combustion systems c u r r e n t l y considered include t h e following options:
- Desulfurization of oil r e d u c e s t h e sulfur content of light oil f r a c - tions t o 0.15 p e r c e n t , heavy fuel oils t o 1 p e r cent.
L o w - e m i s s i o n c o m b u s t i o n p r o c e s s e s :
-
In-furnace lime injection f o r coal combustion removing 30 t o 60%of SOZ. In t h i s technique, lime o r limestone i s blown into t h e combustion chamber and t h e end product is f i l t e r e d o u t of t h e flue gas. The relatively l a r g e amount of residue r e q u i r e s disposal.
Flue g a s d e s u l f u r i z a t i o n p r o c e s s e s (FGD) covering a r a n g e from 50 t o 98% sulfur removal. The following p r o c e s s e s are considered:
-
Wet lime/limestone scrubbing: binds t h e s u l f u r dioxide with a lime- stone s l u r r y producing e i t h e r solid gypsum o r calcium sulfate and sulfite. Gypsum may b e e i t h e r sold o r disposed. This p r o c e s s i s used in about 90% of a l l FGD applications, typically accomplishing sulfur removal rates of 90% (SchZrer and Haug, 1986).-
Wellman-Lord process: h e r e t h e sulfur dioxide is a b s o r b e d into a solution of sulfites and sulfates which may b e f u r t h e r p r o c e s s e d t o obtain liquid SO2, elemental sulfur o r sulfuric acid. This relatively expensive technology i s applied where t h e by-products c a n b e d i r e c t l y used, o r at locations with limited facilities f o r t r a n s p o r - tation and waste disposal. We assume a 98% sulfur removal effi- ciency.Table 2 d e s c r i b e s o u r assumptions regarding t h e applicability of t h e s e c o n t r o l technologies t o t h e d i f f e r e n t s e c t o r s and fuels.
Annualized unit c o s t s of sulfur removal are estimated based on t o t a l investment c o s t s and fixed- and variable operating and maintenance (O&M) co:;ts. Our analysis h a s concentrated on finding t h e most important indica- tczs which r e f l e c t t h e s e items. Table 3 lists t h e v a r i a b l e s used t o compute
a b a t e m e n t .
Table 2. Potential u s e of a b a t e m e n t technologies by s e c t o r s a n d fuels.
S e c t o r
I ~ o n v e r -
I
Hard c o a lId d
ITable 3. V a r i a b l e s used in computing costs of c o n t r o l technologies.
Fuel t y p e
Domestic 1;d c o a l Derived c o a l
- -
G e n e r i c v a r i a b l e s
Technology-specific investment cost functions (FRG) Lifetime (30 y e a r s )
S h a r e of investments to fixed O&M costs Real i n t e r e s t r a t e f o r CPE's (4%)
Boiler c a p a c i t y in i n d u s t r y (50 MWel) N o r e t r o f i t
S u l f u r r e m o v a l e f f i c i e n c y (90
X
wet/dry, 9 8 X Wellman-Lord) S t o i c h i o m e t r i c r a t i o sThermal efficiency of combustion E l e c t r i c i t y p r i c e
A b s o r b e n t p r i c e By-product p r i c e Disposal cost
Additional e n e r g y demand C o u n t r y - s p e c i f i c v a r i a b l e s
Real i n t e r e s t r a t e for m a r k e t economies Boiler s i z e in power p l a n t s
S u l f u r c o n t e n t by f u e l s ( a t p l a n t s i t e ) Heat v a l u e by f u e l s
Capacity utilization
Use of low Limestone Wet Wellman-Lord
s u l f u r fuel injection FGD p r o c e s s
Power H a r d coal
d d d
sion
d d d
Oil
d d d d
d d d
d d d d
d d d
d
I
p l a n t s Brown coal d
d
14 d
I n d u s t r y H a r d c o a l
1
Brown c o a l1
D e r i v e d c o a l T r a n s p o r -t a t i o n
Oil Oil
Investment c o s t s r e p r e s e n t t h e t o t a l d i r e c t costs of t h e investment ( m a t e r i a l s , c o n s t r u c t i o n r e l a t e d l a b o u r , etc.). The b o i l e r s i z e i s used as a n i n d i c a t o r to e s t i m a t e investment costs. Due to t h e r e l a t i v e l y p o o r c o u n t r y s p e c i f i c d a t a o n t h e s i z e d i s t r i b u t i o n of i n d u s t r i a l b o i l e r s w e assume a uni- form s i z e of 5 0 MWel. F o r power p l a n t s investment costs are c a l c u l a t e d using t h e n a t i o n a l a v e r a g e b o i l e r size.
f i x e d 0&M c o s t s (including i n s u r a n c e , t a x e s e t c . ) are assumed to b e p r o p o r t i o n a l t o investment costs. Typical a v e r a g e r a t i o s f r o m t h e l i t e r a t u r e ( S c h a r e r a n d Haug, 1986; OECD, 1986; I n a b a , 1985; Rentz, 1 9 8 4 ) are used f o r all c o u n t r i e s .
Investment a n d f i x e d O&M costs are i n c o r p o r a t e d i n t o c a p a c i t y r e l a t e d a n n u a l c o s t s . Annual investment costs are o b t a i n e d assuming c o u n t r y - s p e c i f i c real r a t e s of i n t e r e s t based o n 1 9 8 4 d a t a (OECD, 1 9 8 5 ) f o r t h e m a r k e t economies a n d 4% f o r t h e c e n t r a l l y planned economies. W e h a v e n o t y e t distinguished new a n d r e t r o f i t installations, b u t i n s t e a d assume t h a t all p l a n t s are new with a n economic life-time of 3 0 y e a r s .
Variable 0&M c o s t s include t h e c o s t s of additional e n e r g y demand, a b s o r b e n t s a n d waste disposal. E n e r g y costs are r e l a t e d to e l e c t r i c i t y p r i c e s a n d combustion p r o c e s s efficiencies. A b s o r b e n t a n d d i s p o s a l c o s t s d e p e n d on s u l f u r c o n t e n t s a n d f u e l h e a t v a l u e s , o b s e r v i n g c o n s t a n t r a t i o s of s u l f u r to a b s o r b e n t a n d a b s o r b e n t to end-product. P o t e n t i a l b e n e f i t s f r o m selling t h e by-products are a l s o c o n s i d e r e d . All p r i c e s p r e s e n t l y used in t h e model are d e r i v e d from d a t a f o r t h e F e d e r a l R e p u b l i c of Germany ( S c h a r e r and Haug, 1986).
Energy-specific total a n n u a l costs are o b t a i n e d by r e l a t i n g t h e c a p a - c i t y r e l a t e d plus v a r i a b l e O&M costs to a c t u a l e n e r g y units. This c a l c u l u s t a k e s i n t o a c c o u n t country-specific c a p a c i t y utilization r a t i o s , i.e., c a p a - city f a c t o r s , e x p r e s s e d in t e r m s of annual o p e r a t i n g h o u r s , as well as t h e e f f i c i e n c i e s of combustion p r o c e s s e s .
C u r r e n t l y t h e b a s i c c u r r e n c y of t h e cost submodel i s D e u t s c h m a r k s (DM). S i n c e a l l p r i c e s h a v e b e e n d e r i v e d f r o m d a t a of t h e FRG, e x c h a n g e rates are n o t used. Because only a limited number of c o n t r o l technologies i s c o n s i d e r e d a n d few c o u n t r y s p e c i f i c v a r i a b l e s are i n t r o d u c e d , t h e cost functions u s e d in t h i s p a p e r are t e n t a t i v e . Consequently, in t h i s p a p e r r e s u l t s are p r e s e n t e d using cost indices.
In summary, t h e a b o v e c a l c u l a t i o n s p r o v i d e country-, s e c t o r - , fuel- a n d c o n t r o l technology-specific v a l u e s f o r t h e cost of a b a t i n g a t o n of s u l f u r p e r u n i t of e n e r g y , a n d t h e s u l f u r removing p o t e n t i a l , c o r r e s p o n d i n g to t h e s t r u c t u r e of a given e n e r g y pathway. T h e s e v a l u e s may b e computed f o r a n y time p e r i o d a n d e n e r g y pathway. The model u s e r may a l t e r t e c h n o l o g i e s , f u e l c h o i c e s a n d c a p a c i t i e s using a menu in t h e RAINS model. E n e r g y flows a n d mass b a l a n c e s are c o n s e r v e d in t h e computations.
4.1.4. National Cost Curves
The n a t i o n a l cost function i s defined as t h e minimal cost e n v e l o p e encompassing t h e e n t i r e r a n g e of s u l f u r a b a t e m e n t o p t i o n s f o r a given coun- t r y , e n e r g y pathway a n d time period. Consequently w e h a v e assumed t h a t a l l national a b a t e m e n t s are cost minimizing, which p e r m i t s i n t e r n a t i o n a l com- p a r i s o n of costs. Legislation i n t r o d u c e d by some c o u n t r i e s (e.g. t h e
Ordinance on L a r g e Firing Installations in t h e FRG) i s neglected.
The c o s t c u r v e s a r e d e r i v e d by minimizing t o t a l c o s t s s u b j e c t t o vari- o u s s u l f u r reduction r e q u i r e m e n t s , which r a n g e up t o t h e maximum techno- logical f e a s i b l e removal. The r e s u l t i n g national c o s t c u r v e consists of piecewise l i n e a r approximations, typically containing 20 t o 3 0 segments.
Typical s h a p e s a r e shown in Figure 4. These c u r v e s were estimated using t h e official e n e r g y f o r e c a s t of t h e governments f o r t h e y e a r 2000 (IEA, 1985;
ECE,
1983). The a r r o w s indicate emission levels c o r r e s p o n d i n g t o a 30% r e d u c t i o n from 1980 emissions. Due t o t h e non fossil fuel b a s e d e n e r g y pathway c o u n t r y A h a s no c o s t in meeting a 30% reduction; c o u n t r yB
must spend 400 million DM.T O T A L A N N U R L C O S T S 1 1 0 # * 9 D M 1 T O T A L A N N U R L C O S T S 110*1"9 DM1
C O U N T R Y A C O U N T R Y
B
SULFUR E f l l S S I O N S I U T 5 ) SULFUR E t l I S S I O N S I H T 5 )
Figure 4 . Two national total c o s t c u r v e s .
4.2. Optimization
This s e c t i o n reviews t h e formalization and use of t h e optimization sub- model of RAINS as applied t o t a r g e t t e d emission c o n t r o l s t r a t e g i e s . F i r s t , t h e g e n e r a l framework i s developed, including a discussion of t a r g e t s and i n d i c a t o r s . Second, t h e c u r r e n t s t a t u s of t h e optimization submodel i s d e s c r i b e d . Lastly, limitations of t a r g e t t e d s t r a t e g i e s are discussed.
4.2.1. Targetted emission control strategies
The optimization submodel of t h e RAINS model permits t h e g e n e r a t i o n and analysis of targetted emission c o n t r o l s t r a t e g i e s based o n i n d i c a t o r s . I n d i c a t o r s r e p r e s e n t environmental impacts, economic f a c t o r s , a n d / o r o t h e r policy objectives. In t a r g e t t e d s t r a t e g i e s , t h e s u l f u r (and p e r h a p s NO ) r e d u c t i o n s of e a c h E u r o p e a n c o u n t r y are determined in a manner whlch meets t h e goals o r c o n s t r a i n t s implied by t h e i n d i c a t o r s in a n econom- F ical o r efficient fashion. Some t a r g e t t e d s t r a t e g i e s of i n t e r e s t might include.
-
Thc country-by-country emission reductions r e q u i r e d t o a c h i e v e a specified S deposition c r i t e r i a at t h e least c o s t .- The emission r e d u c t i o n s r e q u i r e d t o achieve a specified deposition c r i - t e r i a by removing t h e l e a s t amount of sulfur.
- The emission r e d u c t i o n s which yield a low probability of environmental damage a t t h e minimum c o s t .
These a n d o t h e r t a r g e t t e d s t r a t e g i e s c a n b e e v a l u a t e d using t h e optimiza- tion submodel of RAINS.
I n d i c a t o r s in t a r g e t t e d s t r a t e g i e s fall into t h r e e g e n e r a l c l a s s e s : 1. Environmental i n d i c a t o r s m e a s u r e impacts o r t h e r i s k of s u c h impacts
t o 1 ) f o r e s t s ; 2) s u r f a c e and groundwater; 3 ) a g r i c u l t u r a l production;
4) materials; a n d 5) human health. Useful i n d i c a t o r s may include ambient c o n c e n t r a t i o n , deposition, l a k e a c i d i t y , c h a n g e i n soil pH, a n d f o r e s t damage. Environmental i n d i c a t o r s may apply t o some o r a l l of t h e r e c e p t o r s in t h e model.
2. Economic i n d i c a t o r s e s t i m a t e t h e c o s t of emission c o n t r o l s a n d f u e l substitution.
3. Policy i n d i c a t o r s are r e l a t e d t o equity a n d t h e feasibility of t h e con- t r o l s t r a t e g i e s . These i n d i c a t o r s might r e p r e s e n t t h e a b i l i t y of t h e v a r i o u s c o u n t r i e s t o implement c o n t r o l s t r a t e g i e s , t h e d e s i r a b i l i t y of achieving similar environmental impacts o n a p e r c a p i t a b a s i s , minimum r e d u c t i o n s f o r c o u n t r i e s , o r o t h e r goals.
I n d i c a t o r s may b e used s e p a r a t e l y o r jointly. F o r example, t h e t a r g e t t e d c o n t r o l s t r a t e g y might b e a c o s t minimizing solution satisfying both environ- mental a n d policy i n d i c a t o r s . The i n t e r p r e t a t i o n of model r e s u l t s becomes more complex with multiple i n d i c a t o r s .
The c h o i c e of i n d i c a t o r s may c r u c i a l l y a f f e c t t h e outcome of t h e tar- g e t t e d c o n t r o l s t r a t e g y . Consider, f o r example, i n d i c a t o r s r e p r e s e n t i n g environmental e f f e c t s . I n d i c a t o r s r e l a t e d t o l a k e acidification would tend t o a f f e c t depositions and emissions in n o r t h e r n E u r o p e , while i n d i c a t o r s r e l a t e d t o f o r e s t impacts would influence areas in c e n t r a l E u r o p e . Ideally, deposition o r c o n c e n t r a t i o n t h r e s h o l d s should c o r r e s p o n d t o t h e sensitivity of land a n d water areas o v e r E u r o p e . However, t h e specification of deposi- tion o r c o n c e n t r a t i o n t h r e s h o l d s i s difficult given t h e state-of-the-art of p r e s e n t ecological modeling a n d t h e available information. In addition, t h e specification of such t a r g e t s may b e highly c o n t r o v e r s i a l . Some components in t h e RAINS model may b e used t o d e r i v e environmental t a r g e t s , e.g., t h e l a k e acidification submodel, f o r e s t impacts a n d ground water acidity. How- e v e r , t h e l a t t e r two of t h e s e submodels are u n d e r development; a n d t h e l a k e submodel h a s b e e n a p p l i e d t o only a p o r t i o n of E u r o p e . Consequently s e v e r a l a l t e r n a t i v e a n d s i m p l e r a p p r o a c h e s a r e used t o s p e c i f y deposition t a r g e t s , as d e s c r i b e d below.
4.2.2. Current status of the optimization submodel
A t p r e s e n t , t h e optimization submodel employs a single o b j e c t i v e , l i n e a r p r o g r a m o p e r a t e d in a quasi-interactive fashion o n a mainframe com- p u t e r . (A smaller s c a l e v e r s i o n h a s b e e n developed f o r u s e on a p e r s o n a l computer.) Mathematically, goals o r t a r g e t s are specified as c o n s t r a i n t s in t h e l i n e a r p r o g r a m . C o n s t r a i n t s are equations which define t h e "feasible region" of possible solutions, which i s t h e n s e a r c h e d f o r t h e optimum. This formulation i s conceptually equal t o work by Ellis et a l . (1985), Fortin a n d McBean (1983) a n d Morrison a n d Rubin (1985), although t h e application d i f f e r s in num r o u s ways. The extension t o non-linear problems, e.g., using soil o r l a k e -. :idity as t a r g e t s , is a r e l a t i v e l y s t r a i g h t f o r w a r d modification of t h e c u r r e n a p p r o a c h .
The u s e r h a s t h e c h o i c e of o b j e c t i v e s a n d c o n s t r a i n t s ( o r i n d i c a t o r s ) , as discussed below. The existing implementation of o b j e c t i v e s a n d t a r g e t s i s preliminary: work u n d e r development will g r e a t l y e x t e n d t h e c a p a b i l i t y of t h e submodel.
The o b j e c t i v e functions c u r r e n t l y implemented include (1) minimization of t o t a l E u r o p e a n c o n t r o l c o s t s , using t h e c o s t submodel discussed in S e c - tion 4.1; a n d (2) minimization of t o t a l E u r o p e a n s u l f u r removal. Although E u r o p e a n t o t a l s a r e used as o b j e c t i v e s , t h e submodel c a l c u l a t e s a n d displays c o s t s a n d s u l f u r r e d u c t i o n s f o r individual c o u n t r i e s . Note t h a t if c o n t r o l c o s t s are c o n s t a n t a n d equal among c o u n t r i e s , o b j e c t i v e s (1) a n d (2) are equivalent. An " e x p o r t " option allows t h o s e costs o r removal quantities t o b e minimized which r e l a t e t o s u l f u r t r a n s p o r t e d across national boun- d a r i e s . This option i s used tc r e p r e s e n t o b j e c t i v e s e x p r e s s e d in f l u x e s , e.g.
50% r e d u c t i o n of t r a n s b o u n d a r y f l u x e s at minimum c o s t .
S e v e r a l simple c o n s t r a i n t s h a v e been implemented. These include (1) u p p e r a n d lower bounds on t h e removal f r a c t i o n f o r e a c h c o u n t r y ; a n d (2) limits on t h e maximum s u l f u r deposition o r SO2 c o n c e n t r a t i o n at e a c h r e c e p - t o r . Removal f r a c t i o n s are based o n emissions f r o m a b a s e y e a r , s e l e c t e d as 1980. F o r example, specifying a minimum removal of 30% a n d a maximum removal of 60% e n s u r e s t h a t emissions of e a c h c o u n t r y will b e between 40 and 70% of t h e 1980 emissions.
Due t o t h e difficulty of determining s e n s i t i v e areas a n d establishing deposition goals, s e v e r a l a l t e r n a t i v e a p p r o a c h e s w e r e used t o s p e c i f y depo- sition t a r g e t s . These a p p r o a c h e s may n o t p r o d u c e t a r g e t l e v e l s which c o r r e s p o n d to t h e environmental o r ecological sensitivity. However, t h e y d e m o n s t r a t e t h e flexibility of t h e method a n d p r o v i d e a p r e l i m i n a r y indica- tion of t h e implications of t a r g e t t e d policies.
C u r r e n t l y t h e r e are t h r e e options f o r determining deposition limits. In o p t ' n 1 ,
Y
a m a z i m u m d e p o s i t i o n limit i s specified f o r a l l of E u r o p e , e.g., 5 g/m - y r at a l l r e c e p t o r s . With t h i s t a r g e t , f o r example, t h e optimization submodel could d e t e r m i n e t h e lowest cost country-by- o u n t r y emission3
r e d u c t i o n s which r e s u l t in c a l c u l a t e d depositions of 5 g/m - y r or l e s s at a l l r e c e p o r s . However, r e c e p t o r s which a l r e a d y e x p e r i e n c e deposition below
&
5 g/m - y r may n o t o b t a i n f u r t h e r r e d u c t i o n s . In option 2 , deposition limits are determined as t h e deposition r e s u l t i n g from a specified r e d u c t i o n i n e m i s s i o n s f o r a b a s e y e a r , s e l e c t e d as 1980. F o r example, t h e depositions o b t a i n e d by a 50% r e d u c t i o n in 1980 emissions c a n b e used as maximum depo- sitions. This option t e n d s t o p r e s e r v e t h e 1980 deposition a n d / o r concen- t r a t i o n p a t t e r n o v e r E u r o p e , however, t h e a b s o l u t e level of deposition i s d e c r e a s e d from 1980 levels. In option 3, a r e d u c t i o n , -function i s used to s p e c i f y t h e deposition t a r g e t at e a c h r e c e p t o r . In t h e p r e s e n t submodel, r e d u c t i o n s f o r e a c h r e c e p t o r are specified as a function of c a l c u l a t e d deposition levels in a b a s e y e a r (1980). Figure 5 shows two possible func- tions specifying t h e f r a c t i o n by which deposition must b e r e d u c e d . Line (a) shows deposition d e c r e a s e s which are p r o p o r t i o n a l t o t h e 1980 depositions.
F o r example, deposition would b e e d u c e d by 75%
Ti
at a r e c e p t o r with a high ( 1 9 y ) deposition l e v e l of 20 g/m -yr; a r e c e p t o r with a deposition of 5 g/m - y r would r e q u i r e only a 25% d e c r e a s e in deposition. C u r v e (b) con- t a i n s a t h r e s h o l d , implying a deposition level below which no r e d u c t i o n s a r e n e c e s s a r y . In comparison t o option 1 , which may n o t a c h i e v e lowerdepositions at r e c e p t o r s which a r e a l r e a d y below t h e t a r g e t , r e d u c t i o n functions may b e s p e c i f i e d which r e q u i r e r e d u c t i o n s at all r e c e p t o r s .
The p r i n c i p a l o u t p u t s of t h e optimization submodel a r e country-by- c o u n t r y emission r e d u c t i o n s a n d c o s t s . The e n v i r o n m e n t a l i m p a c t s of t h e t a r g e t t e d s t r a t e g i e s , e . g . , deposition l e v e l s , c a n b e o b t a i n e d using t h e s c e n a r i o a n a l y s i s mode of RAINS. Additional o u t p u t s of t h e optimization submodel include (1) amount of emissions p e r c o n t r o l c l a s s i f i c a t i o n r e d u c e d by e a c h c o u n t r y ; (2) marginal c o s t s of t h e c o n t r o l s t r a t e g y (e.g.. maximum c o s t / t o n of SO2 r e d u c t i o n s ) , a n d (3) shadow p r i c e s indicating t h e value of changing c o n s t r a i n t s , e.g. c o s t of control/amount s u l f u r deposition.
-
- (b) proportional reductions with threshold
-
-
-
- (a) proportional reductions
I
-
' Sulfur Deposition (with 1980 emissions)
F i g u r e 5 . Two r e d u c t i o n functions.
4.2.3. L i m i t a t i o n s
Models which f o r m u l a t e t a r g e t t e d s t r a t e g i e s may b e useful as policy t o o l s if t h e model i s c r e d i b l e . To e n h a n c e t h e usefulness of t h e model, r e s u l t s are p r e s e n t e d in a c o m p a r a t i v e fashion, a n d a high d e g r e e of flexi- bility in t a r g e t s i s p e r m i t t e d . However, s e v e r a l shortcomings of t a r g e t t e d emission c o n t r o l a p p r o a c h e s should b e pointed o u t . These include t h e multi-objective n a t u r e of t h e problem; t h e u n c e r t a i n t y of t h e v a r i a b l e s a n d models; a n d t h e inadequacy or i r r e l e v a n c e of e x p e c t e d or a v e r a g e p e r f o r - mance given t h a t decision m a k e r s may b e s e n s i t i v e to p o o r or e v e n catas- t r o p h i c outcomes which are n o t modeled. These i d e a s a r e f u r t h e r d e v e l o p e d below.
In g e n e r a l , t a r g e t t e d emission c o n t r o l s t r a t e g i e s are mult ple o b j e c t i v e optimization problems. W e p r e s e n t r e s u l t s f r o m t h e optimizz .ion submodel in a m a n n e r which shows t h e t r a d e - o f f s entailed b y single o b j e c t i v e policies.
F u t u r e v e r s i o n s of t h e model may p e r m i t a m o r e i n t e r a c t i v e a p p r o a c h s o t h a t model u s e r s c a n i n t e r p r e t policy implications, a l t e r t h e i r assumptions a n d o b j e c t i v e s , a n d t h u s r e f i n e t h e i r g o a l s to o b t a i n s a t i s f a c t o r y r e s u l t s . In addition, t e c h n i q u e s which c o n s i d e r multiple and (usually) conflicting o b j e c - t i v e s of s e v e r a l decision m a k e r s a r e a p p l i c a b l e . We have e n t e r e d discus- s i o n s with r e s e a r c h e r s who may u s e t h e s e t e c h n i q u e s w i t h t h e RAINS model ftVitmuess e t a l . , 1 9 8 4 ) .
A t p r e s e n t , t h e optimization submodel i s a d e t e r m i n i s t i c formulation which d o e s n o t c o n s i d e r model a n d d a t a u n c e r t a i n t y . Moreover, nonlineari- t i e s a n d dynamic effects of t h e environmental impact models a r e highly sim- plified. Nonlinear a n d dynamic e f f e c t s c a n b e modeled using a multistage s t o c h a s t i c optimization based in p a r t on p a s t e f f o r t s t o quantify +.he u n c e r - t a i n t y a n d sensitivity of t h e a t m o s p h e r i c t r a n s p o r t a n d l a k e a c i d i t y com- ponents in t h e RAINS model (e.g., Alcamo a n d Bartnicki, 1985). Comparative u s e of t h e model p r o v i d e s a h e u r i s t i c consideration of u n c e r t a i n t y .
5. OPTIMIZED REDUCTIONS OF SO2 EMISSIONS: SOME EXAMPLES
5.1. Introduction
This c h a p t e r p r e s e n t s s e v e r a l examples of optimal r e d u c t i o n s t r a t e g i e s f o r E u r o p e , which d e m o n s t r a t e t h e formulation and use of thli new c o s t a n d optimization submodels of t h e RAINS model. Because t h e s e submodels are s t i l l u n d e r development, t h e r e s u l t s should b e c o n s i d e r e d as preliminary, possibly, but n o t n e c e s s a r i l y r e p r e s e n t a t i v e of optimal s t r a t e g i e s .
Results of optimal policies, in t e r m s of E u r o p e a n c o n t r o l c o s t s a n d sul- f u r r e d u c t i o n s are given f o r t h e following examples:
1. Development of E u r o p e a n c o n t r o l c o s t c u r v e s 2. Reduction of p e a k s u l f u r deposition
3. Reductions function f o r s u l f u r deposition 4. F l a t rate deposition r e d u c t i o n s
5. Reduction of s u l f u r deposition in s o u t h e r n Fenno-Scandia 6. Reductions of t r a n s b o u n d a r y f l u x e s
These examples, including t h e i r o b j e c t i v e s a n d a summary of r e s u l t s , are d e s c r i b e d in t h e following s i x sections. Examples 2-5, which employ s u l f u r deposition c o n s t r a i n t s , are used l a r g e l y b e c a u s e t h e r e i s n o i n t e r n a t i o n a l consensus o n deposition t a r g e t s f o r E u r o p e . T a r g e t t e d policies using environmental i n d i c a t o r s s u c h as impacts on f o r e s t s or w a t e r quality might n o t r e s e m b l e any of t h e s e examples. Our intention in using t h e s e examples i s to d e m o n s t r a t e t h e u s e of t h e cost and optimization submodels as tools for policymakers. W e n e i t h e r recommend n o r s u g g e s t t h a t t h e s e examples should b e implemented.
All examples h a v e s e v e r a l common f e a t u r e s , including (1) t h e maximum emissions of e a c h c o u n t r y are t h e 1 9 8 0 levels; (2) c o s t s are r e f e r e n c e d to t h e c o n t r o l c o s t s of a f l a t r a t e 30% r e d u c t i o n in 1980 emission levels, which i s assigned a n index of 100; (3) t h e y e a r 2000 c o s t c u r v e s a n d emissions p r o j e c t i o n s are employed, b a s e d o n t h e f u e l mix in t h e single e n e r g y path- way c o n s i d e r e d (derived f r o m IEA (1985)) as explained e a r l i e r ; (4) s u l f u r t r a n s p o r t i s based on a f o u r - y e a r meteorological p e r i o d ; ( 5 ) only a g g r e g a t e European-wide c o n t r o l costs a n d s u l f u r r e d u c t i o n s are p r e s e n t e d , although country-by-country q u a n t i t i e s are calculated; a n d (6) background deposi- tion i s assumed to b e d e r i v e d from e n t i r e l y n a t u r a l or uncontrollable emis- sions. With r e s p e c t t o t h e s i x t h point, "background" c o n t r i b u t i o n s in t h e EMEP model include both n a t u r a l emissions and some a n t h r o p o g e n i c emis- sions, t h e l a t t e r which are n o t a t t r i b u t e d t o emissions from s p e c i f i c coun- t r i e s . W e h a v e assumed t h a t t h e background deposition i s from only n a t u r a l
s o u r c e s . In most c a s e s t h i s will not g r e a t l y a l t e r r e s u l t s s i n c e t h e back- ground f r a c t i o n i s usually small. However, w h e r e i t i s l a r g e , o t h e r assump- t i o n s might c h a n g e r e s u l t s significantly.
5.2. Development of European control cost curves
This s e c t i o n p r e s e n t s c o s t functions which display a g g r e g a t e E u r o p e a n c o s t s f o r s e v e r a l emission r e d u c t i o n policies. These policies, which are independent of s u l f u r t r a n s p o r t and deposition l e v e l s , c o m p a r e t h e follow- ing o b j e c t i v e s :
a . m a t r a t e r e d u c t i o n s . In t h i s c a s e , a l l c o u n t r i e s r e d u c e emissions by t h e same f r a c t i o n , b a s e d on 1.980 emissions. F o r example, in a 50% f l a t r a t e r e d u c t i o n , a l l c o u n t r i e s h a v e emissions from t h e i r 1 9 8 0 levels.
b. Maximum r e d u c t i o n s w i t h a t o t a l E u r o p e a n - w i d e b u d g e t . T h e s e r e s u l t s i n d i c a t e t h e maximum s u l f u r removal o b t a i n a b l e f o r a given budget. H e r e , t h e optimization maximizes t h e totaI s u l f u r removed, s u b j e c t t o a b u d g e t c o n s t r a i n t . S u l f u r emissions from e a c h c o u n t r y a r e p e r m i t t e d t o v a r y from 1980 levels ( t h e maximum) t o a minimum level implied by t h e c o u n t r y s p e c i f i c c o s t c u r v e s .
c . Maximum r e d u c t i o n s w i t h a t o t a l E u r o p e a n - w i d e b u d g e t a n d a 30%
m i n i m u m r e d u c t i o n . This c a s e i s similar t o (b) a b o v e , e x c e p t a l l c o u n t r i e s must r e d u c e emissions from 1980 l e v e l s by a t l e a s t 30%.
In summary, policy (a) p r o v i d e s a n indication of costs f o r f l a t r a t e policies, a n d policy (b) maximizes s u l f u r removal o v e r E u r o p e s u b j e c t t o a budget c o n s t r a i n t .
F i g u r e 6 shows c o s t s and removal q u a n t i t i e s of t h e t h r e e policies.
Costs a r e displayed using a c o s t index, w h e r e 1 0 0 r e f e r e n c e s t h e c o s t of a 30% f l a t rate r e d u c t i o n in emissions f r o m 1980 levels. Removals a r e displayed using emissions in y e a r 1980 as a b a s e . The European-wide 1980 emissions a r e e q u a l t o 29.8 million t o n s / y r . According t o t h e e n e r g y p a t h - way used, most c o u n t r i e s would i n c r e a s e t h e i r y e a r 2000 emissions from 3980 l e v e l s without pollution a b a t e m e n t to a t o t a l of 34.9 million t o n s / y r . Emissions from Denmark, F.R.G., Italy, a n d t h e USSR i n c r e a s e by less t h a n 5% from 1980 l e v e l s while f o u r c o u n t r i e s r e d u c e emissions i.e., Belgium, Fin- land, F r a n c e a n d Sweden.
Emission r e d u c t i o n s a r e c a l c u l a t e d using 1 9 8 0 as a b a s e . A s a n exam- p l e , a 50% removal f r o m 1 9 8 0 l e v e l s r e d u c e s emissions t o 14.9 million t o n s / y r (one-half of 1 9 8 0 emissions). A s t h e e n e r g y pathway shows t h a t y e a r 2000 emissions would total 34.9 million t o n s / y r , a r e d u c t i o n in y e a r 2000 emissions of 20 million t o n s / y r would b e r e q u i r e d . When e x p r e s s e d in t e r m s of y e a r 2000 emissions, t h e 50% r e d u c t i o n in 1980 emission r e q u i r e s a l a r g e r p e r c e n t a g e r e d u c t i o n (57.3%) from t h e u n a b a t e d y e a r 2000 emis- sions.
R e t u r n i n g t o F i g u r e 6, t h e c o s t c u r v e s show s t r o n g l y i n c r e a s i n g c o s t s beyond 60 t o 7 0 % removal. This r e s u l t s as t h e h i g h e s t removal r a t e s c a n on!y b e accomplished using t h e most e x p e n s i v e c o n t r o l options; t h e poten- t i a l of inexpensive c o n t r o l options h a s b e e n e x h a u s t e d . (Similar r e s u l t s w e r e shown in Section 4.1 f o r individual c o u n t r y c o s t c u r v e s . ) The maximum removal possible in y e a r 2000 using t h e c u r r e n t c o s t c u r v e s i s 29 million t o n s / y r , r e s u l t i n g in s u l f u r emissions of 5 . 6 million t o n s / y r . Thus, t h e fully
a b a t e d emissions in y e a r 2000 c o r r e s p o n d s t o 81% d e c r e a s e in 1 9 8 0 emis- sions. The maximum r e d u c t i o n c o s t s 4.7 times as much as a 30% f l a t rate r e d u c t i o n , although only 2 . 1 times as much s u l f u r i s removed.
T h e u p p e r l i n e in F i g u r e 6 shows t h e f l a t rate policy (a). With t h e c u r r e n t cost c u r v e s , all c o u n t r i e s were a b l e to r e d u c e emissions from 1980 l e v e l s by at least 50%. However, additional r e d u c t i o n s w e r e n o t possible f o r s e v e r a l c o u n t r i e s . The maximal removal f o r e a c h c o u n t r y v a r i e d between 50 a n d 91% of 1 9 8 0 levels. The f l a t rate c u r v e c o n t i n u e s to 80%. however, by permitting c o u n t r i e s to "drop out" as t h e i r c o n t r o l options were e x h a u s t e d . This o p e r a t i o n may t e n d to d e c r e a s e t h e d i f f e r e n c e between t h e t h r e e poli- c i e s .
0
1
I I I I I I I Ii
0 2 0 40 60 80
P e r c e n t r e m o v a l f r o m 1980 elmissions
Figure 6. Total E u r o p e a n c o s t s vs. s u l f u r r e d u c t i o n s f o r t h r e e policies.
The maximal removal policy (b) forms t h e lowest c o s t "envelope" in Fig- u r e 6. For example, 30% sulfur removal (14.1 million tons/yr of y e a r 2000 sulfur removed) may b e accomplished f o r only 80% of t h e c o s t of t h e f l a t rate policy. For 50% removal, t h e c o s t is 88% of t h e f l a t rate policy. The c o s t savings are achieved by maximizing removal in c o u n t r i e s with low removal costs. This changes t h e s p a t i a l p a t t e r n of t h e emission reduc- tions, however t h e t o t a l European sulfur reduction remains constant.
The c u r r e n t c o s t c u r v e s d o not include t h e l e a s t expensive c o n t r o l options, e.g. fuel switching. Incorporation of such c o n t r o l options in t h e c o s t c u r v e s would i n c r e a s e t h e d i f f e r e n c e between c o s t s of flat rate and maximal removal policies. Thus, c o s t savings above may b e r e g a r d e d as a lower bound on c o s t differentials. Cost savings of t h e policies discussed in t h e following sections may also b e underestimated f o r similar reasons.
The t h i r d policy (c), maximum removal with a minimum 30% reduction by all countries, h a s c o s t s between f l a t rate (a) and maximum removal (b) poli- cies. A t high removal levels, t h i s policy i s similar t o policy (b).
In summary. t h e European c o s t s c u r v e s show increasing c o s t s with additional sulfur removal, especially above 60-70% removal. This i n c r e a s e would b e more dramatic if additional control options, such as fuel substitu- tion, were considered. T h e r e i s about a 20% d i f f e r e n c e between f l a t rate and reduction maximizing policies f o r moderate sulfur removal levels (30- 60% of 1980 emissions). Because of t h e preliminary n a t u r e of t h e c o s t c u r v e s , t h i s differential may b e r e g a r d e d as a lower bound.
5.3. Reduction of peak sulfur deposition
The s e v e r i t y of some impacts of s u l f u r deposition, including materials damage such as c o r r o s i o n and discoloration, is directly r e l a t e d t o deposi- tion level. Thus, a possible objective f o r optimized emission c o n t r o l policies is t h e reduction of t h e m a z i m u m d e p o s i t i o n levels f o r a l l land areas of Europe. F o r t h i s objective, a maximum deposition level i s selected. Then, t h e optimal country-by-country emission reductions which most efficiently achieve t h e specified deposition levels are determined. With t h e s e reduc- tions, deposition at a l l European s i t e s will b e at o r below t h e specified deposition level.
T h r e e policies were examined t o investigate t h e effects of reducing t h e peak deposition. The policies had d i f f e r e n t objectives, namely:
a. M i n i m i z i n g t o t a l E u r o p e a n c o s t . This case obtains t h e minimum c o s t a p p r o a c h which a c h i e v e s t h e specified deposition level.
b. M i n i m i z i n g r e d u c t i o n s i n t o t a l E u r o p e a n e m i s s i o n s w i t h technolog- i c a l c o n s t r a i n t s . H e r e , t h e reduction e f f o r t , in t e r m s of sulfur remo- val, is minimized. The reductions from each country are limited t o t h e c o n t r o l options discussed in C h a p t e r 4.
c . M i n i m i z i n g r e d u c t i o n i n t o t a l E u r o p e a n e m i s s i o n s w i t h o u t techno- logical c o n s t r a i n t s . This d i f f e r s from policy (b) in t h a t t h e technolog- ical c o n s t r a i n t s imposed by t h e cost c u r v e s are ignored. Reductions of e a c h country may r a n g e up t o 100% of 1980 emissions. Thus, a c o u n t r y may completely eliminate i t s emissions. While unrealistic, t h i s assump- tion helps t o i l l u s t r a t e t h e sensiti rity of t h e solution to t h e c o s t c u r v e s .
