1979_buchanan_ethanol as a petroleum

8/11/2019 1979_Buchanan_Ethanol as a Petroleum

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Proceedings of The South African Sugar Technologists Association une 1979

ETHANOL AS A PETROLEUM EXTENDER AND ADDITIVEIN AUTOMOTIVE ENGINES

y E J BUCHANANTechnical Advisor, S.A. Cane Growers Association

Abstract

Th e history of ethanol-pe trol blend application is sum-mariserd. Pas t and futu re changes in the design of au tomotiveengines are outlined . The properties of ethanol and petroland their blends are compared. Early and recent reports onthe perform ance of ethanol blends are summarised. The oilcrisis coupled with the fact that likely contenders to replacepresent engines will operate efficiently on alcohol confirmsthat there is a future role for ethanol. There is considerableevidence from recent experience in Brazil and the U.S.A. to

confirm that ethanol blends up to 20 percent can be usedwithout problems in spark ignition engines. Up to15 percent,ethanol-diesel oil blends also appear to give no problemsprovided a blend stabilising agent is added. A close liaisonwith oil companies is proposed in order to optimise blendformullations. C redits for certain advantages of ethanol suchas its antiknock value would already appear to justify theuse of blends of 10 percent ethanol produced f rom enrichedmo1ass;es. T he s ituation appears of sufficient economicinterest to justify a more detailed study under local conditions.

Introduction

In the past two decades the local price of p etrol hasincreased by 400 percent and this coupled with the realisationthat pc:troleum oil is a finite resource has led to economisingmeasuires. While we are fortunate in South Africa to haveabundant coal reserves these are also finite and particularlyso in the form of liquified fuel due to the enormous capitalcost involved. Against this we have a rapidly increasing andincreasingly sophisticated population whose dem ands for auto -motive: transport seem likely to escalate in the absence ofadequate public transport facilities while motor manufacture rsappear reluctant to change to alternatives which would dra-matically reduce projections for future liquid fuel demands.

Th e scenario is one which leads inevitably to the considera-tion of renewable fuels of which ethano l from sugar cane(or molasses) would appear to be one of the most attractive,

having a positive net energy balance. This paper aims atsumm ~irising he technical and economic aspects of the appli-cation of ethano l in petroleum blends and in particular thepossible advantages of ethanol blends are considered againstthe present higher cost of production.

Past use of ~ t h a n o l lendsTh e consideration of ethanol as fuel dates almost to the

advent of the internal combustion engine14. Thiswas due tothe favourable physical properties and almost universalavailabili ty of a lcohol.

Attention was soon turned from alcohols to hydrocarbonsdue to their low cost and potentially abundant supply. Afterthe first world war the universal trend towards national self-sufficie:ncy in fuel and the need to expand agriculture revivedinterest and power alcohol became an important aspect ofagricultural programmes in many countries. By 1936 theworld consum ption of power alcohol (largely ethanol) ex-ceeded 800 megalitres per annum . Oil shortages during the

second world war and consequent petrol rationing in manycountries created further interest in alcohol fuels in manycountries especially those producing sugar. For examplealcohol-ether-petrol blends were produced in Brazil andSouth Africa (the latter called Natalite). During the waralthough the largest quantity of ethanol was devoted toexplosives and other war materials special applications werealso made of the ability of alcohol-water mixtures to dra -matically increase the power output of super-charged pistontype aircraft engines.

The National Alcohol Campaign in Brazil probably had itsroots in the post-war research into alcohol fuels which beganin 1951 after the Motors Research Laboratory began opera-tion at Aerospace Technical Centre outside Sao Paulo.

In South Africa a 1 1 ethanol :petrol blend (Union M otorSpirit) became popu lar because of its favourable anti-knockcharacteristics. The blend was normally mixed with petro lin a 3 : 1 ratio (petro1:Union) giving a final 12,5 percentethanol blend. Many motorists used this mixture (an d evenhigher ratios) w ithout any engine adjustments. Minor pro-blems were sometimes experienced in the switch from petrolto ethanol blend due to the solution of pe trol resin depositsblocking fuel filters or jets. In addition some inferior qualitypetrol pump diaphragms perished under the action of ethanol.However, this problem was solved when laboratory trialsshowed that the am moniation of Union in order to neutralisetraces of organic acids in the ethanol generated more corrosivenitrogenous compounds and the ammoniation was discon-tinued. At the same time a 10 percent ethand-shale oil-petrolblend was marketed on the Reef under the name of Satmar.Apart from the unpleasant odour of the fuel and its productsof combustion it was also popular for its antiknock value.

1 900 92s 1 9 ~ 9n xm mzs mu, 207s zloo

CYCLE OF WORLD OIL PRO DUCTIO N

F I G U R E Cycle of world oil production 1900-2100

With the advent of the high octane premium petrol gradesthe use of ethanol blends for the suppression of engine knockwas gradually discontinued during the 1960 s. The petrolalone had a high enough octane rating to cope with themodern high compression engine. The disinterest in alcoholfuels was short-lived. During the 1970 s political and eco-nomic factors have led to an increased awareness of the finitenature of the world s fossil fuel reserves. Studies of past


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roceedings of The South African Sugar Technologists' Association une979

World . . . . . 15 100 3 950 19 50 10 900 800 32 750 66 100'

TABLE 1Measured estimated recoverable) reserves for principal resource regions energy content in millions of terajoules)

I I I I I1 I1

Use of uranium in breeder reactors would increase its usable energy content 60-fold, which with thorium would treble total usable world reserves.(From: World Energy Conference Survey1971)

Africa . . . . . . . .Asia . . . . . . . .urope

U.S.S.R.U.S.A.. . . . . . . .

anada . . . . . . .outhAmerica . . . . .

Australia

CYCLE OF WORLD COAL PRODUCT ION

IGURE 2 Cycle of world coal production 1800-2600

rends and future predictions for oil and coal consumptionFigures 1 and 2) indicate that oil peaks before coal, although

he exact timing will depend on conservation measures12. Th erossover point where coal takes over from oil will probablyccur early in the next century. Th e present reserveso fossiluels (measured and estimated) are shown in Table 1 whilehese are expressed in Table2 in terms of the ratio of re-overable reserves to the 1971 consumption rate giving anstimated life12. This is based on current technology andconomics and is therefore conservative. However, it doesive a clear indication that future fossil fuel energy is going

UraniumThorium

(with Breeder)

12 550200

9 750> 3 40019 75013 7503 7506 250

TABLERatio of recoverable reserves of fossil fuels to 1971

Consumption for principal producing or consuming regions(From World Energy Conference Survey1974)

SolidFossil Fuels

5002 7502 6003 5005 200

15050

500

Africa (Total) 352Western 398Eastern . . . . . . . . . . . 172Middle . . . . . . . . . . . 1 192

orthern 870Southern 149

. . . . . . . . . . . . . . .sia (Total) 201China . . . . . . . . . . 264Japan . . . . . . . . . . . 3India 95Middle East . . . . . . . . . 155Iran . . . . . . . . . . . . 682

urope (Total) 54Western . . . . . . . 58Northern (~hcl.'u.K. 25Southern . . . . . . . . . . 40Eastern 85

U.S.S.R.. . . . . . . . . . . . . . . . 144

U.S.A. . . . . . . . . . . . . . . . . . 180anada 607outh America . . . . . . . . . . . . . . . 100

Crude Oil

5502 350

> 5035025050

350

to escalate in price not just due to scarcity but also due toincreasingly sophisticated technology necessary to exploitdwindling reserves.

It is this thinking which has revived the interest in alcoholfuels; methanol as an attractive liquid fuel which can be pro-duced from coal and ethanol an attractive liquid fuel whichcan be produced from renewable plant material suchas maizeand cane. In Europe research into the use of m ethanol-pe trolblends is widespread, particularly in Germany6. At presentthe use of ethanol blends is prominent in Brazil whereWhas a research team with a $2 million budget.In Sao Pauloand Rio de Janeiro the ethanol blend has reached 20% withcurrent ethanol production around 2 billion litres for 1979

3 billion for 1980 and 4 billion for 1982). Several fleets ofcars are used on a continuous test run e.g. a telephone com-pany has a fleet operating on straight ethanol. In the UnitedStates a 10 percent unleaded ethanol blend Gasohol ismarketed in Iowa and Nebraska, the former from molassesand the latter from grain.A fleet of 45 cars has been on a2 million mile test since 1974 and the blend is on sale withstate taxes subsidised and national subsidies under considera-tion. A series of comprehensive reports has been publishedby S~heller'~.While in South Africa the use of Union MotorSpirit has dwindled, it is reported that motorists have un-knowingly been using ethanol blends produced by SASOL5.Tests on methanol blends are currently being conducted bythe University of Cape Town and on ethanol by the Uni-versity of Natal.

Periodic resumes have been published by the AmericanPetroleum Institute (API) and while earlier comments havebeen critical1, it is evident that the looming fossil fuel crisisis tempering their m ore recent think ing2 leading to morerespect for alcohols as a fossil fuel extender. A study of theliterature cited will indicate that it has beena tendency inthe past for oil companies to draw out the possible problemsassociated with alcohol blends with some confusion betweenethanol and methanol for the unwary reader while chemicalcompanies with an interest in the exploitation of potentialfuture fuel production have adopted the opposite tactic. Forthis reason an inexperienced reader is likely to be thoroughlyconfused by the literature even without the added compli-cation of changes in engine design since the second world

war. For this reason it is advisable to concentra te on morerecent published tests in the assessment of a lcohol blends.

Natural Gas

200450

>I5060030010050

< 0

Australia. . . . . . . . . . . . . . . . . 256New Zealand . . . . . . . . . . . . . . . 88 Design tren s in automotive engines

In order to establish the continued need for liquid fuels. . .o r l d . . . . . . . . . Similar to those presently in use it is necessary to examine

Uranium(Non

Breeder)

200

50

300150

100

Oil Shaleand TarSands

100900

> 100150

6 3603 250

< 50

TotalwithoutBreeder

1 4506 4503 000

>4 60012 4003 700

500600


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12 proceedings of The South African Sugar Technolog,sts Association une 1979

the moitor industry philosophy. In 1970 prior to the emissionlegislation the U.S.A. consumed one th ird of th e world senergy production (half in the form of oil). Just over halfof the U.S. oil was used for transport with nearly a thirdin private cars. (About a quarter of the non-oil energy wasused to manufacture these cars). The fuel consumption incars modified to meet emission legislation increased by 20

percent and could rise to over 30 percent if fu rther proposedlegislation is enacted. It has been argued that increased useof te1et:ommunications and public transport would reducefuel consumption. However, it is generally considered thatthe private car because of its flexibility will remain the mostdesirable form of personal transport, at least during theperiod during which oil conservation is important, unlesstotalitarian measures are adopted to price it off the marketls.

The I-dative mportance of parameters likely to influence thetrend of passenger car engines in futu rela is shown in Table3. This represents the position in 1973 but the arrows indi-cate that fuel consumption and noise will rise to the levelof importance of emissions in the 1980 s. This table also indi-

cates the attributes of the most likely contenders to supple-ment today s piston engines. The stratified charge engine isconsidered to be the leading near-term contender while theStirling engine followed by the turbine are considered to bethe leading long-term contenders. Th e range of expectedmarket penetrationla is shown in Figure 3. Stirling and tur-bine engines are expected to take over from the Wankel witha reduction in catalytic exhausts as the stratified chargeengine takes over.

TABLE

Relative importance of Selection Parameter

Passenger Cars Compared with 4-Cycle

Spark Ignition Piston Eng ineStratifiedl IWankel IVTurbinel Stirlina Charae D~ es el

.ToT y j -qCost - -

idvantage +) or Disadvantage -) Two-Shall Regeneratwe 1900 F Turbine Inlet Temperature

IToml ReclprocetlngEngines I

Share ofMarketPercent

FIGURIZ3 Range of expected m ark et penetration

All of the above possible contenders fo r existing enginereplacement would operate successfully on both ethanol andmethanol5 and would show advantages over petrol in termsof improved efficiencies and emission levels. The history ofthe motor industry has been one of evolutionary not revo-lutionary change. For example the switch to high compressionoverhead valve short stroke engines started in1948 and was

completed only in 1966. Prior to that the last previous newengine was introduced 17 years earlier. Although the fuelcrisis is bound to generate new ideas it is generally consideredthat liquid fuels are going to be in demand for automotiveengines for the foreseeable future and this includes alcoholsas well as petrol.

Properties of ethanolIn order to provide a more meaningful comparison of

ethanol1 and petrol the general properties of methanol arealso included in Table4. The fact that the heating value foralcohols per litre in the tank is lower than for petrol is re-quently used as a criticism. In fact there is a tendency to

quote costs in terms of per unit of heating value thus totallydisregarding the efficiency of conversion of heat in to work.The higher flash points for alcohols are also criticised asindicative of poor cold start characteristics while the higherinitial boiling temperature and latent heat of vaporisation isblamed for vapour lock and inferior driveability.

The properties of ethanol blends9 are shown in T able 5.This indicates a far less drastic departure for blends up to20 percent. Two other characteristics of alcohol blends areworth noting. The Reid vapour pressure of ethanol blendsincreases up to40 percent. This is taken by critics as an indi-cation that vapour lock problems will occur particularly inthe case of methanol blends. The water tolerance is thesecond outstanding point which shouldbe noted. The datain Table 5 indicate water holding capacities of ethano l blends(before phase separation). For comparison the watertolerance of a 10 ethanol blend sat 2 C is 0,35 percentagainst about 0,15 for the equivalent methanol blend.

Performance of ethanol blendsEconomy

Fuel economy is linked to engine tuning and since motoristsare beginning to accept the need for economy checks thetuning on an engine when switching to an alcohol blend willnot be regarded as onerous. The properties of e thanol inclu-ding its relatively lower heating value and higher air ratiofor complete combustion may reqpire minor resetting of thecarburettor with ethanol blends in order to maximise fueleconomy but it has been concluded2 that alcohol blends givethe same economy as petrol at the same mixture strength.However tests conducted more recently in Brazil (Figure 4)have indicated that with the normal petrol settings a slightimprovement in economy is experienced with increasingb.lendconcentration and this breaks even at 15 percent20. Up to20 percent very little loss of economly is experienced. W ithoptimum ethanol settings there is no significant loss of eco-nomy until 40 percent blend is exceeded. These conclusionshave been confirmed using a fleetof various Brazilian cars.

In Nebraska a 3 millionkm test on a fleet of 45 cars wasconducted from December 1974 using Gasohol fuel, a 10percent ethanol blend with unleaded petrol. Th e tests werecontrolled by the Department of Chemical Engineering,University of N ebraskale. It was found that a t temperaturesbelow 2 C there was an improvement in volumetric fueleconomy of up to4 percent over the unleaded petrol,


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oceedings of The south ~ f i i c a n ugar Technologists Association upe 1979 13

GURE4

2 4 6 8 1

ALCOHOL/ PETROL BLEND R AT I O

Volu met ric specific fuel consumption for various blendwith out petro l engine moditication up t o 20%, andengine optimization.

atioswith

These observations confirm numerous other tests conductedearlier to the extent that there is no serious decline in fueleconomy using standard engines and blends up to 20 percente.

PowerSince the stoichiometric airlfuel ratio is much higher for

petrol than for ethanol (Table4 it would theoretically beexpected that in an engine set for pktrol the introduction ofan ethanol blend would lead to a leaning effect with a dropin power and carbon monoxide emissions. Research has infact shown an increase in power output and a drop inemissions8. The explanation for this result is that the higherlatent heat of vaporisation of alcohol resultsin a greater massof charge per cylinder due to the reduced temperature of theinlet gas. It is also possible that the lower flame tempera-ture and slower rate of flame propagation may have more

TABLE 4General prope rties of alcohol and petrol

Property: Methanol 1 Ethanol PetrolFormu la Mixture of

CP o Cl8CH,CH,OH HydrocarbonsCHaOH

TABLESummary of physical-chemical properties of alcohol blends

= 50 cc of blend in100 cc Erlenmeyer flask with2 m m ent, exposed15 days in saturated atmosphere for12 hours at 0 C and 12 hours at 38 each day.= 500 of blend in 1 000 cc bottle with 2 mm vent exposed 15 days out of doors.- 100 of blend in 150 cc beakers at 29' C, exposed for indicated time.

Air-FuelRatio

forCom-pleteCom-

bustionby Wt

14,814,714,714,614,514,314,213,913,6

13,l11,99,O

Fluiditya t 25C

15,3218,9219,l217,6214,s213,9207,6200,6191,6

175,l143,597,l

Sp. Gr.2514C

0,72120,72140,72170,72250,72360,72460,72570,72920,7323

0,73840,75200,7859

CalorificValueLower

inclu-dingLatentHeat at

ConstantVol

Cal./cc

770076757650760075507510747074507240

700065405380,

ReidVaporPres-sureDry)

m bar

529

529

549590611605611486

aH50HontentPer00 cc

Blend

cc

012468

1015203050

100

LatentHeatof

Evapn.a t

Atm.

Cal./cc

54,554,556,558,s60,562,564,870,575,8

86,4111,6170,2

Evapn. loss by wt C

Fall inTemp.

on

Evapn.ofCor-rect

Air-FuelRatio

C

8,819,420,O21,222,423,624,827,930,8

36,849,l79,3

hr_ _ _ _ _ _ _ _ _

6,O6,36,37,86,46,45,55,45,34,53,s0,7

Water Holding Capacityper 100 Blend

WaterAbsorption

per 100 Blend

3 hr

11,s12,211,313,312,913,510,911,611,311,6

8,32,3

20C

cc

00,0080,0180,0450,0800,1120,1500,251

a

cc

00,0100,0140,0610,1010,1480,2180,838

7 hr

27,O28,329,532,733,335,534,532,l32,328,624,l10,2

b

cc

00,0050,0180,0140,0080000000

0,3550,541. . .

. .

O C

cc

00,0130,0300,0800,1310,1880,2450,417

20C

cc

00,0190,0430,1040,1800,2610,3470,589

0,5890,938. . .

0,832 0,3961,357 0,550I 0. . . 0


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14 Proceedings of The South African Sugar Technologists Association -June 1979

significance since these lead to a more efficient conversionof heat into work9.

Antilrcnock ValueThe high antiknock value of ethanol has featured promi-

nently as a reason for lh e pursuit of alcohol fuels. The

Resesrch Octane Number (R ON ) of ethanol blends is deter-mined from the R ON of the petrol base, the fraction ofethan~ol in the blend by volume (x) and the B lendingResearch Octane Value (BOV) of the ethanol:RON1 blend = x BOV ethanol (1 x) RO N petrol.

Th e BOV of ethanol varies from about 107 for blendingwith 98 RO N petrol to 160 for a 40 RO N petrol base1. Agood illustration of the octane raising ability of ethanol isshown in Figure 5 which clearly indicates the fall in octaneraising ability of ethanol for higher petrol grades17.In for-mula1:ing Gasohol in Nebraska a n increase of 5 units on 92for the RO N of unleaded petrol is obtained in a 10 percentblend19. The octane raising ability of ethanol is an aspect

which could have some potential in optimising the cost struc-ture of petrol blending stock and ethanol.

I 2 23PERCENT 0V VOLUME.LTMAW K IN BLEND

FIGUItE 5 Variation of octane ratin,g with per cent of ethyl alcohol in

fuel-alcohol blends.

Driveability (Starting, Vapour Lock, etc.)Ethimol blends up to 20 percent have physical characteris-

tics ( Table 5) which are within the range of variation ofpetrol. Therefore except under extreme conditions whichwould normally require special petrol formulations no unduebehaviour is to be expected for the blends. Reports of coldstart problems emanate usually from extremely cold climatesand. hiwe genenrally less relevance to ethanol than methanol6.It has been found that for a 10 percent blend it is possible tostart at lower temperatures than with petrol if the atmosphereis above 8OC. The reverse applies at lower temperatures

and sliight increases in minimum starting temperatures wouldbe expected in the case of 20 percent blends7. At the samemixture strength, ethanol blends show the same driveabilitydemerits as petrol2.

Vapour lock is a problem more likely to occur under sub-tropicail climate and is as much a function of the engine and

fuel supply system as the fuel type. In addition the formu-lation of the petro l blend stock is also of importance. Gene-rally it is reported that the Reid Vapour Pressure of a 10percent ethanol blend will be higher than that of the petrolbut this is not always the case. It has been reported tha t novapour lock or starting problems have been experienced inBrazil using blends of up to 20 percent ethanolz0. Experiencewith Gasohol gives a similar conclusion for 10 percent blendsbut it is reported in addition that after numerous measure-ments on unleaded petrol base stocks and Gasohol there isno evidence of a higher Reid Vapour Pressure for the latterand in fact it is sometimes lower than for the original basestock. Furtherm ore, after extensive tests driving at tempera-tures of 38OC and more at al titudes of up to 1 524 metres novapour lock conditions have ever been experienced19.

Exhaust EmissionsThe use of a 10 percent ethanol blend can reduce carbon

monoxide emission by up to 75 percent mainly due to theleaning out effect. Hydro-carbons are also reduced but to aslightly lesser extent as are oxides of nitrogen2. Tests byERDA on Gasohol have confirmed these observationsl9 andin addition the use of unleaded ~etr ol -e than ol lends elimi-nates pollution of the atmospheri by lead which is a seriousconsideration in the U.S.A.3. A reduction in emission h sbeen reported in Sao Paulo of abou t 20 percent for 20 percentblends.

A recent report on a 1974 Brazilian vehicle has been pub-lished by General Motorsl l using pet rol of tw o levels ofvolatility and blends of 5,10 and 20 percent ethanol. Hydro-carbon and carbon monoxide emissions were reduced in pro-portion to blend strength to 50 percent of original levels at20 percent ethanol. Oxides of nitrogen increased insignifi-cantly. Aldehyde emissions doubled at 20 percent ethanol.

Aldehyde emission represents about 0,05 g/km against 50g/km for carbon monoxide and 5 g/km for hydrocarbons.At present aldehydes are not regulated by theU.S. Environ-mental Protection Agency13.Engine Wear

Alcohol blends are known to have a decarbonising effecton engines probably due to the ability to dissolve petrol resindeposits. This also applies to deposits in fuel lines. Occa-sional problems may be experienced in the initial change toan ethanol blend if dislodged deposits foul fuel filters9 . Thefew reports of abnormal engine corrosion by ethanol blendshave been traced to corrosive denaturants. Generally lesscorrosion is experienced with ethanol blends. However, high

ethanol content blends could lead to some acetic acid forma-tion, enough to cause corrosion of metals such as aluminiumand copper if present in exhaust systemsg. The 3 million kmGasohol test has confirmed that no unusual engine wearoccurs in the use of a 10 percent blendlg . Bench and roadtests in Brazil have also indicated no unusual engine wearwhile in some instances reduced wear has been experienced20.

Corrosion problems would appear to be isolated and pro-vided correct materials are used for petrol pump diaphragmsand plastic fuel filters then no problems should be ex-perienced in the use of ethanol blends.Note on Diesel Engines

The high latent heat of evaporation of ethanol makesitunsuitable as a straight fuel for compression ignition enginesas does the high flash point. These are characteristics of alow cetane (high octane) rating. Ethanol can be blended withdiesel oil with the use of blend stabil isers or may be used ina dual fuel injection systemz0.The use of dual fuel injectionsystems gives improved diesel efficiency and lower emissions5.


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roceedings of The South African Sugar Technologists Association une 1979 5

y dual fuel injection maintaining the park by a pilot injectionf diesel it is possible to derive 70 to 80 percent of the dieselngine heat requirement from ethanol15.

Research at the CSIR which is currently in progress hashown that certain additives stabilise ethanol-diesel blendsgainst separation by extraneous water and preliminary testuns have given promising results at up to15 percent blends.he cost and availability of the blending agent will cause no

Distribution of ethanol fuelslendingThe distribution of ethanol may be effected either by the

etrol producer (as has been the case for SASOL) or by thecohol producer ( as for Union Motor Spirit). The former

ourse has a possible advantage in permitting the oil refinero formulate the blend base stock to optimise his economynd the physical characteristics of the fuel. This appliesarticularly to the antiknock vapour pressure and emissionharacteristics of the final blend. A good working relation-hip between the ethanol manufacturer and petrol base stockanufacturer is desirable if the greatest advantage of anyhanol blend is to be realised.

oxicologyAn earlier report by a Chicago oil companylohas suggestedat in the use of ethanol blends

The death rate would probably go up from accidentscaused by intoxicated drivers and a poisoned public, withthe adopt ion of the gasoline tank and garage as a source ofalcoholic beverages instead of the roadside tavern wherethe price would be much higher. If alcohol-gasoline be-comes compulsory organised crime might take over the

business it established during prohibition and not onlywould the public suffer from racketeering but it would alsobe called upon to pay the bill for law enforcement.In the case of Union M otor Spirit a small amount of benzol

rovided an adequate denaturant and to the writer's know-dge the blend was never exploited for the above purpose.In the United States13 the available evidence suggests thate substitu tion of alcohols for gasoline offers the followingr quality benefits

Reduced photochemical oxidant formation.Elimination of lead and sulphur emission compounds and,Elimina tion of carcinogenic hydrocarbons currently pro-duced by aromatic fuel compounds.

TABLE 6Comparative toxicity ratings

I I I I

SkinInhala- Penetra- Skin

~ c t tion tion Irritation Ingestion

asoline 2) 3) (3) 1) 2)e t h a n o l . .hanol. . .rmaldehyde 4 3 4 4 3

mild ) estimated--depends on compositionextreme toxicity

Comparative toxicology ratings for the alcohols13 andetrol are shown in Table 6. Formaldehyde is included foromparison. Although the Threshold Limit Value* TLV)r gasoline is generally higher than for methanol (260

T LV irborne concentration under which workers may bea repeatedly exposed without adverse effect.

mg/m , gasoline is much more toxic on inhalation and gaso-line which contains arom atics is more carcinogenic. Table 6shows that denatured ethanol in most aspects is less toxicthan petrol. It is reasonable to assume that damage fromspills or other acute exposure would be significantly lessthan for petrol.

The reduction of carcinogenic aromatic compounds inpetrol is possible in the formulation of petro l blending stocksfo r ethanol blends. This could be a fur ther advantage ofethanol blends13.

Safety

There are no special hazards for ethanol listed by theNational Fire Protection Agency of theU.S.A. for eitherhealth or reactivity. The fire hazard rating is the same as forgasoline. Extinguishing agents are water, alcohol foam orcarbon dio xideldry chemicaP3. While the flash point is abovethat for gasoline the flammability limits are wider(3 to 19percent by volume).

StorageAll ethanol production in South Africa is under excise con-

trol and appropriate security is necessary. While no problemsof ethanol blend separa tion have been experienced in Brazilit is necessary in the initial stages of introducing blends intoformer petrol storage to check for the presence of waterdeposits in the bottom of tanks. The water holding capacityof blends is shown in Table5 which also indicates that phaseseparation is most unlikely to occur as a result of normalatmospheric moisture absorption. Direct contamination musthowever be contrdled.

Economic Aspects

ost of Ethanol and PetrolThe determination of production costs for ethanol is not

within the scope of this paper but it is considered reasonableto assume that alcohol from molasses can be produced atthe current petrol price while direct from cane juice a gateprice of 33 centsllitre is appropriate. The current petrolprice structure from various published sources is shown inTable 7 and by deduction (making allowance for the recent2 centsllitre increase which has temporarily been absorbedin the reduction of excise duty) the refinery gate petrol priceis 17 centsllitre. Against this the ethanol price can vary fromthe petrol price up to 33 centsllitre depending on whethermolasses, high test in termediate products or cane juice isused as the raw material.

TABLEFactory gate price of ethanol blend (33 ce nts/lit re ethanol)

Cost of blend stockpetrol at Refinery

1 4 . . . .15 . . . . . .1 6 . . . .1718 . . . . . .

9 . . . . . .20

21 . . . . . .22 . . . . . .23 . . . . . .24 . . . . . .25 . . . . . .26 . . . . . .

Ethanol in blend

20

17,8018,60

24,2023,50 25,OO24,45 25,SO25,40 26,6026,35 27,40


7/11


DurbianReefPongolaMalelane.Port ShepstonePietermaritzburg

TABLEPump price of various petrol grades

Blend CostsBased on 33 centsllitre for ethanol the blend cost using

petrol at various prices is shown in Table 7 for blends of 5,10,15 and 20 percent.

Locality Grade

It has been estimated that the maximum contribution tothe petrol plus diesel demand which the sugar industry couldmake would be short of the equivalent of a 10 percent blendbut .it is quite possible that augmentation with other cropscould double this. However, in the short term it is unlikelythat the 10 percent blend would be exceeded significantly.In fact experience with Union Motor Spirit would probablybe u~ ed s a starting point. It would be appropriate thereforeto base initial consideration on the 10 percent blend (equi-valent to Gasohol). Table 7 shows that at 17 centsllitre forpetrcll the blend ingredients would cost 18,6 cents/litre, i.e.only 1,6 cents higher than a litre of petrol. The differenceis sufficiently small to warrant consideration of scope forbridging the gap.

Centsllitre

8 93 98

Blend Bonus Points for NarrmCrWlnghe Price Gap

The possible advantages of ethanol blends areii) the high antiknock value of ethanol could lead to cost

savings in the formulation of petrol blend stocks andaddition of tetraethyl lead;

(ii ) decentralisation of ethanol production and blendingcould reduce blend costs through transport savings atpoints remote from oil refineries;

(iii) increased efficiencies as indicated in recent tests inBrazil and the U.S.A. leading to more kilometres perlitre may justify a higher price for blends;

(iv) reduced emissions may lead to advantages which couldreduce air pollution control costs, (e.g. catalyticexhausts) and justify a higher blend price;

(v ) the production of renewable fuels to extend fossilfuel supplies could justify relief from the EqualisationFund levy for such extenders and

(vi) further encouragement may be given in the form ofat least partial waving of excise duties as is thecasefor Gasohol in Nebraska;

(vii) the use of final molasses or higher grade molasseswould reduce the cost of raw materia ls and thus thecost of ethanol.

The above points are discussed in more detail below(i ) In the case of Gasohol the 10 percent blend increases

the RON by units (92 to 97). On this assumption it wouldbe possible to raise regular 93 to the equivalent of 98 premiumby adding ethanol up to a 10 percent blend. Bearing in mindthat tlhe BOV of ethano l is greater for petrol blend stocks oflower RON, then the 10 percent blend should also bridge thegap between 87 and 93 grades used inland. Table 8 ,showsthat the three grades in question each differ by 0,7 cents/litre. It is possible that liaison with oil refineries maylead

to greater savings in blend stock formulation to mutualadvantage of the producers of bo th petrol and denaturedethanol and the consumers. Certainly it could be expectedthat the form ulation of 87 octane blends from a base petro lof say 80 octane (or less). with 10 percent ethanol would leadto greater savings than Table 8 suggests. However, based onTable 9 a saving of 0,7 cents llitre on the 90 percent petrolwould reduce the blend price by 0,63 centsllitre and reducethe 1,6 centsllitre excess (see previous subsection) down to1 centllitre.

(ii) On the assumption that ethanol production is con-ducted in small backend distilleries and the denatured ethanolis mixed with transported petrol blend stock then a cost ad-antage would be possible on the ethanol as shown in Table8. This applies only to the ethanol constituting 10 percentof the blend and the maximum saving on the blend wouldbe about up to 0;3 centsllit re. This would leave a gap of 0,7centsllitre.

(iii) and (iv) Although there is much evidence to showthat consumption and emission adlvantages can be expectedthe savings in practice under local conditions would have tobe evaluated before any additional fuel costs could be justi-fied. However, at 36,3 centsllitre a2 saving would justifya 0,7 centsllitre price increase and this would bridge the gap.For this reason a careful study on 10 percent ethanol blendeconomy against petrol would be justified as a matter ofurgency.

(v) and (vi) There would be no moral justification forapplying the Equalisation Fund levy to ethanol which is arenewable extender to finite fossil fuels and this could justifya price saving of up to 0,8 cents /litre on the blend. As thiscombined with (i) and (ii) above would already bridge thegap further excise relief would not be necessary.

(vii) Should relief f rom the Equalisation Fund levy notbe possible then current prices would restrict the permittedraw mater ial cost and an equivalent of 7 centslli tre wouldhave to come off the raw material (and processing) costs.Details of the methods of achieving this are beyond the scopeof this paper but it would be pertinent to point out brieflythat at R14 per ton cane the raw material cost is 18,7 cents/litre against about 6 centsllitre for final molasses at R17/tonor 12 centsl litre at R34/ton. The use of final molasses wouldsave 6,7 centsllitre to 12,7 centsllitre in raw material costsand would also save the debit of juice extraction and p ro-cessing costs on ethanol (being borne by sugar) which wouldsave a further 7 centsllitre. The total saving for final

molasses is therefore 13,7 to 19,7 centsllitre depending onwhether the local or export price is applied. This results ina 1,4 to 2,O centsllitre credit to the blend cost gap. Sincethis at least doubles the outstanding gap to be filled (0,7cents llitre) it is appa rent that the use of ethanol blends frommolasses at either local or export price can be economicallyjustified. Furtherm ore since this would apparently leave acredit in the petrol blend price gag in favour of the blendit is apparent that it would be economically feasible to useblends of 10% produced from enriched molasses.

The above data suggest that for molasses at the export pricea mixture of final molasses containing additional sucrose upto the equivalent of doubling the ethanal production fromfinal molasses alone would produce an economical 10 percentblend under present conditions selling at the current petrolprice. The economic level of molasses enrichment woulddepend upon local circumstances and those mills havinghigh molasses transport costs and hngh petrol costs would beat the greatest advantage for blending and distributingt ~ocal outlets.


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Proceedings of The South African Sugar Technologists Association une 1979 17

Insufficient information is available at present to permitan appraisal of the economics of ethanol-diesel oil blends.However, moves to extend diesel with petrol wwld balancethe importance of diesel and petroll supply and dem and. Ina crisis situation this aspect mayfall away.

Conclusions1 It is evident that all likely contenders to replace present

automotive engines will operate efficiently onalcohol fuelblends and it is concluded thatin the period during whichpetroleum demand begins to exceed supplyin the 1980 salcohol fuels will assume increased importance as petrolextenders.

2. The physical properties of up to 20 percent ethanol blendsdo not differ markedly from petrol and favourable ex-perience in Brazil and the U.S.A. in extensive test runsand routine motoring confirms that there are no problemswith blends up to 20 percent in standard spark ignitionengines. Up to 15 percent ethanol blends with diesel oilalso appear not to cause problems provided a blend stabi-lising agent is added while increased ethanol ratios maybe utilised in the dual fuel mode.

3. Ethanol blends have a number of advantages over straightpetrol including a higher antiknock value, lower exhaustemissions, higher efficiency and possibly more kilometresper litre.

4. The cost difference between ethand blends at 10 percentis already sufficiently low to warrant production frommolasses. However by making allowance for advan tagesof the blend it appears possible, depending on localtransport advantages, to justify increasing the purity offinal molasses to up to the equivalent of doub ling theethanol production from normal final molasses.

5. It is suggested that the present economics are sufficientlyinteresting to justify a carefu l evaluation of ethanol advan-tages under local conditions.

6. Close liaison with oil companies in form ulating petrolblending stocks will lead to mutual advantage for theethanol and petrol producers and the blend consumers.

EFERENCES1. Anon (1971). Use of alcohol in mo tor gasoline review. American

Petroleum Inst. Publication No.4082.2. Anon (1976). Alcohols tech n~c al ssessment of their application

as fuels. American Petroleum Inst. Publication No.4261.3. Anon (1978). Octane boosters for gasoline pool. Chem. Eng.87 (9)

101-4.4. Bennett, R. F (1979). Utilisation of methanol in motor transport.

S.A.1.Mech.E. Symposium on Alternative Transport Fuels. CSIRPretoria.

5. Bernhardt, W. (1977). Methanol and ethanol for combustion enginesand alternative power units. Symposium on Alternative Fuels andEnergy Sources for Road Transport in South Africa. S.A.1.Mech.E.Symposium.

6. Bernhardt, W. et a1 (1978). Alcohol fuels in automobiles. AlcoholFuels Conference, Sydney. 1.Chem.E. SW Gro up.

7. Bridgeman, 0 . C. (1936). Utilisation of ethano l -gasoline blendsas motor fuels. Ind Eng. Chem. 8 (9) 1102-1 112.

8. Brown, L. T. et a1 (1936). Use of alcohol motor fuels. Ind. Eng.Chem. 8 (9) 650-2.

9. Christensen, L. M. (1936), Alcohol-gasoline blends. Ind. Eng. 8 (9)1090

10. ~ g l o f f ,G . et a1 (1936). Alcohol-gasoline as motor fuel. Ind. Eng.Chem. 8 (9) 1080-8.

11. Furey, R. L (1976). Exhaust and evaporative emissions from aBrazilian chevrolet fueled with ethanol-gasoline blends. G en. M otorsCorp. Report, Warren, M ichigan.

12. Grainger, L (1975). Introductory address. Conference on PowerPlants and F uture Fuels. 1.Mech.E. London.

13. Hagey, G. et a1 (1977). Methanol and ethanol fuels -environmentalhealth an d safety issues. Second International Symposium on A lcoholFuels Technology, Wolfsburg. Paper 8 .

14. Lucke, C. E.et a1 (1907). Use of alcohol and gasoline in farm engines.USDA Farmers Bulletin No.277.

15. Murthy, B. S. et a1 (1977). Factors that improve the performance ofan ethanol-diesel oil dual-fuel engine. Second International Sym-posium on Alcohol Fuels. Wolfsburg. Paper2 .

16. Myburgh, I . Private communication. CSIR.17. Porter, J. C. et a1 (1952). Alcohol as an antiknock agent in auto-

mobile engines. Ind. Eng. Chem. 44(5) 1098-1104.18. Richardson, R. W. (1975). Automotive engines for the1980's. Con-

ference on Power Plants and Future Fuels. 1.Mech.E. London.

19. Scheller, W. (1977). Tests on unleaded gasoline containing 10ethanol. Second International Symposium on Alcohol Fuel Tech-nology, Wolfsburg. Paper 2 .

20. Stumpf, U. E. (1978). Brazilian research on ethyl alcohol as an auto-motive fuel. Conference on Alcohol Fuels. Sydney. 1.Chem.E.NSW Group. Paper2.

21. De Wilde, F. W. Egenes,R. J J (1979). Moto r fuel from bagasse.Conference on Alternative Transport Fuels. CSIR Pretoria. S.A.I.Mech.E.

For Discussion see page 18


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P NEL DISCUSSION FUEL FROM SUG RC NE

Professor E T Woodburn : The Department of Chem icalEngineering at the University of Natal has concentratedits research efforts on the production of motor spirit frombagasse, which is considered to be a longer term objectivethan the direct production of ethanol from sucrose.

I believe that the technology of designing ethanol plantsfrom sucrose is already available and what is needed is notresearch in this area but in fact a commitment by the sugarindustry to a t least a provision of funds for the constructionof a meaningful pilot plant based onmodern concepts for theproduction of industrial alcohol.

With respect to the research on bagasse, it is clear that ifbagasse:can be utilised to produce motor spirit, then the con-tribution of the raw m aterial cost has been shown to be themajor individual cost factor, as reported by Dr.A B. Ravno,then there is strong motivation for the urgent prosecutionof this research .

The research itself can bgsubdivided into three areas:1. Development of energy efficient techniques for the pre-

paration of the fibre prior to hydrolysis. (Conservationof Angular Momentum).

2. The development of energy efficient techniques for thecontxntra tion of the alcohol from the dilute beer pro-duced by fermentation (Reversible separation).

3 The production of glucose and xylose by hydrolysis ofthe cellulose and hemicellulosic materials in the fibre.

Progress to date.

The departm ent of Chemical Engineering has run a mixtureof one-third rectified spirit, one-third furfura ldehyde and one-third gasoline as a motor fuel for a standard Chevair car nowhaving done at least 14 kilometres of essentially cross-town traffic. With only minor modifications this fuel hasproved to be eminently suitable s a motor spirit and no dis-cernible mechanical deterioration of the engine parts has beennoticed over this period.

The object of the prolonged test has been to dem onstra te:(a) that it is not necessary to dehydrate the ethanol com-

pletely before blending it with gasoline.(b) that it is possible to add a third component which is also

derl~ved rom bagasse firstly as a mere volume-extenderof the fuel but potentially and more importantly as thebasiis for the production of solvents which would enhancesignificantly the fuel characteristics of an ethanol/gasoline blend.

In parallel, laboratory and semiscale work concerned withthe procluction of glucose from residual cellulose has pro-ceeded using the fungus Trichoderma viride which has nowbeen suicessfully grown on bagasse. In addition the resultingcellulase broth has now been successfully used to produceglucose from the cellulose fibre.

The major technical difficulty in this area was the sterili-sation of the bagasse and techniques have been successfullydeveloped whereby this can be achieved.

Immedi~rteFuture Programme.1. The con tinuation of investigations into differential acid

hydrolysis to produce xylose solutions.2 Devellopment of optimum enzyme pro files for cellulose

hydrcdysis.

3 It is the immediate intention of the Department to builda general purpose hydrogenation reactor whereby thefurfuraldehyde can be converted into hydrogenated deriva-tives which will enable aqueous alcohol mixtures to beblended successfully both with gasoline and dieseline.The modification of the properties of the complex solutionby preparing various chemical derivatives of the furfura l-dehyde is an interesting possibility and by doing this weshould certainly be able to change the total vapourpressure curve thus facilitating cold starts and possiblyby adding side chains and additional rings to the solvent wecould significantly improve the combustion charateristicsof the combined fuel in both spa rk ignition and dieselengines.

Finally, I might say that I regard this work as being ofmajor technical importance to the country and also of verysignificant socio-economic value. It seems to me that thesugar industry ought to participate in this programme asvigorously as it possibly can, starting now.

Mr S W A C Matthews : Much publicity has been givento views tha t someone should get on and m ake ethanol for usein motor fuel but so far no rules seem to have been spelt out.It is common cause that something has to be done roma national viewpoint.

For a company to be able to decide it is necessary to knowon what basis to forecast revenue,i.e. what will be deductedfrom the bowser price specially by way of levy or duty.

An article in a Cape newspaper last week had it that SasolI1 viability was based on 12 or 13 cents per litre. We havethe anomaly that SASOL is extracting alcohol from its motorspirit stream for sale in the alcohol market while all the talkgoes on about producing alcohol to blend with petrol ordieseline.

Ethanol production technology is not a problem nor isits use.

From what has been said earlier today it seems disposalof effluent on the lands is a possibility.

The necessity must again be stressed for having rules speltout so that economicscan be studied.

D J L Huleta : n 1978 50 of the vinhasse (distillery slops)in the state of SZo Paulo was disposed of in the rivers hisyear, 1979, not one drop of distillery effluent goes to therivers.

No mill was allowed to start up unless it had an approvedsystem of effluent disposal together with a 28 day safety areawhere the effluent could be disposed of should the mainsystem fail.

Various methods are being used to dispose of this effluentand in my opinion the best one is to dispose of it through theirrigation system. One factory , Usina da Pedra, for instancedilutes the vinhasse 4 : 1 with water, adds in all the filtermud and a little lime, and pumps this mixture to the top ofa hill from where it is used to furrow irrigate a large area ofcane. The amount of irrigation is contolled by the potassiumlevel of the soils as this salt is the predom inant mineral con-taminant in the effluent. Nitrogen is added to the field at alater date by airplane if this appears necessary from the con-dition of the cane.

A second method to distribute the vinhasse to the field,where an irrigation system is not available is to haul the liquid


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Proceedings of The South African Sugar Technologists Association une 1979 19

away in 8 ton road tankers and apply it to the fields as aspray directly from the tankers. This system is expensiveand various evaporator schemes are being developed to con-centrate the vinhasse removing 80% or more of the water.Most of these evaporators will make use of the steam goingto the distillery and the hot vapours being condensed in thedistillery to achieve this concentration without the use of any

additional steam.At present all motor fue l (gasoline) in Brazil contains 20%

alcohol and the intention is to produce enough alcohol tosupply 100% of the country's liquid fuel needs. Alreadyvarious centres have alcohol pumps which supply96 alcoholwhich cannot be mixed with petro l. Conversion kits areavailable for V.W. engines and Fiat is marketing an alcoholengined car. Alcohol at the pump is two thirds the price ofpetro l. Various flects of vehicles such as the Post Office fleetin the City of SZo Paulo ar e completely powered by alcohol.

In the diesel field work is being done on dual fuel engines(there is a Sconia truck running on a dual fuel conversion inPorecatu) and also on alcohol additive replacement fuel.

Usina S3o Jouo has a GM Diesel truck running on a mix-ture of alcohol 15% castor oil.

However, no general solution to the diesel problem is avail-able at the moment and this little problem has been leftto solve the easier ones first. In the meantime surplusgasoline is being exported to neighbouring countries.

Mr. J. B. Alexander : n Brazil, the Miller receives the sameprice for making alcohol as he would receive for makingsugar.

Mr. J. L. du Toit : The world at present is living on capitalwith regard to its use of fuel. Oil will maybe last for fiftyyears, coal for a hundred years or so, and there is only alimited amount of concentrated uranium available. The useof nuclear power could cause catastrophic problems.

We must therefore turn to the sun for energy. It must beeconomic to use sugarcane for alcohol, particularly in timesof surplus, as at present. Are we quite sure tha t we willalways be able to export sugar?

The energy problem is a national problem and some firmdecisions must be taken now as to how the matter will betackled.

The SASOL plants are extremely necessary but vulnerablewhereas alcohol distilleries can be spread, for example, byhaving them on the South Coast, the North Coast and Zulu-land.

The Sugar Association should present its case to thegovernment and press for a firm decision. Although anobjection has been raised to producing fuel from food, ifsuch food is being exported at a loss then the argument fallsaway.

Mr. 0 d Hotman de Villiers : have little to say after whatMr. du Toit has just said. Th e US has enormously in-creased cane production per hectare in Hawaii by correct useof fertilizer. In Texas, with a 12 month crop and 4 ratoons,average production is 90 tons cane per hectare, but a fewgrowers average 180 tons. It is estimated that theaverageyield in 12 to 20 years' time will be 134 tons per hectare(Hipp) as compared with the 90 tons average at present. InMauritius a cross between wild Marot cane andPOJ28 hasproduced a vigorous low purity Ethacane which is very suit-able for alcohol production.

Tate Lyle has made a significant contribution to thespillage disposal problem by using continuous fermentation.

Th e cost of alcohol is quoted at 24 4 cents per litre inAustralia but if the full value of by-products is taken intoaccount this figure, it has been stated, can be reduced t o about21 cents.

Professor P. Meiring : The d iesel/petrol ratio is our very shortterm problem . Because 25% of ou r diesel is used in agri-cultural practice these tractors m ust be m aintained in service.

Adding ethanol to diesel could improve the diesel/petrolratio because less diesel would be used.

However, if the diesel that will be supplied by the com -panies has a changed specification, e.g. allowing more of thelighter fractions in the diesel, we might have difficulty in theamount of ethanol that can stillbe added to this diesel.

Furfurol could perhaps play a role as its derivatives helpas a mixing agent and it is itself a fuel. However, furfurolproduction at this stage is still too expensive.

The mixing problems could be overcome by modifyingtractor engines, e.g. by means of twin fuel systems, but thetotal cost of such a conversion for 300 tractors wouldbe prohibitive at this stage.

A word of warning efore ethanol is introduced timewill still be required for research.

I believe that we need a policy statem ent as to what qualitydiesel will be supplied and whether the production and useof ethanol from agricultural crops will be encouraged by theauthorities.

Mr. P. V. van Breda: I was recently at a n alcohol symposiumin the United States which was attended by 500 delegates

from about 15 countries and where 70 papers were presented.A country's prosperity and standard of living is closelyrelated to energy availability and dependence on outsidesources for energy requiremen ts should therefore be m inimal.

It takes so long to apply new technology that it is essentialthat a decision on ethanol be taken now.

Canada has plen tiful supplies of oil and gas and yet isspending large sums researching energy from forests and otherrenewable energy sources.

Cost of production is not the only factor to consider.Availability is also important, as is the fact that in the caseof locally produced alcohol money is spent inside the coun try.

In South Africa land and sunshine are plentiful and urgent

attent ion should be given to increased production of agricul-tural crops and forestry for energy in regions where rainfallor water supply permits. The Forestry Council has recentlyprovided a grant for a feasibility study of fuel from timber.It is time for agriculturalists to be regarded as industrialists,using sun, soil and water to produce energy and the price theyreceive for their products should be placed at a level whichmakes production attractive and bears this important aspectin mind.

The introduction of fuel alcohol must be a combinedeffort on the part of Government, oil companies, car manu-facturers and public. The sugar industry should examine theextent to which present surplus cane and molasses andpotential cane can be harnessed for the manufacture of

alcohol and ask the Government to assist in formulating anoverall energy plan including alcohol so that the industry caninvest and operate profitably.

South Africa should take a lead from Brazil on the alcoholfront ess talk and more action.


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2 Pro

Dr R E Robinson Let me first say how delightedI amto be standing bp before an audience of people who areobviously complete alcoholics. This is a most pleasantchange from previous situations of even a year ago whenthere were very few people indeed who were converted to theconcept of making alcohol out gricultural materials, leastof all, sugar-cane. It is very pleasant to obtain the impression

that at least 99 of this audience today are completely con-verted to the concept that we must produce ethanol from ouragricultural materials in this country and that sugar-cane ispotentiidly one of the most important sources.

In this regard I would like to take issue with one of theprevious speakers who placed a lot of emphasis on the so-called NER (Nett Energy Ratio) as being one of the mostimportant criteria for selecting the particular agriculturalproduct from which ethanolcan be made. I certainly acceptthat thi ,~s an importan t concept in many parts of the worldwhere they have no significant energy resources at all. How-ever, in South Africa where we have abundant supplies ofcoal, where our reserves have been estimated at60 million

tons, with an annual consumption of the order of 100 milliontons per annum, it is quite clear that we have enough coalsupplies to last us for a long time. Under these conditionsand prcvvided that we use coal as our main energy source forevaporating the solutions necessary in ethanol production, Ido not believe that the nett energy ratio or the overall thermo-dynamic balance is an important criterion. After all, if welook at our mammoth Sasol undertakings, without any doubt,these have a very small nett -energy ratio ell below anyfigures that have been quoted here today for ethanol pro-duction. In fact, one can extend this further to any electricpower station and any of the many other activities that weundertalke in th is country to generate useful forms of poweror energy from coal. Thus I believe that, in assessing theviability of a lcohol production from various agriculturalproducts, we can ignore the NER parameter.

lceedings of The South African Sugar Te ch no lo gi ~t ~ ssociation une 1979

amo unts of capital establishing plan ts to produce fuel, it mustbe assured of its raw materials supply.

The third point I would like to makein my presentationand which I believe will be of particular interest to the techn i-cally oriented audience here today, is 1.he importance of main-taining efforts at a high level of research, and in this regard1 believe you will be interested to learn of some of the new

research directions that we in the Sentrachem organizationare taking. Of par ticular importance is our attempt to utilizeall by-products arising from an ethanol production pro-gramme by fermentation and one of the by-products that hasbeen sadly neglected in the past is the carbon dioxide whichis an inevitable product from any fermentation reaction.Sentrachem, in collaboration with Professor Toerien at theUniversity of the Orange Free State has now established aresearch group which is going to look at the utilization ofthis carbon dioxide fo r the cultivation of algae. Youprobably all know that algae are a form of living materialthat is a very efficient converter of carbon dioxide into anumber of different useful materials such as carbohydrates,sugars and proteins. Some indications in the literature revealtha t it should be possible, with the help of sunlight andphotosynthesis, to cultivate algae at a rate which couldamount to well over 100 tons per hectare per annum. I wouldremind you that typical rates in the case of maize are3 tonsper hectare per annum , and in the case of sugar, app roxi -mately 10 tons, and with some of the other crops, like theSAVA people claim, 3 to 4 tons per hectare per annum.However, it is quite clear that if one can cultivate algae in asuitable system, the utilization of land area and sunlight couldbe very much higher than in the mere cultivation of agri-cultural crops. It is hoped that the algae themselves caneither form the base for further fermentation reactions or willform a product which can be incorporated in animal feeds andproviding proteins for their food value. Indeed, it woulda p p r that many of the algae are efficient producers ofproteins which contain lycine in high quantities. This

Of far greater importance to me is the total availability material will form a perfectbalance to some i f the other formsof material and it is surprising how difficult it isto get hard of protein material that are available and it could well pro-factual informaton. F~~ xample, I have asked many p opl vide the answer to the major Kwashiokor that exists in Southto proviide an estimate of what the to tal sugar-cane production Africa ndeed in Africa as a whole.potential is in South Africa and I have received many dif- We believe tha t this line of research work will not onlyferent c>ph ion s from experienced and informed people, produce additional valuable products to an ethanol pro-ranging from a statement to the effect that we easily gramme but will also in effect Solve all effh.lent treatmen tdouble our sugar-cane production, to other estimates that problems since any idfluent from the plant can now easilymaybe increase of existing levels is perhaps all that we be diverted into these algae ponds and converted into usefulcan antic ipate . Clearly one of the reasons for this is the products.uncertai~nty egarding the availability of water for irrigation I mention this approach by Sentrachem and the University

and I accept that this is a difficult task, nevertheless, the long- he O range Free State because we welcome any collabora-term supply potential of any agricultural material is an tion that may be forthcoming from other scientists in Southimportan t consideratoin. If industry is going to spend large Africa.

1979_buchanan_ethanol as a petroleum

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