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# .fr-Vi-ca-l.-A-l ,Energ y an d Resource Consultants , Inc . P. 2

DIESE L FUE L QUALIT

YEFFECT S O NEMISSIONS , DURABILITY , AN D PERFORMANC E

Arepor t to :
Th e U.S . Environmenta l Protectio n Agenc y Offic e o f Polic yAnalysi s Washington , D.C .

Draf t fina l repor t

EPAContrac t //68-01-654 3 Wor k Assignmen t No . 5 0

by :

Crai g Mille r Christophe r Weave r Energ y an dResourc e Consultants , Inc . P O Drawe r 0 Boulder , Co . 8030 6 an d WilliamJohnso n Terrenc e Higgin s Sobotk a Consultants , Inc . 250 1 M Stree t N.W . Suit e 50 0 Washington , D.C . 2003 7

Septembe r 30 , 198 5P. 3

EXECUTIV E SOrMAR Y
Diese l engine s i nligh t an dheavy-dut y vehicle s emi t significan t amount s o f oxide s o f nitroge n(NOx) , particulat e matter , sulfu r oxides , an dunburne dhydrocarbons . Etaission s level s fo r thes e pollutant s ar e strongl y affecte db y

th e qualit y

an dcompositio n
o f th e diese l fue l used . Thi s stud y briefl y review s th e availabl e dat a an dexamine s th e feasibility , costs , an d cost-effectivenes s o f reducin g diese l emission s b y mandator y change s i ndiese l fue l conposition . Tw o type s o f change s ar e considered : (1 ) a drasti c reductio ni ndiese l fue l sulfu r content , alon e o r i nccotinatio nwit ha moderat e reductio ni nth e fractio no f aromati c hydrocarbon s i nth e fue l an d(2 ) effect s o n engin e durability , fue l economy , an drefinin g costs . Th e wor kreporte dher e i s intende da s a preliminar y evaluatio no f th e feasibilit y

an dcost-effectivenes s o f diese l emission s contro l throug hfue l modifications , lh e purpos e o f thi s preliminar y

stud y i s t o identif y

th e majo r issue s an dt o roughl y quantif y th e cost s an dbenefit s o f som e potentia l fue l modification s i norde r t o determin e whethe r thi s approac hshow s sufficien t premis e t o warran t furthe r regulator y attentio nb y EFA . A__EBL_t____ i

A thoroug hrevie w

o f th e technica l literatur e an dothe r availabl e informatio no nfuel-qualit y effect s o nemission s wa s undertaken . O nth e basi s o f thi a review , tw o scenario s fo r fue l qualit y i iP. 4

improvemen t wer e defined . Th e firs t scenari o include dreducin g diese l fue l sulfu r conten t t o O.O S percen t b y weight , wit ha n accompanying " decreas e i naromatics . Th e secondscenari o include d
a furthe r decreas e i naromati c content . A linear-program

mode l
o f the refinin g industry wa s use dt o mode l th e effect s o f thes e tw o scenario s coapare dwit ha baselin e case . Th e result s o f the modelin g effor t wer e combine dwit hinformatio no nmaintenanc e cost s andsaving s andemission s reduction s du e t o the improve d fue l qualit y

t o estimat e the overal l cost s an dcost-effectivenes s
o f eac hscenario . 

### CTm„BTfW t
Th e majo r conclusion s o f th e stud y ar e th e following . First , th e mos t importan t emissions-relate dpropertie s o f diese l fue l ar e the sulfu r conten t andthe fractio no f aromati c hydrocarbons . Reducin g fue l sulfu r woul dreduc e S O emission s andth e sulfat e 2 fractio no f diese l particulates, , andwoul dindirectl y reduc e ambien t level s o f sulfat e particles . Reducin g fue l aromati c conten t woul dreduc e th e carbonaceou s fractio no f diese l particulat e emissions . Contrar y t o canno nbelief , change s i nthe distillatio nteaperature s (suc ha s th e 9 0 percen t poin t andend point ) hav e littl e potentia l fo r emission s control . Second , the sulfu r conten t o f automotiv e diese l fue l coul db e reduce dfrom

th e presen t averag e o f abou t 0.27 4 percen t t o 0.04 8 percent , withou t reducin g th e availabilit y o f diese l fuel , and usin g onl y

the presen t capita l stock . Thi s woul drequir e ii iP. 5

segregatin g productio n o f diese l fue l fro mtha t o f distillat e burne r fuels , a s wel l a s hig h rate s o f utilizatio n o f existin g desulfurizatio n capacity
. Th e increas e i n averag e refinin g cos t du e t o desulfurizatio n woul d b e abou t 1. 2 cent s pe r gallon . Th e averag e aromati c conten t o f th e fue l woul d als o b e reduce d by desulfurizatio n fro mth e presen t 28. 7 percen t t o abou t 20. 3 percen t byvolume . Third , reducin g th e sulfu r conten t o f diese l fue l woul d significantl yreduc e corrosiv e wea r an d deposi t formation , extendin g engin e lif e an d reducin g maintenanc e costs . A conservativ e estimat e base d o n th e limite d dat a availabl e indicate s tha t thes e saving s woul d b e abou t fou r time s th e increas e i n refinin g costs . Lowerin g th e sulfu r conten t woul d thu s resul t i n significan t ne t saving s t o societ yeve n ignorin g th e environmenta l benefits
. Th e lowe r aromati c conten t du e t o desulfurizatio n woul d als o improv e cetan e number s an d ignitio n quality , reducin g col d startin g problem s an d noise
. Finally , i t woul d b e feasibl e t o reduc e aromati c conten t t o 1 7 percen t byvolum e usin g th e presen t capita l stock . Thi s woul d increas e refinin g cost s byabou t 0. 4 cent s pe r gallo n beyon d th e
cos t o f desulfurization . Th e incrementa l cos t o f particulat e contro l b ythi s mean s woul d b e abou t $5.5 0 t o $10.0 0 pe r poun d o f particulat e matte r eliminated
.

i vP. 6

TABL E OF CONTENT

S

EXEOTnV E SOMAR

Y i i PREFAC E x #30m_EIX£MENT S xi i 1. 0 INTRODUCTIO

N 1- 1 1. 1 __A_XG_a_N

D INKFMATIO N 1- 1 1. 2 OUTLIN

E O F TH E APHCMO . 1- 3 1. 3 MAJO

ROaCXJUSIOMS OF TH

E STUD Y 1- 6 1. 4 LIMITATIONS fiND CAVEAT S 1- 7
2 . 0 DIESE L FUE

L QUALIT Y AN D COrlPOSITION 2- 1 2 . 1 OCMPOSITIO

N A © PROPERTIES O F A_7IO>CTIV E DIESE L FUE

L 2- 1 2. 2 DIESE L FUE L QUALIT YINDICE S 2- 6 2 . 3 OH-EN T FUE

L QUALIT Y STANDARD

S AM ) I-EOILATIONS 2-1 1 2 . 4 TREND

S I N DIESE L FUE

L QUALIT Y 2-1 3
3 . 0 FUE L QUALIT Y EFFECTS O

N DIESE L ENGINES 3- 1 3 . 1 FUE L SULFU ROQNTON

T 3- 2 3 . 2 AROMATI

C OCNTEN

T AN D ICN_TIO N QUALIT

Y 3-1 5 3 . 3 FUE L BOILIN G RANG

E AM ) VOLATILITY 3-2 9 3. 4 EBBIT Y AN

D VISCOSIT

Y 3-3 4 3 . 5 STABILITY , E__F06I T FCRMATIO N AM ) OTHE

RFRDPERTIE S 3-3 6
4 . 0 MXELIN G TH

E COSTS OF REFININ G CHANGE S 4- 1 4 . 1 REFINHtY MCEE

L 4- 1 4. 2 MCCELIN

G APPROAC

H 4- 4P. 7

4. 3 MXE

LASSUVPTION

S 4- 5 4. 4 MCCE

LAN D DAT A LIMITATION

S 4-1 3
5. 0 MXE

L RESULT

S AM ) CC6T-I-FFBCTIVENES S fl(ALYSIS 5- 1 5.1 : EEFINITIO

NO FTH ETW O SCENARIO

S 5- 1 5.2 : RESULT

S FROMTH

EREFININ

GCOS T MXE L5- 4 5.3 : SCENARI

O ONE : I2ESULFURIZATTO NLlrHJUr

S O NENGINE

S AM ) EMISSION

S
. 5-1 2 5.4 : SCENARI

O TVO : EEARCMATIZATia NEFFECT

S O NENGINE

S AN D EMISSION

S
. 5-1 6 5.5 : COOT--__TBCT

I VENES S C FFUE LQUALIT Y REGULATION

S 5-1 7
6. 0 CONCLUSION

S AN D REOOrt'teNDATION

S 6- 1
BIBLICXBAPH

Y BIB- 1

v iP. 8

LIS T O F FIGURE S

2. 1 Classe s o f hydrocarbo nmolecule s foun dindiese l fue l 2- 4 2. 2 Relationshi pbetwee naromati c conten t andcetan e nixnbe r 2- 8 2. 3 Trend s i nsem

e propertie s o f typ e T- T andgrad e 2- D 2-1 5 diese l fue l oil s 2. 4 Distributio no f diese l fue l aromati c conten t frcm th e 2-1 7 MVM A sunnie r survey s 2. 5 Distributio no f AP I gravit y o f diese l fuel s fro m th e MVM A 2-1 8 surrme rsurvey s 2. 6 Distributio no f calculate dcetan e indexo f diese l fuel s 2-1 9 from th e MVMA

sunnie r survey s 2. 7 Distributio no f 9 0 percen t poin t o f diese l fuel s frcm th e 2-2 0 MVM A suome r survey s 2. 8 Distributio no f sulfu r conten t o f diese l fuel s from th e MVM A 2-2 1 surrme r survey s 3. 1 Effec t o f fue l sulfu r conten t andoi l alkalinit y o n3- 9 pisto nring wea r rate s ina locomotiv e engin e 3. 2 Los s o f alkalinit y inoi l durin g us e du e t o neutralizatio n3-1 1 by sulfu r 3. 3 Effec t o f fue l sulfu r conten t o npisto nring wea r rat e 3-1 3 durin g engin e warmu pina nautomotiv e diese l engin e 3. 4 Effect s o f fue l aromati c conten t o nparticulat e emissions : 3-1 9 stead y stat e vs . transien t test s o na heavy-dut y engin e 3. 5 Regression s o f particulat e emission s vs . fue l aromati c conten t 3-2 4 fro m a nunbe r o f studie s usin g differen t light-dut y engine s 3. 6 Regressio no f particulat e emission s vs . fue l aromati c conten t 3-2 6 canbine ddat a fro

m a nwfce r o f light-dut y engin e studie s 3. 7 Effec t o f change s i nccopressio nrati o o nfue l consumptio nand3-2 8 smok e 3. 8 Regressio no f particulat e emission s vs . fue l 9 0 percen t point : 3-3 1 cen t ineddat a fro

m a mutoe r o f light-dut y engin e studie s 3. 9 Effect s o f 9 0 percen t poin t o nparticulat e emissions : transien t 3-3 3 vs . 13-mod e steady-stat e cycl e

vi iP. 9

5. 1 Refinin g cos t vs . aromati c conten t o f diese l fue l from the 5-1 1 Bonne r andMoor e stud y

vii iP.1 0

LIS T O F TABLE S

2. 1 AST M criteri a for gradin g o f distillat e diese l fue l 2-1 2 2. 2 Ccnparisio n o f AST M an d othe r specification s fo r diese l fue l # 2 2-1 4 2. 3 Statistic s o n selecte d diese l fue l propertie s byregio n 2-2 3 4. 1 U.S . Refiner yproduc t demand : 198 7 4- 7 4. 2 Refiner yproduc t deman d byregion s ,. . 4- 8 4. 3 Refiner yinputs : 198 7 4- 9 4. 4 Price s o f ra wmaterial s an d refine d products : 198 7 4-1 1 4. 5 Refine d produc t specification s 4-1 2 4. 6 U.S . Refiner yprocessin g capacities : 198 7 4-1 4 5. 1 Refinin g cos t mode l result s fo r PAED s I throug h I V 5- 5 5. 2 Refinin g cos t mode l result s fo r PAI D V 5- 6 5. 3 Refinin g cos t mode l result s fo r th e entir e U. S 5- 7 5. 4 Fue l costs , maintenanc e benefit , an d cost-effect!venes s o f 5-1 9 regulation s fo r a typica l light-dut yca r o r truc k --.-- . 5. 5 Fue l costs , maintenanc e benefit , an d cost-effectivenes s o f 5-2 0 regulation s for a typica l light-heav ydut ytruc k 5. 6 Fue l costs , maintenanc e benefit , an d cost-effectivenes s o f 5-2 1 regulation s for a typica l medium-heavytruc k 5. 7 Fue l costs , maintenanc e benefit , an d cost-effectivenes s o f 5-2 2 regulation s fo r a typica l line-hau l truc k 5. 8 Fue l costs t maintenanc e benefit , an d cost-effectivenes s o f 5-2 3 regulation s fo r a typica l transi t bu s

i xP.1 1

PREFAC E

Thi s documen t i s th e fina l repor t o f a ninvestigatio no f diese l fue l qualit y

effect s o nemission s ando f the feasibility , costs , andbenefit s o f a nationwid e diese l fue l standar dfo r emission s control . Th e desirabilit y o f conductin g suc ha stud y ha dbee n suggeste dinpreviou s wor kby Energ y an dResourc e Consultant s (Weave r andMiller , 1983 ; Weave r e t al , 1984) , i nwhic hsome othe r aspect s o f diese l emission s proble m wer e examined . A numbe r o f engin e manufacturer s hav e also expresse dconcern s ove r deterioratin g fue l qualit y t o the EPA . Thi s wor kwa s intende da s
a preliminar y

investigation , i norde r t o identif y th e issue s and t o determin e whethe r furthe r regulator y attentio ni s warranted .

Th e stud y wa s conducte da s a collaborativ e effor t betwee nEnerg y
andResourc e Consultant s andSobotk a andConpany , wit hfundin g provide db

y the U.S . EP A

Offic e o f Polic y

Analysis . Th e EP A projec t office r fo r thi s effor t wa s Willar dSmith . Energ y and Resourc e Consultant s wa s responsibl e fo r evaluatin g the effect s
o f fue l qualit y

o ndiese l engines , developin g th e tw o regulator y scenario s modeled , andcarryin g ou t the cost-benefi t analysis . Sobotk a an dCompan y

consulte do nthe developmen t o f th e tw o scenarios , an dcarrie dou t th e refinery cos t modeling .

Th e initia l projec t manager s fo r the tw o firm s wer e Christophe r Weave r fo r Energ y

andResourc e Consultant s andWillia m Johnso n for Sobotk a andCompany . Bot hprojec t manager s lef t employmen tP.1 2



### wit hthei r respectiv e firm s nea r th e en d o f th e project ; the y wer e replace da s projec t manager s byCrai g Mille r an d Terrenc e Higgins , respectively
. Bot ho f th e initia l projec t manager s complete d thei r wor k o n thi s projec t a s independen t consultant s t o thei r forme r employers ; bot hparticipate d i n th e authorshi p o f thi s fina l report .

x iP.1 3

^O-NOWLEDGEMENT S

Th e EP AProjec t Office r fo r thi s wor k wa s Mr . Wil l Smit h o f th e Offic e o f Polic yAnalysis
. Th e author s wis h t o expres s thei r thank s t o hi mbot h fo r arrangin g th e fundin g fo r th e wor k an d fo r hi s continuin g interes t an d suppor t durin g th e project
.

I n conpilin g thi s report , w e hav e draw n o n man ydiscussions , bot h forma l an d informal , wit h numerou s intereste d parties
. Thes e hav e include d refiners , automotiv e manufacturers , additiv e suppliers , independen t consultants , an d Stat e an d Federa l regulator yagencies
. I n additio n t o providin g data , thes e discussion s hav e provide d a valuabl e chanc e t o ai r preliminar y conclusions , brin g ou t hidde n issue s an d concerns , an d otherwis e refin e th e analysis
. W e gratefull ythan k al l o f th e partie s involved , bu t especiall yJoh n Wal l o f Chevro n Research , Do n Dowdal l o f Caterpillar , Lo u Broerin g o f Cuomin s Engine , Charle s Hudso n o f Internationa l Harvester , Richar d Luck i an d Barr yCahil l
o f Peugeot , an d Dou g Decke r an d Maci e LaMott e o f th e Colorad o Healt h Dept . Thei r informatio n an d assistanc e hav e bee n invaluable . However , non e o f thes e person s i s responsibl e for , no r d o they

necessaril y

agre e with , th e conclusion s expressed .

xi iP. M



## 1.0 : iNnracnc M

Diese l engine s i nligh t an dheavy-dut y vehicle s emi t significan t amount s o f oxide s o f nitroge n(NOK) , particulat e matter , sulfu r oxides , an dunburne dhydrocarbons . Emission s level s fo r thes e pollutant s ar e strongl y affecte db

y th e qualit y

andcompositio n o f the diese l fue l used . Thi s stud y briefl y review s th e availabl e dat a andexamine s th e feasibility , costs , and cost-effectivenes s o f reducin g diese l emission s b y mandator y change s i ndiese l fue l composition . Tw o type s o f change s ar e considered : a drasti c reductio ni ndiese l fue l sulfu r content , alon e o r i ncombinatio nwit ha moderat e reductio ni nth e fractio n o f aromati c hydrocarbon s i nth e fuel . Effect s o nengin e durability , fue l economy , an drefinin g cost s ar e considere dalon g wit hemission s effects .



### 1. 1 fyqainu n iwimuTif M

Th e natur e an dqualit y o f th e fue l bein g burne daffect s th e emission s frc m

virtuall y

ever y clas s o f engine . I ndiese l engines , thes e effect s ca nb e eithe r positiv e (resultin g i n reduce demissions ) o r negative , dependin g o nth e fue l an dthe



### 1- 1P.1 5

engine
. I n th e las t decade , disruption s i n th e suppl yo f oi l an d rapi d increase s i n it s cos t hav e le d t o th e widesprea d us e o f heavie r an d higher-sulfu r crud e oils , wit h a consequen t deterioratio n i n ignitio n quality , sulfu r content , an d othe r indice s o f diese l fue l quality
. Increase s i n diese l fue l consumptio n relativ e t o gasoline , an d phase-ou t o f lea d antiknock s i n gasolin e hav e als o contribute d t o thi s trend . Mos t knowledgeabl e observer s anticipat e tha t fue l qualit ywil l continu e t o deteriorat e i n th e futur e i f marke t force s ar e permitte d t o operat e freel y(McMilla n (ed.) , 1983) .

Th e prospec t o f furthe r degradatio n i n fue l qualit yha s generate d
concer n fo r th e possibl e effect s o f thes e change s o n emissio n levels . A t th e sam e time , concer n ove r diese l emission s i n genera l ha s le d t o th e establishmen t o f stringen t ne wemission s standard s fo r oxide s o f nitroge n (NOx ) an d particulat e materia l fro mne wlight-dut ydiese l vehicle s an d heavy-dut ydiese l engines
. Th e step s take n t o mee t thes e requirement s wil l plac e
ne wdemand s o n fue l quality
. Fo r example , th e change s i n fue l injectio n timin g i n heavy-dut yengine s require d t o conpl ywit h th e NO x standar dwil l mak e the mmor e sensitiv e t o ignitio n qualit ytha nheretofore , an d contaminant s suc h a s sulfu r an d as h hav e complicate d th e developmen t o f trap-oxidizer s fo r particulat e control .

Th e establishmen t o f emission s standard s fo r ne wvehicle s ha s


### 1- 2P.1 6

als o focusse dattentio no nemission s fro m the significan t numbe r
o f existin g diese l vehicle s tha t wil l no t b e affecte db y th e standards . Improving diese l fue l qualit y i s on e apparentl y reasonabl e approac ht o reducin g thes e emissions , an dha s attracte dconsiderabl e attentio nfo r thi s reason . Fo r instance , the Californi a Ai r Resource s Boar d(CARB ) ha s recentl y establishe da limi t o nsulfu r indiese l fue l a t 0.0 5 percen t b y weigh t i nth e Sout hCoas t Ai r Qualit y Managmen t District , whic h include s Lo s Angeles . Thi s actionwa s take nt o reduc e S O 2 emission s andambien t particulat e levels .
Th e CAR B standar do f 0.0 5 weigh t percen t sulfu r i s one-tent ho f th e presen t (non-binding ) standar dfo r # 2 diese l fue l establishe d b y the An e r i ca nSociet y fo r Testin g andMaterial s (ASTM) . Th e CAR B i s presentl y

considerin g extendin g thi s standar dt o cove r the res t o f California . Furthe r limitation s o naromati c conten t and/o r volatilit y

characteristic s ar e als o bein g considere dt o provid e additiona l particulat e control .


### i. 2 anmgjQ f

TH E APPBOK

H

Th e wor kreporte dher e wa s intende da s a preliminar y evaluatio n o f th e feasibilit y

andcost-effectivenes s o f diese l emission s contro l throug hfue l modifications . Th e purpos e o f thi s preliminar y

stud y wa s t o identif y

the majo r issue s an dt o roughl y



### 1- 3P.1 7

quantif yth e cost s an d benefit s o f som e potentia l fue l modification s i n orde r t o determin e whethe r thi s approac h show s sufficien t premis e t o warran t furthe r regulator yattentio n by EPA .

Th e wor k o f th e projec t wa s divide d int o fou r tasks . Th e firs t
an d mos t time-consumin g tas k wa s a thoroug h revie wo f th e recen t technica l literatur e dealin g wit h diese l fue l properties ; fue l effect s o n emissions , durability , an d performance ; an d relate d topics
. Thi s wa s supplemente d bynumerou s telephon e an d in-perso n discussion s wit h refiners , engin e manufacturers , an d othe r knowledgeabl e parties
. Th e result s o f thi s revie war e reporte d i n Chapter s Tw o an d Three . Chapte r Tw o present s a n overvie wo f diese l fue l conpositio n an d qualit yissues , am i set s th e stag e fo r th e mor e detaile d discussion s t o follow . Chapte r Thre e contain s a detaile d discussio n an d synthesi s o f th e availabl e dat a concernin g fue l effect s o n emissions
.

Th e informatio n develope d i n Tas k On e wa s use d i n Tas k Tw o t o develo p tw

o scenario s fo r improvement s i n diese l fue l quality
. Th e firs t scenari o consiste d o f a reductio n i n th e sulfu r conten t
o f diese l fue l t o 0.0 5 percen t byweigh t —th e sam e leve l mandate d b yth e CARB . Alinear-progra mrefinin g cos t mode l wa s
use d t o estimat e th e cos t t o th e refinin g industr yo f achievin g thi s reduction
. Somewha t surprisingly , th e mode l result s showe d
a substantia l decreas e i n aromati c conten t (fro m28-3 0 percen t t o


### 1- 4P.1 8

2 0 percen t b

y volume ) du e t o re-optimizin g for low-sulfu r fuel . A secondscenario , including lo w sulfu r plu s a furthe r reductio n i naromati c hydrocarbon s t o 1 7 percent , wa s als o modeled . Chapte r Fou r contain s a descriptio no f th e mode l use dandthe assumption s whic hwen t int o it .

I nTas kThree , th e mode l result s fro m Tas kTw o wer e cen t inedwit h the informatio ngathere di nTas kOn e i norde r t o asses s th e effect s o f eac hfuel-qualit y chang e o nemissions , durability , fue l economy , andcosts . Th e result s o f thi s assessmen t ar e containe di nChapte r Five . Chapte r Six , th e fina l chapter , present s th e conclusion s o f thi s analysi s an dreconmendation s fo r furthe r actio nb

y EPA . Thes e conclusion s ar e briefl y sunmarize d i nSectio n1. 3 below .



### 1- 5P.1 9

1 a >ujr R nrMrri^fi ^ m ? TOR gnn y

Th e majo r conclusion s o f th e stud y wer e th e following .
(1 ) Th e mos t importan t emissions-relate dpropertie s

o f diese l fue l ar e th e sulfu r conten t andth e fractio no f aromati c hydrocarbons . Reducin g fue l sulfu r woul dreduc e S O emission s andth e sulfat e fractio no f diese l particulates , andwoul d indirectl y

reduc e ambien t level s o f sulfat e particles . Reducin g fue l aromati c conten t woul d reduc e th e carbonaceou s fractio no f diese l particulat e emissions . Contrar y t o ccomo n belief , change s i nth e distillatio ntemperature s (suc ha s th e 9 0 percen t poin t anden dpoint ) hav e littl e potentia l for emission s control . (2 ) Th e sulfu r conten t o f automotive diese l fue l

coul db e reduce dfrom th e presen t averag e o f abou t 0.27 4 percen t t o 0.04 8 percent , withou t reducin g th e availabilit y o f diese l fuel , an

d usin g onl y

th e presen t capita l stock . Thi s woul d requir e segregatin g productio no f diese l fue l fro m tha t o f distillat e burne r fuels , a s wel l a s hig hrate s o f utilizatio no f existin g desulfurizatio ncapacity . Th e increas e i n averag e refinin g cos t du e t o desulfurizatio n woul db e abou t 1. 2 cent s pe r gallon . Th e averag e aromati c conten t o f th e fue l woul dals o b e reduce dby

desulfurizatio nfro

m th e presen t 28. 7 percen t t o abou t 20. 3 percen t b y volume . (3 ) Reducin g th e sulfu r conten t o f diese l fue l woul d

significantl y

reduc e corrosiv e wea r anddeposi t formation , extendin g engin e lif e an dreducin g maintenanc e costs . A conservativ e estimat e base d o nth e limite ddat a availabl e indicate s tha t thes e saving s woul db e abou t fou r time s th e increas e i nrefinin g costs . Lowerin g th e sulfu r conten t woul dthu s resul t i nsignifican t ne t Saving s t O societ y «w« niynnrin

y th o <>nvirmmpnt« i tvmafiti . Th e lowe r aromati c conten t du e t o desulfurizatio nwoul dals o inprove cetan e nunber s andignitio nquality , reducin g col dstartin g problem s an dnoise .



### 1- 6P.2 0

(4 ) I t woul d b e feasibl e t o reduc e aromati c conten t

t o 1 7 percen t b yvolum e usin g th e presen t capita l stock . Thi s woul d increas e refinin g cost s by abou t 0. 4 cent s pe r gallo n beyon d th e cos t o f desulfurization
. Th e incrementa l cos t o f particulat e contro l b ythi s mean s woul d b e abou t $5.5 0 t o $10.0 0 pe r poun d o f particulat e matte r eliminated
.

1. 4 UMITATICr e AM ) CAVEAT

S

Th e conclusion s o f thi s repor t rel yheavil yo n estimate s o f th e reductio n i n wea r rate s du e t o us e o f low-sulfu r fue l an d o f th e reductio n i n particulat e emission s du e t o lowe r aromati c content . Neithe r estimat e i s wholl ysatisfactory , du e t o th e limite d dat a available
. Thes e dat a ar e sufficien t t o establis h th e directio n an d approximat e magnitud e o f th e effects , bu t th e estimate s coul d b e inprove d bybette r data . Furthe r researc h o n th e effect s o f lo wvs . moderat e sulfu r fuel s o n engin e lif e woul d b e highl ydesirable , a s woul d additiona l carefully-designe d studie s o f th e relationship s betwee n aromati c conten t an d particulat e emission s i n a variet yo f heavy-dut yengines
.

Th e conclusion s als o rel yheavil yo n th e result s o f a linear-programnin g mode l o f th e U.S . refinin g industry
. Thi s mode l ha s bee n use d extensivel ybefore , an d i s considere d t o b e reasonabl yreliable
. Th e aggregate d natur e o f th e mode l result s i n som e over-optimization , however , s o tha t th e actua l refinin g



### 1-7P.2 1

cost s experience dwoul dprobabl y b e somewha t highe r tha nthe mode l predicts . Th e effect s o f thi s problem hav e bee nminimize d b y taking th e result s onl y a s th e differenc e betwee ntwo mode l
run s — thus , onl y

difference s i nth e degre e o f overoptim i zatio n betwee nth e tw

o run s woul daffec t th e results . On e are a wher e thi s ma y hav e occure di s i nthe usag e o f distillat e desulfurizatio ncapacity . Th e mode l indicate s tha t deman dfo r low-sulfu r diese l fue l coul db e me t usin g onl y th e existin g capacity , bu t a ver y

hig hrat e o f utilizatio nwa s required . I n reality , som

e refinerie s migh t hav e t o inves t i na smal l amoun t
o f ne w capacity , whic hwoul dincreas e the cost s o f desulfurizatio nsomewhat .

Th e mode l i s als o limite dt o accountin g fo r change s i nrefinery operatin g costs . Change s i ndistributio nan dmarketin g cost s du e t o th e segregatio no f diese l fue l from burne r fue l oi l wer e no t accounte dfor , an dw e wer e unabl e t o quantif y thes e costs . The y
ar e believe dt o b e small , however , whe ncompare dt o th e increas e i nrefinin g costs .



### 1- 8P.2 2

2.0 : niESET . BTTRT . CUALITY AM ) COffOSITIC N

Diese l fue l i s a coople xsubstance , surrounde db y a nequall y comple xse t o f definitions , qualit y indices , tes t methods , an d standards . Thi s chapte r review s th e compositio nandpropertie s
o f automotive diese l fuels , discusse s th e indice s o f fue l qualit y no w i nuse , review s the currentl y applicable fuel-qualit y standards , an ddiscusse s curren t andprojecte dqualit y trends . Thi s review

i s intende dprimaril y t o establis hth e necessar y backgroun dfo r th e section s whic hfollow ; it i s b y n o mean s complete . Mor e complet e discussion s ar e availabl e i nDor nan d Moura o (1984 ) andLill y (1984) , amon g others .

2 . 1 fTwPnRTTTf

W UsW) PHnPERTTE S CV ACTiTMnrnV

E nfESET . FTTET

.

Al l petroleun-derive dliqui dfuel s ar e coople xblend s o f differen t hydrocarbo nspecies . Automotiv e diese l fuel s ar e compose do f hydrocarbon s whic hboi l a t teaperature s betwee nabou t 30 0 an d70 0 F . Thi s rang e fall s betwee ntha t o f gasolin e (whic h i s a mi xo f ligh t hydrocarbons ) an dheav y ga s oils . Diese l fue l i s separate dfrc m

th e lighte r an dheavie r hydrocarbon s i ncrud e oi l by distillation , andi s thu s a "middl e distillate " fuel .



### 2- 1Othe r middl e distillat e fuel s includ e je t fuel , kerosene , and

severa l grade s o f distillat e fue l oil s fo r boiler s andothe r stationary

combustors .

Th e diese l fue l sol di nthe Unite dState s i s o f thre e types , onl y tw o o f whic har e use dfo r highwa y vehicles . Diese l # 1 contain s hydrocarbon s boilin g betwee nabou t 18 0 and25 0 C , whil e diese l #2 , a heavie r fuel , contain s hydrocarbon s boilin g betwee n20 0 and 35 0 C . Diese l # 1 i s mos t coomonl y use da s city-bu s (C-B ) fuel , sinc e bu s fleet s —

whic hpay

a premiu

m fo r i t becaus e it produce s lowe r smok e emission s — ar e it s primar y

users . Du e t o it s lowe r viscosity , diese l # 1 i s als o use di nver y col dweather , o r fo r blendin g wit hdiese l # 2 fo r col dweathe r operation . Diese l # 2 i s use db

y highway , farm , andconstructio nvehicle s fo r almos t al l othe r purposes , andaccount s fo r th e grea t preponderanc e o f fue l sol dfor automotiv e use . Diese l # 4 i s a stil l heavie r fue l whic hi s use di nrailroad , larg e stationary , andsome marin e engines , bu t no t i nhighwa y vehicles .

Thi s repor t deal s onl y wit hdiese l fuel s use dfo r highwa y vehicles , an dconcentrate s o ndiese l # 2 a s the mos t importan t o f these . I nadditio nt o th e fa r greate r usag e o f th e # 2 grade , diese l # 1 i s already

perceive da s (andprice das ) a premium fuel , an dha s thu s bee nles s subjec t t o deteriorationi nquality .
Diese l fue l i s mad e u po f thre e primar y type s o f hydrocarbons :


### 2- 2paraffin s (straight-chai nhydrocarbons) , napthene s (als o know na s cycloparaffins) , andaromatics . Th e thre e group s ar e distinguishe dby

thei r differin g molecula r structures , whic hi n tur nleadt o differen t physica l andchemica l properties . Thes e propert y difference s affec t the combustio nprocess , andthu s affec t engin e performanc e andemissions .
Figur e 2. 1 show s some typica l molecule s o f eac ho f th e thre e hydrocarbo ngroups . Th e aromati c hydrocarbon s ar e distinguishe d fro m the othe r tw

o classe s b

y the presenc e o f on e o r mor e "benzene-ring " structures , compose do f si xcarbo natom s strongl y bonde dint o a hexagon . The y ca nb e distinguishe dfrom th e napthenes , whic hals o hav e a ring structure , b y the fac t tha t the carbo natom s inthe napthen e ring ar e eac hbonde dt o four othe r atom s (tw

o carbo natom s i nth e ring andtw o hydroge no r "side-chain " atoms) . Th e carbon s i nthe aromati c ring ar e bonde d t o onl y on e hydroge no r side-chai natom , rathe r tha ntwo . Thi s strengthen s th e carbon-carbo nbond s i nth e ring structur e itself , s o tha t aromatic s d o no t bur na s readil y a s napthene s o r paraffins .

Th e hydrocarbon s i ndiese l fue l diffe r i nvolatilit y a s wel l a s chemica l i nstructure . Volatilit y i s closel y

relate dt o th e molecula r weight s o f th e hydrocarbo nspecie s involved . Lighte r hydrocarbon s boi l andca nb e distille dof f a t a lowe r temperature . Th e boilin g poin t o f a fue l sampl e increase s wit h



### 2- 3P.2 5

(.ont-r.i l <r"u n Tvn e l-urmul u i " Lxampl cStructur e I n iMrafftna s r N M :sf ^ C 16 H 1 « oi J -(ni J ) 1 4 -on J CH—-ai

. Monocvclop.traf fIn s "^' N ''ld^l' 1 \ / C H 3

a"i 7

' u Cll . IllcyrJoparur.l. m C^. , «:, A " 3 0 0~y c „ rrlccvclop.r.ffln. s l^ll,. ^ C^H,, , Q-Oai , III , \- ^ Bonzeuo . C^H ^ C,,^ , CH j
T«"alln » C„H, N

_ 8 r lfc ll, 4 «:H,]Q U N.prh,l„ii „ S M 2N-1 2 C I6 M 2 0 "'©Ov ,

Figur e 2.1 : Classa M o f hydrocarbo n Molecule s foun d i n diese l fua l (Hilde

n e t alia , 1962) .

2- 4P.2 6

prolonge ddistillation, a s the lighte r o f it s constituen t hydrocarbons-boi l of f first . Thi s i s use dt o provid e a convenien t wa y

o f characterizin g th e mi xo f molecula r weight s i n
a fuel , b

y mean s o f the "distillatio ncurve" . Th e distillatio n curv e i s give nb

y specifyin g the initia l boilin g point , the "1 0 percen t point " (the teaperatur e a t whic h1 0 percen t o f the mas s ha s boile daway , (a t atmospheri c pressure ) th e 2 0 percen t point , ands o fort hupt o th e 9 0 percen t poin t andth e end-point , whic h i s the temperatur e a t whic hal l o f the fue l ha s evaporated . Th e 1 0 percent , 5 0 percent , an d9 0 percen t point s (reflectin g "front-end" , averag e and"back-end " volatility ) generall y receiv e th e mos t attention .

I nadditio nt o th e hydrocarbon s whic har e it s primar y constituents , diese l fue l als o contain s a smal l amoun t o f organically-boun dsulfur . Th e amoun t o f sulfu r i s dependen t o n the sulfu r i nthe crud e oi l ando nrefinin g procedures . I n diese l #2 , sulfu r generall y constitute s abou t 0. 1 t o 0. 5 percen t
o f th e fue l b

y weight . Organi c coapound s o f othe r element s suc h
a s nitrogen t vanadium , aluminum , cobalt , lead , an dbariu m ar e als o presen t i ntrac e amounts .

Th e conpositio no f any particula r batc ho f fue l i s determine db y th e propertie s o f th e crud e oi l i t wa s refine dfrom , th e capabilitie s o f th e refinery , an dth e competin g demand s o f th e othe r fuel s tha t ar e bein g refine dsimultaneousl y from th e same


### 2- 5P.2 7

crude . I nadditio nt o diese l fuel , othe r fue l type s compet e fo r th e "pool " of-hydrocarbon s availabl e i nthe middl e distillat e range . Thes e includ e # 2 burne r fue l oi l (whic hi s physicall y
ver y simila r t o diese l #2 ) andje t fuel . T o sav e o ntankin g and othe r costs , man y

refiner s anddistibutor s hav e combine ddiese l # 2 and# 2 burne r fue l a s th e same product , althoug hth e qualit y requirement s fo r burne r fue l ar e les s stringen t tha nthos e fo r diesel . Thi s result s i nsome "give-away " o f fue l qualit y ("give-away " i s define da s producin g a fue l o f highe r qualit y tha nneede dt o mee t specifications) .



### 2. 2 PTFfiFJ , FQE L CPALIT YINDICE S

Th e qualit y

o f diese l fue l i s mos t ofte nmeasure di nterm s o f it s cetane nuaber . Th e cetan e nunbe r i s a measur e o f th e eas e o r difficult y

o f igniting th e fue l whe nit i s injecte dint o th e combustio nchamber . High-cetan e nunbe r fuel s ignit e readily ; low-cetan e fuel s tak e longe r t o ignite . Cetan e i s mos t importan t fo r engine startin g a t low temperatures , whe na fue l wit hto o low
a cetan e ratin g ma y

no t Ignit e a t all . A warmed-u pengin e wil l
runo nfuel s wit hmuc hlowe r cetane rating s tha nit wil l star t
on , bu t to o low

a cetan e stil l affect s engine nois e an dfue l economy .

Cetan e nunbe r i s measure db y comparin g the ignitio nqualitie s o f



### 2- 6a fue l agains t thos e o f standar dmixture s o f cetan e (whic hha s

very highignitio nquality ) andheptainethylnonane (whic hha s poo r ignitio nqualities) . Sinc e thi s tes t i s expensive , th e "cetan e index" , whic hca nb e calculate dfrom th e physica l propertie s o f the fuel , i s ofte nuse da s a napproximatio no f the cetan e number . Thi s indexcontain s considerabl e error , however , andit i s no t applicabl e t o fuel s containin g cetan e improving additive s
o r t o non - petroleum-derive dfuels . A cetan e numbe r (o r cetan e index ) o f 5 0 t o 5 5 indicate s a premiu m qualit y fuel , whil e on e fro m abou t 4 5 t o 5 0 i s goo dquality . Th e An e r i ca nSociet y fo r Testin g andMaterial s (ASTM ) standar dfo r diese l fuel s # 1 and# 2 specifie s a minimum

cetan e numbe r o f 40 .

Cetan e nunbe r andignitio nqualit y ar e closel y

relate dt o th e hydrocarbo nconpositio no f the fuel . Generally , paraffin s ignit e
mor e readil y

tha nnapthenes , whic hignit e mor e readil y tha n aromatics . Th e effec t o f aromatic s o ncetan e i s especiall y strong . Figur e 2. 2 show s th e relationshi pbetwee ncetan e numbe r
andaromati c conten t fo r a larg e saapl e o f diese l fuels .
Withi neac hclas s o f hydrocarbons , heavie r (highe r molecula r weight ) hydrocarbon s ignit e mor e readil y tha nlighte r ones . Thi s probabl y account s fo r the outlyin g point s i nFigur e 2.2 . Th e relationshi pbetwee naromatic s content , molecula r weight , and cetan e i s als o th e basi s fo r the cetan e indexcalculation . Thi s calculatio nuse s th e densit y and5 0 percen t poin t o f th e fuel .


### 2-7P.2 9

TOTA L PARAFFINS

. vol % 10 0 9 0 8 0 7 0 6 0 5 0 4 0 3 0

cc U J m 

### z z U J
U J o o U J > tc LM tA a. o 7 0
6 0
5 0
4 0
3 0

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- Tr- - t i

o 0

o o

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,£ 0 °° 0 a «* *

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. vol %

Figur e 2.2 : Relationshi p betwee n aroaati c conten t an d cetan e nuabe r

(Glavincefsk i e t alia , 1984) .

2- 8P.3 0

Condition s durin g th e cetan e rating tes t resembl e thos e i na n engin e durin g col dstarting , andthe presen t tes t doe s appea r t o giv e a reasonabl e measur e o f cold-star t propertie s o f fuels . However , ther e i s a growin g consensu s (McMilla n(ed. ) 1983 ) tha t the presen t cetan e measuremen t doe s no t adequatel y measur e th e ignitio npropertie s relevan t t o today' s engine s i nnorma l operation . A

recen t stud

y b y Barr y andco-worker s (1985 ) showe d almos t n o effec t o f cetan e numbe r o nignitio ndelay . I n addition , numerou s studie s hav e show ntha t diese l engin e emission s ar e mor e closel y correlate dwit hth e aromati c conten t
o f th e fue l tha nwit hit s cetan e nunbe r (althoughthe cetan e and aromatic s conten t ar e themselve s closel y correlated) . Althoug h alternativ e measure s hav e bee nsuggeste d(Ple e andAhmad , 1983 ; Wad e e t alia , 1984 ) ther e i s a s ye t n o widel y accepte dsubstitut e measur e for overal l ignitio nqualit y i nmoder ndiesels .

Two measure s whic har e relate dt o th e cetan e nunbe r ar e th e volun e fractio no f aromati c hydrocarbon s inthe fue l an dth e anilin e point * Th e measuremen t techniqu e fo r aromati c conten t i s define dby

AST M procedur e D-1319 , whic huse s fluorescen t indicato r absorbtion , abbreviate dFIA . Mos t studie s o f fue l effect s o nemission s hav e foun da bette r correlatio nwit hFI A aromati c fractio ntha nwit hcetan e number . Th e anilin e poin t i s th e teaperatur e a t whic hpur e anilin e become s miscibl e wit hth e fuel , measure di naccordanc e wit hAST M procedur e D-911 . Thi s i s a



### 2- 9P.3 1

fas t andsimpl e measur e o f the aromati c andnaptheni c characte r
o f the fuel , andha s bee nfoun dt o correlat e wel l wit hcetan e nunbe r (Collin s andUnzelman, 1982 ; Steere , 1984) .

Cetan e nunbe r (lik e octan e nunbe r fo r gasoline ) i s th e mos t
coomo nandvisibl e qualit y indicato r fo r diese l fuel . Othe r fue l propertie s whic har e ofte nspecifie dinclud e th e back-end volatilit y

(9 0 percen t poin t o r endpoint) , sulfu r content , viscosity , density , cold-flow properties , copper-stri p corrosivity , andConradso ncarbo nconten t ( a measur e o f coke-formin g tendencies) . Density , viscosity , andback-end volatilit y

ar e al l determine dby th e hydrocarbo nmakeu po f the fuel , bu t sulfu r and(t o a nextent ) col dflow propertie s ca nb e independentl y

varied . Sulfu r conten t ca nb e reduce db y hydrotreating , whil e col dflow propertie s ca nb e improve db y col d flo w improving additives .

A t lo w teaperatures , th e long-chai nparaffin s i ndiese l fue l condens e t o form

wa xcrystals , whic hca nbloc k th e fue l filter . A t stil l lowe r temperatures , diese l fue l gel s conpletely . Col d flow propertie s suc ha s th e clou dpoin t (th e teaperatur e a t whic h
wa xcrystal s firs t appea r i nth e fuel) , th e pou r poin t (th e teaperatur e belo w

whic hth e fue l wil l no t flow) , andth e col d filte r pluggin g poin t (referrin g t o a specifi c tes t o f flow througha fue l filter ) affec t th e abilit y t o star t andruna t lo w teaperatures , andar e ver y importan t fo r operatio ni ncol d

2-1 0P.3 2

climates , bu t hav e littl e significanc e fo r engin e operatio n otherwise
. The yar e determine d b yth e conten t o f long-chai n paraffin s i n th e fue l (whic h i s relate d t o th e back-en d volatilit yan d th e overal l paraffi n content) .

Ther e i s a trade-of f betwee n cetan e an d cold-flo wproperties : highl yparaffini c fuels , whic h hav e hig h cetan e numbers , als o tend t o for mwa x crystal s mor e easily
. Thi s proble mca n b e alleviate d b

ydewaxin g (a n expensiv e process ) o r b yth e us e o f cold-flo wimprovin g additives , whic h hampe r th e formatio n o f wa x crystals . Refiner s als o typicall yincreas e th e amoun t o f ligh t hydrocarbon s an d reduc e th e back-en d boilin g poin t i n winte r t o provid e bette r cold-weathe r performance .

2. 3 CURREN T FUE L QUALIT Y STANDARD S AN D REGDLATION S

Th e criteri a whic h defin e th e differen t grade s o f diese l fue l ar e
se t b yAST M Standar d D-975 . Thes e criteri a ar e reproduce d i n Tabl e 2.1 . Th e AST M i s no t a governmen t agency , an d it s standard s hav e n o lega l force , bu t the yar e widel yadhere d to . Afe w state s hav e establishe d lega l requirement s fo r diese l fuel ; excep t fo r California , thes e generall yfollo wth e AST M guidelines
. Californi a ha s establishe d a limi t o f 0.0 5 weigh t percen t sulfu r i n diese l fue l sol d i n th e Sout h Coas t Ai r Basin , an d i s considerin g extendin g thi s requiremen t t o th e remainde r o f

2-1 1I\ >

I Otod e e < MOM I Ptta l O N No . ID A voiotf e ditlilol . lue l oi l lo r «agin. t i n Mrvic . (.quirin g lr.qu.n l ipaa d oa d loa d chaogn . No . J O A diililut . too l o d a l low w valolilit y lo r tagina t l a industria l ao d boav y n^il e service . No . 4 0 A IIM I oi l lo t lo wan d loadim e •pu d lagi.st . Mat h Point . • c
Mi a

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* T o mo. 1 ip.cia l oporolia g cenditieat , aioditicatiaa t o l indiv i may b e ograa d upo n betwee n pwchoMt , itltr , on d manulaclMt«f . k I t h unteofttli c t o tpecit y low-ltwipetolut o prop*ti« t dia l wi l a a a broo d botit . SaMtloctory epewibe n thoU d b e achieve d i a moi l lo t wa a gppontoac o point ) I t tpodlw d a t A* C IIO'F I abov . lh . t t oatbiM l Itwpsiuluio t lo t a Wanadr t o l October . Novmbtt . an d Marc h at . giv n i n AST M 0 97 5 i n map s lo r lb . 4 1 conliguou t guidanc e i t e l a gtnsin l notor. ) taa wnuipintn l datignt . M M o l I ridua l limitin g r«quit«eienl t

< Wb M doo d poin t Ut t t l 1. 7 cS l an d * •90 % poin t i pioptitil l thoul d b e agree d < us o an d eapocle d ombien l tetnpatolwfe i i -I2* C |I0"F | i t tpecilied . dt . M M •b o waived . tatitloclot y operatio n coto t i l lh . clou d poin t iMtl b percentil e miniame i lean tpercentil e minimM n January , February , tlaie t an d Alati o thi i towIwptone i additiv.t , poin tluelt . Appropri di . IIM I tupplie r vitcotit y ' I n couatriet ouitid e lb . U.S.A. , olh m MiHu r hnil t mas/ apply . •What . clan . numl m b y Malbo d 0 d l 3 . i t not o.oiiobU . AST M M.lho d 0 976 . Cakulola d C.Ian . Inda a o l Dittilol . fuo h an y b o uta d a t a n opptoaininlio. . What . <Mr t i t ditograomonl , Medio d 0 61 3 tha i b * d » nloro . mediod . 1 lo wonooiphtri e Iteipsrolurs s a t wt a t tngin t operatio n a t hig h allilude i ma y raquire ut o o l loab) wid i higha t cton o rotingt . •MilwMt wtquara d p « tocon d loiKcio l S I unil ) (Not* . 1 cS l ~ I am'/i) . k Th . vobn t i n S I wdt t at . t o b . ngardV d a t di . ttondord . Th . vahM S i n U . S . cuilnwnr y imit t at . lo r informatio n only . •Nadiin g ia da t tpacrlicaao a dia l ptadud . abtwvaac . o l lodoral . Hole , o t loca l ragulaliaai • y b . an t totitictiv .

Tabl e 2.1 : AST

M criteri afo rgradin g o f distillat e aiese l fue l (SAE , 1984) . 

# Ith e Stat e (GARB , 1985) . Ther e i s presentl yn o Federal-leve l

regulatio n o f diese l fue l quality
.

Th e criteri a se t b yAST M D-97 5 allo wfo r a grea t dea l o f variatio n i n quality
. Bot h a ver ygoo d fue l an d a ver ypoo r on e
ma yconpl yperfectl ywit h th e AST M specifications , bu t produc e radicall ydifferen t performanc e i n use . Tabl e 2.2 , reproduce d fro mth e curren t SA E Handbook , compare s th e AST M specification s fo r diese l # 2 wit h thos e establishe d b yth e U.S . military , b ya nunbe r o f foreig n government s o r standard-settin g organizations , an d b yEF Afo r fue l t o b e use d i n emission s certificatio n testing
.
Thi s latte r specificatio n i s o f especia l interest , sinc e diese l engine s ar e require d t o mee t emission s limit s onl ywhe n runnin g
o n certificatio n fuel . A s these.limit s (especiall yth e NO K limit ) ar e tightened , engine s wil l becom e mor e sensitiv e t o fue l qualit y(Weave r e t al , 1984) , an d th e us e o f fuel s outsid e th e EP Aspec s bu t withi nthos e o f th e AST M coul d resul t i n significantl ygreate r emission s tha n woul d b e predicte d b yth e certificatio n test .



### 2. 4 TTOf B T

N PIEfiFJ , i m

ffltVLUX
Figur e 2. 3 show s th e trend s i n th e nationwid e average s o f a

2-1 3rs )

I C.ton . Numb. i Sullur , mat t % DiililatKx i T«apwatufe , ° C 50 % Pom l 65 % Poin t 85 % Poin l 90 % Poin l En d Poin l Kmoaaoti c Vitcotily . cS l ol20" C 0130- C ol40* C Owitily . g/m l a t IS' C AST M 097 S OtMat e NI.1- D 4 0 mi x O. S M I

382-33 8

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Figur e 2.3 i Trend s i nsoa e propertie s o f type T- T an dgrad e 2- D diese l fue l oil s (Shelto nan dDickson . 1984) .

2-1 5numbe r o f propertie s o f diese l # 2 (or truck-tracto r fue l — th e classificatio nwa s change di n1979 ) sinc e 1960 . A s thi s figur e indicates , th e las t tw o decade s hav e see na stead y declin e inthe averag e cetan e nunbe r o f th e fue l sold , andthi s declin e ha s become especiall y

marke dsinc e 1976 . Thi s declin e ha s bee ndu e t o
a marke dincreas e i nth e averag e fractio no f aromatic s i nth e fuel . Endpoint s an

d9 0 percen t point s hav e increase dmarkedl y a s well , andsulfu r conten t ha s increase dsomewha t a s well . Thes e graph s ar e base do nth e annua l survey s conducte db y th e Nationa l Institut e fo r Petroleu m an dEnerg y

Researc h(Shelto nan dDickson , 1984) .

Othe r surveys , suc ha s thos e o f th e Moto r Vehicl e Manufacturer s Associatio n(Pless , 1984 ) hav e show na neve ngreate r increas e i n sulfu r conten t an di naromatic s i nrecen t years . Figure s 2. 4 through2. 8 show

th e trend s anddistributio no f aromati c content , cetan e index , 9 0 percen t point , AP I gravit y (whic hi s inversel y relate dt o density) , andsulfu r fro m th e MVM A surveys . Thes e dat a sho w

a substantia l increas e i nbot haromati c conten t and sulfu r conten t sinc e 1980 . Dat a fo r aromatic s wer e no t availabl e i n1983 , bu t th e continuin g increas e i ndensit y anddecreas e in cetan e indexdurin g 198 3 indicate s tha t th e aromati c conten t continue dt o increase .
Thi s genera l declin e i ndiese l fue l qualit y i s du e t o th e nee dt o proces s heavie r andlower-qualit y crud e oil s a s mor e desirabl e

o_ i a

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## MVMA

. SUMME R SURVEY S P£RC£iV T<7r

* r"</tU S * T<7r

t ABOVE
M M MMMM M M



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Figur e 2.4 » Distributio no f diese l fue l aroeati c content frot a th t MVM A sueee r survey s (Pless , 1984) .

2-1 7P.3 9



## MVM ASUMME R SURVEY S p£ftc«rv- r OF

FU&LS Ar OR ABova

r a« s M <

d M n 

### A-of a j !

i • !



### pe.RCc.Nr

OF F<J£LS 

### Ar OR. B^LCW

Figur e 2.5 » Distributio no f AP I gravit

y o f diese l fuel s fro e th e MVW A suaae r survey s (Pless , 1964) .

2^1 8P.4 0



## MVM ASUMME R SURVEY S p£RC6fi/r

OF FUELS

AT OR ABO\/a
n m M t

a»

H M t t 

### pe.Rce.nrOFFU&LS 

### ArOR BSLOW

Figur e 2.6 : Distributio no f calculate

dcetane inde

xo f diese l fuel s fro a th e MVM A suaaer surveys (Pless , 1964) .

2-1 9P.4 1



# MVM ASUMME R SURVEY S p€RC£Hr

OF FU£LS Ar OR ABOV £

2 0 J

O « J

O M » 0 1 0 PERCENT

Of FU6LS Ar OR BELOW

Figur e 2.7 : Distributio no f 9 8 percen

t poin t o f diese l fuel s fro a th e HVM A suaae r survey s (Pless , 1964) .

2-2 0

## MVMA

. SUMME R SURVEY S PERCEkr

OF FUCLS Ar OR ABOV&

PIRCEHr

OF FU£LS AX OR BELCW

FigUr V 2<a i O*«trib«tio n o fsulfu r conten t o fdiese l fuel , fro a th . at* * suaae r survey s (Pless . 1964) . «*»»• * ruei s rro a th e MVM A

2-2 1oi l resource s ar e exhauste d(Strange , 1982 ; McMilla n(ed. ) 1983) . Thes e lowe r qualit y

crude s contai nmor e heav y hydrocarbon s and
mor e aromatic s tha nth e highe r qualit y oils . Low-qualit y

crude s
ar e usuall y

als o riche r i nsulfur , bu t th e sulfu r conten t o f th e refine dfue l ha s bee nkep t i nchec k by consume r resistance , occasione db

y th e fac t tha t hig hsulfu r fue l ha s destructiv e effect s o nengines . Th e us e o f lo w qualit y crude s ha s thu s require da nincreasing amoun t o f desulfurizatio ntreatmen t for diese l fue l an dothe r middl e distillates .
Examinatio no f averag e number s doe s no t adequatel y reflec t th e variatio ni nfue l qualit y frcm supplie r t o supplie r an dfro m tim e t o time . A s discusse da t greate r lengt hi nChapte r Three , thi s variatio ni s itsel f a significan t problem fo r emission s control , sinc e engine s mus t b e abl e t o cop e wit ha noccasiona l tank o f
ver y poo r fue l withou t disastrou s consequences . Tabl e 2. 3 show s th e minimum , mean , andmaximum value s i neac hregio nfor a numbe r
o f diese l fue l propertie s foun db y th e 198 4 NIPE Rdiese l fue l survey * Figure s 2. 3 through2. 8 als o sho w th e distributio no f propertie s foundb

y th e MVM A fue l survey s i nrecen t years . A s thes e figure s an dth e tabl e show , a significan t fractio no f diese l fuel s no w

o nth e marke t fai l t o conpl y wit heve nth e lax AST M specification s fo r on e o r mor e properties .

I nth e absenc e o f governmen t o r othe r initiative s t o th e contrary , mos t knowledgeabl e observer s expec t tha t diese l fue l

### TABL E 2 . - SUMMAR YFO R 2- D FUEL S Diese l Fue l Survey , 1984

N > I M m-t fafliliwirtqat^ a IMMtailHaltiil * Maaaharei'teal e T M OeeWtr.'A M flaa k aalaa.* P Catae.A5T M W i n III.M.aat.Hc.rfltMlOO- F OaaapeM.' r fta t Haa . * T Mfc><ea«eal,*t« j Itta i t. f Cll l Ilna a 10* . at m Aak.artf t GaaMaaatke r Ow.ti e te e

M a Mf . H a fclpelal AST M DM T D M DlM O D44 6 DM0 0 Df ? D I M M i l DM 4 D M t D M D f » D M Ml.l-.e t

M J I M L U I M -1 1 G O 0.01 1 t i l OJ M OJ M M O M O
l i t » 4 4 M 4 M I M A3. C Dxr. a M Averag e M. 7 ' I M I M • 0.2 M 1*1 1 0.14 1 000 1 44 1 M J
M O 43 7 t i l f M 04 * Mt.lata a

43. 4 M O U 4.1 4 4 1 M OU O I M A OM O O.OI O t i l t i l
4 M U l 17 1 US 71 6 11. 0

14 0 U t t I I I •4 -I f oot a 127. 0 0.0 M ooo o 41 1 40 1
3 M M t M 7 M t 11 4 D A.B.C.I.K.Q. I M

•Averag e M. 4 '17 1 10 6
0.23 6 I46 J O I U O.M I 41 1 4 U
M 2 4 M t i t I M M l Mulan a

M l l i t l t 3. M 4 2 I t OM O 177. 0 OM O 0.00 6 61. 1 M O
44 2 4 M M 2 M l 71 1 B.P. 0

A.B.C.D.HJJ. K
Miaiaea i M. 6 I M L0 6 I. M J 6 0 006 0 106. 0 0.00 0 0.00 0 M. O 11 2
l i t 174 4 M 4 M U t M a Avera# e M. » ' I M 2. M
0.26 6 143 7 014 4 000 1 41. 0 4* 4
M l 43 3 10 7 M t M f tt-.i —

41. 1 11 1 2. 6 3* 0 4 2 1 6 0.6 M 177. 0 OM O 0.01 0 t i t M O
44 2 4 M M l M l 71 1 H.U. K

D.K.F.O.UI. N
Mtaiaaa i M J 14 1 lil t r»
m - I t ou t I B l ooo o OO M 41 t M O
M l 40 6 4 M I M U f M Averag e Huiat a M J M J ' I M I M

U 2* 1 3 8 0

4 1 M 0.37 0 OM O 140. 1 I& M 0.O M OM O 000 2 0.01 0 46 1 M l 4 U 16. 3
M O 4 M 43 1 M l t i l M O • M M 7 M l T M UtNA F HJ.JX M Miaaaa a Averag e Haiiat a M l 14 0 U t t 11 6 -4 0 4 6 001 0 1M. 1 0.04 0 OOO O M A M O
H I 4 M 4 M 17 1

- f a a. i

•IT I 12 3
0 3 M 141 1 J I M uo n 44 J 46. 4
M 7 46 1 u i 11 0 • M M J

M l 2 6 43 0 4 1 4 1 OM O i t u 0.14 0 0.01 0 41. 1 6 7 1
M l M l M O M 7 T M Mlatae a

M J I M L0 6 1. M -4 0 -6 0 0.01 0 t i l OOO O 0.0 M M O 33 1
l i t 374 4 M 4 M t M Natioaa l

A U I M Areaj i M J ' I M 11 7
0.26 7 143. 3 013 4 0.00 3 46 1 41 3
M 4 43 1 61 3 10 2 •6 3 Maaiaae a

43 4 M O I t 47 4 a 4 6 0*4 0 I M 6 OM O 001 0 63 2 11 3
60 1 M l M O M 7 7 M

Taol e 2.3 : Distribution'o f diese l fue l propertie s b yregion s (Shelto n an dDickspn , 1984) .P.4 5

qualit y wil l continu e t o declin e for the remainde r o f thi s century . Averag e cetan e number s wil l decline , anda nincreasing fractio no f fuel s wil l fal l belo w th e AST M

mininu ncetan e o f 40 . Similarly , averag e sulfu r conten t wil l increas e towar dthe AST M maxinu no f O. S percen t b y weight , anda nincreasin g nunbe r o f fuel s wil l excee dtha t level . Back-en dboilin g point s ar e expecte dt o increas e steadil y a s well , excep t wher e they ar e constraine dby

th e need s o f cold-weathe r operability . Th e potentia l effect s o f thes e change s o ndiese l emissio nlevel s ar e discusse di nth e nex t chapter .P.4 6

3.0 : TORT. CTIALITY EFFECT S f M TOPSE.. tTMTvTMB S

Th e propertie s o f diese l fuel , th e indice s bywhic h thes e propertie s ar e measured , an d th e criteri a use d t o defin e diese l fue l qualit ywer e discusse d i n th e previou s chapter . Thi s chapte r review s th e effect s o f change s i n th e propertie s an d compositio n o f diese l fue l o n th e durability , fue l economy , performance , an d emission s level s o f diese l engines
. Th e purpos e i s t o establis h a n analytica l framewor k agains t whic h t o evaluat e th e engin e an d emission s effect s o f th e tw o fuel-qualit y regulatio n scenario s discusse d i n Chapte r Five , an d t o provid e a startin g poin t fo r furthe r researc h i n thi s area .

Studie s o f th e effect s o f change s i n fue l propertie s o n engin e performanc e an d emission s ar e complicate d byth e fac t tha t fe w change s i n fue l propertie s ca n b e carrie d ou t independentl y— ther e ar e stron g correlation s amon g individua l properties , an d i t i s seldom

clea r whic h i s th e propert yo f greates t interest
. Th e propertie s single d ou t fo r discussio n her e ar e thos e whic h ar e generall yconsidere d (eithe r fo r theoretica l reason s o r fro m practica l experience ) t o b e th e critica l one s fro ma n emission s
an d performanc e standpoint
. Thes e are : sulfu r content , aromati c conten t an d ignitio n quality , back-en d volatility , density , an d



### 3-1P.4 7

viscosity . A

numbe r o f secondar y

propertie s ca nals o affec t emissions , bu t ar e generall y relate dt o on e o r mor e o f the precedin g five . Thes e secondar y propertie s ar e briefl y discusse d i na fina l section .

3. 1 ffTEi- CTm*ncrwrew r

Diese l fue l normall y

contain s betwee n0. 1 and0. 5 percen t b y weight sulfur , wit hth e averag e i n198 4 bein g abou t 0.2 7 percen t accordin g t o the NIPE Rsurve y (Shelto nandDickson , 1984) . A s discusse di nSectio n2.4 , thi s averag e ha s increase dsomewha t sinc e 1980 . Th e MVM

A diese l fue l surve y

show s a neve nsharpe r increas e i nsulfu r content , fro m a media no f .1 9 percen t i n198 0 t o .3 1 percen t i n198 3 (Pless , 1984) .
Fnvlponm»nta 1 mttrntitm

Sulfu r i ndiese l fue l contribute s t o environmenta l deterioratio n i nbot hdirec t an dindirec t ways . Mos t o f th e sulfu r i nth e fue l burn t t o S O , whic hi s emitte dt o th e atmospher e inth e diese l

2 exhaust * Becaus e o f this , diesel s ar e significan t contributor s t o ambien t S O level s i nsome areas , an dindirec t contributor s t o

2 aci ddepositio na s well . I nCalifornia' s Sout hCoas t Ai r Basin , diesel s ar e projecte dt o accoun t fo r 2 4 percen t o f al l S O 2 emissions , despit e a requiremen t tha t larg e refiner s marke t



### 3- 2P.4 8

desulfurize d fue l (CARB , 1985) . Nationwide , diese l fue l accounte d fo r abou t 37 0 thousan d ton s o f S O i n 1985 , assumin g tha t 1,24 5 2 thousan d barrel s pe r da yaveragin g 0. 3 percen t sulfu r wer e produced .

Mos t o f th e sulfu r whic h i s no t emitte d a s S O i s converte d t o 2 variou s meta l sulfate s an d t o sulfuri c aci d durin g th e combustio n process . Bot h o f thes e material s are emitte d i n particulat e form . Th e typica l rat e o f conversio n i n a heavy-dut ydiese l engin e i s abou t 2 t o 3 percen t o f th e fue l sulfur ; an d abou t 3 t o 5 percen t i n a light-dut yengine
. Eve n a t thi s rate , sulfat e particle s typicall yaccoun t fo r 0.0 2 t o 0.0 5 g/BHP-h r o f particulate s i n heavy-dut yengines
. Th e effec t o f th e sulfat e particle s i s increase d b ythei r hygroscopi c natur e —the ytend t o absor b significan t quantitie s o f wate r fro mth e air
.
Certai n precious-meta l catalyst s suc h a s thos e use d i n th e Johnson-Matthe ywire-mes h trap-oxidize r ca n oxidiz e S O t o S O , 2 3 whic h combine s wit h wate r i n th e exhaus t t o for msulfuri c acid
. Th e rat e o f conversio n wit h th e catalys t i s dependen t o n th e activit y o f tb e catalys t —

catalys t formulation s whic h are mos t effectiv e i n oxidizin g hydrocarbon s an d carbo n monoxid e ar e als o
mos t effectiv e a t oxidizin g S O . Th e presenc e o f significan t 2 quantitie s o f sulfu r i n diese l fue l thu s limit s th e catalyti c activit ypossibl e i n th e trap , makin g regeneratio n mor e difficul t (Weaver , 1983 ; 1984b) . Lo wsulfu r fue l woul d mak e catalyst s an d


### 3-3P.4 9

catalyti c trap s mor e effectiv e fo r particulat e (a s wel l a s hydrocarbo n an d odor ) reduction
.

Sulfu r dioxid e i n th e atmospher e oxidize s t o for msulfat e particles , i n a reactio n simila r t o tha t whic h occur s wit h th e precious-meta l catalyst . Viewe d i n anothe r way , th e presenc e o f th e catalys t merel yspeed s u p a reactio n whic h woul d occu r anywa y (althoug h thi s ca n hav e a significan t effec t o n huma n exposur e t o th e reactio n products) . Accordin g t o analysi s b yth e Californi a Ai r Resource s Boar d staf f (1984) , roughl y1.5 3 l b o f secondar y particulat e i s forme d pe r poun d o f S O emitte d i n th e Sout h Coas t 2 Ai r Basin
. Fo r a diese l engin e burnin g fue l o f 0.2 9 weigh t percen t sulfu r a t 0.4 2 l b o f fue l pe r horsepower-hr , thi s i s equivalen t t o 0.8 5 gram s pe r horsepower-hour . Fo r comparison , th e averag e rat e o f primar yo r directly-emitte d particulat e emission s fro mheavy-dut ydiese l engine s i n us e wa s abou t 0. 8 grams/BHP-h r i n a recen t study(EMA , 1985) .
Quit e asid e fro mit s particulate-formin g tendencies , sulfu r dioxid e i s recognize d a s a hazardou s pollutan t i n it s ow n right
. Th e healt handwelfar e effect s o f S O emission s fro mdiese l 2 vehicle s ar e probabl ymuc h greate r tha n thos e o f a n equivalen t quantit yemitte d fro ma utilit ystac k o r industria l boiler , sinc e diese l exhaus t i s emitte d clos e t o groun d leve l i n th e vicinit y
o f roads , buildings , an d othe r concentration s o f people .



### 3-4Engine durability effect s

Sulfu r i ndiese l fue l ha s bee nrecognize dfo r man y year s a s a majo r — an dprobabl y

it e majo r —

caus e o f wea r i npisto nring s
andcylinde r liner s (Blanc,1947 ; Furstoss , 1949) . Th e ring s and liner s ar e generall y

th e critica l wearin g part s i nth e diese l engin e (Lilly , 1984) , s o tha t th e rat e o f wea r i nthes e part s i s directl y relate dt o th e frequenc y o f engin e overhauls .

Th e relationshi pbetwee nring an dline r wea r an doverhau l frequenc y

i s supporte db

y th e result s o f a survey comnissione dby th e Engin e Manufacturer' s Associatio n(Survey Dat a Research , 1981) . Thi s stud

y foundtha t 8 0 percen t o f th e fleet s surveye d considere dhig hoi l consumptio na primar y indicato r o f th e nee d t o rebuil da nengine , whil e 5 7 percen t considere dexcessiv e blowb y rate s a primar y

indicator . Bot ho f thes e indicator s ar e directl y relate dt o ring an dline r wear . Severa l othe r ccomo n criteri a fo r rebuildin g — including reductio ni noi l pressure , majo r engin e failures , an dpoo r oi l analysi s result s — ar e indirectl y

relate dt o ring an dline r wear . Thi s i s du e t o th e effec t o f increase dblowb y i nincreasing th e rat e o f aci d depositio ni nth e oil .

Sulfu r contribute s t o ring an dline r wea r throug htw o mechanisms : corrosiv e wea r an ddeposi t formation . Corrosiv e wea r occur s whe n th e sulfu r i nth e product s o f coabustio nattack s an dcorrode s th e


### 3- 5P.5 1

pisto nrings , cylinde r liners , an dothe r expose dparts . Thi s corroeio ni s mos t sever e whe nline r temperature s ar e below the dewpoin t o f sulfuri c aci di nthe exhaus t gases . Operatio nbelo w the aci ddewpoin t allow s sulfuri c aci dt o condens e o nthe line r surface . Thi s occur s durin g col dstartin g andwarmup , andca n als o occu r a t ligh t loads . Turbochargin g (whic hraise s the aci d dewpoint ) ca nexacerbat e thi s problem (Lilly , 1984) . Experiment s wit hfuel s o f differen t sulfu r level s hav e show ntha t corrosiv e
wea r als o occur s (a t a slowe r rate ) eve na t norma l operatin g temperatures .

I nadditio nt o thei r corrosiv e attac ko nring s andliners , th e sulfu r compound s i nthe blowby gase s ca ncoonbin

e wit handacidif y the oil . I f unchecked , thi s lead s t o rapi dcorrosio nandwea r o f bearings , camshafts , andothe r lubricate dparts . I norde r t o kee pthes e effect s withi nbounds , al l heavy-dut y engine oil s ar e
no w formulate dwit hhighl y alkalin e dispersan t additives . Thes e additive s ar e typicall y base do nmetal s suc ha s calciu m an d barium , whic hconbin e wit han dneutraliz e the acid . Withou t suc h additives , o r wher e the additive s hav e bee ndeplete db y combinin g wit hth e acid s i nth e blowby , corrosiv e wea r rate s wit hhig h sulfu r fue l ar e ver y

hig h(Dyso ne t alia , 1957) ; wit hthem , wea r rate s ca nb e kep t withi nreasonabl e bounds .

I nadditio nt o corrosiv e wear , ring scuffin g an dstickin g and los s o f oi l contro l du e t o har dcok y deposit s o nth e pisto nar e


### 3- 8P.5 2

th e othe r majo r source s o f wea r o n pisto n ring s an d cylinde r liners * Deposi t formatio n a t lo wan d moderat e temperature s i s heavil yaffecte d bysulfu r —lo wsulfu r fuel s resul t i n fewe r
an d lighte r deposit s (McGeeha n e t alia , 1983) . A t hig h temperatures , suc h a s thos e i n th e to p ban d o f th e piston , sulfu r doe s no t directl yaffec t deposi t formation
. Ther e i s a n indirec t effect , however , sinc e th e alkalin e additive s i n th e engin e oi l
ar e als o responsibl e fo r th e contro l o f pisto n an d othe r engin e deposits , an d thei r dispersan t activit yi s los t a s the yar e neutralize d bycombinatio n wit h sulfur .

Th e greate r th e concentratio n o f alkalin e additive s i n th e oil , th e greate r th e degre e o f protectio n agains t corrosiv e wear . Th e permissibl e additiv e concentratio n i s limite d byothe r considerations , however , t o a maximu mo f abou t 6-1 0 Tota l Bas e Number s o r TB N(Gergel , 1980) . On e TE Ni s a n alkal i concentratio n equivalen t t o 1 m g o f potassiu mhydroxid e pe r gra mo f oil
. Th e rat e o f neutralizatio n o f th e alkalin e additive s i s proportiona l t o th e rat e o f sulfu r additio n t o th e oil , whic h i s proportiona l t o th e sulfu r conten t o f th e fue l an d th e blowbyrate .
Presently , additiv e depletio n i s a limitin g facto r i n th e lengt h
o f tim e permissibl e betwee n oi l change s (othe r limitin g factor s
ar e soo t accumlation , contaminatio n wit h wate r o r fuel , an d oxidatio n o f th e oil)
. Greatl yreducin g sulfu r migh t mak e i t possibl e t o exten d oi l chang e interval s significantly
.


### 3-7P.5 3

Alternatively , o r perhap s i naddition , th e amoun t o f metalli c additiv e i nth e oi l coul dpossibl y b e reduced . Thi s woul db e desirabl e fo r trap-oxidize r equippe dvehicles , sinc e the noncombustibl e meta l sulfat e as hfro m the alkalin e additive s i s collecte db

y andeventuall y

clog s cerami c monolit htrap s (Sachdev
e t alia , 1983 ; Hardenburg , 1985) .
Generally , the us e o f alkalin e additive s wit hadequat e oi l chang e frequenc y

ha s resulte dinacceptabl e wea r rate s andengine lifetime s wit hfue l o f les s tha n0. 5 percen t sulfu r b y weight . However , despit e th e presenc e o f alkalin e additives , engin e wea r rate s ar e greate r wit hmor e sulfu r i nth e fuel , an dmos t observer s agre e tha t us e o f very lo w sulfu r fue l woul dprobabl y extendengine life . Becaus e the wea r rate s i nquestio nar e small , however , they

hav e attracte dlittl e attention , and applicabl e recen t dat a comparin g th e effect s o f moderat e vs . ver y low sulfu r level s i nautomotiv e engine s ar e no t available . Ther e i s abundan t informatio nconcernin g th e effect s o f high-sulfu r fue l i nshortenin g engin e life , bu t virtuall y n o dat a
o nth e effect s o f ver y low-sulfu r fue l i nlengthenin g it .
Figur e 3.1 , take nfrom a stud y b y Tennyso nan dParke r (1970) , represent s th e bes t availabl e informatio no nth e effect s o f very lo w sulfu r fuel s o nrelativ e wea r rates . Th e figur e show s the effect s o f fue l sulfu r o npisto nring wea r rate s i na tw o cycl e locomotiv e engin e a s a functio no f the tota l bas e numbe r (TBN )



### 3-8P.5 4

IRO N FAC E WEA R VERSU S FUE L SULFU R

FRES H AN O USE O OIL S
Op« n Painl j •Fret H Oil s Clota d Point t - used Oil s

0. 2 a3 a ta ; a ta ra : Fu* l Sulfur . Weian t Ptretn l L1A V

1. 0

Figur e 3.1 : Effec t o f fue l sulfu r content an

doi l alkalinit

y o npisto nrin g t r rate s i

na locoeotiv

e engine (Tennyso

nan dParker , 1970) .

3- 9P.5 5

remainin g i n th e oil
.

Th e corrosiv e wea r rate s measure d byTennyso n an d Parke r ar e probabl ylowe r tha n thos e whic h woul d b e experience d i n automotiv e engines , an d thu s th e effect s o f differin g sulfu r level s ar e probabl yunderstated . Th e dat a wer e take n a t hig h load s an d i n steady-stat e operation , an d car e wa s take n tha t th e engin e wa s no t allowe d t o coo l dow n i n orde r t o preven t possibl e condensation
. High-loa d operatio n promote s abrasiv e wear , whil e condensatio n greatl yincrease s corrosiv e effects . Thus , th e
curve s i n Figur e 3. 1 probabl ysho wth e minim m effec t o f lo w sulfu r fue l —tha t whic h woul d b e observe d i n constan t high-powe r operation
. Th e differenc e i n wea r rate s woul d probabl yb e muc h highe r durin g warm-u p an d light-loa d operation , wher e condensatio n ca n occur .

Eve n give n thes e limitations , i t i s instructiv e t o conside r th e implication s o f Figur e 3. 1 fo r engin e lif e estimate s o n low-sulfu r fuel . Th e TB No f a n oi l decline s i n use , a s th e alkalin e additive s ar e deplete d b ycombinatio n wit h sulfur . A n exampl e o f thi s i s show n i n Figur e 3.2 . Fo r a typica l heavy-dut y oi l wit h a n initia l TB No f 6 t o 10 , th e averag e TB Nove r th e perio d betwee n oi l change s i s probabl ysomewher e betwee n 4 an d 7 , dependin g o n th e sulfu r conten t o f th e fue l an d th e blowbyrat e
o f th e engine
. Fo r thi s TBN , Figur e 3. 1 indicate s tha t goin g fro m0. 3 percen t sulfu r t o 0.0 5 percen t woul d decreas e wea r rate s

3-1 0P.5 6

1 9

Figur e 3.2 : Los s o f alkalinit y ino i b y sulfu r (Sergei , 196*1) . 1 durin g us e due t o neutralizatio n

3-1 1b y abou t 30-4 0 percent , whil e goin g fro m 0. 3 percen t t o the maximum o f 0. 5 percen t permitte db y the AST M

standar dwoul d increas e wea r b

y abou t 4 0 percent . Extrapolatin g thes e difference s ove r the whol e lif e o f the engin e woul dresul t ina n increas e o r decreas e i nengin e lif e andmileag e betwee nmajo r overhaul s o f u pt o 4 0 percent !

I t shoul db e emphasize dtha t thes e ar e probabl y mintm m difference s —

durin g warmu pandlow-loa dcondition s th e effec t
o f sulfu r level s i s muc hgreater . Figur e 3.3 , take nfro m a pape r b y Peugeo t (1984) , show s relativ e rate s o f ring wea r durin g
warm-u pa s a functio no f fue l sulfur . Thi s plo t show s roughl y a 6 5 percen t reductio ni nwea r i ngoin g fro m 0. 3 percen t t o 0.0 5 percen t sulfur . Automotiv e diese l engine s experienc e varyin g dut y cycles , bu t man y

se e a significan t amoun t o f col doperation , andwea r durin g startin g andwarmu pi s disproportionatel y high .

I t shoul db e note dtha t laboratory test s o f wea r rates , eve n relativ e wea r rates , requir e corroboratio nby fiel dexperience befor e they

ca nb e considere dreliable . T bdate , controlle d test s o f wea r rate s andengin e lif e wit hlow-sulfu r diese l fue l d o no t appea r t o hav e bee ndone , andth e estimate s give ni nth e precedin g paragraph s ar e thu s somewha t speculative . Experience gaine di nth e Sout hCoas t Ai r Basin , wher e low-sulfu r fue l i s no w mandatory , ma y

she dconsiderabl e ligh t o nin-us e wea r effects , bu t severa l mor e year s o f operatio no ntha t fue l wil l b e

3-1 2TEiVf^WIUR E D'EA U KJTEU R 60 ' C00L0N G WATE R A T60° C P.5 8

Tauxd'usur e de l a segmentatio n (Base 1 pou r0 2 d e soufrt )

8 RAT E O F WEA

RO F RING S % (BAS E 1 FOR0 2 SULPHUR )


### L 7



# U

L 3

0,2

5 

### Or * Z SULPHU RB YWEIGH T I N TH E FUE L %dt soufre^nasse

) urten u dan s l e oas e 

### cy s

• » •» . c**mr~±nf *UM 1 sulfu r content o

npisto nrin g wear rat e Fl8U TM ?•? : !""! ! °l^ l i ^ I nauto~tiv . diese l -ngin . (P«ugeot , 1984a , durin g engine Mareu

pi na nautoeot

S-1 3 ,P.5 9

required .

I nthi s context , it i s instructiv e t o conside r the experienc e o f gasolin e engine s wit hunleade dgasoline . Leade dgasolin e contain s bromin e andchlorin e additive s a s leadscavengers , whil e unleade dgasolin e doe s not . Thes e additives , lik e sulfur , ar e burne dt o for

m stron g minera l acid s i nthe blowb y andexhaust . A s discusse di nWeave r (1984a) , extensiv e in-us e experienc e wit h unleade dgasolin e ha s demonstrate da substantia l decreas e i n engin e wea r rate s compare da s a resul t o f eliminatin g thes e additives . A

serie s o f compariso ntest s intaxicabs , fo r instance , showe d70-30 0 percen t greate r wea r inbearing s and pistonring s usin g leade dgasolin e anda moder n(universa l type ) oil .

Fo r comparison , th e aci dconcentrationinleade dgasolin e a t 3. 0 gram s o f leadpe r ga l i s abou t .01 5 mole s o f aci dpe r gallon , whil e the aci dconcentratio ni ndiese l fue l a t 0. 3 percen t sulfu r i s 0. 3 mole s pe r gallo n— abou t 2 0 time s a s great . Presently , mos t heavy-dut y

diese l an dspar kignitio nengine s us e oil s formulate dfo r bot h(universa l oils) . I t i s reasonable , therefore , t o expec t tha t the effect s o f a low sulfu r fue l i n reducin g wea r rate s i ndiesel s woul da t leas t b e comparabl e t o thos e o f unleade dgasolin e inspar kignitio nengines .

T bsum up , ther e i s a consensu s amon g knowledgeabl e parties tha t

3-1 4wea r woul db e reduced , probabl y significantly , wit ha chang e t o lo w sulfu r fuel . Quantitativ e dat a definin g him ouc hengin e lif e wil l b e extende dar e very scarce , andin-us e dat a o nthi s poin t
ar e unavailable . Th e bes t indicato r availabl e i s th e locomotiv e stud y conducte db

y Tennyso nandParke r (1970) , whic hi s probabl y somewha t conservativ e fo r estimatin g differentia l wea r effect s i n automotiv e engines . Furthe r researc h— including carefull y controlledfiel dtest s — woul db e highl y

desirable .

3 . 2 ABTMA.TI

C OTWTFN

T AN D ICNTTIC N QDALITY

Th e volume fractio no f aromati c hydrocarbon s inth e fuel , o r aromati c content , ha s importan t effect s o nemissions , noise , and performanc e i ndiese l engines , anda nindirec t effec t o nfue l economy . Th e emission s andperformance/fue l econom y effect s ar e discusse dseparatel y

below . 

### Rntuion i ftffflcti

Th e emission s effect s o f aromatic s ar e du e t o a t leas t tw o an d possibl y thre e causes . Th e firs t reaso ni s th e clos e correlatio n betwee naromati c conten t andignitio nquality , a s measure db y th e cetan e nunber . A s discusse di nth e las t chapter , thi s i s especiall y

importan t fo r col dstar t andlight-loa doperation , bu t i t affect s particulate , noise , andhydrocarbo nemission s eve ni n

3-1 5P.6 1

norma l operation .

Th e secondeffec t i s du e t o the fac t tha t aromati c hydrocarbon s
ar e dense r tha nparaffin s o r napthenes . A s a result , highl y aromati c fuel s ar e dense r tha nles s aromati c ones , s o tha t (sinc e fue l injectio nsystem s mete r b y volume ) a greate r mas s o f fue l
ca nb e injecte dint o the cylinder . Thi s increase s the powe r outpu t o f th e engine slightly , bu t ca nals o rais e th e fuelin g rat e abov e the smok e limi t — resultin g i ndisproportionatel y greate r smok e andparticulat e emissions .

A third , possibl e effec t o nemission s ma y resul t fro

m th e greate r soot-formin g propertie s o f aromatics . Th e aromatics ' propensit y t o for m soo t i nsteady-stat e coabustio ni s wel l known . I t ca nb e explaine db

y th e fac t tha t th e aromati c ring decompose s readil y t o acetylene , whil e soo t i s know nt o b e forme db

y a rapi d polymerizatio no f acetylene . Th e relativ e importanc e o f thi s effec t i ndiese l engin e emission s i s no t known , however .

Th e effeet s o f aromati c hydrocarbon s o nignitio nqualit y an d densit y ar e no t unique . Napthene s ar e als o dense r an dhav e lowe r ignitio nqualit y

tha nd o paraffins , althoug hth e difference s i n eac hcas e ar e muc hles s tha nfo r aromatics * I t i s conceivable , therefore , tha t some weighte dinde xo f aromati c an dnaptheni c qualitie s migh t b e a bette r predicto r o f emission s effect s tha n aromatic s alone . On e indexwhic hha s thi s characte r already i sthe aniline-point , whic hals o ha s the advantag e o f bein g simpl e

andwidel y

used . Th e dat a availabl e ar e mostl y expresse di n terms o f th e aromati c content , however , andtha t i s th e index whic hwil l b e discusse dhere .

Th e effect s o f aromati c conten t o nemission s appea r t o b e differen t fo r light-dut y ID I an dheavy-dut y

D I engines . Emission s level s i nID I engine s appea r t o b e fairl y sensitiv e t o ignitio nquality , a s measure db y the cetan e number . Thi s ma y b e du e t o difference s i nthe effec t o f cetan e numbe r o nignitio n delay . I nnaturall y

aspirate dID I engine , Olre e an dLenan e (1984 ) founda goo dcorrelatio nbetwee nmeasure dignitio ndela y
andcetan e numbe r fo r a variet y o f operatin g conditions , whil e Barr y andcoworker s (1985 ) foundn o correlatio nbetwee nth e tw o i na highl y

turbocharged , intercoole dheavy-dut y engine . I t appear s that , fo r heavy-dut y engines , cetan e i s mostl y importan t fo r col dstarting , an ddoe s no t greatl y affec t warmed-u p emission s level s a s long a s th e ignitio nqualit y i s sufficien t t o allo w norma l combustion .

Measurement s o f aromati c conten t effect s o nemission s als o appea r t o b e sensitiv e t o th e testin g condition s used , an dt o th e specifi c engin e mode l bein g tested . Fo r instance , i na serie s o f light-dut y

test s conducte dfo r th e Coordinatin g Researc hCounci l (Hare , 1985) , worker s a t Southwes t Researc hfounda significan t correlatio nbetwee naromati c conten t an dparticulat e emission sP.6 3

for eac hof-fou r light-dut y automobiles . Th e magnitud e o f the regressio ncoefficien t relatin g th e two , however , varie dby a facto r o f mor e tha neigh t fro m on e engin e t o another . Majo r difference s wer e als o foun dbetwee nthe effect s measure do nthe Federa l Tes t Procedur e cycl e andthos e measure da t 3 0 and5 6 MP H cruis e conditions . Bergi n(1983 ) als o foundlarg e difference s i n the effect s o f aromatic s a s a functio no f engin e load .

Th e dependenc e o f aromati c effect s o nthe specifi c tes t cycl e als o appear s i nheavy-dut y engines . Barr y

e t ali a (1985 ) foun d majo r difference s i naromati c effect s i na moder nheavy-dut y engin e betwee nthe Federa l Heavy-Dut y Transien t tes t cycl e and the earlie r 13-mod e test * Th e engin e use dwa s a Caterpilla r 3406 B turbocharge dan daftercoole dline-hau l truc kengine , and ha dbee ncalibrate dfo r a lo w NO xemissio nrat e o f 6. 5 g/EHP-hr . Th e fuel s use dwer e speciall y compounde ds o tha t they ha dsimila r back-endvolatilit y

andsulfu r content , andth e fue l pum pwa s adjuste dt o compensat e fo r variation s i nfue l density . Thus , the onl y majo r emissions-relate dparamete r bein g varie dwa s th e aromati c content .
Figur e 3. 4 compare s th e tes t result s obtaine dby Barr y and co-worker s wit ha nunbe r o f fuel s wit hdifferin g aromati c contents . Dat a wer e obtaine do nbot hth e EP A transien t an dthe 13-mod e cycle . A s th e figur e indicates , bot hset s o f dat a li e alon g reasonabl y

straigh t lines , bu t th e slope s o f th e tw o

## AROMAH C CONTEN TEFTCCT O N WSRnCULAIE S P.6 4

I I I 

## AfttMM C CONTENT. VO L % .

Figur e 3.4 : Effect s o f fue l aroeati c conten t o nparticulat e eaissions : stead y stat e vs . transient test s o na heavy-duty

engine (Barr y e t alia , 1983) .

3-1 9regressio nline s diffe r b y a facto r o f abou t ten .

Tw o inportantjeonclusion s ca nb e draw nfro m the dat a inFigur e 3.4 . First , the aromati c conten t o f the fue l ha s a significan t effec t o nparticulat e emission s a s measure di nthe Federa l transien t test . Second , dat a take no nth e 13-mod e steady-stat e tes t cycl e (an

dpresumabl y

othe r steady-stat e cycles ) canno t b e use dt o predic t fue l effect s o nthe transien t test . Th e same i s als o tru e o f extrapolatio nfrom the 13-mod e tes t t o in-us e emissions . Th e transien t tes t cycl e wa s designe dt o b e representativ e o f condition s i nactua l use , whil e th e 13-mod e an d othe r steady-stat e cycle s d o no t represen t in-us e operatio nver y well . Thus , any

extrapolatio no f laboratory tes t result s t o in-us e emission s shoul db e don e usin g transient-cycl e data .

Th e restrictio nt o usin g onl y transien t cycl e dat a t o predic t in-us e emissio neffect s i s inconvenient , sinc e suc hdat a ar e extremel y

rare . Th e transien t cycl e i s stil l fairl y new , an d engin e tes t cell s capabl e o f runnin g it hav e mostl y bee n dedicate dfull-time t o developmen t wor kfo r the 198 8 NO xan d particulat e emission s standards . Wor kt o examin e th e relativ e effect s o f fuel s o nemission s ha s hadmuc hlowe r priority , and generall y

ha s no t bee ndone .

A comprehensiv e stud

y — funde db

y the Coordinatin g Researc h Counci l —

t o examin e fue l effect s o na nunbe r o f heavy-dut y

3-2 0P.6 6

engine s i s no wunderwa ya t Southwes t Researc h Institute , bu t th e dat a fro mthi s studywil l no t b e availabl e fo r a t leas t tw o years . I n th e meantime , onl yfou r studie s examinin g fue l effect s i n heavy-dut yengine s ar e availabl e i n th e literature
. O f these , tw o dea l wit h th e effect s o f syntheti c fuel s (Ullma n an d Hare , 1983 ; Ullma n e t alia , 1984) . Thi s introduce s th e potentia l fo r confoundin g effect s due t o othe r changes . Th e partia l result s o f
a thir d studyare reporte d byWal l an d Hoekma n (1984) , bu t th e author s di d no t repor t numerica l dat a fo r th e transien t test . Wal l an d Hoekma n reporte d onl yth e fac t tha t "statisticall y significant " relationship s betwee n aromati c conten t an d particulate s an d betwee n sulfu r conten t an d particulate s (bu t no t betwee n back-en d volatilit yan d particulates ) wer e found .

Th e fourt h studyshowin g fue l effect s o n emission s i n th e transien t tes t i s tha t o f Barr yan d co-workers , whic h ha s alread y bee n cite d above . Thi s studywa s specificall ydesigne d t o examin e th e effect s o f sulfur , aromati c content , an d back-en d volatilit yo n emissions
. Test s wer e ru n o n a se t o f fuel s whic h
wer e speciall ycompounde d t o var yonl yon e o f thes e indice s a t a time
. A s a result , th e tes t dat a ca n b e interprete d clearl yan d unambiguousl ya s showin g a stron g effec t o f aromati c conten t o n particulat e emissions
. A t a fue l sulfu r leve l o f 0.2 5 percent , th e relationshi p betwee n aromati c conten t an d particulat e emission s fo r th e Caterpilla r 3406 B engin e teste d wa s roughl y

3-2 1P.6 7

Particulat e = 0.14 3 + A • 0.011 3 (3.1 )

wher e particulat e i s i ngram s pe r EHP-h r andA i s th e aromati c conten t o f th e fue l i npercent . However , abou t 0.03 3 g-EHP/h r o f sulfat e wer e include di nth e particulate s i neac htes t (thi s lo w leve l wa s du e t o storin g th e filter s ove r a dessican t t o remov e the boundwater) . Subtractin g thi s valu e fro m the constan t term i nequatio n3. 1 give s

Carbonaceou s Particulat e = 0.12 0 + A • 0.011 3 (3.2 )

wher e the unit s ar e th e same a s fo r equatio n3.1 . "Carbonaceou s particulate " i s define dt o includ e bot hthe soot y fractio nand the solubl e organi c portio no f the particulat e material , bu t no t ... . _ the inorgani c sulfates . Sinc e variation s i naromati c conten t coul donl y

affec t emission s o f carbonaceou s particulate , thi s i s the appropriat e variabl e t o consider .
Equatio n3. 2 i s vali donl y fo r a singl e engine , andi s base do n onl y a singl e serie s o f tests . However , it agree s moderatel y wel l wit hon e o f th e syntheti c fue l studie s reporte dby Ullma n andco-workers , andwit hth e findin g by Wal l andHoekma ntha t aromatic s ha da statisticall y significan t effec t o nparticulat e emissions . Th e othe r syntheti c fue l stud y showe dlittl e o r n o effec t o f aromatic s o nparticulates , bu t thi s ma y hav e bee n

3-2 2P.6 8

confounde d bychange s i n th e othe r hydrocarbo n component s o f th e fuels .

Agrea t man ystudie s o f fue l effect s o n light-dut ydiese l emission s hav e bee n reporte d i n th e literature
. Bykowsk i an d co-worker s (1983 ) hav e sunmarize d an d combine d th e dat a fro ma nunbe r o f thes e studies
. Mos t o f thes e studie s hav e agree d i n findin g tha t aromati c conten t an d back-en d boilin g poin t ar e th e importan t variable s affectin g emissions
. Unfortunately , non e o f thes e studie s examine d fue l sulfu r a s a n independen t variable , no r di d Bykowsk i e t ali a reanalyz e fo r sulfu r effects . Sinc e sulfu r conten t i s no wknow n t o hav e a stron g effec t o n particulat e emissions , thi s cast s seriou s doub t o n th e validit y
o f th e correlation s developed .

I n additio n t o possibl e confoundin g o f aromati c an d sulfu r effects , i t appear s tha t th e effect s o f aromati c conten t o n light-dut yparticulat e emission s var ygreatl yfro mengin e t o engine
. Figur e 3.5 , take n frc mBykowsk i e t alia , show s th e regressio n line s relating aromatic s t o particulat e emission s calculate d fo r eac ho f a nunbe r o f differen t studies
. A s th e figur e shows , thes e studie s d o no t al l agre e eve n o n th e sig n o f th e effect , muc h les s o n it s magnitude
.

Fro mth e dat a a t hand , i t i s impossibl e t o giv e a reliabl e quantitativ e estimat e o f th e chang e i n light-dut ydiese l

3-2 3P.6 9

3. 2

2. 8 •

0 *• « • R M P 2. 0 • A R T •. 6

• . 2 •

.8 0

.4 0 *" *

X 0. 0 • .• . 0 . .•. .

t o .•. . 13 .•. . 2 0 .•. . 2 3 .•....•....•. .

3 3 3 0 4 0 AMOMATI C , /

, .•. . 4 3 .•. . 3 0 .•. . 3 3 .•. .

6 3 6 0 .• .

7 0

Figur e 3.S : Regression s o f particulat e eaission s vs . fue l aroeati c content

fro a a nuabe r o f studie s usin g different light-dut y engine s (Bykowsk i et alia , 1983) .

3-2 4P.7 0

emission s tha t woul d resul t fro ma chang e i n aromati c content . A s a n order-of-magnitud e estimate , th e regressio n lin e fo r al l petroleum-derive d fuel s calculate d byBykoswki , e t ali a ma yb e representative
. Thi s regressio n i s show n i n Figur e 3.6 . I t give s th e normalize d particulat e inde x a s

I = 0.63 5 + 0.0126 9 * A (3.3 )

wher e I i s th e rati o o f particulat e emission s wit h th e tes t fue l t o thos e usin g a standar d referenc e fuel , an d Ai s th e volum e fractio n o f aromati c hydrocarbons .
Effect * o n fue l economy , performanc e an d diirnMHt y

A s note d i n Chapte r Two , th e aromati c conten t i s closel y correlate d wit h cetan e nunber . Cetan e nunber s ar e importan t fo r col d startin g o f bot h direc t injectio n (DI ) an d indirec t injectio n (IDI ) engines
. The yar e especiall yimportan t fo r D I engines , sinc e th e universa l us e o f glo wplug s o n ID I engine s make s the mles s susceptibl e t o startin g problems . Daimler-Ben z (1984 ) ha s state dtha t 4 5 cetan e i s th e minimu mallowabl e fo r col d starting , whil e number s abov e 5 0 ar e muc h preferred . B y thi s criterion , almos t al l U.S . diese l fuel s woul d b e margina l a t best , whil e a larg e fractio n woul d giv e unsatisfactor y performance .

3-2 5s. 2 •;

2. e •; N 0 '. R 2. « •; M *
P 2. 0 * A . R T 1. 6 •

1. 2 •A A A A A A A A A A

A A 8 A

. AT " A A A A A^-*Ol "

. A A A A A

A 4—***T* ^ A . 8 0 •A *

- **—*^" ^ V-A' a ; XA-KJT A A A AA >

. A A A > " A

. A >»" ^ A A . 4 0 * A > * X ^ A m» m*

. m* A - '

* •-" ' ^-— —\ A A^ "

^-—""" A AA A *, '

^.^J*—-" ^ • l - 4 ^ —^^ A AA8 B X-TAR T-1. 0 A A A A A • A

•^

3 . I S 2 3 3 3 4 5 J J 6 S 0 . 1 0 2 0 3 0 4 0 S O 6 0 7 0 AROMATIC , X

Figur e 3.6 : Regressio n o fparticulat e eaission s vs . fue l aroeati c content :

coabine d dat a fro a a nuabe r o flight-dut y engin e studie s (Bykowsk i e t alia , 1983) .

3-2 6 P.7 1 iP.7 2

Reducin g th e aromati c conten t o f diese l fue l ma yslightl yreduc e fue l econom

yan d maximu mpowe r i n existin g engines
. Thi s i s du e t o th e fac t tha t a les s aromati c fue l contain s slightl yles s energype r uni t o f volume . I n ne wengines , however , thi s effec t woul d b e mor e tha n offse t byth e reductio n i n compressio n rati o mad e possibl e byhighe r cetan e nunbers . Presently , heavy-dut yD I engine s ar e require d t o hav e highe r compressio n ratio s tha n woul d b e optima l fo r fue l econom yi n orde r t o ensur e satisfactor ycol d starting
. I f a highe r cetan e leve l wer e guaranteed , manufacturer s coul d decreas e compressio n ratio s slightly , wit h significan t benefit s i n fue l econom yan d (possibly ) emissions
.

Arecen t repor t byworker s a t Cummin s give s som e ide a o f th e magnitud e o f th e effect s involved
. Phata k an d Nakamur a (1983 ) experimente d wit h compressio n ratio s o f 14:1 , 16:1 , an d 18: 1 i n a naturall yaspirate d D I diesel
. The yfoun d tha t powe r an d fue l
econom ywer e best , an d smok e wa s lowest , a t 14:1 , nex t bes t a t 16:1 , an d wors t a t 18:1 . Figur e 3. 7 show s som e o f thes e results . Th e brake-specifi c fue l consumptio n a t 14: 1 wa s abou t 10-1 5 percen t lowe r tha na t 18: 1 i n thes e tests . A t 14:1 , however , th e engin e coul d no t b e starte d eve n a t 3 2 F , whil e a t 16: 1 i t too k 9 0 second s t o star t a t 3 2 F an d woul d no t star t a t al l a t 1 4 F . A t 18: 1 th e engin e starte d satisfactoril ya t temperature s a s lo w
a s - 4 F . Th e cetan e nunbe r o f th e fue l use d wa s no t given , bu t
wa s probabl yi n th e rang e o f 4 2 t o 4 5 whic h i s typica l o f diese l

3-2 7P.7 3

7 5 r

o e I ai

. x .6 3

a .5 7 vt 0 9 .5 1

.4 5 COMPRESSIO N RATI O

_l
_ J

_ J
_ _ L 100 0 120 0 140 0 160 0 180 0 200 0 220 0 240 0 SPEE O (RPM )

> S 4 < O o s 6.0 0 r
5.20 -
.40 -

3.6 0

2.8 0

2.0 0 100 0 120 0 140 0 160 0 180 0 200 0 220 0 240 0 SPKOtRPM l

Figur e 3.7 : Effec t o f change s i ncoapressio

nrati o o

nfue l consueptio

nan d »k e (Phata

k an d Nakaaura , 1984) .

3-2 8P.7 4



### #2 .

Muc h o f th e nois e produce d bya diese l engine , especiall ya t ligh t loads , i s du e t o th e rapi d pressur e ris e whic h result s fro m premixe d burnin g du e t o th e ignitio n delay . Alower-aromati c fue l woul d reduc e thi s nois e byreducin g th e ignitio n delay , whil e a highl yaromati c fue l woul d increas e it
. Afue l wit h sufficientl ypoo r ignitio n qualit ycoul d eve n affec t th e durabilit yo f th e engine , du e t o th e hig h transien t pressure s resultin g fro mth e lon g ignitio n dela yperiod
. Thi s i s no t a significan t proble ma t present , excep t fo r margina l fuels , bu t coul d conceivabl ybecom e a proble mi f fue l qualit ycontinue s t o decline
.

3. 3 PUE L BOILIN

G RANC S AM D tt»ATIL IT

Y

Man ydiscussion s o f fue l effect s o n particulat e emission s hav e concentrate d o n th e 9 0 percen t point , en d point , o r othe r indicator s o f back-en d volatility
. Anunbe r o f studie s hav e indicate d significan t correlation s betwee n back-en d volatilit y
an d particulat e emission s i n ligh t dut yvehicle s (e.g . Burle yan d Rosebrock , 1979 } Har e an d Baines , 1979) . Researcher s a t Chevron , however , hav e show n tha t thes e result s ma yhav e bee n confounde d wit h th e effect s o f sulfur , whic h i s strongl ycorrelate d wit h back-en d volatilit yi n petroleum-derive d fuel s (Chevron , 1984) .

3-2 9Bykowsk i an dco-worker s (1983 ) combine dth e result s o f 1 1 studie s

o f fue l effect s o nemission s inlight-dut y vehicles . Figur e 3. 8 i s a plo t o f normalize dparticulat e emission s versu s fue l 90-percen t poin t fo r th e combine ddata , alon g wit hth e best-fi t line s calculate dfo r petroleum-derive dfuel s (soli dline ) and alternativ e fuel s (dashe dline) . A s the figur e shows , thes e dat a
ar e highl y

scattered , an dneithe r regressio nequatio npredict s
ver y well . I naddition , the fac t tha t the slop e o f th e regressio nlin e fo r alternativ e fuel s i s nearl y zer o (an

d negative ) whil e tha t fo r petroleum-derive dfuel s i s large r an d positiv e strongl y

suggest s tha t the result s ar e bein g confounde d b y some othe r variable , suc ha s sulfu r content .
Bergi n(1983 ) use da variet y o f low-sulfu r fuel s t o examin e th e effect s o f aromati c conten t and9 0 percen t poin t o nlight-dut y emission s a s function s o f engin e load . H e foun dtha t 9 0 percen t poin t accounte dfo r abou t hal f th e variatio ni nparticulat e emission s a t ligh t loads , wit haromatic s accountin g fo r th e othe r half . A t highe r loads , wher e particulat e emissio nrate s ar e greater , 9 0 percen t poin t ha dlittl e effect , anda t th e highes t loads , a highe r 9 0 percen t poin t wa s actuall y correlate dwit h lowe r particulat e emissions .
Comparativel y

littl e wor kha s bee ndon e comparin g heavy-dut y engin e emission s o ndifferen t fuel s usin g th e heavy-duty

3-3 0P.7 6

J. 2

2. 8

N 0 2. 4 R M f 2. 0 A R T 1. 6

'. 2

.8 0

.4 0 .••.•••••..• .

i.*....*....*....*....*...**....*....*....*....*....*....*....*....*,
. 75 . 12 5 11 5 22 5 27 5 32 5 37 5 10 0 IJ

O 20 0 25 0 30 0 33 0 40 0

8PNINETY , ° C

Figure 3.8 : Regressio no f particulate eaission s vs . fue l 9* J percen t point : coabine ddat a fro a a nuabe r o f light-dut y engin e studie s (Bykowsk i e t alia , 1983) .

3-3 1P.7 7

transien t test . A s discusse di nSectio n3.2 , fuel-effect s result s obtaine da t steady stat e appea r t o diffe r significantl y fro m thos e obtaine do nth e transien t test . Tw o recen t studie s whic hinclude dbot htype s o f test s wer e conducte db y Chevro n Researc h(Chevron , 1984 ; Wal l andHoekman , 1984) , an dth e wor ko f Barr y e t a l (1985) . Th e Chevro nstud y showe da sligh t positiv e effec t o f 9 0 percen t poin t o nparticulate s i nsteady-stat e operation , whil e Barr y an dco-worker s showe da sligh t negativ e effect . Mor e importantly , neithe r stud y showe dan

y statisticall y significan t effect s i nth e transien t test . Th e dat a o f Barr y e t ali a ar e reproduce di nFigur e 3. 9 .

Frc m thes e data , i t appears tha t change s i nback-en dvolatilit y pe r s £ hav e littl e effec t o nparticulat e emission s fro m heavy-dut y

D I engines , andonl y a mino r effec t o nthos e fro m light-dut y

ID I engines . Increase s i nback-en dvolatilit y i n conmercia l diese l fuel s wil l b e limite dby th e AST M

specificatio n for diese l #2 , an db

y th e nee dt o maintai nacceptabl e cold-flow performance . Significantl y decreasin g back-en dvolatilit y woul d b e ver y expensive , an dwoul dmak e achievemen t o f othe r fuel-qualit y

goal s mor e difficult . Fo r thes e reasons , considerationo f a nemissions-relate dstandar dfo r back-en d volatilit y

i ndiese l fuel s appear s t o hav e littl e justificatio n
a t thi s time .

3-3 2P.7 8

Stil l unde r

developmen t



# « - " «rnuL-.=riru»,^ ^

3-3 3P.7 9

3. 4 DENSIT YAN DVISCOSIT Y

Fue l densit y

ha s a nimportan t effec t o nfue l econom y ando n particulat e emissions . Th e energy conten t o f a give nmas s o f diese l fue l i s (roughly ) constant , whic hmean s tha t a dense r fue l (containin g mor e mas s pe r uni t o f volune ) wil l resul t i na lowe r volumetri c fue l consumption . Sinc e fue l i s metere dandsol db y volume , no t mass , thi s ca naffec t the economic s o f fue l use .

Th e effect s o f densit y o nparticulat e emission s deriv e from the same cause . Th e powe r outpu t o f a diese l engin e i s determine db y the amoun t o f fue l injecte dint o the cylinde r t o burn . Beyon d
som e poin t (know

na s the smok e limit) , smok e andparticulat e emission s increas e ver y rapidl y

a s the amoun t o f fue l injecte d increases . Fb r thi s reason , diese l fue l injectio npump s ar e se t t o limi t the maximum

volume o f fue l injecte dt o a valu e nea r t o th e smok e limit . A nincreas e i ndensity , however , mean s tha t a greate r mas s o f fue l i s containe di nthi s maximum volune . Thi s ca nresul t i na smal l increas e inpower , accompanie db y a larg e (an ddisproportionate ) increas e i nsmok e an dparticulat e emissions .

Fue l viscosit y

i s als o importan t t o fue l econom y an demission s performance . I nmoder nD I engines , a grea t dea l o f developmen t effor t ha s bee nexpende do noptimizin g th e combinatio no f fue l spray characteristics , airflow patterns , an dinjectio ntiming i n

3-3 4P.8 0

orde r t o obtai nthe bes t tradeof f betwee nemissions , fue l economy , driveability , andothe r factors . Fue l viscosit y change s
ca nsignificantl y

affec t fue l spra y

characteristics , andthu s degrad e the coitustio nprocess . Tb o hig ha viscosit y als o increase s th e force s o nthe fue l injectio npump , whil e to o lo w a viscosit y

ma y affec t the lubricatio no f th e pump . Eithe r chang e
ma y resul t i nexcessiv e wea r o nth e fue l injectio nsystem .

I t i s importan t t o not e tha t th e absolut e value s o f th e densit y
andviscosit y

ar e no t especiall y

importan t —

engin e design s ca n b e optimize dfor any

reasonabl e value s o f thes e parameters . Wha t i s importan t i s tha t the variatio ni ndensit y andviscosit y value s b e minimized , s o tha t engine s optimize dfo r on e se t o f value s ar e no t face dwit ha fue l havin g a radicall y differen t set .

A s discusse di nSectio n2.3 , densit y andviscosit y

ar e determine d by th e hydrocarbo ncompositio no f th e fuel . Thus , regulator y change s whic htende dt o standardiz e hydrocarbo nconten t (e.g . by limitin g aromatics ) ar e likel y t o reduc e th e variatio ni nthes e propertie s a s well . Th e issu e o f whethe r furthe r standardizatio n
o f thes e propertie s woul dsufficientl y reduc e emission s t o b e wort hth e cos t i s a difficul t one , andbeyon dth e scop e o f th e presen t effort . I t i s recomnende dtha t thi s questio nb e considere da s par t o f a mor e detaile dstudy o f potentia l fue l regulations .

3-3 5P.8 1

3. 5 STABILITY , TIOTT T TTRHATION . AN D OTHF RPHTPraTTFS

Th e oxidatio n stabilit yan d deposit-formin g qualitie s o f diese l fue l affec t bot h th e long-ter memission s an d th e long-ter m performanc e o f th e engine s usin g it
. Fue l oxidatio n i n storag e lead s t o pluggin g o f fue l filters , an d ca n damag e th e fue l injectio n system . Formatio n o f excessiv e deposit s o n fue l injector s ca n affec t fue l spra yan d injectio n timin g characteristics , degradin g bot h emission s an d performance . Diese l fuel s containin g a larg e percentag e o f catalyticall y cracke d stock s ar e generall yconsidere d t o hav e poore r stabilit y
an d greate r deposit yformin g characteristic s tha n straight-ru n diesels , an d th e increasin g us e o f cracke d stock s worldwid e ha s create d concern s i n thi s area .

Bot h oxidatio n stabilit yan d deposit-formin g characteristic s ca n b e effectivel ycontrolle d byth e us e o f additives , an d stability-enhancin g additive s ar e routinel yuse d byman yU.S . refiners
. Additive s t o contro l deposi t formatio n ar e mor e expensive , an d ar e no t widel yused . A s a result , som e diese l engine s (especiall yEuropea n an d light-dut yengines ) hav e suffere d fro memission s an d performanc e problem s du e t o injecto r deposits
. Severa l Europea n manufacturer s hav e advocate d greate r
us e o f thes e additive s i n orde r t o contro l thes e problem s

3-3 6P.8 2

(Hardenburg , 1985 ; Lucki , 1984) . Sinc e thes e problem s ar e linke d t o othe r indice s o f diese l fue l qualit y (suc ha s cetane an

d arcmaU c content) , i t appear s likel y tha t a genera l inprovemen t i nthos e characteristic s woul dalleviat e thes e problem s a s well .

3-3 7P.8 3

4.0 : MTTEUN G TH

E COST S Q F REFININ G CHANCE S

Th e approac huse dt o determin e th e cost s resultin g fro m change s i ndiese l fue l specification s wa s t o develo pa mode l o f annua l U.S . refinin g operation s an dt o simulat e operation s a t variou s level s o f diese l fue l specifications . Th e refiner y mode l determine dth e chang e i noveral l refiner y margi n(i.e . refine d produc t revenue s les s raw materia l an doperatin g costs ) associate dwit hrestriction s i ndiese l fue l qualit y specifications . Th e analysi s focuse do nth e domesti c refinin g industry andrefine dproduc t deman dprojecte dfo r th e yea r 1987 .

Thi s sectio nprovide s a descriptio no f th e refinery mode l andthe approac huse dt o develo pth e refiner y cos t estimates . Th e firs t thre e section s describ e th e model , it s applicatio nt o th e analysis , an dth e modelin g assumptions . A fina l sectio n discusse s limitation s o f th e analysis .

4 . 1 PV7WMV7B

Y MTFf .

Th e mode l use dfo r the refinery cos t analysi s wa s a versio no f th e Depart - men t o f Energy' s Refiner y Evaluatio nModelin g System



### 4- 1P.8 4

(REMS) . Th e Refiner y

Evaluatio nModelin g System (REIVE ) i s a modelin g system

use db y th e Departmen t o f Energ y (DOE ) t o analyz e U.S . petroleu

m suppl y issue s an dt o provid e inpu t int o othe r energy models .

RIM S consist s o f tw

o parts : a serie s o f refinery I P model s whic h simulat e geographi c refinery operations , anda transportatio n aggregato r whic hsimulate s crud e an dproduc t movemen t throughou t the Unite dStates . Th e refinery mode l wa s designe dt o ru n separatel y

i norde r t o generat e extreme poin t vector s fo r th e refinery secto r o f the transportatio nmodel . I t i s the refiner y mode l tha t wa s use dt o develo pestimate s o f refinin g cost s associate dwit hdiese l specificatio nchanges .

Th e refiner y

mode l i s a single-time perio dL P representatio no f crud e an ddownstream

processin g andfina l produc t blending . "Tt'~ - i s simila r t o thos e typicall y employe db

y refiner s fo r plannin g
andschedulin g bu t i nseme respect s simplified . I t ha s prove nt o provid e a goo drepresentatio no f aggregat e regiona l operation s o f U.S . refiner s an dha s successfull y undergon e a nunbe r o f validation/verificatio ntests .

Th e mode l "begins " wit ha representatio no f crud e oi l distillatio nthrougha serie s o f crud e assays . Fo r eac ho f abou t 10 0 crud e oils , the assay s describ e the yiel do f intermediat e o r fina l refine dproduct s generate ddurin g th e initia l distillatio n



### 4-2P.8 5

andthei r quality . Downstream fro m the crud e distillatio nunit , th e mode l contain s comprehensiv e representation s o f al l majo r refiner y units . Th e downstream uni t representation s contai n yiel dandcos t correlation s for variou s type s andqualit y feedstock s a s wel l a s correlation s use dt o determin e outpu t quality .

Th e refinery

mode l i s capabl e o f producin g approximatel y 2 5 product s i nit s curren t configuration , roughl y correspondin g t o the produc t categorie s a s reporte dby COE . Majo r products , suc h
a s gasoline , je t fuels , middl e distillates , andresidua l fuel , ar e blende dt o specifi c user-specifie dqualit y parameters . Othe r smalle r volume product s ar e recip e blended .

Th e mode l determine s a noptimu m solutio nt o a specifie dobjectiv e (suc ha s profi t maximization ) base do nprevailin g economi c -- . -- . condition s an da s limite dby capacit y

constraints , produc t specification s o r othe r user-specifie dcon - straints . I n additio nt o th e optimu m answer , th e mode l provide s economi c and processin g informatio no nal l aspect s o f th e refinin g industry' s operations , suc ha s proces s utilization s o r th e rat e a t whic h cost s chang e a s operation s ar e altered .

Th e refiner y

yiel dmode l wa s originall y develope di n1976 , a t whic htime i t wa s use dt o suppor t analysi s relate dt o th e Strategi c Petroleu

m Reserve . I t sinc e ha s bee nuse dby DO E and



### 4- 3EP Afo r severa l purposes . EP Aha s use d th e mode l t o predic t th e cost s o f lea d phasedow n durin g th e 198 2 an d 198 4 rule

- makings
.



### 4. 2 Wm__AWm_Qi

Fo r thi s analysis , tw o regiona l model s wer e develope d t o represen t easter n U.S . (PAED s I throug h IV ) an d wester n U.S . (PAD D V) . Th e existin g petroleu mdistributio n networ k allow s refiner s t o somewha t optimiz e aggregat e operation s throug h produc t exchanges , crud e variations , etc. , i n eac h o f thes e regions
. However , ther e i s ver ylittl e connectio n betwee n th e Wes t Coas t an d th e remainde r o f th e U.S . distributio n system ; hence , th e tw o operat e independently
.

Fo r eac h region , projection s wer e mad e o f refiner ysuppl yan d deman d petroleu mprices , produc t qualitie s an d processin g capacitie s fo r th e yea r 1987 . Th e industr ywa s limite d t o processin g facilitie s currentl yi n plac e o r projecte d t o b e complete d b y1987 ; ne winvestment s beyon d thes e wer e no t assume d t o b e availabl e withi n thi s timeframe
. Eac h mode l wa s ru n wit h produc t demand s fixed , excep t fo r liqui d petroleu mgas , coke , sulfu r an d residua l fuel . Mos t input s wer e als o fixed , bu t th e model s wer e allowe d t o var ya margina l crude , butan e an d utilit y purchases . Thes e initia l run s define d a "bas e case " fore

- cas t
o f industr yoperatio n i n eac h regio n wit h diese l fue l qualit y



### 4-4P.8 7

conformin g t o curren t specifications
.

Afte r establishin g th e bas e cases , th e model s wer e agai n ru n wit h th e sam e ra wmaterial , product , an d pricin g assumptions , bu t wit h
mor e restrictiv e diese l fue l specification s a Becaus e al l othe r parameter s wer e hel d constan t betwee n cases , th e cos t associate d wit h change s i n diese l specification s coul d b e compute d a s th e
su mo f change s i n crud e oil , butan e an d utilit ypurchases ; IfG , coke , sulfur , an d residua l fue l revenues ; an d othe r margina l operatin g cost s (catalysts , chemicals , etc.) . Fixe d cost s an d capita l charge s wer e no t include d i n th e cos t computations
. Thes e latte r cost s ar e alread y"sunk " an d wil l no t var ywit h diese l fue l specifications
.

Th e mor e restrictiv e diese l fue l specificatio n case s firs t considere d a reductio n i n sulfu r conten t fro mcurren t level s t o 0.0 5 weigh t percent . Then , wit h th e sulfu r conten t maintaine d a t 0.0 5 weigh t percent , diese l fue l aromatic s conten t wa s lowere d t o 1 7 volun e percent .



### 4. 3 MTH . xggwsmrMS

Refine d produc t deman d fo r 198 7 wa s base d o n DOE' s Annua l Energ y



### 4- 5P.8 8

Outloo k(EIA , 1985 ) andgasolin e demand s projecte db y EP A for thei r leadphasedow

ncos t benefi t analysi s (Schwart z e t alia , 1984) . Tabl e 4. 1 sunmarize s th e projecte ddemand s use dfo r th e analysis .

Produc t demand s wer e disaggregate dint o PAED s I-I V andPAD DV base do nhistori c market shares . Gasoline , nunbe r tw o heatin g oil , anddiese l fue l demand s wer e the nadjuste dt o accoun t fo r imports , arrivin g a t the projecte ddeman do nrefinerie s show ni n Tabl e 4.2 . Gasolin e anddistillat e import s wer e assume dt o declin e frcm

curren t hig hlevel s du e t o growt hi nworl dpetroleu m deman dan da declin e i nthe worldwid e refinin g capacit y surplus .

A diese l fue l deman do f 1.2 5 millio nbarrel s pe r da y (42. 8 percen t o f middl e distillat e demand ) wa s estimate dbase do nDOE*?- , projectio no f transportatio ndistillat e fuel . Th e same diese l fue l percentag e wa s applie dt o bot hregion s simulated . Fo r PAE D V , diese l fue l demandi nth e Lo s Angele s are a wa s assume dt o accoun t fo r 26. 5 percen t o f th e region s demand .
(Viiai * «nr i rtthe f

Ra wMateria l Suppl y

A forecas t o f crud e supplie s fo r eac hregio nwa s base do nth e DO E Annua l Energ y

Outlook , th e HSM S mode l update , an dcurren t trend s
o f importedcrud e oil . Supplie s o f unfinishe doi l feedstock s
wer e als o estimate dbase do nhistori c trends . Refiner y input s



### 4- 6Tabl e 4.1 : U.S . Refinery Produc t Demand : 198 7 (Thousand Barrel s Pe r Day) .

Produc t Deman d Unleade d Regula r Gasolin e 3,63 5 Unleade d PremiumGasolin e 1,21 0 Leade d Gasolin e 1,66 5 Aromatic s 13 0 Naphtha s 14 0 Naphth a Je t Fue l 24 5 Kerosen e Je t Fue l 98 5 Kerosen e 11 0 Diese l Fue l 1,25 0 Othe r Distillat e 1,67 0 Residua l Fue l (1 ) 1,42 0 Lube s an d Wa x 18 5 Asphal t an d Roa d Oi l 44 0 Othe r (2 ) 3,07 5 (1 ) Residua l fue l varie s i n PAI D scenarios
. (2 ) Othe r include s aviatio n gas , ga s oi l t o petrochemicals , stil l ga s to
p e trochem i cals , ethane , propylen e t o petrochemicals , propan e t o petrochemicals , butylen e t o petrochemicals , coke , sulfur , proces s gas , norma l butane , an d LP G som e o f whic h ar e allowe d t o var y i n PAH ) scenarios
.



### 4-7P.9 0

Tabl e 4.2 : Projecte ddemandfro m refineries : 198 7 (thousan d barrel s pe r day )



### Produc t Unleade dRegula r Gasoline UnleadedPremiu

nGasoline Leade dGasoline Aromatic s Naphtha s Naphth a Je t Fue l Kerosene Je t Fue l Kerosene Diese l Fue l Othe r Distillat e Residua l Fue l Lube s an

dWa x Asphal t an

dRoa dOi l Othe r Deman d 

### PAC KI-I V PACD V 2,97 0 1,00 0 1,33 0 

### 13 0 13 0 18 0 71 5 10 0 1,04 0 1,39 0 open 

### 17 0 37 0 open 

### 59 0

20 0 27 0 1 10 6 5 27 0 10 165 22 0 open 

### 1 5 7 0 open



### 4- 8P.9 1

Tabl e 4.3 : Refiner y inputs : 198 7 (thousandbarrel s pe r day) .



### Crud e Oi l Hig hSulfu r Low-Sulfu

r Hig hAromatic s Low-Sulfu

r Lo w Aromatic s Margina l MexicanIsthmus Margina l AlaskanNort hSlope

Unfinishe

dOil s Natura l Gasoline/Condensat e Butane Alcohols/MIB E PACE S I-I V pAJD Y

4,10 0 4,20 0 80 0 Varie s 0

20 5 19 5 Varies * 4 5 1,62 0

0 21 5 0 Varie s

0 1 0 Varies * 0

* Limite dt o maximu m o f 198 4 volumes .



### 4- 9ar e sunmarize d i n Tabl e 4.3 .

I n eac h region , availabl e crud e oil s wer e aggregate d int o fou r crud e mi x pools : hig h sulfu r crudes , lo wsulfu r hig h aromatics , lo wsulfu r lo waromatics , an d th e margina l crude . I n PAED s I-I V th e margina l crud e wa s assune d t o b e Mexica n Isthmu s an d i n PAD D V , Alaska n Nort h Slope .

Bew Materia l an

dRefinedProduc t PHee a

I n th e analysis , th e cos t o f mor e restrictiv e diese l fue l specification s i s determine d bymargina l crud e oi l an d othe r ra w materia l costs , margina l produc t revenue s an d miscellaneou s operatin g costs . Refiner ycost s determine d byth e mode l ar e therefor e a functio n o f price s specifie d fo r margina l ra w material s an d products . Thes e price s wer e assune d t o remai n roughl ya t curren t level s i n rea l term s a s show n i n Tabl e 4.4 .

RefinedProduc t Speeifieatlon g

Refine dproduc t specification s fo r major refine d product s ar e show n i n Tabl e 4.5 . Gasolin e specification s an d je t fuel , distillate , an d residua l fue l sulfu r specification s wer e base d o n estimate s o f curren t quality
. Other specificatio n parameter s
wer e base d o n AST M specifications
.

4-1 0P.9 3

Tabl e 4.4 : Ra w

Materia l an d Refine d Produc t Prices : 198 7 (Dollar s Pe r Barrel )



### Ra w Materia l Pri TM */mr . Margina l Mexica n Isthmu s Crud e $29.4 6 Margina l Alaska n Nort h Slop e Crud e 28.7 5 Isobutan e 23.2 3 Norma l Butan e 22.2 0

Product s LP G 18.4 4 Lew-Sulfu r Resi d (PAED s I-IV ) 27.5 0 Low-Sulfu r Resi d (PAI D V ) 27.8 0 High-Sulfu r Resi d (PADD s I-IV ) 26.2 0 High-Sulfu r Resi d (PAI D V ) 26.2 0 Sulfu r 50.0 0 High-Sulfu r Cok e 15.0 0

4-1 1P.9 4



### Tabl e 4.5 : Refine dProduc t Specification s

Gasoline s PAI D I-I

V Uni . Reg . Uni . Prm . Leade d Pad dV Uni . Reg . Uni . Prm . Leade d Keroje t Fue l Al l Region s
Distillate s an

dResi d PAD D I-I

V Diese l N o 2 Fue l L.S . Resi d H.S . Resi d PADD V Diese l N b2 Fue l L.S . Resi d H.S . Resi d Octan e

HCN W UR4M/ 2 91. 7 83. 0 87. 4 96. 4 86. 8 91. 6 92. 9 85. 3 89. 1 92. 5 83. 4 88. 0 96. 5 86. 7 91. 6 93. 4 85. 1 89. 3
Sulfu r AP I Gravity 

### RV

P ps i 12. 0 12. 0 11. 9 10. 5 10. 7 10. 5 Lea

d ffPff

— 

### 0. 1
~ ~ 

### 0. 1

Lum . Nb . max . min . max .

. 1 39 . 51 .
Sulfu r AP I Grav . 

### mi n 0.2 8 3 0 0.2 8 3 0 0.4 0 2.5 0 0.3 0 3 0 0.2 4 3 0 0.4 0 2.5 0 Flas h min . 

### 125 125 15 0 150 125 125 15 0 150 mio a 45
Min . 

### 44 0 10 10
10 10 Ma x% Eva

p a t 21 2 F 

### 6 0 6 0 6 0 6 0 6 0 6 0

% Eva p 

### 64 0 9 0 9 0
9 0 9 0 Visco s min . 

### 1. 9 1. 9
1. 9 1. 9 it y mn* . 

### 4. 1 4. 1 2S0 ~ 

### 30 0 4. 1 4. 1 30 0 30 0

4-1 2P.9 5

Curren t Numbe r 2 heatin g oi l an ddiese l fue l sulfu r level s o n averag e ar e belo w

level s specifie dby AST M o r Federa l andstat e environnenta l regulations . Thi s i s du e t o a nunbe r o f factor s suc ha s th e availabilit y o f ver y

low sulfu r stock s incertai n refining areas , th e us e o f desulfurizatio nprocessin g for purpose s othe r tha nmeetin g sulfu r standard s (i.e. , stabilization , mercapta nreduction , etc.) , product s distributio n constraints , etc . I nthi s analysis , i t wa s assune dthat'thes e factor s impos e a n"artificial " limi t o nthe sulfu r conten t o f distillat e fuels . Therefore , curren t Numbe r 2 sulfu r level s wer e maintaine da s diese l fue l sulfu r level s wer e furthe r constrained . Th e Ninibe r 2 heatin g oi l poo l wa s no t allowe dt o serv e a s a "sink " for sulfu r remove dfro m th e diese l fue l pool .

Refiner y

capacitie s wer e limite dt o thos e facilitie s i nplac e a s
o f Januar y

1 , 1985 , andannounce dexpansion s schedule dfor completio nby

1987 . Refiner y

processin g capacit y assumption s ar e sunnarize di nTabl e 4.6 . ,

4. 4 Mm , Att

n TWT A LIMITATTfl C

Bot hth e modelin g approac han dth e dat a use dt o suppor t mode l assumption s for thi s analysi s ar e t o some exten t limited . Th e

4-1 3Tabl e 4.6 : U.S . refinery processin g capacities : 198 7 (thousand barrel s pe r day )

Proces s PAffi g 1'I YPAI D y Crud e Distillatio n 12,27 0 2,94 9 Vacuu mDistillatio n 5,33 4 1,55 2 Coker-Delaye d 84 8 37 7 Coker-Flui d 11 6 8 7 Visbreake r 15 7 7 5 Naphth a Hydrotreate r 3,26 6 65 6 Distillat e HD S 2,28 9 34 3 FG C Fee d Hydrofine r 1,09 3 39 4 Resi d Desulfurize r 31 6 2 4 Ca t Reforme r 15 0 PS I 1,03 8 6 1 Ca t Reforme r 35 0 PS I 14 1 53 9 Ca t Reforme r 45 0 PS I 58 8 4 1 Flui d Ca t Cracke r 4,52 6 68 5 Hydrocracke r 64 9 41 0 Alkylatio n Plan t 81 2 14 6 Ca t Polymerizatio n 8 5 6. 8 Pen/He x Poyme r izatio n 18 9 0 Butan e Isomerizatio n 5 9 1 7

4-1 4us e o f a linea r programin g representatio no f aggregat e regiona l refinin g operation s result s i n"over - optimization " whic hcanno t b e achieve di nreality . Th e refinin g industry ha s historicall y operate dsomewha t a s a nintegrate dsystem anddemonstrate dit s abilit y t o efficientl y

utiliz e availabl e raw material s and processin g capacit y

throughexchange s andchange s i nfeedstoc k qualities , etc . However , th e exten t o f system optimizatio n achieve db

y the mode l overstate s actua l capabilities .

Some mode l optimizatio ni s negate db y analyzin g difference s i n tw o optim - izedsolutions . Optimizatio noccur s i nbot hth e bas e cas e an dthe mor e restric - tive specificatio ncases . Difference s i ncost s ar e onl y

affecte di f th e over - optimisti c assumption s generat e greate r saving s inon e cas e tha ni nth e other , andthe . siz e o f erro r i s onl y th e differenc e i noveroptimization . Fo r thi s reason , th e operatin g cos t estimate s fo r reducin g diese l specification s ma y

b e reasonable .

On e mode l overoptimizatio nwhic hi s no t negate dby examinin g difference s i noveroptimize dsolution s i s i nth e are a o f proces s utilization . Th e mode l optimall y allocate s variou s qualit y refinery stream s inorde r t o minimiz e th e cos t o f processing . A s
a result , th e mode l tend s t o underestimat e th e leve l o f processin g require di nindividua l refinin g situations . A s a n illustration , distillat e desulfurizatio nutilizatio nwa s les s tha n6 0 percen t i nth e bas e case . A t th e 0.0 5 percen t sulfu r

4-1 5P.9 8

level , distillat e desulfurizatio nutilizatio nincrease db y ove r 2 0 percent . I nreality , industry utilization s ar e abou t 6 5 percen t (Nationa l Petroleum Council , 1985) . Thus , i t migh t no t b e possibl e t o reduc e diese l fue l sulfu r conten t t o 0.0 5 percen t b y weigh t withou t some investmen t i nne w desulfurizatio ncapacity .

Anothe r limitatio no f thi s analysi s i s i nth e are a o f aromatic s data . Th e aromatic s conten t o f distillate s varie s considerabl y betwee ncrude s an dbetwee nrefinery intermediat e streams , an dth e availabilit y

o f informatio no nthes e value s i s limited . Th e characterizatio no f distillat e stream aromati c conten t i nth e mode l wa s base do nth e limite dinformatio navailable . Mor e complet e informatio no nth e aromati c content s o f thes e stream s migh t chang e th e modelin g result s somewhat , especiall y for the-.- - lo w aromatic s scenario . Th e overal l conclusion s o f the mode l — tha t desulfurizatio nwoul dresul t i na significan t reductio nin averag e aromati c content , andtha t additiona l reduction s coul db e obtaine da t moderat e cos t b y segregatin g diese l fue l fro m # 2 burne r oi l —

ar e unlikel y

t o b e greatl y

affected , however .

4-1 6P.9 9

5.0 : MTO . RRglT.T S AN DGDST-EFFBCTIVENES S ANALYST g

Thi s chapte r define s tw o scenario s fo r diese l fue l qualit y regulation , andpresent s the result s o f the refinin g cos t mode l fo r each . I t the ndiscusse s the resultin g effect s o nthe fue l economy , durability , andemission s level s o f typica l diese l engines . Estimate s o f the fue l econom y andmaintenanc e saving s du e t o the us e o f the higher-qualit y fue l ar e develope dfor typica l vehicle s ineac ho f five classes : passenge r cars , light-heav

y dut y trucks , mediun-heavy dut y trucks , line-hau l trucks , andtransi t buses . Th e reduction s inparticulat e and sulfu r emission s pe r vehicl e du e t o bette r fue l qualit y ar e als o estimate dfo r eac htyp e o f vehicle . Thes e estimate s ar e combine d wit hthe refinin g cos t result s andthe estimate dmaintenanc e saving s t o calculat e the overal l cost s andcost-effectivenes s o f
eac hscenario .

S. l EKFINITK H O P TH E TV P SCENARIO S

A s th e discussio ni nChapte r Fou r ha s indicated , the fue l variable s havin g the mos t importan t effect s o nemission s ar e sulfu r an daromatic s content . Preliminar y analyse s by

bot hth e



### 5- 1p. 1

author s andother s (Wal l andHoekman , 1984 ; CARB , 1984 ) indicate d tha t the cost-effectivenes s o f reducin g the sulfu r conten t wa s likel y t o b e ouc hgreate r tha ntha t o f reducin g the aromatics . Furthermore , the majo r technologie s availabl e fo r reducin g aromati c conten t als o reduc e sulfu r (althoughth e convers e i s no t tru e — desulfurizatio ndoes no t necessaril y hav e a significan t effec t o naromatics) . Fo r thes e reasons , w e selecte dtwo scenario s for modeling : on e i nwhic honl y the sulfu r conten t woul db e regulate danda secondi nwhic hbot hsulfu r an darconati c conten t woul db e limited .
Althoug hback-en dvolatilit y i s ofte ncite da s a ninportan t variabl e i ndiese l emissions , n o scenario s involvin g change s i n thi s variabl e wer e modeled . Th e reason s fo r thi s wer e twofold : the evidenc e linking back-en dvolatilit y t o emission s i s weak ; andth e cos t o f changin g th e back-en dvolatilit y t o reduc e emission s woul db e ver y high .

Fo r the firs t scenario , a sulfu r limi t o f 0.0 5 percen t by weigh t
wa s specified , liti s valu e wa s chose nsomewha t arbitraril y a s roughl y th e lowes t leve l achievabl e withou t sever e hydrotreating . Thi s i s desireabl e bot hfor cos t reason s andt o ensur e tha t enoug hpola r molecule s remai ni nth e fue l t o provid e adequat e boundar y

lubricatio ni nth e fue l injectio npuap . Thi s
wa s als o th e leve l selecte da s a sulfu r limi t fo r fue l sol di n the Sout hCoas t Ai r Basin , whic hprovide s a convenien t



### 5- 2P. 2

harmonizatio n o f regulations
. I t shoul d b e clearl ynoted , however , tha t n o optimizatio n studie s wer e carrie d ou t i n choosin g thi s particula r sulfu r level , an d tha t suc h studie s certainl yshoul d b e don e befor e anysuc h regulatio n i s promulgated . Th e optima l leve l o f contro l coul d jus t a s easil y by0.0 3 o r 0.0 7 percen t byweigh t a s 0.05 .

Th e origina l pla n fo r thi s studywa s fo r th e secon d scenari o t o includ e th e son e 0.0 5 percen t sulfu r limi t a s th e first , wit h a n additiona l limi t o f 22. 5 percen t o n th e aromatic s content . Thi s leve l wa s chosen , agai n somewha t arbitrarily , a s bein g approximatel yth e lowes t leve l o f aromatic s whic h coul d b e achieve d b

ymean s o f change s i n blendin g procedure s an d segregatio n o f diese l fue l frc mburne r fue l oil
. However , th e mode l run s fo r th e firs t scenari o produce d th e surprisin g resul t tha t aromatic s woul d b e muc h lowe r wit h desulfurization , eve n i n th e absenc e o f a specifi c limi t o n aromatics
. Thi s reductio n i n aromati c conten t i s th e resul t o f proces s an d blendin g change s whic h ar e necessar yt o achiev e th e lo wsulfu r leve l a t minimu m cost . Th e aromati c conten t o f th e fuel s i n scenari o on e turne d
ou t t o b e slightl yove r 2 0 percent . A s a result , th e aromati c limi t fo r th e secon d scenari o wa s reduce d t o 1 7 percent , whic h (accordin g t o th e model ) i s a leve l whic h ca n stil l b e achieve d b yblendin g an d segregatio n alone .



### 5-3P. 3

5. 2 RESULT S FRC M TOE REFININ G OT6 T MHTF L

Table s 5. 1 throug h 5. 3 compar e th e refinin g cos t mode l result s fo r th e tw o regulator yscenario s wit h thos e fo r th e bas e case . Al l o f th e cost s an d volume s show n i n th e Table s ar e annua l total s fo r th e yea r 1987 . Thi s yea r wa s chose n a s bein g abou t th e earlies t on e i n whic h th e fue l regulation s bein g modele d coul d b e implemented
. Th e costs , an d especiall yth e costs-per-gallo n show n i n th e table s ar e considere d t o b e representativ e o f thos e fo r late r year s a s well .

A s discusse d i n Chapte r Four , PAD D V wa s modele d separatel yfro m PAED s I throug h IV , sinc e pipelin e connection s betwee n PAE D V an d th e remainde r o f th e U.S . ar e poor . Tabl e 5. 1 show s th e modelin g result s fo r PAED s I throug h IV , whil e Tabl e 5. 2 show s th e result s fo r PAE D V . Tabl e 5, 3 combine s th e result s fo r th e tw o region s t o giv e sum s o r average s fo r th e entir e U.S .

A s ha s bee n mentioned , th e mode l result s fo r Scenari o On e wer e somewha t surprising
. A s th e table s show , th e optima l refinin g strateg yfo r producin g th e give n quantit yo f low-sulfu r diese l fue l als o reduce s th e fuel' s aromati c conten t fro ma n averag e o f 28. 7 percen t t o 20. 3 percen t byvolume . Thi s result s i n a n increas e i n AP I gravit y(correspondin g t o a decreas e i n density) , a sligh t reductio n i n th e volumetri c energ ycontent , an d a n increas e i n th e calculate d cetan e inde x o f th e averag e fuel ,



### 5-4P. 4

Tabl e 5.1 : Refinin g cos t mode l result s for PAED s I throughIV . 

### Physica l Propertie s AP I Gravit y Sulfu r (w

t * ) Aromatic s (vol . %) Distillatio nTenperature s

1 0 percen t 5 0 percen t 9 0 percen t Calculate dCetan e Inde x Volumetri c energy

(M3TU/gal ) Viscosit y

(centistoke s a t 2 0 C )
Productio nan

dCost s Tota l diese l fue l (N M gal/yr ) Chang e intota l cos t (N M $/yr ) Chang e incos t pe r gallo n($/gal ) Shadow pric e o f diese l ($/gal ) Chang e i nshadow

pric e ($/gal ) 34. 3 0.28 0 28. 4 

### 41 8 52 0 60 5 47. 0 131. 0 

### 3. 1

15,92 8
—

• — 0.76 9
— 38. 0

0.04 8 20. 2 

### 39 0 47 8 58 5 47. 7 129. 0 

### 2. 6

15,92 8 

### 18 8 0.01 2 0.78 1 0.01 2 38. 0

0.04 8 17. 0 

### 38 0 50 3 60 0 51. 2 129. 2 

### 2. 2

15,92 8 

### 23 6 0.01 5 0.78 5 0.01 6



### 5- 5P. 5

Tabl e 5.2 : Refinin g cos t mode l result s fo r PAE D V .

Physlcfi T Propertie s AP I Gravit y Sulfu r (w

t %) Aromatic s (vol . %) Distillatio nTenperature s

1 0 percen t 5 0 percen t 9 0 percen t Calculate dCetan e Inde x Volumetri c energy

(NBTU/gal ) Viscosit y

(centistoke s a t 2 0 C )
Productio nan

dCost s Tota l diese l fue l (N M gal/yr ) Chang e i ntota l cos t (N M $/yr ) Chang e i ncos t pe r gallo n($/gal ) Shadow pric e o f diese l ($/gal ) Chang e i nshadow

pric e ($/gal ) 32. 5 0.23 5 30. 3 

### 44 0 54 5 61 0 46. 7 131. 8 

### 3. 6

2,53 7
—
— 0.74 3

• — 34. 6

0.04 8 20. 7 

### 44 0 545 61 0 50. 0 131. 2 

### 3. 4

2,53 7 

### 2 6 0.01 0 0.76 4 0.02 1 37. 3 0.04 8 17. 0 

### 38 0 55 0 61 0 55. 9 129. 6 

### 3. 2

2,53 7 

### 4 1 0.01 6 0.77 8 0.03 5



### 5- 6P. 6



### Tabl e M i Cbrtlne drefinin g ooe t mode l result s fo r th e entir e U.S .
Physio l Propertie s AP I Gravit y Sulfu r (w

t %) Aromatic s (vol . * ) Distillatio nTenperature s

1 0 percen t 5 0 percen t 9 0 percen t Calculate dCetan e Index Volimetri c energ

y (NBTU/gal ) Viscosit y

(centistoke s a t 2 0 C )
Productio nan

dCost a Tota l diese l fue l (N M gal/yr ) Chang e intota l cos t (N M $/yr ) Chang e incos t pe r gallo n($/gal ) Shadow pric e o f diese l ($/gal ) Chang e inshadow

pric e ($/gal ) 

### Baselin e 34. 0 0.27 4 28. 7 

### 42 1 52 3 60 7 46. 0 131. 1 

### 3. 2

18,46 5

_ _ ) 0.76 5 Scenari o On e 37. 5 0.04 8 20. 3 

### 39 7 48 7 58 8 48. 2 129. 3 

### 2. 4

18,46 5 

### 214 0.01 2 0.77 9 0.01 4 Scenari o Tw o 37. 9 0.04 8 17. 0 

### 38 0 50 9 601 51. 8 129. 3 

### 2. 7

18,46 5 

### 27 7 0.01 5 0.78 4 0.01 9



### 5- 7P. 7

especiall y

i nPAE DV .

Th e chais e i ncetan e indexi s o f limite dsignificanc e — neithe r the cetan e indexno r the cetan e nunbe r i s a linea r property , and thu s the cetan e indexcalculate dfrcm averag e propertie s i s no t the same a s th e averag e cetan e index . Furthermore , the cetan e indexma y

diffe r frcm

the cetan e nurbe r b

y a s muc ha s tw

o ninnbers . Th e chang e inthi s paramete r probabl y doe s indicat e a significan t improvemen t i nignitio nquality , however , a s woul db e expecte dfro

m th e shar pdecreas e i naromati c content . Thi s improvemen t woul db e especiall y marke di nPAE DV , whic hinclude s the U.S . Pacifi c Coast .

A s expected , the dat a for th e secondscenari o sho w a furthe r reductio ni naromati c content , accompanie db y a sligh t decreas e i ndensity , n o chang e i nvolunetri c energy content , anda substantia l increas e inth e calculate dcetan e index . Thi s woul d produc e a nextremel y

high-qualit y

fue l o naverage . I naddition , standardizatio no f th e aromati c conten t a t 1 7 percen t woul d greatl y reduc e th e variatio ni ndensity , ignitio nquality , and viscosit y

betwee ndifferen t fuels . A s wa s discusse dinChapte r Four , thi s woul db e a valuabl e resul t i nitself .

Th e cos t dat a show

ni nTable s 5. 1 through5. 3 ar e o f tw o kinds . Th e firs t typ e i s th e chang e i ntota l refinin g cost s resultin g fro m eac hscenario , andth e chang e inaverag e cos t pe r gallo no f



### 5-8P. 8

diese l fuel , assumin g tha t th e differenc e i n refinin g cost s wer e allocate d onl yt o diese l fuel . Thi s i s a goo d measur e o f th e socia l cost s (th e cost s pai d b yAmerica n societ yconsidere d a s a whole ) o f th e refinin g change s i n eac hscenario
.

Th e secon d typ e o f cos t show n i s th e chang e i n th e "shado wprice "
o f diese l fue l calculate d byth e refiner ycos t model . I f deman d fo r diese l fue l wer e perfectl yinelasti c an d fue l market s wer e perfectl ycompetitive , thi s woul d b e th e chang e i n th e marke t wholesal e pric e o f diese l fue l a s a resul t o f eac h scenario
. Sinc e deman d fo r diese l fue l i s fairl yinelasti c an d th e market s
ar e fairl ycompetitive , thi s i s probabl ya reasonabl e approximatio n o f th e pric e change s tha t woul d actuall yb e experienced
. A s th e table s show , th e chang e i n th e shado wpric e i s somewha t greate r tha n th e chang e i n th e averag e cost , especiall yi n PAE D V . Th e differenc e i s du e t o a decreas e i n th e shado wpric e o f distillat e burne r fuel , whic h i s use d a s a "sink " fo r th e exces s aromatic s remove d fro mdiese l fuel .

Th e cos t dat a show

ni n th e table s reflec t onl yth e change s i n refinery operatin g an d raw-material s cost s whic h woul d resul t fro m eac hscenario . Sinc e th e mode l result s showe d tha t eac h scenari o coul d b e achieve d usin g onl yth e existin g refiner y capacity , n o capita l o r depreciatio n charge s wer e include d i n th e costs . However , thi s accountin g fail s t o conside r th e cost s o f mino r proces s an d pipin g change s whic h woul d b e require d t o



### 5-9P. 9

achiev e thi s scenario
. Th e mos t importan t o f thes e woul d b e th e cost s associate d wit h segregatin g th e productio n an d distributio n
o n diese l fue l an d distillat e burne r fuel . Whil e w e wer e unabl e t o quantif ythes e cost s withi n th e scop e o f thi s study , the yar e considere d t o b e smal l relativ e t o th e change s i n operatin g cost s presente d above .

Th e cos t estimate s fo r reducin g aromatic s develope d i n thi s stud y
ar e considerabl ylowe r tha n thos e develope d b yothe r worker s (e.g . CARB , 1984 ; Chevron , 1984 ) wh o considere d onl yth e cost s o f applyin g a ne wproces s uni t t o th e existin g diese l fue l stream . Thes e estimate s sho wth e grea t potentia l fo r cost s saving s inheren t i n th e refinery' s abilit yt o alte r blendin g an d processin g parameter s i n orde r t o achiev e desire d qualit y levels . Th e exten t o f thi s flexibilit yi s born e ou t byth e onl y othe r simila r studyo f whic h th e author s ar e aware . Thi s study , conducte d b yBonne r an d Moor e (1983 ) an d publishe d b yth e America n Petroleu mInstitute , indicate d tha t th e averag e aromati c conten t o f diese l fue l i n PAE D I I coul d b e reduced-t o abou t 2 0 percen t a t virtuall yn o cost , an d t o aroun d 1 5 percen t fo r les s tha non e cen t pe r gallon . Thi s wa s accomplishe d bymean s o f blendin g changes , an d segregatio n o f distillat e burne r fue l fro m diese l oil
. Som e o f th e result s fro mtha t studyar e show n i n Figur e 5.1 .

5-1 0P.1 0

l.S O

1.2 5

l.OO

0.7 5

0.50 " Averag e Adde d Cost , S/B3 L

0.2 5 - •

1 0 1 5 20 2 5 3

0 Ar-omitics Contant , Volum e Percen t

Figur e 5.1 : Refinin g cos t vs . aroeati c conten t o f diese l fue i fronth e

Bonne r an

dMoore stud

y (Bonne r an

dMoore , 1983) .

5-1 1P.1 1

5. 3 SCENARI O CKF.. rFSUTTTTRIZATIC N EFFECT S CK

ENGINE S AN DF^fgJO 1 ?

Th e result s o f the refinin g cos t mode l for Scenari o On e indicat e tha t the reductio ni ndiese l fue l sulfu r conten t t o 0.0 5 percen t by weigh t shoul db e accompanie dby a reductio ni naverag e aromati c conten t a s well . Bot ho f thes e woul dhav e beneficia l effect s o nemissions . However , a s discusse di nChapte r Three , the refinin g cos t mode l use di s highl y aggregated , andthe result s reporte dar e average s ove r al l the refinerie s i na region . Actua l refinery processe s andcrud e slate s vary , s o tha t the reductio ni naverag e aromatic s du e t o th e sulfu r limi t i n thi s scenari o woul dno t b e see ni never y case . Thi s variatio n woul doccu r du e t o individua l difference s i ncrud e mi xand processin g equipment .

I norde r t o minimiz e variation s i nfue l ignitio nquality , a separat e limi t o naromati c conten t woul db e highl y desirabl e eve n i nScenari o One . Thi s limi t shoul dprobabl y b e se t a t abou t the 2 2 percen t leve l t o allo w some deviatio nfro

m th e averag e result s give ni nthe model , whil e stil l minimizin g the variatio ni n ignitio nquality . Th e incrementa l cos t o f suc ha limi t canno t b e coopute dfrom

th e mode l i nit s presen t form , sinc e i t woul d involve n o chang e i nthe mea naromati c content , jus t a reductio n i nit s variation . Th e cos t woul dprobabl y b e quit e low , however , sinc e th e capacit y

t o achiev e i t exist s wit hth e presen t capita l stock .

5-1 2P.1 2

Reducin g th e sulfu r conten t o f diese l fue l woul d directl yreduc e diese l emission s o f S O an d particulat e sulfates . Frc mth e dat a 2 i n Tabl e 5.3 , thes e reduction s woul d amoun t t o mor e tha n 8 0 percen t o f th e total , o r abou t 285,00 0 ton s pe r yea r o f S O an d 2 abou t 7,00 0 ton s pe r yea r o f particulat e sulfate s nationwide
. Sinc e th e sulfu r conten t o f diese l fue l i s generall yexpecte d t o increas e i n th e future , th e actua l reduction s fro ma low-sulfu r standar d migh t b e eve n greater . Th e reductio n i n S O emission s 2 woul d resul t i n a correspondin g decreas e i n th e formatio n o f secondar ysulfat e particles , aci d deposition , an d material s damag e du e t o sulfur .

Th e reduce d S O concentratio n i n th e exhaus t ga s woul d als o

2 permi t th e us e o f mor e activ e catalyst s i n catalyti c trap-oxidizers , makin g th e desig n o f catalyti c trap s muc h easier , an d indirectl yreducin g HC , CO , odor , an d particulat e emission s fro mtrap-equippe d vehicles
. Desulfurizatio n woul d thu s b e ver y helpfu l i n meetin g EPA' s 199 1 particulat e standar d o f 0.2 5 g/BHP-h r for heavy-dut ytruc k engines ; i t woul d probabl yb e essentia l fo r meetin g th e 0. 1 g/BHP-h r standar d fo r transi t bu s engines
.
Reducin g th e sulfu r conten t o f diese l fue l woul d resul t i n reduce d corrosiv e wea r o f cylinders , rings , an d bearings
. Thi s woul d hel p t o increas e th e tim e betwee n overhaul s i n heavy-dut y

5-1 3P.1 3

engines , andwoul dextendtota l engin e lif e i nbot hligh t and heavy-dut y

vehicles . Althoug hther e i s universa l agreemen t o n the qualitativ e effect s o f thi s change , quantitativ e dat a supportin g it ar e scarce . Th e bes t dat a availabl e ar e thos e o f Tennyso nandParke r (1970) , whic hwer e discusse di nChapte r Four . Thos e result s (whic har e probabl y conservative ) indicat e a 3 0 t o 4 0 percen t reductio ni nwea r rate s wit hthe us e o f fue l containin g 0.0 5 percen t rathe r tha n0.2 7 percen t sulfur . Fo r the cost-effectivenes s calculation s i nthi s stud y w e hav e assume da 3 0 percen t extensio ni nmileag e betwee noverhaul s andi ntota l engin e life . W e conside r thi s t o b e a reasonabl y conservativ e estimate .

I nadditio nt o reduce dcorrosiv e wear , a lowe r sulfu r conten t woul dhel pt o reduc e deposi t formatio no nthe pistons an dothe r ~ critica l parts . This , combine dwit hthe reduce daci dloading i n the engin e oi l migh t als o mak e i t possibl e t o exten doi l chang e interval s and/o r t o reduc e the alkalin e as hconten t o f the oil . Th e forme r woul db e desirabl e i norde r t o reduc e cost s andthe environmenta l problem s o f used-oi l disposal , whil e th e latte r woul dhel pt o extendtrap-oxidize r life . Reduce ddeposi t formatio nwoul dals o hel pt o improve oi l control , reduc e oi l consuiption , an dincreas e engin e life .

Th e reductio ni naromatic s conten t whic hwoul dresul t frcm desulfurizatio nwoul dals o hav e a beneficia l effec t o n

5-1 4P. M

emissions . Extrapolatin g from the dat a develope db y Barr y e t alia_(1985) , w e estimat e tha t the reductio ninaverag e aromati c conten t fro

m 28. 7 t o 20. 3 percen t shoul dresul t i na 2 2 percen t decreas e i nth e carbonaceou s (non-sulfate ) fractio no f th e particulat e materia l i nheavy-dut y engines . Th e dat a o f Bykowsk i
andco-worker s (1983 ) indicat e a neffec t o f simila r magnitud e for light-dut y

engines , althoug hthi s i s highl y engine-dependent . Th e reduce dsoo t productio ni nth e engin e woul dreduc e th e soo t conten t o f th e blowby , reducin g soo t foulin g andcontsminatio no f the oil . Thi s woul dals o hel pt o reduc e oi l chang e frequency .

Th e reduce daromatic s andinprove dcetan e nunbe r s wit hthi s scenari o woul dimprove cold-startin g andidling performanc e an d reduc e engin e noise . Th e reductio ni nthe us e o f catalyticall y cracke dblendin g stock s woul dals o b e expecte dt o hav e a beneficia l effec t o ndeposit-formin g tendencie s i nth e fue l injectors , reducin g th e maintenanc e requirement s fo r thes e parts . O nth e negativ e side , the reductio ni naverag e aromati c conten t migh t resul t i nsome inpairmen t o f cold-flo w propertie s du e t o th e increase dparaffi nconten t o f th e fuel . Thi s woul db e offse t t o some exten t by th e reductio ni n90-percen t poin t i n thi s scenario .

Th e lowe r densit y

o f th e fue l i nthi s scenario , resultin g from th e lowe r densit y

o f paraffini c tha naromati c hydrocarbons , woul d reduc e th e volunetri c energ y conten t somewhat , resultin g i n

5-1 5P.1 5

sligh t increas e i nvolumetri c fue l consuiptio ni f al l othe r factor s wer e t o remai nequal . Fro m the dat a i nTabl e 5.3 , thi s woul damoun t t o a los s o f abou t 1. 4 percen t i nfue l economy . O n th e othe r hand , the inprove dandmor e consisten t ignitionqualit y
o f the fue l woul dmak e i t possibl e t o improve fue l efficienc y somewhat , a t leas t i nne w o r newl y

rebuil t engines . Thi s coul d b e don e by

smal l timing inprovement s t o optimiz e NO xcontro l fo r the higher-cetan e fuel , an db y slightl y

reducin g the compressio n ratio . I naddition, th e inprove dcold-startin g capabilit y o f th e higher-cetan e fue l woul dreduc e fue l wastag e i ncol dstar t and
warmu poperations . Thu s th e overal l effect s o nfue l econom y woul dprobabl y

b e positive .

5. 4 SOKARI O TWO : DEAKMATIZATIC KEFFECT S C KBONE S AN DEMISSIO N

Scenari o Tw o include s al l o f the action s inScenari o One , plu s a furthe r reductio ni naromatic s content . I t i s therefor e mos t appropriat e t o conside r the incrementa l cost s an dbenefit s o f Scenari o Tw o a s compare dt o Scenari o One , rathe r tha ncooperin g i t t o th e baseline . Al l o f the beneficia l effect s o f desulfurizatio nnote dfor Scenari o On e woul dals o appl y t o thi s scenario , a s woul dthe effect s (goodandbad ) o f decrease d aromati c content . Thes e latte r effect s are , i ngeneral , greate r i nthi s scenari o tha ni nScenari o One , however .

5-1 6P.1 6

Th e additiona l reductio n i n fue l aromati c conten t i n Scenari o Tw o woul d resul t i n a furthe r reductio n i n particulat e compare d t o Scenari o One . Fro mth e dat a i n Barr ye t ali a (1985) , a reductio n i n th e carbonaceou s fractio n o f th e particulat e o f abou t 3 1 percen t (compare d t o th e baseline ) woul d b e expected . Thi s represent s a n additiona l nin e percentag e point s beyon d th e reductio n estimate d fo r Scenari o One . Ther e woul d als o b e sem e furthe r reductio n i n hydrocarbo n emissions
.

Th e incrementa l maintenanc e benefit s ove r Scenari o On e woul d b e minor
. Afurthe r reductio n i n soot-foulin g o f th e oi l an d i n deposi t formatio n i n th e injector s woul d b e expected , bu t th e effec t o f thes e woul d no t b e great . Col d star t performanc e woul d b e furthe r improve d wit hthi s scenario , resultin g i n stil l greate r reduction s i n hydrocarbo n emissions
. O n th e othe r hand , th e decrease d aromatic s an d highe r 9 0 percen t poin t wit h thi s scenari o woul d furthe r impai r th e cold-flo wpropertie s o f th e fuel , an d thi s migh t prov e troublesom e i n winte r operation
. Th e volumetri c energ yconten t fo r thi s scenari o i s littl e change d fro m Scenari o One , an d thu s th e effect s o n fue l econom ywoul d b e abou t th e same . Asmal l furthe r increas e i n fue l econom yi n ne w engine s throug htighte r calibratio n fo r NO x an d a lowe r compressio n rati o migh t b e possible , however .

5. 5 qQST-EFFECTIVFUESS O F FUE L QUALIT

Y RFffiTATTfNS

5-1 7P.1 7

Thi s sectio ndevelop s some approximat e comparison s o f th e fuel , maintenance , depreciation , andothe r cost s o f operatin g eac ho f five typica l vehicle s fo r the baselin e cas e andfo r eac ho f the tw o scenario s discusse dabove . Thes e comparison s ar e show ni n Table s 5. 4 through5.8 . I t shoul db e note dtha t th e cos t and emission s change s andth e cost-effectivenes s value s i nthes e table s ar e show

na s th e incrementa l change s from the baselin e t o Scenari o One , andfrom Scenari o On e t o Scenari o Two . Th e specifi c assumption s goin g int o thes e table s ar e discusse dbelow .

Th e value s show

ni nTable s 5. 4 through5. 8 ar e considere dt o b e reasonabl e estimates , andar e generall y somewha t conservativ e i n tha t they

hav e tende dt o er r towar dunderstatin g benefit s and overstatin g cost s wher e thes e wer e doubtful . I t shoul db e born e i nmind , however , tha t many o f the estimate deffect s show nar e base do nincomplete ddata , andshoul dthu s b e interprete d cautiously . Th e table s als o fai l t o accoun t fo r some difficult-to-quantif y benefits , suc ha s reduction s i ninjecto r deposit s andimprovement s i ncol dstartin g performance .
Despit e thes e weaknesses , the result s show ni nTable s 5. 4 throug h 5. 8 mak e a strong cas e fo r actio nt o reduc e diese l fue l sulfu r andaromati c content . Fo r the firs t scenario , thes e table s indicat e tha t substantia l ne t benefit s woul daccru e from desulfurizatio nanddearomatizatio no f diese l fuel , eve n

5-1 8Tabl e 5.ft ; Fue l coata , maintenanc e benefit s an d cost-effectivenes s o f fue l regulation s fo r a typica l light-dut y ca r o r truck .

Fue l an d Maintenanc e Coat s Lifetim e mileag e Miles/yea r Discoun t rat e Equivalen t cos t facto r Fue l econom

y(mpg ) Fue l cos t (t/eal ) Tota l annua l cos t Oi l chang e frequenc y(mi ) Cos t o f oi l chang e (§ ) Annua l ccs t Engin e cos t (new ) Equivalen t annua l cos t Tota l annua l cos t Chang e frompreviou s
flflawltwm an d fn.^t-gffftfttlv«ne» a Particulate s (&/aile ) Carbonaceou s Direc t Sulfat e Tota l Direc t Part . SC ? emission s (g/mile ) Icairec t Part , (g/mile ) Baselin e
100,00 0 15,00 0 0.10 0 0.21 3 28.00 0 1.13 0 605.3 6 5,00 0 20.0 0 60,0 0 4,000.0 0 850.5 6 1,515.9 2 130,00 0 15,00 0 0.1C 0 0.17 8 28.00 0 1.14 5 613.3 9 6,50 0 20.0 0 46.1 5 4,000.0 0 711.4 7 1,371.0 2 (144.90 ) 

### SceoarifiJTa a

130,00 0 15,00 0 0.1C 0 0.17 8 28.00 0 1.14 8 615.0 0 6,50 0 20.0 0 46.1 5 4,000.0 0 711.4 7 1,372.6 3 1.6 1

0.3 1 0.0 4 C.3 5 0.6 0 Tota l Part . ($/mile ) Tota l annua l Part , (lb ) Reductio n fromprev . (lb/yr ) Ccst-Effectivenea s Ct/lb ) 1.0 8 35.5 2 0.2 U

0.C 1 0.2 5 0.1 1 0.1 3 0.3 8 12.4 2 23.1 0 t6.27 ) 0.2 1

0.0 1 0.2 2 0.1 1 0.1 3 0.3 5 11.5 0 0.9 2 1.7 4

5-1 9P.1 9



### . . v.,.-, ~,«t » M-UWiianc. b.Mflt aan d co.t-.fr.etly.M M o f fu. l « " W, 

### -SSlSJ2 : S » W- l U*W— » duty truck
.

^,^ 1 an d rfrjptenanc. e Coat a Lifetim e mileag e Miles/yea r Discoun t

rat e Equivalen t

cos t facto r Relativ e Fue l Consumptio n Fue l econom

y (npg ) Fue l cos t

U/gal ) Tota l annua l cos t Oi l chang e frequenc y (mi ) Cos t o f oi l chang e ($ ) Annua l cos t Engin e cos t

(new ) Equivalen t

annua l cos t USSUBS. ^fnarl o On e SflfiflMifl-Ii a 120,00 0 20,00 0 0.10 0 0.23 0 1.00 0 14.65 0 1.13 0 1,542.6 6 5,00 0 25.0 0 1C0.0 0 6,000.0 0 1,377.6 4 156,00 0

20,00 0 0.1C 0 0.19 1 1.00 0 14.65 0 1.14 5 1,563.1 * 6,50 0 25.C O 76.9 2 6,000.0 0 1,143.9 1 156,00 0

20,CC 0 0.1C 0 0.19 1 1.00 0 14.65 0 1.14 8 1,567.2 4 6,50 0 25.0 0 76.9 2 6,000.0 0 1,143.9 1

Tota l annua l cos t Chang e from

previou s 3,020.3 1 2,783.98 (236.33 ) 2,783.0 7

.... . a . 1 0

Particulate s (g/SKP-hr ) Carbonaceou s Direc t Sulfat e Tota l Direc t Fart . EEP-h r pe r Ril e Direc t part . (7/nile ) SO , emission s (s/raile ) Irlirsc t Part , (g/aile ) C.5 6 0.0 4 C.6 0 0.8 9 C.5 3 1.1 5 1.3 9 0.^ 4

0.C 1 0.1 4 0.5 9 C.3 9 0.2 0 0.2 4 0.3 9

0.C 1 0.3 9 0.8 9 C.3 5 0.2 0 0.2 4

Tota l Part , (c/xile ) Tota l annua l Part , (lb ) Reductio nfrcm

prev . (lb/yr ) Cost-Effectiver.es s ($/lt ; 1.9 2 84.5 7 0.6 4

28.Q 9 56.4 8 (4.18 ) 0.5 9

26.1 2 1.9 8 2.0 7Tabl * 5-*6 : Fue l costs , maintenanc e benefit s an dcost-effectivenes s o f fue l regulation s fo r a typica l aediua-hear y truck .

Lifetim e mileag e Miles/yea r Discoun t rat e Equivalen t cos t factor Relativ e Fue l Consumption Fue l econom

y (mpg ) Fue l cos t ($/gal ) Tota l annua l cos t Oi l chang e frequenc y (mi ) Cos t o f oi l chang e ($ ) Annua l cos t Engine cos t (new ) Equivalen t annua l cos t Mileag e t o overhau l Cos t o f Overhau l Equivalen t annua l coa t Tota l annua l cos t . Chang e fro

m previou s 400,00 0 40,00 0 0.10 0 0.16 3 1.00 0 7.78 0 1.13 0 5,809.7 7 11,00 0 35.0 0 127.2 7 9,000.0 0 1,464.7 1 221,00 0 3,000.0 0 288.3 6 7,690.1 1 Scenari o On e

520,00 0 40,00 0 0.10 0 0.14 1 1.00 0 7.78 0 • 1.14 5 5,886.8 9 15,00 0 35.0 0 93.3 3 9,000.0 0 1,267.0 1 287,30 0 3,000.0 0 212.9 9 7,460.2 2 (229.89 ) trfflrffi"i O TW O

520,00 0 40,00 0 0.10 0 0.14 1 1.00 0 7.78 0 1.14 8 5,902.3 1 15,00 0 35.0 0 93.3 3 9,000.0 0 1,267.0 1 287,30 0 3,000.0 0 212.9 9 7,475.6 4 15.4 2

^ " 1 " " - »"* ftt«t-KffMtlWlJM Particulate s (g/BHP-hr ) Carbonaceou s Direo t Sulfat e Tota l Direc t Part . BHP-h r pe r mil e Direc t part , (g/mile ) S0 2 emission s (g/mile ) Indirec t Part , (g/mile ) 0.7 5 0.0 5 0.8 0 2.0 7 1.6 6 2.1 7 2.6 1 4.2 7 375.8 1 0.5 8

0.0 1 0.5 9 2.0 7 1.2 3 0.3 8 0.4 6 1.6 9 148.5 6 227.2 4 0.5 2 0.0 1 0.5 3 2.0 7 1.0 9 0.3 8 0.4 6 1.5 5 136.2 5 12.3 1 Tota l Part , (g/mile ) Tota l annua l Part , (lb ) Reductio nfro a prev . (lb/yr ) Cost-Effectivenes s ($/lb ) (1.01 ) 1.2 5

G-O lTabl a 5.7 : Fue l costs , aaintenanc e benefit s an d cost-effectivenes s o f fue l regulation s fo r a typica l line-hau l truck . P.21

Pn« l an dMalnfr.-anan-Rf l CQ?t ? Lifetim e mileag e Miles/yea r Discoun t rat e Equivalen t cos t factor Relativ e Fue l Consumptio

n Fue l econom

y (mpg ) Fue l cos t ($/gal ) Tota l annua l cos t Oi l chang e frequenc y (mi ) Cos t o f oi l change ($ ) Annua l cos t Engine cos t (nev ) Equivalen t annua l cos t Mileag e t o firs t overhau l Cos t o f Overhau l Equivalen t annua l cos t Mileag e t o secon

doverhau l Cos t o f Overhau l Equivalen t annua l cos t Tota l annua l cos t Chang e fro

m previou s ^ifltlln t
800,00 0 100,00 0 0.10 0 0.18 7 1.00 0 5.67 0 1.13 0 19.929.U 5 13,00 0 50.0 0 . 384.6 2 20,000.0 0 3,748.8 8 300,00 0 5,000.0 0 704.1 5 550,00 0 10,000.0 0 1,109.7 2 25,876.8 1

ftrlftfllannj* an dCOflt-Eff-SfifciYenea S Particulate s (g/BHP-hr ) Carbonaceou s Direo t Sulfat e Tota l Direc t Part . BHP-h r per mil e Direc t part , (g/mile ) SO . emission s (g/mile ) Indirec t Part , (g/mile ) Tota l Part , (g/mile ) Tota l annua l Part , (lb ) Reductionfro o orev . (lb/yr ) 0.7 5 0.0 5 0.8 0 3.1 2 2.5 0 2.9 8 3.5 8 6.0 8 1338.4 4 1,040,00 0

100,00 0 0.10 0 0.15 9 1.00 0 5.67 0 1.14 5 20,194.0 0 17,00 0 50.0 0 294.1 2 20,000.0 0 3,180.2 6 390,00 0 5,000.0 0 548.2 4 715,00 0 10,000.0 0 804.4 1 •25,021.0 3 (855.78 )

0.5 8 0.0 1 .0.5 9 3.1 2 1.8 5 0.5 2 0.6 3 2.4 8 546.2 0 792.2 3 S<v««qrio Tw o
1,040,00 0 100,00 0 0.10 0 0.15 9 1.00 0 5.67 0 1.14 8 20,246.9 1 17,00 0 50.0 0 294.1 2 20,000.0 0 3,180.2 6 390,00 0 5,000.0 0 548.2 4 715,"00 0 10,000.0 0 804.4 1 25,073.9 4 52.9 1

0.5 2 0.0 1 0.5 3 3.1 2 1.6 4 0.5 2 0.6 3 2.2 7 499.8 2 46.3 $
Cos t Effectivenesses/lb ) (1.08 ) 

### I. KTabl e 5.8 : Fue l costs , oaintenanc e benefit s an dcost-effectivenes s o f fue l regulation s fo r a typica l transi t bus .

FUfl l ffT" 1 tfcHnfciiQa.Q'-Q f Coat a Lifetim e mileag e Miles/yea r Discoun t rat e Equivalen t cos t facto r Relativ e Fue l Consumptio n Fue l economy

(mpg ) Fue l cos t ($/gal ) Tota l annua l cos t Oi l chang e frequenc y (mi ) Cos t o f oi l chang e ( H Annua l cos t Engin e cos t (new ) Equivalen t annua l cos t Mileag e t o firs t overhau l Cos t o f Overhau l Equivalen t annua l cos t Mileag e t o secon doverhau l Cos t o f Overhau l Equivalen t annua l cos t Tota l annua l cos t Chang e fro m

previou s
RBiaair-in * an dCoat-Kffaatlvenea i Particulate s (g/BHP-hr ) Carbonaceou s Direc t Sulfat e Tota l Direc t Part . 500,00 0 40,00 0 0.10 0 0.14 4 1.00 0 4.00 0 0.92 0 9,200.0 0 8,00 0 50.0 0 250.0 0 16,000.0 0 2,298.2 0 180,00 0 8,000.0 0 748.3 3 350,00 0 8,000.0 0 499.0 8 12,995.6 1

I 0.7 5 0.0 5 0.8 0 Scenari o On e

650,00 0 40,00 0 0.10 0 0.12 7 1.00 0 4.00 0 0.93 5 ' 9,350.0 0 10,00 0 50.0 0 200.0 0 16,000.0 0 2,031.7 6 234,00 0 8,000.0 0 581.6 9 455,00 0 8,000.0 0 343.5 6 12,507.0 1 (488.59 )

0.5 8 0.0 1 0.5 9 krfftTiari

o T w
650,00 0 40,00 0 0.10 0 0.12 7 1.00 0 4.00 0 0.93 8 9,380.0 0 10,00 0 50.0 0 200.0 0 16,000.0 0 2,031.7 6 234,00 0 8,000.0 0 581.6 9 455,00 0 8,000.0 0 343.5 6 12,537.0 1 30.0 0

0.5 2 0.0 1 0.5 3 BHP-h r pe r mil e Direc t part , (g/mile ) 4.4 0 3.5 2 4.4 0

2.6 1 4.4 0

2.3 2 SO - emission s (g/mile ) Indirec t Part , (g/mile ) Tota l Part , (g/mile ) Tota l annua l Part , (lb ) Reductio nfrom

prev . (lb/yr ) 4.2 3 5.0 8 8.6 0 757.3 0 0.7 4 0.8 9 3.5 0 308.5 2 448.7 8 0.7 4

0.8 9 3.2 0 282.3 5 26.1 7
Cos t Effectivenes s (1.09 ) 1.1 5exeindipy ^p y mi^inn s benefits . I nadditio nt o the benefi t t o societ y a t larg e fro

m reduce demissions , inprove dfue l qualit y woul ddirectl y

benefi t vehicl e owner s throughreduce dmaintenanc e cost s andincrease dengin e lifetime . Thes e benefit s outweig hth e increas e infue l cos t du e t o improve dqualit y for every

clas s o f vehicle s considered .

Scenari o Tw o call s for additiona l dearomatizatio nbeyondthe leve l i nScenari o One . Thi s woul dresul t i na sligh t furthe r increas e i nfue l costs , anda furthe r reductio ni ncarbonaceou s particulat e emissions . Th e incrementa l cost-effectivenes s o f thi s furthe r ste pwoul db e abou t $5.5 0 t o $10.0 0 pe r poundo f particulat e removed , dependin g o nthe whic hvehicl e clas s i s bein g considered . Fo r comparison , EP A (1984 ) ha s estimate dth e - cost-effectivenes s o f th e ne w heavy-dut y

engin e particulat e standard s fo r 198 8 and199 1 a t $0.2 1 and$1.7 5 t o $2.6 0 pe r pound , respectively . Man y observer s (includin g the ER C author s
o f thi s report ) conside r thes e las t figure s t o b e understate dby a facto r o f tw

o o r three , whic hwoul dbrin g th e cost-effectivenes s o f the trap-oxidize r standar dint o th e same rang e a s th e cost-effectivenes s o f additiona l aromati c controls . I t shoul db e recognize dtha t ther e i s considerabl e uncertaint y i n thes e values , however , andadditiona l detaile dstud y i s strongl y recomnended .

Th e dat a i nTable s 5. 4 through5. 8 represen t typica l vehicle s o f

5-2 4P.2 4

roughl y 198 2 vintag e ineac hclass . Thi s i s reflecte dinthe estimate s o f mile s pe r gallo nando f EHP-h r pe r mil e show nfor heavy-dut y

trucks , whic hwer e take nfro m Energ y andEnvironmenta l Analysi s (1983) . Th e factor s for buse s andlight-dut y vehicle s
ar e estimate s b

y the authors . Similarly , the emission s factor s (g/mi o r g/EHP-hr ) show ni nthe table s ar e typica l for severa l yea r ol dengine s whic har e no w i nuse . Fo r the heavy-dut y vehicles , thes e emissio nfactor s ar e base do ntes t dat a showin g tha t typica l in-us e emission s fro m properl y

maintaine dengine s
ar e abou t 0. 8 g/EHP-h r (EMA , 1985) .

Th e majo r assmption s mad e indevelopin g Table s 5. 4 through5. 8
concer nthe effect s o nfue l costs ; the effect s o f reducin g fue l sulfu r o nengin e life , tim e betwee noverhauls , an doi l life ; -and~ - the effect s o f reducin g aromati c conten t o nparticulat e emission s
andfue l economy . Th e fue l cos t change s show nwer e develope db

y takin g th e averag e cos t increase s show ni nTabl e 5. 3 andaddin g 0. 3 cent s pe r gallo nt o eac ht o allow for overoptimizatio nand the capita l cost s o f segregatin g diese l fro m burne r fuel . Thes e estimate s thu s represen t th e increase dsocia l cos t o f the refinin g changes . A s Tabl e 5. 3 shows , the chang e i nsocia l cos t i s no t greatl y

differen t fro

m the estimate dchang e inthe marke t pric e o f the fue l (represente db y the chang e i nit s shadow price) . Us e o f the marke t pric e woul dchang e th e magnitude s o f the cost s shown , bu t woul dno t affec t the conclusions .

5-2 5P.2 5

I n developin g th e tables , th e chang e fro m0.27 4 percen t t o 0.04 8 percen t sulfu r i n th e fue l wa s assume d t o exten d engin e life , oi l life , an d tim e betwee n overhaul s by3 0 percent . Th e baselin e dat a o n tim e betwee n overhaul s fo r heavy-dut ytruck s wer e obtaine d frc ma studyccomissione d b yth e EM A(Surve yDar a Research , 1981) , whil e th e overal l engin e lifetime s show n wer e estimate d byth e authors . Representativ e dat a o n th e cost s o f overhaulin g differen t classe s o f engine s wer e obtaine d fro ma n experience d diese l mechani c (D . Decker , Colo . Dep t o f Health , persona l coamunication)
. Dat a o n th e cost s o f th e engine s themselve s wer e take n fro m Gale f (1984) . Th e cost s o f oi l change s fo r eac h clas s o f engin e wer e estimate d byth e authors .

Th e reductio n i n th e fue l aromati c conten t fro m28. 7 t o 20. 3 percen t i n Scenari o On e wa s assune d t o resul t i n a 2 2 percen t reductio n i n th e carbonaceou s (soo t plu s organic ) fractio n o f th e particulat e matter . Th e reductio n t o 1 7 percen t aromatic s i n Scenari o Tw o wa s assune d t o giv e a furthe r 9 percen t reductio n i n th e carbonaceou s fraction , fo r a tota l reductio n o f 3 1 percen t fro m th e baseline
. Thes e change s wer e assune d t o hav e n o effec t
o n fue l econom

y— i t wa s assune d tha t th e sligh t reductio n i n volumetri c energ yconten t du e t o th e lowe r aromati c conten t woul d b e offse t b yimprove d efficienc ydu e t o bette r ignitio n quality
.

5-2 6P.2 6



### 6.0 : mruusio s AN

D rami/MFNrwrKis

Thi s stud

y ha s examine dthe feasibility , costs , andmaintenanc e benefit s o f tw

o possibl e diese l fue l qualit y regulations , andha s examine dthei r cost-effectivenes s for emission s control . Th e followin g conclusion s ca nb e stated .
(1 ) Th e mos t importan t emissions-relate dpropertie s

o f diese l fue l ar e the sulfu r conten t andthe fractio no f aromati c hydrocarbons . Reducin g fue l sulfu r woul dreduc e S O emission s an dthe sulfat e fractio no f diese l particulates , andwoul d indirectl y

reduc e ambien t level s o f sulfat e particles . Reducin g fue l aromati c conten t woul d reduc e th e carbonaceou s fractio no f diese l particulat e emissions . Contrar y t o canno n belief , change s i nth e distillatio ntenperature s (suc ha s the 9 0 percen t poin t andendpoint ) hav e littl e potentia l for emission s control . (2 ) I t woul db e feasibl e t o reduc e the sulfu r conten t

o f automotiv e diese l fue l fro m the presen t averag e o f abou t 0.27 4 percen t t o 0.04 8 percen t b y weight . Thi s coul db e don e withou t reducin g the availabilit y

o f diese l fuel , andcoul d probabl y b e don e usin g onl y

the presen t capita l stock . Thi s woul drequir e segregatin g productio n o f diese l fue l fro

m tha t o f distillat e burne r fuels , a s wel l a s hig hrate s o f utilizatio no f existin g desulfurizatio ncapacity . Th e increas e i naverag e refinin g cos t du e t o desulfurizatio n woul db e abou t 1. 2 cent s pe r gallon . (3 ) Desulfurizatio no f diese l fue l t o 0.04 8 weigh t

percen t a s i n(1 ) woul dals o produc e a decreas e i nth e averag e aromati c conten t o f diese l fuel ,



### 6- 1P.2 7

fro m th e presen t 28. 7 percen t t o 20. 3 percen t by volune . Sinc e refinery processe s differ , thi s reductio nwoul dno t b e see ni never y case . I n orde r t o minimiz e variation s inignitio nquality , a separat e limi t o naromatic s conten t woul db e desirable . Th e cos t o f suc ha limi t woul db e smal l i f i t wer e se t somewha t abov e the averag e aromati c content . (3 ) Reducin g the sulfu r conten t o f diese l fuel s woul d

reduc e corrosiv e wea r an doi l foulin g andwoul d extendengin e life . Thes e benefit s ar e difficul t t o quantif y

du e t o a lac ko f applicabl e quantitativ e data . However , a conservativ e estimat e base do nth e limite ddat a availabl e indicate s tha t the saving s du e t o reducin g sulfu r t o 0.04 8 percen t woul db e abou t fou r time s the increas e inrefinin g costs . Substantia l reduction s i nS O emission s andambien t sulfat e particle s woul dAlso occur . (4 ) Th e lowe r aromati c conten t resultin g fro m desulfurizatio nwoul dimprove cetan e nurber s an d ignitio nquality. Thi s woul dai dcol dstartin g andreduc e noise , an dmigh t mak e possibl e change s i nengin e desig nandcalibratio ntha t woul d improve fue l economy. Th e reductio ninaromatic s woul dalso resul t i nroughl y a 2 2 percen t decreas e incarbonaceou s particulat e emission s fro m heavy-dut y

diese l engines . Th e reductio ni n light-dut y

particulat e emission s i s uncertain , bu t woul dprobabl y

b e similar . (5 ) I t woul db e feasibl e t o reduc e the aromati c

conten t o f diese l fue l belo w th e leve l attaine d wit hdesulfurization . A reductio nt o 1 7 percen t aromatic s coul db e achieve dusin g th e presen t capita l stock , andwoul dincreas e refinin g cost s b y abou t 0. 4 cent s pe r gallo nbeyon dth e leve l tha t woul db e experience dwit hdesulfurization . Thi s woul dresul t i nmino r furthe r improvement s i ncol dstartin g an dothe r performanc e characteristics , but.migh t caus e col dflow problem s a t low

tenperatures . Carbonaceou s particulat e emission s woul dalso b e reduce db y abou t a furthe r nin e percen t o f th e baseline . Th e incrementa l cos t o f particulat e contro l b y thi s mean s woul db e abou t $5.5 0 t o $10.0 0 pe r poundo f particulat e matte r eliminated . Thi s i s



### 6- 2P.2 8

thre e t o fiv e time s a s grea t a s EPA' s estimat e o f the cos t pe r poundo f diese l particulat e matte r eliminate dby

trap-oxidizer s o nheavy-dut y vehicles . 

### Bficam£odAliojQ &

I t appear s tha t lowe r limit s o ndiese l fue l sulfu r andaromati c conten t coul dproduc e significan t reduction s i nemission s whil e savin g mone y

fo r U.S . society . Furthermore , thes e limit s coul d b e attaine dquickly , usin g th e existin g capita l stock . I t i s recoomende dtha t EP A

conside r establishin g suc hlimit s through regulatio no r othe r appropriat e means . Th e numerica l limit s o n sulfu r andaromatic s conten t considere di nthi s repor t wer e selecte djudgementally , andma y no t represen t globa l optima . Additiona l detaile dstudie s i nthi s are a woul db e desirabl e i n orde r t o defin e the sociall y optima l limit s for thes e quantities .

Th e conclusion s o f thi s repor t rel y heavil y o nestimate s o f the reductio ni nwea r rate s du e t o us e o f low-sulfu r fue l ando f th e reductio ni nparticulat e emission s du e t o lowe r aromati c content . Neithe r estimat e i s wholl y satisfactory , du e t o th e limite ddat a available . Furthe r researc ho nth e effect s o f lo w vs . moderat e sulfu r fuel s o nengin e lif e woul db e highl y desirable , a s woul dadditiona l carefully-designe dstudie s o f th e relationship s betwee naromati c conten t andparticulat e emission s i na variet y

o f heavy-dut y

engines . Finally , existin g dat a o n



### 6- 3P.2 9



### th e relationship s betwee n light-dut yparticulat e emission s an d aromatic s shoul d b e reanalyze d t o accoun t fo r th e effect s o f sulfur .

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