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Life Cycle Assessm ent o f Bio-ethanol Derived from Cel luloseGloria Zhi Fu*, A lbert W. Chan and David E. MinnsI n s t it u t e f o r C h e m i c a l P r o c e ss a n d E n v i r o n m e n t a l T e c h n o l o g y , N a t i o n a l R e s e a r c h C o u n c i l C a n a d a , O t t a w a , O N K 1 A 0 R 6 , C a n a d a* C o r r e s p o n d i n g a u t h o r ( g l o ri a .f u @ n r c . g c .c a )

D O h h t t p : / / d x . d o i . o r ~ 1 0 . 1 0 6 5 / I c a 2 0 0 3 . 0 3 . 1 0 9A b s t r a c tO b j e c t i v e , S c o p e , B a c k g r o u n d . A c o m p r e h e n s i v e L i fe C y c l e A s -s e s s m e n t w a s c o n d u c t e d o n b i o - e t h a n o l p r o d u c e d u s i n g a n e wp r o c e s s t h a t c o n v e r t s c e ll u lo s i c b i o m a s s b y e n z y m a t i c h y d r o l y -s is . O p t i o n s f o r s o u r c i n g t h e f e e d s t o c k e i t h e r f r o m a g r i c u l t u r a la n d w o o d w a s t e , o r , i f t h e d e m a n d f o r b i o - e t h a n o l i s s u f fi c i e n t,f r o m c u l t i v a t i o n a r e e x a m i n e d . T h e m a i n f o c u s o f th e a n a l y s i sw a s t o d e t e r m i n e i t s p o t e n t ia l f o r r e d u c i n g g r e e n h o u s e g a s e m i s -s i o n s in a 1 0 % b l e n d o f t h i s b i o - e t h a n o l w i t h g a s o l i n e ( E l 0 ) a sa t r a n s p o r t a t i o n f ue l.M e t h o d s . S i m a P r o 4 . 0 w a s u s e d a s t h e a n a l y si s t o o l, w h i c h a l -l o w e d a r a n g e o f o t h e r e n v i r o n m e n t a l i m p a c t s a ls o t o b e e x a m -i n e d t o a s s e ss t h e o v e r a l l r e la t i v e p e r f o r m a n c e t o g a s o l i n e a l o n e .A l l im p a c t s w e r e a s s i g n e d t o t h e f u e l b e c a u s e o f u n c e r t a i n ti e s i nm a r k e t s f o r t h e b y - p r o d u c t s . T h i s L C A t h e r e f o r e r e p r e s e n t s aw o r s t c a s e s c e n a r io .R e s u l t s , C o n c l u s i o n . I t i s s h o w n t h a t E l 0 g i v e s a n i m p r o v e de n v i r o n m e n t a l p e r f o r m a n c e i n s o m e i m p a c t c a t e g o r i e s , i n c l u d -i n g g r e e n h o u s e g a s e m i s s i o n s , b u t h a s i n f e r i o r p e r f o r m a n c e s i no t h e r s . W h e t h e r t h e p o t e n t i a l b e n e f i t s o f t h e b i o - e t h a n o l b l e n dt o r e d u c e g r e e n h o u s e g a s e m i s s io n s w i l l b e re a l i z e d i s s h o w n t ob e p a r t i c u l a r l y s e n s it i v e t o t h e s o u r c e o f e n e r g y u s e d t o p r o d u c et h e p r o c e s s s t e a m r e q u i r e d t o b r e a k d o w n t h e c e l lu l o s e t o p r o -d u c e s u g a r s a n d t o d i st il t h e f i n a l p r o d u c t . O n e k e y a r e a w h e r ei m p r o v e m e n t s i n e n v i r o n m e n t a l p e r f o r m a n c e m i g h t b e d e r i v e di s i n e n z y m e p r o d u c t i o n .R e c o m m e n d a t i o n s a n d O u t l o o k . T h e L C A p r o f i l e he l ps t o h i g h-l i g h t t h o s e a r e a s w h e r e p o s i t iv e a n d n e g a t i v e e n v i r o n m e n t a l i m -p a c t s c a n b e e x p e c t e d . T e c h n o l o g i c a l i n n o v a t i o n c a n b e d i r e c t e da c c o r d i n g l y t o p r e s e r v e t h e b e n e f i ts w h i l e m i n i m i z i n g t h e n e g a -t i v e i m p a c t s a s d e v e l o p m e n t p r o g r e s s e s t o c o m m e r c i a l s c a le s .K e y w o r d s : B io-e thano l ; b io - fue l ; b iomas s ; ce l lu los e b io - e tha-no l ; en zym at i c hydro lys i s ; e than o l ; LC A; l i f e cyc le ana lys i s ; l if ecyc le as s es s men t ; l if e cyc le eng ineer ing

I n t r o d u c t i o nE t h a n o l h a s b e e n v i e w e d a s a n a l t e r n a t i v e t o g a s o l i n e , a n dh a s b e e n u s e d a s a t r a n s p o r t a t i o n f u el i n a n u m b e r o f c o u n -t r ie s . In C a n a d a , t h e u s e o f b i o - e t h a n o l i n th i s c o n t e x t i s o n eo f t h e i m p o r t a n t m e a s u r e s b e i n g c o n s i d e r e d t o h e l p m e e tt h e c o m m i t m e n t t o r e d u c e g r e e n h o u s e g a s e m i s si o n s . Io g e nC o r p o r a t i o n , a n O t t a w a - b a s e d b i o t e c h n o l o g y c o m p a n y , h a s

c o n s t r u c t e d a p i lo t p l a n t t o d e m o n s t r a t e t h e v i a b il i ty o f p r o -d u c i n g b i o - e t h a n o l o n a c o m m e r c i a l s ca l e f r o m w o o d a n da g r i c u l t u r a l w a s t e . T h e p r o c e s s ( F i g . 1 ) u s e s e n z y m a t i c h y -d r o ly s is t o b r e a k d o w n t h e c e ll u lo s e f r o m w a s t e w o o d , s t r a wa n d o t h e r a g r i c u l tu r a l w a s t e s t o m a k e s u g a rs . T h e s e s u g a r sa r e f e r m e n t e d t o p r o d u c e e t h a n o l , w h i c h i s t h e n p u r i f i e dt h r o u g h d i s t il l a ti o n . T h e i n t e n t o f t h e p r e s e n t s t u d y i s t op e r f o r m a q u a n t i ta t i v e a n a l y si s o f t h e p o t e n ti a l e n v i r o n m e n -t a l b e n e f it s a n d l i m i t a t i o n s o f u s in g b i o - e t h a n o l a s a t r a n s -p o r t a t i o n f u e l. I n p a r t i c u l a r , t h e a n a l y s i s c o m p a r e s t h e l if e -c y c le e ff e c ts o f g a s o l i n e , b l e n d e d w i t h 1 0 % b i o - e t h a n o lp r o d u c e d b y e n z y m a t i c h y d r o ly s i s ( E l 0 ) , w i t h t h o s e o fu n b l e n d e d g a s o li n e .T h e c o m m e r c i a l s o f t w a r e S i m a P r o 4 . 0 ( h t t p ./ / w w w . p r e . n l /s i m a p r o / ) w a s u s e d t o c o n d u c t t h e L C A . T h e r e l a t iv e c o n t r i -b u t i o n s o f t h e d i f f e r e n t p a r t s o f th e e t h a n o l - b l e n d e d f u e lp r o d u c t i o n c y c le to t e n e n v i r o n m e n t a l i m p a c t c a t e g o r ie s -g r e e n h o u s e e f f e c t, a c i d i f ic a t i o n , e u t r o p h i c a t i o n , w i n t e r s m o g ,

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I nt J L C A 8 ( 3 ) 1 3 7 - 1 41 ( 2 0 0 3 )9 e c o m e d p u b l i s h e r s , D - 8 6 8 9 9 L a n d s b e r g , G e r m a n y a n d F t . W o r t h / T X * T o k y o ,, M u m b a i ~ S e o u l ~ V i c t o r i a * P a r i s 137

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s um me r s mog , c a rc inogen ic s ubs tances , heavy me ta l s , ozonelaye r dep le t ion , pe s t i c ide s , and s o l id was te s - we re de te r -m i n e d . T h e s t u d y a l s o r e v e al s t h o s e c o m p o n e n t s o f t h e l if ec y c l e t h a t a r e t h e m o s t d e m a n d i n g w i t h r e s p e c t t o e n e r g yc o n s u m p t i o n a n d u s a g e o f m a t e r i a l r es o u r ce s . T h i s p r o v id e sa c o m p r e h e n s i v e e n v i r o n m e n t a l p i c tu r e o f t h e p o t e n t i a l b en -e f it s a n d i m p a c t s o f s u b s t i t u t in g g a s o l i n e w i t h b i o - e t h a n o l /ga s o l ine b lend and h igh l igh t s s pec i f i c a rea s whe re fu r the rt e c h n o l o g i c a l d e v e l o p m e n t c o u l d y i e l d e n v i r o n m e n t a l i m -p r o v e m e n t s . T h e s e i n s i g h ts a r e i m p o r t a n t t o b o t h r e s ea r c h -e r s o f t h e t e c h n o l o g y a n d p o l i c y m a k e r s .1 L i fe C y c l e A s s e s s m e n t1 .1 E t h a n o l f u e l a n d f u n c t i o n a l u n i tAs a veh ic le fue l , e thano l i s ma in ly us ed in one o f two ways[1,2] . The f i rs t one is b lend ed w ith gasol ine , typica l ly 5 to 2 0percen t by volum e, for use in exis t ing vehic les w ith no enginemodi f i ca t ions . T he s econd i s to u s e the e thano l , a lm os t in i tspure form (85 to 100%), in vehic les with specif ica l ly modi-f i ed eng ines . In th i s s tudy , e thano l i s a s s umed to be us ed a s am i x t u r e o f 1 0 % e t h a n o l a n d 9 0 % g a s ol in e b y v o l u m e ( te r m e dhe re E l0 ) on n ew veh ic l es w i th n o eng ine mod i f i ca t ions .T h e f u n c t i o n a l u n i t c h o s e n i s to c o m p a r e t h e l if e c y c le f l o w so n t h e b a si s o f o n e - k i l o m e t e r d i s t a n c e d r iv e n b y n e w p a s -s enge r ca r s .Unde r the s e cond i t ions , t he am oun t o f fue l r equ i red fo r t r av -e l ling I km i s c a l cu la t ed to be 62 . 4 g and 61 . 94 g fo r E l0 andgasol ine , respect ive ly . This is based o n fu el econo m y of 11.9ki lom eter per l i t re (or iginal 28 m iles /ga l lon, c i ted from the USE ne rgy In fo rm a t ion Adm in i s t ra t ion in [3 ] ). Fue l e conom y isa s s umed to be the s ame fo r E l0 and gas o l ine , a l though , a srepor t ed in [3 ] , i n -use expe r i ence ha s ind ica ted tha t E l 0 ma yhave approx im a te ly a 1 % fue l e cono my penal ty .1 . 2 S c e n a r i o s a n d a l l o c a t i o nT h e r a w b i o m a s s m a t e r ia l f o r e t h a n o l p r o d u c t i o n m a y e i th e rcome f r om ag r i cu l tu ra l and fo re s t wo od w as te s o r, i f t he p rod -uc t dem and i s s u f f ic i en t ly la rge , f rom cu l t iva ted feeds tock (as -s umed to be hay p roduc t ion in On ta r io ) . T he p roces s s t eamrequ i red fo r b reak ing dow n the s ubs t ra t e and s ubs equen t hy -d ro lysi s , f e rmen ta t ion and d i s ti l la t ion ma y be p rov ided th ro ughconven t iona l fo s s il / e lec t r ic i ty s ou rce s o r th rou gh the us e o fwas te b iom as s . Aga in , i f p rod uc t d em and i s s u f f ic i en t ly a rge ,the re ma y be an incen t ive to d ive r t t he was te b iomas s us ed a sa p roces s ene rgy s ou rce fo r u s e a s feeds tock and to s ubs t i tu t ean a l te rnat ive , poss ibly foss i l -based, source . To examine thecons equences o f the s e op t ions , fou r s cena r ios we re ana lyzed .T hes e a re s hown in T ab le 1 .T a b le 1 : F o u r s c e n a r io s o f b io - e t h a n o l f u e l s tu d ie d

C a ~ ] F ~ s t o c k I p r o c e s s E n ~ o u r c eE1 0 - A [ C u l t i v a t e d ] F o s s i l E le c t r ic G r idE1 0 - B I W a s t e B io m a s s I F o s s i l E le c t r ic G r idE 1 0 - C I C u l t i v a t e d [ W a s t e B i o m a s s ( li g n in , e t c . )E1 0 - D I W a s t e B io m a s s [ W a s t e B io m a s s ( lig n in , e t c . )

T h e r e a r e a n u m b e r o f p o t e n t i a l b y - p r o d u c t s a s s o c i a te d w i t hb io -e than o l p roduc t io n , i nc lud ing l ign in , pen tos e s uga rs an dan ima l feed p roduc t s . Bes ide s be ing us ed fo r e thano l p ro -d u c t i o n , p e n t o s e s u g a r s ca n b e c o n c e n t r a t e d t o 4 8 % s y r u p ,w h i c h c a n t h e n b e s o l d a s a n i m a l f e e d m o l a ss e s o r b e u s e da s s u b s t r a t e f o r y e a s t p r o d u c t i o n . T h e y c a n a l s o b e u s e d t op r o d u c e a m e t h a n e - r i c h b i o g a s t h r o u g h a n a e r o b i c d i g e s t i o n ,o r be co nve r t ed to fu r fu ra l , wh ich i s a u s e fu l chem ica l in te r -med ia te in s ome indus t r i e s . Any exces s yeas t no t r equ i redf o r f e r m e n t a t i o n c a n b e d r i e d t o a b o u t 1 0 % m o i s t u r e c o n -t e n t ( M . C . ) a n d s o l d a s f o d d e r y e a s t . L ig n i n c a n b e s o l d f o rl ign in chemica l s , i n the a rea o f pheno l i c s ubs t i tu t ion , o r c anbe us ed to p rodu ce s t eam o r e l ec t r i c i ty fo r p l an t u s e , o r c anbe s o ld d i rec t ly a s fue l [4 ]. How eve r , becaus e the b io -e tha -no l p roduc t ion p roces s i s s t i l l a t t he p i lo t -p lan t s t age , t h i sL C A h a s t r e a t e d t h e b y - p r o d u c t s a s i f t h e y h a d n o v a l u e b ya l l o c a ti n g 1 0 0 % o f t h e i n p u t s t o t h e m a i n p r o d u c t - b i o -e thano l . T h i s i s a cons e rva t ive e s t ima te o f the env i ronmen-ta l l oads a t t r ibu tab le to b io -e thano l , bu t i t c an be ju s t i f i ab leg i v e n t h a t s u f f ic i e n t m a r k e t s f o r t h e b y - p r o d u c t s m a y n o te x i s t a t c o m m e r c i a l sc a le p r o d u c t i o n v o l u m e s . A n L C A w i t hs i g n i fi c a n t b y - p r o d u c t a l l o c a t io n w o u l d o n l y b e v a l i d t o t h ee x t e n t t h a t t h e b i o - e t h a n o l p r o d u c e r d e v e l o p s a n d m a i n t a i n st h e se b y - p r o d u c t m a r k e t s .1 . 3 S y s t e m b o u n d a r y a n d d a t a s o u r c e sF i g. 2 s h o w s t h e m a j o r o p e r a t io n s i n c l u d e d w i t h i n t h e b o u n d -a r y o f t h e b i o - e t h a n o l s y s t e m f o r c o n d u c t i n g t h e l if e c y c lei n v e n t o r y ( L C I ) ca l c u l a ti o n s . D a t a g a p s r e s u l t in g f r o m c o m -merc ia l con f iden t i a l i ty o r gene ra l da ta unava i l ab i l i t y a re f i ll edb y m a k i n g a v a r i e t y o f a s s u m p t i o n s a s n o t e d b e l o w . T o p r o -t ec t i n t e l l e c tua l p rope r ty r igh t s , i ndus t ry ave rage da ta a regene ra l ly u s ed , p re fe r r ing On ta r io ave rages whe reve r the s ee x i st . P r o d u c t i o n a n d e n d - u s e c o m b u s t i o n t e c h n o l o g i e s r e -f l e c t cu r ren t be s t -ava i lab le pe r fo rm ance . Da ta in the s tud ywere co l l ec ted f rom a va r i e ty o f s ou rce s inc lud ing re s ea rchrepor t s , expe r t s , l i te ra tu re , and recen t env i ronm en ta l r epo r t so f the wor ld ' s l e ad ing comp an ie s in re l a t ed f i e ld s . Som e da taw e r e t a k e n d i r e c tl y f r o m t h e S i m a P r o 4 . 0 d a t a b a s e .N o t i n c l u d e d a r e t h e m a n u f a c t u r i n g a n d m a t e r i a l s o f c o n -s t ruc t ion o f c ap i t a l equ ipmen t and fac i l i t i e s u s ed fo r e tha -n o l p r o d u c t i o n a n d a u t o m o b i l e s , o r t h e p a c k a g i n g s y s t e mf o r e t h a n o l d i s t r i b u t io n .1 . 4 K e y a s s u m p t i o n sI n t h i s s tu d y , t h e t r a n s p o r t a t i o n o f m a t e r i a ls a n d p r o d u c t s i sa s s u m e d t o b e b y r o a d , u s i n g m e d i u m - h e a v y d ie s el t r u c k sw i t h a l o a d o f 6 . 4 t o 1 5 t o n n e s . T h e t r a n s p o r t a t i o n d i s t a n c ei s a s s u m e d t o b e 1 5 0 k m ( 3 0 0 k m b o t h w a y s ) u n le s s sp e ci -f i e d o th e r w i s e . I n th e S i m a P r o 4 . 0 d a t a b a s e , t h e L C I d a t aa s s o c ia t e d w i t h m e d i u m - h e a v y p e tr o - d ie s e l t r u c k t r a n s p o r -t a t i o n a r e r e la t e d t o a v e r a g e e m i s si o n a n d f u e l c o n s u m p t i o nf o r t r a n s p o r t i n g 1 3 . 8 t o n n e - k m i n th e N e t h e r l a n d s . T h i s iscons ide red to be rep re s en ta t ive o f med iu m-h eavy d ie se l t ruckp e r f o r m a n c e s f o r t h e p u r p o s e s o f t h e s t u d y r e p o r t e d h e r e .S u b s e q u e n t l y , i t w a s f o u n d t h a t t h i s w o u l d n o t r e p r e s e n t

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I= LigninExcess Yeast

b Pentose

F i g . 2 : S y s te m b o u n d a r y a n dprec is e ly the L CI da ta fo r pe t ro -d ie s e l in C anada . In Ca nada ,the pe t ro -d ie s e l is a b lend s ourced f rom heavy o i l , o f f - s horeoi l and so-cal led 'synth et ic ' o i l (derived fro m oi l sands) . Thisb lend va r ie s ac ross C anad a . Ho wever , s ince th i s on ly a f fect st h e t r a n s p o r t a t i o n c o m p o n e n t o f t h e a n a l y s is , it i s n o t c o n -s idered s ignif icant .T h e m a n u f a c t u r i n g o f g a s o li n e a n d o f E l 0 h a s b e e n c o n s i d -e red a t a comparab le l eve l o f de ta i l . T he L CI da ta a s s oc i -a t e d w i t h p e t r o l e u m g a s o l i n e m a n u f a c t u r i n g h a v e b e e nt a k e n d i r e c t l y f r o m t h e S i m a P r o 4 . 0 d a t a b a s e , w h e r e a s d a t af o r t h e m a n u f a c t u r e o f b i o - e t h a n o l h a v e b e e n d e r i v e d f r o mC a n a d i a n s o u r c e s . A l t h o u g h t h e L C I f o r g a s o l i n e s o u r ce di n C a n a d a d i f fe r s f r o m t h a t i n S i m a P r o , s i n c e E l 0 f u e l c o n -t a i n s 9 0 % g a s o l in e a n d t h e c o m p a r i s o n s r e p o r t e d h e r e a r eb e t w e e n 1 0 0 % g a s o l in e a n d E l 0 , a n y r e g io n a l d if f e re n c e sin L CI t end to cance l ou t . I t wo u ld be s ign i f i can t i f thea b s o l u te , r a t h e r t h a n r e l at i v e, n u m b e r s w e r e u s e d i n d r a w -ing the conc lus ions .

da t a s ou r c es f o r b io - e t hano l LCAFor g reenho us e gas em is s ions , on ly fos s i l -based C O 2 emis-s ion i s coun ted ; b io -bas ed CO z i s t rea ted a s ze ro ( i. e. c a rbo nneu t ra l ) , a s s uming th i s ba lances wi th s eques t ra ted ca rbono v e r t h e l o n g t e r m .2 R e s u l t s a n d D i s c u s s i o n s

I n t h e p r e s e n t a t i o n o f t h e f i n d i n g s th a t f o l l o w s , i t w o u l d b eu s e f u l t o b e a b l e t o p u t e r r o r b a r s o r c o n f i d e n c e b o u n d s o nthe re s u l t s to con f i rm tha t the d i f fe rences obs e rved be tw eenthe s cena r ios i s s ign i f i can t. T h i s can be done th ro ugh s ens i-t i v it y an a l y s is , b u t h a s n o t b e e n c o n d u c t e d o n t h i s s t u d y a st h is i s c u m b e r s o m e u s i n g S im a P r o . H o w e v e r , i t is i m p o r t a n tt o p o i n t o u t t h a t t h e L C I f o r g a s o l in e i s c o m m o n t o a l l sc e-na r ios , the on ly d i f fe rence be ing tha t fo r gas o l ine a lone i tr e p r es e n ts 1 0 0 % o f t h e e m i s si o n s , w h i l e f o r E l 0 i t is 9 0 % .T hus , the d i f fe rences obs e rved b e tween the s cena r ios a re duea l m o s t e n t i r e l y t o t h e e f f e c t o f 1 0 % b i o - e t h a n o l r e p l a c i n g10% gas o l ine .

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Fig. 3: Characterization result - distribution of l i fe-cycle environmentalperformance of ElO-a

The LCA results associated with scenar io E10-a are pre-sented in Fig. 3 for ten impact categor ies . Per km dr iven,they are:9 greenhou se gases: equiva lent to 0.256 kg CO 2 ( the CO 2 emission

of b iomass or ig in is treated as zero)9 acid i fy ing gases: equiva lent to 1.88 g SO 29 eutrophicat ion: equiva lent to 0.278 g PO 49 winter smog: equiva lent to 0.689 g dust9 summ er smog: equiva lent to 1.08 g C2H 49 ozone deplet ing gases: equiva lent to 0.318 mg CFC119 heavy meta ls: equiva lent to 0.654 mg Pb9 carc inogenics: equiva lent to 0.00608 mg benzo[a]pyre ne9 so l id wastes: 0 .719 g9 energy consumption: 5 .1 MJ.For scenario E10-a, m ost o f the energy consumption and emis-sions originate f rom the comb ustion of the fuel and the pro-duction of gasoline. This is not unexpected, since 90% of El0is made up of gasoline. Similarly, most of the emissions ofozone depletion substances, heavy metals, and carcinogenicsubstances or iginate f rom gasoline manu factur ing.For bio-ethanol production , Fig. 3 indicates that enzym e manu-factur ing, s team production, and transpor tat ion are the mainhot spots in terms o f most impact categor ies , including energyco n s u m p t i o n , g r een h o u s e g as em i s s i o n s , a c i d i f i ca t i o n ,eutrophication, winter smog, and summer smog. Feedstockcu l t iva t ion i s a l so a major con t r ibu to r to ac id i f ica t ion ,eutroph ication, hea vy metals, and carcinogenic substances. Italso involves land use and bio-diversity issues, w hich, whilecr i tical, cannot be examined using current LCA methods.Fig . 4 compares the env i ronmenta l per fo rmance o f E l0 fuelwith petroleum gasoline for all four scenar ios. I t can be seenthat E l0 consumes less energy than gasoline man ufactu r ingunder al l condit ions. The method of producing process en-ergy seems more inf luential than the source of feedstock.This ar ises because in the LC A for electr ici ty generat ion,fuel extract ion and fuel processing are both energy consum-ing. In contrast , bio-fuels for process energy made f rombiomass such as s traw, wo od chips a nd l ignin, demand lessenergy for extract ion an d processing.From Fig. 5 , i t can be seen that the source of energy forprocess s team generation is cr i t ical for determining whichfuel , gasoline or El 0, is cleaner in terms of greenhouse gas

Fig. 4: Score sheet (reference to gasoline)

emissions. I f bio-fuel has been used to generate s team forbreaking down the feedstock, El0 fuel wil l produce lessgreenhouse gases than tradit ional gasoline. On the otherhand, i f fossi l-based electr ici ty has been used in e thanol pro-duction, gasoline seems to be mo re cl imate change f r iendly.The greenhouse gas contr ibution f rom feedstock cult ivationis relat ively small . Here, the emissions are due mostly toN20 f rom the cult ivation step, and methane, fossi l CO2,etc. f rom the p roduc tion of fer ti l izers and pest icides.

Fig. 5: Comparison of l i fe-cycle greenhouse gas emissions for El0 fuelsand gasol ine per km driven

From Fig. 3, it is evident that bio-ethanol feedstock cultiva-t ion and enzym e manufa ctur ing are the main contr ibutors toeutrophication. For feedstock cultivation, the eutrophicationimpacts derive principally from the use of nutrients to enha ncegrowth and from the production of fertilizers. For enzymemanufactur ing, the main impacts come f rom feed production,since grains are needed for enzyme nutrition, an d air and wa-ter emissions from the en zyme ferm entation process.For winter smog em issions, the relat ively high contr ibutionmad e by enzyme manu factur in g is due to the emissions f romits energy consumption and f rom the fermentat ion process.The r e la t ive ly high con t r ibu t ion m ade by s team prod uct ionis due to the com bustion of the fuels. I f the s team ha s beengenerated using bio-fuel for the purpose of breaking downthe feedstock, winter smog emissions wil l be lower , s incethe em ission of SO 2 f rom the com bustion of bio-fuel will belower th an t hat of fossi l fuels.

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F ig . 4 i n d i ca t es t h a t t h e ch o i ce o f fu e l fo r s t eam g en e ra t i o na n d t h e s o u r c e o f f e e d s t o c k m a k e s n o d i f fe r e n c e t o s u m m e rsmo g emi ss io n s . Th i s i s b ecau se , f o r b io -e th an o l man u fac-t u r i n g , s u m m e r s m o g e m i s s i o n s a r e m o s t l y a r e s u l t f r o men zy m e p ro d u c t i o n , a s i l l u s t r a t ed i n F ig . 3 . As o n e mig h te x p e c t , t h e m a i n c o n t r i b u t i o n t o s u m m e r s m o g c o m e s f r o mf u e l c o m b u s t i o n i n a u t o m o b i l e s .F o r so l i d was t e em i ss io n s , t h e r e l a t i v e ly h ig h co n t r i b u t i o nb y e n z y m e a n d f e r ti li z e r m a n u f a c t u r i n g i s d u e p r i m a r i l y t oth e ash c r ea t ed t o su p p ly t h e p ro cess en erg y r eq u i r ed f o rp r o d u c t i o n .F o r imp ac t s o n ac id i f i ca t i o n , t h e co n t r i b u t i o n f ro m en zy mema n u fac tu r i n g r esu l t s f ro m th e emi ss io n s f ro m i ts en erg y co n -sumpt ion , the agr icu l tu ral act iv i t ies fo r i t s raw mater ial p ro-d u c t i o n , an d f e rmen ta t i o n p ro cess fo r i ts man u fac tu r i n g . Th eco n t r i b u t i o n f ro m feed s to ck cu l t i v a t i o n is main ly d u e t o t h eemissions f rom the nu t r ien ts in the cu l t ivat ion s tep , the f ieldo p era t i o n s an d p h o sp h a t e f e r t i li ze r man u fac tu r i n g .Al th o u g h t h e t o t a l ca r c in o g e n i c emi ss io n s a r e r e l a t iv e ly l o w( 0 . 07 m g b e n z o [ a ] p y r e n e - e q u i v a l e n t p e r f u n c t i o n a l u n i t ),f e e d s t o c k c u l ti v a t io n , m a i n l y t h r o u g h p e s ti c id e m a n u f a c t u r -i n g , is c r i t ica l f o r d e t e rm in in g w h e th e r b io -e th a n o l fu e l g iv esmo re ca rc in o g en i c emi ss io n s t h an t r ad i t i o n a l g aso l i n e . I f t h ef e e d s t o c k h a s b e e n g r o w n f o r t h e p u r p o s e o f e t h a n o l p r o -d u c t i o n , t h e ca rc in o g e n i c emi ss io n s mu s t b e as s ig n ed t o t h eb io -e th an o t p ro d u c t , an d t h e E1 0 wi l l b e le ss c l ean t h an g aso -l in e a l o ne . O n t h e o t h e r h a n d , i f w a s t e w o o d o r a g r i c u l tu r a lwas t e i s u sed , th i s a s s i g n men t wi l l n o t b e mad e an d ca rc in o -g en i c emi ss io n s fo r E l0 wi l l b e mu ch l es s an d s imi l a r t oth o se o f g aso l i n e .

3 C o n c l u s i o n sBased o n t h e as su mp t io n s an d t h e d a t a so u rces ap p l i ed t oth i s LCA s tu d y , t h e fo l l o win g co n c lu s io n s can b e d rawn :9 E th an o l fu e l a s a b l en d i n g aso l i n e m ay h e lp t o r ed u ce

o v era l l l i f e -cy c l e g reen h o u se g as em i ss io n s o n ly i f t h e en -e rg y r eq u i r ed t o g en era t e t h e p ro cess s t eam d er iv es f ro mbiom ass (e .g . l ign in o r b io-fuel ) rath er tha n foss i l fuelf o r p r e t r e a t m e n t o f t h e f e e d s t o c k .

9 Rep l ac in g t r ad i t i o n a l g aso l i n e b y E l 0 fu e l ma y sav e en -e rg y , l ead t o le s s su mm er sm o g an d o zo n e d ep l e t i n g su b -s t an ces , an d l o wer d i sch arg es o f h eav y meta l s . I t may ,h o wev er , r e su l t i n i n c reased eu t ro p h i ca t i o n , ac id i f i ca t i o na n d w i n t e r s m o g , a n d g e n e r a t e m o r e s o l id w a s t es .

9 F o r b i o - e t h a n o l p r o d u c t i o n , e n z y m e m a n u f a c t u r i n g , en -e r g y c o n s u m p t i o n f o r b r e a k i n g d o w n f e e d s t o c k a n d h a u l -ag e a r e t h e main so u rces o f imp ac t . I t i s i n t h ese a r easth a t r ese a rch can b es t b e fo cu ssed t o imp ro v e o v era l l l i fec y c le e n v i r o n m e n t a l p e r f o r m a n c e .

9 Feeds tock cu l t ivat ion con t r ib u tes s ign i f ican t ly to env i ron -men ta l imp ac t i n a lmo s t a l l ca teg o r i es , b u t p a r t i cu l a r l y t oac id i f i ca t i o n , eu t ro p h i ca t i o n , h eav y meta l s an d ca rc in o -gen ic substances . I t can also be expected to g ive r i se tob iod ivers i ty , landsca pe m odif icat io n and land-use impacts .Use o f b io mass was t e as a f eed s to ck av o id s t h ese imp ac t s .

4 R e c o m m e n d a t i o n s a n d O u t l o o kT h e L i fe C y c l e A s s e s s m e n t c o n d u c t e d o n b i o - e t h a n o l s e r v e dto h ig h l i g h t t h e co n d i t i o n s an d t h e l ev e l o f b en ef i t s t h a t canb e d e r i v ed f ro m th e u se o f b io -e th an o l b l en d ed fu e l fo r t r an s -p o r t a t i o n . F o r e x a m p l e , i t w a s f o u n d t h a t a n y a d v a n t a g e so f b i o - e t h a n o l o v e r g a s o li n e i n t h e a r e a o f g r e e n h o u s e g a sred u c t i o n a r e h ig h ly sen s i ti v e to t h e s o u rce o f p ro cess en -ergy , and less sensi t ive to fee dstock cu l t ivat ion . As wel l , thosep ar t s o f t h e l i fe cy c l e an d t h e sp ec i f i c a r eas wh ere t h e u se o fb i o - e t h a n o l w i ll l e a d t o n e g a t i v e e n v i r o n m e n t a l i m p a c t s a r eid en t i f i ed . Th i s h e lp s t o d i r ec t f u tu re r esea rch o n t ech n o -l o g ic a l i n n o v a t i o n t o e n s u r e t h e e n v i r o n m e n t a l b e n e f i t s o fb io -e th an o l wi l l b e p rese rv ed , wh i l e t h e l imi t a t i o n s wi l l b eap p ro p r i a t e ly ad d ressed , a s t h e t ech n o lo g y i s s ca l ed u p fo rc o m m e r c i a l e x p l o i ta t i o n .

A c k n o w l e d g e m e n t s . T h e a u th o r s w o u l d l ik e to t h a n k K e it h R a i d o f t h eOnta r io M in is try o f Agr icu ltu re and R ick Upfo ld o f the Un ive rs i ty o f Gue lphf o r p ro v i d in g s o m e o f t h e d a t a u s e d i n th e s t u d y . T h e s u p p o r t o f J e f fPassmora o f Iogen Corpora t ion fo r ca r ry ing o ut th is s tudy and rev iew-ing th is manuscr ip t i s a lso gra te fu l ly ac kno wled ged .

R e f e r e n c e s[1] Keller JL (1984): Ethanol an d Meth anol as Fuel, in Encyclo-ped ia o f Chemical Processing and Design , 4 th ed i t ion ,(McK etta JJ, editor), Ne w York, M. D ekker, v. 20, pp. 11-3 9[2] Hom ew ood B (1993): Will Brazil's cars go on the Wagon?New Scientist, v. 137, pp. 22-24[3] Wang M, Saricks C, Wu M (1997): Fuel-Cycle Fossil EnergyUse and Greenhouse Gas Em issions of Fuel Ethanol Producedfrom U.S. Midw est Corn. Center for Transportation Research;Argonne National L aborato ry; Prepared fo r Ill inois Depart-

ment of Commerce; December[4] Edwards WC, Quan RG (1989): A Study of the Me rits andDifficult ies of Coupling a Softwood Sawmill and EthanolPlant. B.H. Levelton & Associates LTD. Prepa red for Effi-ciency and Alternative Energy Technology Branch; Energy,Mines and Resources Canada; Ottawa; Ontario; DSS Con-t ract No. 51SZ.23283-7-6026; September, 1989[5] SimaPro 4.0 Database[6] Environmental Data 1998 for Division Agribusiness, Novartis1998 Health, Safety and Environment Report (http:/ /www.info.novartis.com/media/main.html)[7] Sim aPro .0 Database (DieselB; diesel pre-combustion; source:BUWAL 132)[8] Ontario Ministry of Agriculture, Food, and Rural Affairs (http://www.gov.on.ca/OMAFRA/english/stats/crops/estimate.html/[9] Environmental Data 1997; Fran klinton Site, U.S.A.; Environ-men t & Bioethics Repo rt , Nov o Nordisk, (http://www.novo.dk/environm/ebr98/grafer/Site/site 35 1.html)

[10] SimaPro 4.0 Database (Petrol pre-combustion; sou rce: EMP A,BUWAL 300[11] SimaPro 4.0 D atabase (Medium-heavy diesel truck for trans-port of 13.8 tonne-km in the N etherlands with average load;source: IDEMA T 96)

Rece ived: June 5th, 2002A c c e p t e d : March 28th, 2003O n l i n e F i r s t : M a r c h 3 1 s t , 2 0 0 3

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