Journal of Scientilic & Industri al Research

Vol. G2, January-February 2003 , pp 90-96

Biofuels as Blending Components for Motor Gasoline and Diesel Fuels

R K Malhotra and L M Das

Indian Institute of Technology, New Delhi 11 0 OIG, India

. The paper reviews the pote J1li al for usc of vari ous biofu els in India and isslIes related to their application in gasoli ne and (li esel vehi cles :111d the associated environmental benefit s. ~

Introduction

The single larges t source of energy in India after coa l is petroleum, about two- third of which is imported . The petroleum derived fuels , i.e., motor gasoline and diesel are being used almost by the entire road transport vehic les. The diesel fuel is also being L1sed in agriculture operati ons. The hi gh dependence on imported outside source of energy is an issue related to energy security of the country. In the recent times the combustion of these fossi I fue ls has been recognized as a major cause of air pollution in Indian cities. Although CNG and LPG are being promoted as cl eaner alternatives but both of them are in short supply and we will have to depend on imports to meet increased req uirements of these fuels. We therefore need to look for cleaner alternatives, whi ch, could not onl y reduce pollution but also reduce our dependence on imports . Amongst various alternati ves, bio-fuels like ethanol and trans-es terified fatty oil esters, commonly known as bio-diesel match the fea tures of oil at relative ly low price. The typical properti es of gasoline, di esel, ethanol and bio-diesel are given in Table I (refs 1-3). These fuels can be produced from host of bio-source and can easily be used as bl ending components of both gaso line and di ese l III eX lstlllg engines without any major mod ifications . Unlike CNG and LPG, they would not require any signifi cant investments for crea ti on of new infrastructure for suppl y and distributi on of the fu el. Further, these fuels producti on wi II help use surplus agriculture produce and also he lp in rural deve lopment. Whil e ethan ol finds application more in gaso line and to some ex tent in di ese l engines, the bio­di ese l finds appli cati on in di ese l engines . The ethanol and biodiesel adds oxygen to the motor gaso line or di esel fu el, whi ch helps in improving the combusti on

effici ency and reducing the harmful ex haust emissions . This paper reviews the potential for use of such biofuels in India and the issues related ( 0 its application in gaso line and diesel vehicl es and the associated environmental benefits .

Production Of Bio-fuels

Elhal/ol

India produces nearly 1.3 bL of et hanol util siing less than half of its total installed capacity. There are 295 alcohol di stilleri es in the count ry with an installed producti on capac ity of 3 198 mL. Et hanol is conventi onall y produced through fermentation processes from grains or other sugar bearing material s like sugar cane juice or molasses. Brazil produces most of its I I bL of ethanol from sugarcane. The US produces ethanol mostl y from corn starch. In India, molasses from suga r factories is the main source of ethanol production . Ethanol can be produced from abundant source of biomass, including agriculture and fores try residues, municipal solid wastes ; rotten grains , etc . With the advances in the field of biotechnology the producti on of ethanol from va riety of biosources is now feasible and also becomin g economica ll y viable to04.

Following are the bas ic steps in convertin G b

. b

lomass to ethanol:

• Biomass producti on, which results in the fixing of atmospheric carbon diox ide into orga n ic CaJ·bO~l.

• Fermenting the biomass with help of biocatalys ts .

• Di stillati on of the fermented biomass to yield ethanol

• B yproducts can produce other fue ls, chemica ls. heat, and electricity.

MALHOTRA & DAS: BIOFUELS 91

Table 1- Properties of fuel s

Characteri sti cs Gaso line

Chemi stry Mi xture of hydrocarbons

Speci fic gravit y @ 60 F 0.72-0.75 *

Boiling point "F 85-437 "C 30-225

Net Heating value (Mass) BTU/lh 18,700 mJ/kg 43.5

Net Heating value (Volume) BTUlib 117,000 kJ/kg 32

Heat of Vaporization BTU/lb 170 KJ/kg 400 Vapor pressu re @ 100 F psi 9- 13 kpa 62-90

Octane number Research 91-100 Motor 82-91

Cetane number Below 15

Stoich. 14.6 Air/Fuel ratio

Vapo r Ilammahilit y Limits 0.6-8

Vapor tox icity Co lorl ess to light amber co lor

Vapor toxi cit y Moderate irritant

Biodiesel

Another approach for use of biofuels which is be ing considered by various agencies in India is by converti ng the noned ible oi ls into es te rs through the process of trans-este rification. Variou s edib le and nonedible o ils , like rice bran oil, coconut o il , Jatropha curcas, castor oi l, cotton seed oil , mahua, karonj ia, etc ., which are e ither surp lus or are of nonedible type can be used for preparat ion of such este rs by using methanol or ethano l. Accordi ng to an economic survey conducted by Government of Ind ia the cul tivable land area of about 175 mha has been classified as waste or degraded land wh ich is suitab le for cu ltivat ion of some of the p lants, li ke Jatropha curcas . Even if 100 mha of such waste land is brought under cu ltivation , 150 mt of seeds can be produced

Diese l Ethanol Biodiesel

Mixture of C2H,OH R I COOR hydrocarbons R2 COOR

R3COOR

0.82 0.79 0.g8

360-350 173 190-280 78.3 182-338

18,500 11,600 16.000 43 27

126,000 76,000 120,910 35.3 21.3

250 390 600 900

0.05 2.5 0.34 17

Not III 47-52 (A KI ) Applicable 92

40-55 Below 15 48-60

14.6 9 13.8

0.6-6 .5 3.5- 15

Colorless to li ght Colorless Colorless to light amber color amber color

Moderate irritant Tox ic in only large <Diese l doses

which can yield up to 37.5 mt of o il which is almost an equivalent amount of the di esel be ing consumed in the country at present. Even if one person is emp loyed per hectare of land , 100 m additional jobs wi ll be created for cu ltivatio n a lone and, in additi on, there will be jobs in the ex traction units for c ru sh ing the seeds and product ion of biodiese l. Bes ides the biodiesel, there wi ll be g lycero l avai lab le as a byproduct.

The process in volves reacting a vegetabl e oil and a lcoho l in the presence of a cata lyst to produce glycero l and fatty acid esters. The g lycero l is dra ined from bottom of the reactor. T he es ter fu e l then requ ires washing process to purify it.

The material s used in the process and products from the transeste rification process are shown below:

92 J SCIIND RES VOL 62 JAN UARY-FEBRUARY 2003

.. Vegetable Oil Alcohol (Methanol/ethanol) Catalyst (NaoH / KOH)

~ Biodiesel (Ester) ----1:~ Reactor for ... ----t .. ~ Transesterification ... --1~"Glycerin

Bas ically , any vegetable oil can be used for producing biodiese l. The main inte rest in Europe has been in the rapeseed oil. In US various oils like soya bean , canola, sunflower, and peanut have been used . In India , we can consider o il s like mahua, karanjia, neem, ri ce bran, and j atro pha curcus. It may be des irabl e to use non-edib le o il s, parti cul arl y those which can be grown on non-fe rtil e or waste lands unfit for growing food c rops. Thi s will he lp in not onl y use o f waste land but also c reate jobs for rura l poor. Both ethan o l and methanol can be used duri ng es terifi cati on. Worldover, methanol is preferred purel y on economic cons iderati on. However, in Indi a, depending on ethano l availability we can consider using it during the process o f transeste rifi cation.

Ethanol as Fuel for Ie Engin es

E th ano l has been used as fuel since the early days of th e inte rnal combusti on engine deve lopment. Countri es like Brazil and the US have been promoting the ethano l fu e l produc ti on. While main consideration for Brazi l has been to reduce dependence on o il imports, the US has been promoting e thano l to promote agriculture and a lso fro m environmenta l conside ration.

Ethanol os Fuel/or Gasolin e Ellg ines

Ethanol has hi gh octane number, w hich makes it an excell ent gaso line blending component . This earli e r he lped in remova l of lead and can now he lp reduce benzene or remove MTB E from motor gaso line. Blending of e th anol in gasoline ra ises the vapour pressure of the fu e i, which leads to inc reased vo latility of e th ano l-gaso line bl ends. This could lead to hot startab ility problems under ex treme hot weather and the evaporative emi ss ions may a lso inc rease. The volatility of base gaso line may need to be adjusted by remova l o f more vo latil e components to take care of these problems. On account of increased oxygen content in the fuel , the oxidation stability of the bl ended fue l could be s li ghtly poorer which may require use of higher dosage of additive to keep the engines c lean.

T he increased ox ides emi ssions from four-stroke

of nitrogen (NO,) gaso line engines is

another issue of concern as most o f the studies indicate reduced CO and HC but increased NOx with ethanol blends. In the case of two stroke engines, which do not emit NO" the use of ethanol gaso line blends can result in substantial environmental benefits . The two stroke engines in Ind ia from year 2000 are also fitted with ox idati on cata lysts. In the tests conducted at 10C, R&D on scoote rs and mopeds it has been seen that cata lyst effic iency improves with use of suc h blends, thus giving bonus of substantial reduction of hydrocarbons and carbon monox ide emi ss ions f rom such vehicl es). Typi cal results of carbon monox ide and hydrocarbons em iss ions from two stroke vehicles with 5 pe r cent and 10 per cent ethanol and gaso line with and w ithout cata lyti c converte r are presented in Figure I (a b). It is interesting to see that while in non-catalyst vehic le the hydrocarbon e mi ss ions had marg ina ll y gone up with ethanol blended fue l, in catal ys t fitted vehic le substantial reduct ion s in hydrocarbon emi ss ions were observed with ethano l blended fue ls . Hi gher reducti ons of carbon monoxide with b lended fuels in catalyst fitted vehicles were also seen.

The above findings indi cate strong potential of environment improvement w ith use of e th anol ­gasoline blends in the hi gh populati on o f two-stroke vehic les in Indi an c iti es, parti cularl y if they are retrofitted with ox idati on cata lyst while us ing the ethano l blended fue l.

The mate ri a l compatibility o f e ngll1e components is an issue, which needs to be looked into by Indian manufacture rs. As mos t of the car manufacture rs have fore ign ti e-ups the materia ls of such engines are already compatible w ith bl ended fu e ls. However, some of the Indi an two-wheele r manufac ture rs wi ll have to examine the mate ri al compatibility, if highe r blends of e thano l in gaso line are to be used .

Ethanol as Fuel/or Diesel Engines

In Indi a , where we use diesel in much larger ratio as compared to gaso line which is unlike the developed world the biofuels thu s make more sense fo r use in diesel engines.

MALHOTRA & DAS: BIOFUELS 93

3.5

3

2.5

2

1.5

1

0.5

0 -; ·u

10. Q)

E E 0

U

"0 Q) c ~ .5 ~ 0 ..c "0 ~ -'" ~

C-' ~ to

"0 C ~

..c .... ~

mWithout CJI.

Converter

DWith Converter

Figure I (a) - CO emission-two-stroke vehicle with and without catalyti c converter

(5 ;!2. c o 1\1

~= W

DWithout Cat. Converter

DWith Converter

Figure I (h) - He emissions-two-stroke vehicle wi th and without cata lyti c convert er

It is we ll known that good spark ignition (SI) engine fue ls are poor diesel fu e ls. This is true for ethanol , whi ch has hi gh octane and hi gh latent heat, which are virtues for SI engines application but render it as an undes irable fue l for diesel engines. Stoichiometri c considerations require rough ly 1.7-times more o f ethano l mass compared to diesel fuel.

Then considering the latent heat of vaporization of 900 kJfkg of ethanol compared to 600 kJf kg fo r diesel , it is possible to estimate the mixture temperature as a result of vaporization of ethano l. Cooling can be detrimental at low ambient air temperatures when the co ld start may become difficult. The charge air cooling will a lso act to quench combustion in diesel engines. Thi s makes ethanol a difficult fuel to combust in the compression ignition diesel engines. It is for this reason that ethanol is not being used on large commercial scal e anywhere in the world for diesel applications. Variou s researches have tri ed to use pilot injec tions and biofuels approaches for part substitution of diesel fuel 6,7 . All these approaches require engine des ign changes, which are difficult to imple me nt.

An approach , more like ly to be successful, is to use ethanol-diese l blends as no eng ines modificat ions are required. This can a lso enabl e the use of ethano l in the farm sector near the source of producti on as and when surplus ethano l is ava i lable . Phase separation has been the most c ritical problem with blends of diese l and ethanol. Add iti on of traces of water will separate the diese l and ethanol. The wate r tolerance is extreme ly poor at low temperatures and improves with increase in temperature.

The anhydrous e thanol can be blended with diesel fuel by use of additives commonly known as couplers. Such blends could use up to 10 per cent e thanol in di ese l. A few companies a re inte rnationall y marketing these addit ives which bes ides mak ing the blend stable also contain cetane improvers to compensate for the lower cetane quality of e thanol. As the lubric ity of the e thano l is also poorer, additional additives for enhanc ing lubricity may a lso be required . The tightening o f e missi on norms require diesel sulphur removal which re nder the fuel even poorer in lubricity and this would definite ly call for additional lubricity tmprovers In di ese l-ethanol blends.

A typical ethanol-d iesel blend marketed in Europe as E-diesel is reported to result in 19 pe r cent reduction in CO and 17 pe r cent red uction in Pm with no significant change in HC and NOx (re f. 8). Another marketed ethano l-diesel blend as O 2 diesel is claimed to have resu lted in consistentl y red uced emissions of vis ible smoke, NO", CO, Pm, and aldehydes during extensive emi ss ion tes ts conducted at independent the US , European, and South American laboratories'}

94 J SCIIND RES VOL 62 JANUAR Y-FEBRUARY 2003

If the water tolerance of blends could be improved, it would be possible to use even the cheaper grade of hydrous ethanol. In addition to lowering cost, the diesel- ethanol- water emulsion could improve combustion . The water serves as a heat sink, lowering combustion temperatures and reducing NO, emission 10. Its volatility serves to improve atomization thus reducing Pm emissions. The oxygen content on account of ethanol in the fuel could reduce carbon monox ide.

Biodiesel for Diesel Engines

The use of vegetable oils either raw or more usually after esterificati on has been of interest for diesel engine applications . Although neat vegetable oils could be combusted in diesel engine, there are problems reported from long term use". Most of the engine problems related to injector coking, piston, and ring deposits and lubricating oil incompatibility can be eliminated by modifying the oi l into vegetable es ters called biodiesel through the process of transesterification related to injector coking, pi ston and ring deposits and lubricating oil incompatibility. The bio-diese l exhibits chemical and thermodynamic properties which are substantially similar to diesel fuel. The bio-diesel has higher cetane number and therefore is quiet suitable fo r combusti on in a di esel

engine. The biod iese l also has good lu bric ity and can compensate fo r the loss of lubricity on accou nt of removal of sulphur in the blend with low sulphur diesel fuels. The use of bio-diesel-d iesel blends increase the oxygen content in the fuel like ethanol and therefore results in reducti on of carbon monox ide emi ss ions. The other incentives for using bio-diesel are that it is non-toxic, bio-degradable and a renewable fuel with virtuall y no su lphur, low aromatics and low volatility.

In a study conducted with biod iesel and diesel blends containing 10, 20, 30, 50 and 100 per cent blends reported that in comparison with low sulphur diesel the blends generally resu lt in lower black smoke emissions. As a result of their influence on soot formation all of the ester blends result in substantial improvements in total particulate emi ss ions. However the fuel consumption as well as the NO, emissions tend to increase with the increase in percentage of ester. A summary of the fuel consumption and emiss ion test conducted under 13 mode test cyc le by FEY is given in Figure 2 (ref. 12). Biodiesel when blended up to 20 per cent in low sulphur diesel can improve the performance of the engine particul arl y in terms of emissions of HC, CO and particulates with minimum penalty of fuel

~.-------------------------------------------------------------------------

-1ffiL------------------------------------------------------------------------

ON:x

o PcJtiajciES

me om 1(ffC

Figure 2 -- Comparison between 100 per cent Iwo sulphur and blends of biodiesel having 10.20,30,50. and 100 per cent biodiesel

MALHOTRA & DAS: BIOFUELS 95

economy and NO, emissions. In the FEY study, with the 20 per cent biodiesel blend, reduction of the order of 24 per cent of particulates and 32 per cent of hydrocarbons was observed with only 5 per cent increase in the NO, and on ly 2 per cent increase in the specific fu e l consumption. With the change in engine settings it is poss ible to reduce both NO, and particulates wh ile maintaining fuel consumption reasonably closed to the di ese l fue l.

In a study conducted on a Navistar diesel 1.1

engine unde r 13 mode steady state test conditions, reducti on in the total particulate was seen. Under the light load conditions, however, a slight increase in the particulate emissions was seen due to increased Soluble Organic Fraction (SOF). In most of the studies i

.) , conducted with diese l and bio-di esel bl ends, the SOF portion of the particulates is reported to increase with the inc reasing proportion of bi o-diesel, even though the total partic ulates are lower on account of lower soot generation .

It is reported that the use of a diese l oxidation catalyst in the ex hau st system burn the part of particu lates due to e leva ted temperatures in the cata lys t bed . Reduction ofSOF con.tent is particularly of interest H·ith catalyst vehicles. The higher oxygen content o f bio-diesel could he lp in improving the performance of the oxidation catalyst , thus he lping further reductions of parti culates bes ides the hydroca rbons and carbon monoxide. Use of Bio­Diesel and Diesel blends therefore has potential for significant ell1ission reduction s including particulates /i"O I11 diesel engines .

Issues Related To Success of Biofuels Programme In India

India has an excellent potential for increas ing the product ion of ethano l not only from the sugarcane but also by utili zat ion o f various other biosources, res idues and wastes . Indi a also has large degradable land where non-edi ble o il seeds could be grown for conversion into biodiesel. This can he lp in creation of millions of jobs particularly in the rural sector, besides prov iding energy security through the production of home grown renewable fuels which will also he lp in reduc ing pollution .

However, there are several issues re lated to the success of this programme in Indi a which need to be addressed .

India at present , has surp lus refining capac ity of both motor gaso line and diesel fuel. The o il

companies will find it difficult to start using these biofuel s as blending component unless the same is avai lable at be low the inte rnational price of motor gasoline and diesel. In case, these biofuel s could be produced economically, the oi I companies cou Id consider blending these fuels with petroleum fuels and exporting the surplus pe trol eum fu e ls . Alternatively the Government intervention in the form of fi scal incentives, excise duty concessions, e tc ., would be required for the success of the programme.

In addition to the issue of pnclllg the oil companies would look forward to the sustained ava ilability of such fue ls before making any investments on creation of blending facilities of these fuels. In India the a lcohol is sometimes ava ilable in abundance and also scarce at different times during last few years . This has been one of the major factor for the non-implementation of the a lcohol programme in India in the past. The biodiesel production is yet to commence on a commercial scale in the country. Although, there seems to be strong pote ntial for the production of biodiese l, the implementati on of programmes for plantati on in degraded land , co llection of seeds and in vestments for the economic producti on of fue l grade bi odiese l would need Government support.

Another issue which would need to be addressed is the assessment of the suitability of Indian des igns of engines and vehicles to perform satisfactorily whi le operating on the blends o f biofuel s and petroleum fuels . There is an urgent need for R&D programmes to be taken up jointly or independentl y by the automobile industry and the oil indu stry so as to ensure that biofue ls could be utilized as and when they are available in sufficient quantiti es at econom ic rates .

At this point of time, we may, however, consider using biofue ls from emissions po int of vie w in the polluted c ities as alternative to the eNG and LPG which are on ly be ing regarded as ollly c leaner options . The ethanol gasoline bl ends have been found to result in reductions of cal·hon monoxide emi ssions , particularly from the two stroke eng ine powered vehicles which constitute large proportion of the tota l vehicle population in Indian cities. The addit ional advantage of hydrocarbon e mi ss io ns hes ides higher reduction of carbon monoxide are achievable, if these vehicles are fitted with catal ytic converte rs. Indi a also has a large populatio n of diesel veh ic les which are

96 J SCiIND RES VOL 62 JANUARY-FEBRUARY 2003

under attack from the environmentalists on account of higher smoke and particulates. The use of biofuels in diese l engines as blending component of diesel fuel may help in reduction of such emissions to some extent.

References A performance study o f iso-butano l-meth anol- ,and ethanol­gasoline bl ends using a s ingle cylinder engine, by S S Sri ram, Popuri et aI. , SAE Paper No.:932953 .

2 Plant oils - Fucl of the future, J Sci Ind Res, 61 (2002) 7-16.

3 Guidebook lo r evaluating, selec ting, and implementing fuc l choices for transit bu s operat ion s, TCRP Report 38, 1998.

4 Handbook on bi oethanol: producti on and utilisation, by Charles E Wyman , 1996.

5 Produ cti on and utili sat ion of bi o-ethano l fo r rural development and environment protection , Pre Ph 0 Proj ec t Report by R K Malhotra at Indian Institute o f Technology, Delhi . November, 2000.

6 Sub zero cold starting o f a port inj ected M 100 engien using plasma jet ignition and prompt EGR, by 0 Gardiner el al., Alternate fuel s - A decade of success and pro mi se, SAE PT-48 .

7 Performance and emissions o f a DOC 8V -7 1 transit bus engine using ignitio n improved methano l and eth anol, by R Bechtold et aI. , Alternate fu els-A decade o f success and promise, SAE PT-48 .

8 Inlormation provided in the commercial lite rat ure o f MIs Akzo Di ese l.

9 Information provided in the commercia l lite rature of MIs AAE Technologies.

10 Evaluation of diesel fu el- e thanol mi cro emul sions, by P A Boruffet et aI., 1982-Trans ASAE.

II A review o f the potential lo r biofue ls as transpo rtation fuel s, by 0 J Rickeard et a I. , SAE Paper No. 932778.

12 The effects of rapeseed oil meth yl es ter on diesel engi ne performance, exhaust e missions and lo ng - term behaviour ­a summary of three years of experimentatio n. F Staat , et a i. , SAE Paper No. 950053.

13 Emissions and perlormance characteristics o f a 4-s troke, direct injecti on diesel engine fu eled with blends o f biodiesel and low su lphur diesel fuel , R J Last ct al.. SAE Paper No. 950054.

14 14 Determinat io n of particul ate and unburned hydrocarbon emissions from diesel engines fue led with biodi esel, David Y Chang et aI., SAE Paper 982527

Mr R K Malh olra is holding Ihe posilion (~j' DepUl)' Geneml Mallager al R&D Celllre oj' lndian Oil Corporalion Lillliled. He is illcharE;e of Vehicle Teslillg, Fuels and Emissions Division. He did his Mechanical Engineering in 1975 fr0 1l1 In .l'lilllle of Technology, Ballams Hilldll Ulliversit\'. He has 27 vears of experience ill Ihe field of File!.\', Lllhricanls and Vehiclliar Emissions. He has pllblished more Ihan 30 research papers in Ihisfield and holds Ihree inlel'llalional palen Is 10 his C/wlil.

Dr L M Das is a Professor ill Ihe Cenlre f or Energy SlIldies, Indian Inslilllie of Techno lo.'{l' (I1T) , Delhi. He has Il earlv Ihirly years oj' leachinE; Iresearch experience. His prilll(// ), areas of research inlereSI include developllleni of ailernalive fll els for 101V emission inlernal COIT/huslion engine/vehicles. He has pllblished I/ lOre Ihan 75 papers in Ihe area of allernalive fil I' I SlIch as hydrogen, biodiesel, bylhane, CNG as \Veil as Oil vehiclliar emissions. He had had several resea rch and CO/lsllliancy assiglll1lenls abroad, such as ill University of California, Riverside; 111.l'Ii11llO Superior Technico, Lishon , Shell Research Lid, Thornlon Research Cenlre, England and fl lS/il 11 I Naliollal de Recherche SlIr Les Transpor!s 1'1 Lellr Sec/.lrile (INRETS), Bran, France. He is also on Ih e Ediloria! Boa rd of Ihe Journal of Sciel/lijic and IndllSlrial Research.