Monohydric Alcohols - American Chemical Society

5 Ethanol in Motor Gasoline

Downloaded by UNIV OF CALIFORNIA SAN FRANCISCO on December 5, 2014 | http://pubs.acs.org Publication Date: June 15, 1981 | doi: 10.1021/bk-1981-0159.ch005

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TED TARR Office of Alcohol Fuels, U.S. Department of Energy, Washington, DC 20585 J. R. JONES TRW Energy Engineering Division, McLean, VA 22102 Transportation fuels derived by blending of biomass derived ethanol and gasoline offer immediate potential to significantly supplement petroleum derived fuels. Ethanol can supplement the supply of gasoline produced from foreign crude oil. Oil imports currently provide the raw material for production of half of the liquid fuels consumed in the U.S., and represent a cash outflow of almost $9 million per hour. Events in recent years have dramatically illustrated the substantial economic cost, supply vulnerability, and resulting economic instability resulting from the high degree of dependency on imported oil. Biomass derived ethanol offers an immediate method of reducing oil imports since it is one of a very limited number of alternative fuels that is likely to be available in significant quantity before 1985. Alcohols fuels have been under detailed study in the United States, Brazil, West Germany and other countries. In the United States, evaluation of the use of ethanol as an automobile fuel dates back to the earliest years of automotive use. For example, the U.S. Department of Agriculture published a report in 1907 entitled "Use of Alcohol and Gasoline in Farm Engines"(1). Interest in ethanol from grain has continued to the present day. As an example, by late 1974 the Nebraska Agricultural Products Industrial Utilization Committee had started sponsorship of a gasoline-ethanol blend fleet testing program. Since the initial testing, a broad-based grass roots movement has developed to support the development of ethanol as a renewable alternative domestic liquid fuel. Much recent attention and investigation has been focused on the use of ethanol as a gasoline extender, octane enhancer, or as an alternative fuel. Many studies have been performed to evaluate the engine performance, emission characteristics, and the advantages and problem areas encountered in conventional spark 1

Current Address: Vulcan Cincinnati Inc., P.O. Box 86, Mt. Airy, Maryland 21770 0097-6156/81/0159-0055$05.00/0 © 1981 American Chemical Society In Monohydric Alcohols; Wickson, E.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.


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i g n i t i o n engines when ethanol i s used as a f u e l . These studies have defined the performance of ethanol and g a s o l i n e i n v a r i o u s proportion blends i n conventional engines. F l e e t t e s t i n g of various blends i s c u r r e n t l y being performed. Gasohol, which i s a mixture of 10 percent by volume anhydrous ethanol i n 90 percent unleaded g a s o l i n e , has expanded to include more than 2000 o u t l e t s in 35 s t a t e s . On 11 January, 1980, the A d m i n i s t r a t i o n announced an expanded alcohol fuels program which w i l l provide s u b s t a n t i a l stimulus to a c c e l e r a t e domestic production of alcohol f u e l s from sources other than petroleum. A target was set for domestic production c a p a b i l i t y of 500 m i l l i o n gallons during 1981. If t h i s amount of ethanol were a l l blended to make gasohol, gasohol would then account for almost 10 percent of our a n t i c i p a t e d 1981 demand for unleaded g a s o l i n e or about one percent o f t o t a l gaso l i n e use. This represents approximately a s i x - f o l d increase over e x i s t i n g alcohol fuel production c a p a c i t y . The program includes a v a r i e t y of i n c e n t i v e s , from tax c r e d i t s to loan and loan gurantees, which focus on two main o b j e c t i v e s : o F i r s t , to permit gasohol to become economically competitive with unleaded g a s o l i n e at the pump o Second, to stimulate new investment in f a c i l i t i e s to produce ethanol These i n i t i a t i v e s are designed to g r e a t l y increase the use of gasohol in passenger and commercial v e h i c l e s , as well as to encourage increased use of alcohol as fuel for off-highway use, such as in farm equipment. Key elements of the expanded program include: Permanent exemption for gasohol from the 4^/gallon federal gasoline excise tax. The President o r i g i n a l l y proposed an exempt i o n of gasohol from the 4j£/gallon federal excise tax in 1977. In November 1978, the c u r r e n t exemption which expires i n 1984 was signed into law. In A p r i l 1979, the A d m i n i s t r a t i o n proposed that the exemption be made permanent i n order to provide a long-term i n c e n t i v e which i n v e s t o r s i n ethanol plants can count on over the l i f e of t h e i r f a c i l i t i e s . The Senate version of the Windfall P r o f i t s Tax b i l l would extend the exemption to the year 2000. This exemption provides a subsidy equal to 40£ per g a l l o n of e t h a n o l . In concert with the tax c r e d i t discussed below, i t i s the most important i n c e n t i v e a v a i l a b l e to a c c e l e r a t e alcohol production and use. 40^/gallon production tax credit. The Adtainistration supports the establishment of a tax c r e d i t for producers who use the alcohol d i r e c t l y without blending with g a s o l i n e . This use i s expected to occur mainly on farms. The Senate v e r s i o n of the Windfall P r o f i t s Tax b i l l would provide a production tax c r e d i t o f 40^/gallon for alcohol over 190 p r o o f , 30^/gallon for alcohol from 150 to 190 proof.

In Monohydric Alcohols; Wickson, E.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.


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Ethanol in Motor Gasoline

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$3 billion federal credit program, A $3 b i l l i o n , ten-year program of loans and loan guarantees for c o n s t r u c t i o n of small and medium-scale alcohol and other biomass production f a c i l i t i e s has a l s o been proposed. The smaller f a c i l i t i e s would be located mainly on i n d i v i d u a l farms for use in farm equipment. This program w i l l also a s s i s t farmer cooperatives for the production of alcohol for e i t h e r on-farm or commercial use. In g e n e r a l , plants e l i g i b l e for t h i s a s s i s t a n c e w i l l produce l e s s than 30 m i l l i o n gallons per y e a r , with most f a c i l i t i e s located on farms producing l e s s than 5 m i l l i o n g a l l o n s per y e a r . Funding for t h i s program would be authorized at an annual l e v e l of $300 m i l l i o n , $250 m i l l i o n for loan guarantees and $50 m i l l i o n for l o a n s , and w i l l be administered through the Departments of A g r i c u l t u r e and Energy. Energy Security Corporation programs for biomass. The Administration supports the a l l o c a t i o n of up to $1 b i l l i o n o f a s s i s t a n c e a v a i l a b l e through the proposed Energy S e c u r i t y Corporation for the c o n s t r u c t i o n of plants for the production of ethanol from biomass. The ESC w i l l have a number of financing t o o l s , i n c l u d i n g l o a n s , loan guarantees, p r i c e guarantees and purchase agreements to encourage p r i v a t e investment i n f a c i l i t i e s with s i g n i f i c a n t p o t e n t i a l to reduce imports. The Senate b i l l , S. 932, includes such a p r o v i s i o n and prompt Conference Committee action on t h i s l e g i s l a t i o n i s expected. Revision of the entitlements program. The Department of Energy has revised the crude o i l entitlements program to include ethanol produced from biomass. This provides an i n c e n t i v e c u r r e n t l y equal to about $t per g a l l o n of ethanol used i n gasohol. Since the entitlement program phases out along with crude o i l p r i c e c o n t r o l s — ending on September 30, 1981 — t h i s program o f f e r s i t s b e n e f i t s to those who begin production soon, thereby a c c e l e r a t i n g our near-term use of gasohol. 10% investment tax credit. The Energy Tax Act of 1978 authorizes a 10% a d d i t i o n a l investment tax c r e d i t for equipment to produce l i q u i d s or gases from biomass sources i n c l u d i n g the production of a l c o h o l . This tax c r e d i t i s i n a d d i t i o n to the e x i s t i n g 10% investment tax c r e d i t , for which alcohol production f a c i l i t i e s are also e l i g i b l e . Under c u r r e n t law t h i s c r e d i t w i l l expire in 1982. Alcohol production research and development. The Department of A g r i c u l t u r e and the Department of Energy a d n i n i s t e r research and development programs to improve our methods f o r producing alcohol fuels from biomass and to broaden the range o f biomass products which can be used to make a l c o h o l . In FY 1980, a t o t a l of over $30 m i l l i o n i s dedicated to t h i s e f f o r t . This R&D i s important for improving the competitive v i a b i l i t y of alcohol fuels as well as the net energy balance.



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500 million gallon target. The President announced a national target for alcohol production c a p a c i t y — 500 m i l l i o n gallons annually during 1981. Substantial amounts of alcohol w i l l probably be burned d i r e c t l y , p a r t i c u l a r l y for on-farm uses, rather than used for gasohol for commercial s a l e . Today, without i n c e n t i v e s , production of ethanol i s not economically a t t r a c t i v e when compared to g a s o l i n e , although r i s i n g world o i l p r i c e s continue to improve the economics of gasohol. Net production costs for ethanol ( a f t e r c r e d i t s for sale of by-products) are approximately $1.30 per g a l l o n compared to wholesale unleaded gasoline p r i c e s of $0.85 - $0.95 per gallon. (Jan. 1980 v a l u e s ) . With the various federal subsidies in p l a c e , however, i t i s expected that an equivalent federal subsidy of almost $0.50 per g a l l o n of alcohol w i l l be a v a i l a b l e to producers. With t h i s program combined with s u b s i d i e s already a v a i l a b l e in over h a l f of the s t a t e s , the r e s u l t i n g economics for ethanol production are even further improved. Ethanol F u e l s P o l i c y Issues E x i s t i n g and proposed federal and state i n c e n t i v e s for fermentation ethanol production and use have c o n t r i b u t e d to the rapid expansion of the gasohol market. In a d d i t i o n , a broad spectrum of options i s c u r r e n t l y being pursued at the federal l e v e l .to help a c c e l e r a t e the commercialization of gasohol by s t i m u l a t i n g both i t s production and uses. Maximizing ethanol production w i l l require a mix of various sized ethanol p l a n t s . Because of the lead time involved in b u i l d i n g and operating l a r g e r f a c i l i t i e s , the Department of Energy and the Solar Energy Research I n s t i t u t e (SERI) have produced a guide to provide basic information to i n d i v i d u a l s i n t e r e s t e d in c o n s t r u c t i n g s m a l l - s c a l e facilities (2). Several p o l i c y issues must be addressed when c o n s i d e r i n g production of s i g n i f i c a n t q u a n t i t i e s of ethanol for automotive fuel use; these i n c l u d e : o The p o t e n t i a l near-term demand for biomass-derived ethanol o The a v a i l a b i l i t y of raw material feed for ethanol p r o d u c t i o n , and the degree to which ethanol fuel production would i n f r i n g e on food production o The o v e r a l l ethanol production economics, i n c l u d i n g s e n s i t i v i t y to such f a c t o r s as the cost of raw feed m a t e r i a l , scale of p r o d u c t i o n , and co-product c r e d i t s o the e f f e c t of state and federal i n c e n t i v e s on the production economics o The net energy gain achieved when producing ethanol o The environmental impacts of ethanol fuel production and the automotive emission c h a r a c t e r i s t i c s of e t h a n o l gasol ine blends



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P o t e n t i a l Demand f o r Biomass Derived E t h a n o l , 1980-1995. Review of annual g a s o l i n e demand for use in passenger cars and projected demands from various sources (3,4) i n d i c a t e continuing strong demand for g a s o l i n e through the 1980-1995 period as shown in Figure 1. The reduced automotive consumption of g a s o l i n e , r e s u l t i n g p r i m a r i l y from Corporate Average Fuel Economy (CAFE) standards imposed on automobile manufacturers, w i l l reduce annual g a s o l i n e demand during the 1980-1990 p e r i o d . A f t e r 1990, the growth in the t o t a l number of automobiles w i l l again become the predominant e f f e c t and o v e r a l l passenger car g a s o l i n e demand w i l l rise. In the near-term the l e v e l of imported o i l w i l l remain high, and ethanol blended with gasoline w i l l continue to o f f e r a method of reducing substantial o i l imports. A v a i l a b i l i t y of Feedstocks. In the long term, i f ethanol fuel conversion c a p a c i t y exceeds l e v e l s r e a d i l y sustained from surplus and d i s t r e s s e d g r a i n s , and i f c e l l u l o s e - t o - e t h a n o l or coal-to-methanol technology should be slow to develop and be b u i l t , then i t may be worth c o n s i d e r i n g the encouragement o f a d d i t i o n a l crops ( i n c l u d i n g energy c r o p s , such as sweet sorghum, which need not compete with food, feed, and f i b e r ) or the use of s e t - a s i d e acreage for alcohol crop p r o d u c t i o n . It appears that an upper l i m i t of approximately 3.3 b i l l i o n g a l l o n s per year (216,000 b a r r e l s per day) of ethanol could be produced from raw material supplies using e x i s t i n g t e c h n o l o g i e s , i f conversion c a p a c i t y capable of processing these feedstocks e x i s t e d ( 5 h The c o n t r i b u t i o n of various a g r i c u l t u r a l commodities i s shown i n Table I. This l i m i t could be achieved by bringing into product i o n a l l e x i s t i n g grain land and by supplementing food processing by-products with sugar s u r p l u s e s . However, achieving t h i s l i m i t would be expensive, and would reduce the f l e x i b i l i t y of U.S. a g r i c u l t u r a l land and r e s t r i c t options for food p r o d u c t i o n . This table shows the quantity of ethanol which could be produced i f : (a) USDA e l i m i n a t e s a l l future s e t - a s i d e and d i v e r s i o n programs, and a l l e x i s t i n g grain land i s brought into productive use; (b) cane sugar surpluses are converted to e t h a n o l , (c) no new or marginal cropland i s assumed to be brought into p r o d u c t i o n , and sweet sorghum p o t e n t i a l i s not i n c l u d e d . Grain Alcohol F u e l s Process Economics. As of l a t e 1978, the posted p r i c e by r e f i n e r s and operators for unleaded regular gasoline was in the range o f $0.45-0.50 per g a l l o n . During the same p e r i o d , the production cost of ethanol from corn was e s t i mated to be from $1.05-1.16 ($1978). This would y i e l d a d i s counted cash flow rate of return of 15-20 percent with corn feed cost o f $2.30 per bushel and a by-product c r e d i t o f $110 per ton of d i s t i l l e r ' s dried g r a i n s . From December 1978 to December 1979, the p r i c e of gasoline had increased d r a m a t i c a l l y from $0.45-0.50 per gallon to the range of $0.70-0.85 per g a l l o n . While the cost of producing ethanol has undoubtedly increased during the past year due to increased c a p i t a l and operating expense, the p r i c e d i f f e r e n t i a l between unleaded


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Figure 1

Comparison of annual gasoline demand projections for passengers cars to 1995



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regular gasoline and grain ethanol motor fuel has narrowed d r a m a t i c a l l y in recent months. Grain ethanol fuel i s becoming i n c r e a s i n g l y cost competitive as the p r i c e of gasoline continues to r i s e at a rate greater than general i n f l a t i o n . E x i s t i n g analyses i n d i c a t e that the production cost o f grain ethanol has a high degree of s e n s i t i v i t y to the cost of grain feedstock and the c r e d i t s claimed for by-products such as the d i s t i l l e r ' s d r i e d grain ( 6 , 7 ) . As a rough guide, the cost per gallon of ethanol must r i s e 12 cents for each 10 percent increase in corn purchase p r i c e . F u r t h e r , the cost per g a l l o n could be reduced 4 cents for an increase of 10 percent in the by-product c r e d i t for d i s t i l l e r ' s d r i e d g r a i n . These approximate numbers assume a new 50 m i l l i o n g a l l o n per year ethanol plant with a 20-year l i f e r e q u i r i n g an investment o f $58 m i l l i o n (1978) at 20 percent return on investment. Federal and State S u b s i d i e s . The l a r g e increase i n demand for gasohol i s believed to be based, at l e a s t to some degree, on consumer preference for v e h i c l e fuel derived from renewable resources, and the perception of the fuel as a high q u a l i t y motor fuel. In a d d i t i o n , increased demand has occurred because grain ethanol for use i n gasohol fuel mixtures has been made cost comp e t i t i v e with unleaded gasoline through state and federal p r i c e incentives. Alcohol fuels c u r r e n t l y receive a wide range o f federal and state government i n c e n t i v e s . These i n c e n t i v e s subs t a n t i a l l y improve the cost competitive p o s i t i o n of grain ethanol when used in gasohol, r e l a t i v e to unleaded g a s o l i n e . These i n c e n t i v e s as sunmarized i n Table II i n c l u d e : o

o o

o

The National Energy Act motor fuel excise tax exemption which a p p l i e s through 1984 to g a s o l i n e / a l c o h o l blends. This exemption i s worth $.04 per g a l l o n of gasoline/ alcohol blend, or $0.40 per g a l l o n or $16.80 per barrel of alcohol in 10 percent blends. The exemption does not apply to alcohol which uses petroleum, natural gas or coal as a feedstock. Some states have also exempted these blends from State excise taxes, E l i g i b i l i t y of alcohol f u e l s for Department of Energy e n t i t l e m e n t s , worth roughly 5 cents per g a l l o n , Loan guarantees for alcohol p i l o t p l a n t s , administered through the U.S. Department of A g r i c u l t u r e , the Department of Housing and Urban Development, the Small Business A d m i n i s t r a t i o n , the Economic Development Administration and Department of Energy, An a d d i t i o n a l 10 percent investment tax c r e d i t on top o f the c u r r e n t 10 percent base. The value i n Table II i s based on a new 50 m i l l i o n g a l l o n per year ethanol p l a n t with a 20-year plant l i f e and investment of $58 m i l l i o n (1978).


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Table I.

Biomass Feedstocks Potentially Available for Ethanol Fuel Production

MATERIAL POTENTIALLY AVAILABLE FOR ETHANOL PRODUCTION BIOMASS FEEDSTOCK MILLION BUSHELS

MILLION DRY TONS 0.9


Cheese W h e y . ,

16.0

640

Grain Sorghum

2.7

110

Sugar Cane . . ,

2.6

Corn

Wheat

PRODUCTION POTENTIAL, MILLION GALLONS PER YEAR ETHANOL

11.4

,

420 3,310

TOTAL

Table II.

Impact of Incentives Cost of Alcohol Used in Gasohol

SUBSIDY (Dollars)

EFFECTIVE NET PRICE (Dollars)

PER GALLON PER BARREL OF ALCOHOL OF ALCOHOL

PER GALLON PER BARREL OF ALCOHOL OF ALCOHOL

Base: Market Price (Dec. 1979) of 1.62

68.04

Subsidy: 1. Exemption of Federal excise tax ($0.04 per gallon of fuel containing 10 percent 2. 20 percent investment tax credit 3. Entitlement credit (approximately

0.40 0.01

16.80 0.42

1.22 1.21

51.24 50.82

0.05

2.10

1.16

48.72

0.95 0.50 0.50 0.10 0.32 0.65 0.50 0.80 0.10 0.70 0.50 0.50 0.40 0.65 0.40 0.40

39.90 21.00 21.00 4.20 13.44 27.30 21.00 33.60 4.20 29.40 21.00 21.00 16.80 27.30 16.80 16.80

0.21 0.66 0.66 1.06 0.84 0.51 0.66 0.36 1.06 0.46 0.66 0.66 0.76 0.51 0.76 0.76

8.82 27.72 27.72 44.52 35.28 21.42 27.72 15.12 44.52 19.32 27.72 27.72 31.92 21.42 31.92 31.92

4. State Incentive: Rebate of State Tax on Gasoline:

Louisiana

Nebraska

South Dakota Wyoming



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Net Energy Gain i n Biomass Derived Ethanol P r o d u c t i o n . Numerous studies have examined the net energy balance issue o f alcohol production and use. The majority conclude that the net balance i s small but p o s i t i v e , but exact estimates d i f f e r , depending on the feedstock and process employed. It i s expected that advances i n technology and a b i l i t y to u t i l i z e feedstock by-products more e f f e c t i v e l y w i l l improve the net energy balance. For example, a plant using food processing residue for feedstock and coal for fuel may achieve a net reduction i n imports approaching i t s t o t a l production. A l s o , the use o f coal i n the alcohol production process improves the o i l savings a t t a i n a b l e through increased use of gasohol. Thus, the use o f coal or renewable f u e l s such as wood, a g r i c u l t u r a l r e s i d u e s , geothermal energy or s o l a r energy for alcohol production i s highly p r e f e r a b l e to use of o i l or natural gas. Ethanol conversion f a c i l i t i e s can r e a d i l y be designed to use fuel sources other than o i l or natural gas. S m a l l - s c a l e on farm plants can u t i l i z e corn stover as a b o i l e r f u e l , and l a r g e r plants can r e l y on coal as a b o i l e r fuel to produce process steam. The ethanol production process can then be viewed as a means of converting lower grade energy forms, such as c o a l , d i s t r e s s e d crops or s o l a r energy, i n t o premium t r a n s p o r t a t i o n fuel. Environmental E f f e c t s o f Ethanol P r o d u c t i o n . Production of ethanol could p o t e n t i a l l y produce two forms of a i r p o l l u t i o n : the release of p o l l u t a n t s from the b o i l e r used to produce process steam, and v a p o r i z a t i o n of ethanol during the production process. If crop residues or lower grade fuels such as coal (low s u l f u r ) are used as b o i l e r f u e l , which i s preferable from a net energy gain b a s i s , the r e s u l t i n g p o l l u t a n t s may be c o n t r o l l e d through use of f l u e gas stack scrubbers. The release of ethanol vapors at the plant s i t e i s not considered a major concern at t h i s time. In s m a l l - s c a l e farm production of ethanol a p o s s i b l e environmental impact could occur through removal of crop residues for use as a b o i l e r f u e l . Crop residues are important because they help control s o i l erosion through t h e i r cover and provide n u t r i e n t s , m i n e r a l s , and fibrous material which help maintain soil quality. However, not more than o n e - t h i r d to o n e - h a l f of the residues from a grain crop devoted to ethanol production need be used to fuel the process. A l s o , there are several methods, such as crop r o t a t i o n and winter cover c r o p s , which lessen the impact of crop residue removal . A second environmental impact which might occur i s r e l a t e d to the a p p l i c a t i o n of t h i n s t i l l age to the l a n d . Thin s t i l l age, a product of the grain fermentation f i l t e r i n g process i s composed of very small s o l i d p a r t i c l e s and s o l u b l e s . Two kinds o f problems can r e s u l t from applying thin s t i l l a g e to the l a n d : odor and a c i d i t y . The impacts of applying t h i n s t i l l a g e to the land


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can be attenuated by using a sludge plow, p o s s i b l e r e c y c l i n g of the thin s t i l l a g e w i t h i n the p l a n t , or use of anaerobic d i g e s t i o n to reduce the p o l l u t i o n p o t e n t i a l of the thin s t i l l a g e .


Technical Aspects of the Use of E t h a n o l - G a s o l i n e Blends i n Spark I g n i t i o n Engines Consideration of the l a r g e scale use of e t h a n o l - g a s o l i n e blends in conventional g a s o l i n e spark i g n i t i o n engines r e q u i r e s evaluation of several key t e c h n i c a l i s s u e s . In p a r t i c u l a r , i n blends with high proportions of e t h a n o l , the c h a r a c t e r i s t i c s and performance may change s u b s t a n t i a l l y from the p r o p e r t i e s of gasoline. E v a l u a t i o n of e t h a n o l - g a s o l i n e blends, i n c l u d i n g gasohol have focused on the following t e c h n i c a l areas: o The r e l a t i v e d i f f e r e n c e s in chemical and physical p r o p e r t i e s of e t h a n o l , g a s o l i n e , and e t h a n o l - g a s o l i n e blends o The performance of e t h a n o l - g a s o l i n e blends and ethanol in conventional spark i g n i t i o n engines o E f f e c t of e t h a n o l - g a s o l i n e blends on engine emissions o The c o m p a t i b i l i t y of e t h a n o l - g a s o l i n e blends with automotive fuel and engine systems Chemical and P h y s i c a l P r o p e r t i e s of Ethanol and G a s o l i n e . The d i f f e r i n g performance of ethanol and e t h a n o l - g a s o l i n e blends in conventional spark i g n i t i o n engines compared to s t r a i g h t gasoline can be a t t r i b u t e d to the d i f f e r e n c e s in chemical and physical p r o p e r t i e s . While g a s o l i n e i s a mixture of about 4 to 12 carbon atom hydrocarbons, ethanol i s a s i n g l e compound with uniquely and narrowly defined p r o p e r t i e s . Differences in engine performance and system c o m p a t i b i l i t y between g a s o l i n e , e t h a n o l , and ethanol blends can be a t t r i b u t e d predominantly to f l a s h p o i n t , b o i l i n g p o i n t , octane q u a l i t y , heat of v a p o r i z a t i o n , heating v a l u e , s t o i c h i o m e t r i c a i r / f u e l r a t i o required for comb u s t i o n , and water s o l u b i l i t y . As a greater percentage of ethanol i s added to s t r a i g h t g a s o l i n e , the d e v i a t i o n of c h a r a c t e r i s t i c s i s approximately proportional to the percentage of ethanol. The octane-boosting p r o p e r t i e s of ethanol in gasoline were p a r t i c u l a r l y a t t r a c t i v e at a time when higher octane l e a d - f r e e gasolines were in short supply and other octane enhancers such as MMT (methylcyclopentadienyl manganese t r i c a r b o n y l ) and lead are under r e s t r i c t i o n s . For example, a three percent ethanol a d d i t i o n increases t y p i c a l g a s o l i n e octane (measured as the average of " r e s e a r c h " and "motor" octane) by roughly one p o i n t . In a gasohol m i x t u r e , the a d d i t i o n of 10 percent ethanol increases the octane by 2 to 3 p o i n t s depending on the composition of the gasoline. Ethanol has been permitted by the Environmental P r o t e c t i o n Agency for use as a gasoline a d d i t i v e under Section



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211(f) of the Clean A i r A c t . Two other chemicals - TBA ( t e r t i a r y butyl alcohol) and MTBE (methyl t e r t i a r y butyl ether) also have been permitted as octane enhancers. However, both are c u r r e n t l y made l a r g e l y from petroleum. Performance o f E t h a n o l - G a s o l i n e Blends i n Spark I g n i t i o n Engines^ A number of gasohol f l e e t t e s t s have been run to evaluate performance under normal d r i v i n g c o n d i t i o n s . In a d d i t i o n , a number of authors have compiled t e c h n i c a l information or performed l a b o r a t o r y and performance t e s t s to evaluate various proportional blends of g a s o l i n e and ethanol ( 8 , 9 , 1 0 ) . The gasohol f l e e t t e s t s performed so f a r , have not been performed under the degree of rigorous c o n t r o l s and t e s t i n g procedures that would ensure complete accuracy. However, none of the f l e e t t e s t i n g which has been performed i n d i c a t e s any major problems with the use of gasohol in normal automotive use. The Department of Energy has received the r e s u l t s of extensive t e s t s conducted by the state governments of I l l i n o i s , Nebraska and Iowa and also by the American Automobile A s s o c i a t i o n . These t e s t s i n d i c a t e that the great majority of unmodified v e h i c l e s tested ran as well or better with gasohol than with fuel previously used. Specifically, o The American Automobile A s s o c i a t i o n t e s t showed that 88% of the v e h i c l e s ran as well or better on gasohol, which suggests that 12% of the v e h i c l e s showed negative r e s u l t s and would require some minor m o d i f i c a t i o n for comparable or improved performance on gasohol. o I l l i n o i s state government o f f i c i a l s i n d i c a t e that t h e i r t e s t , (began in June 1978 and continuing beyond the date of t h i s paper) which has used approximately 1,800 s t a t e v e h i c l e s i n c l u d i n g state p o l i c e c a r s , has y i e l d e d p o s i t i v e r e s u l t s i n each category t e s t e d , o The Iowa Development Commission (a state agency) conducted a 90 day gasohol marketing (customer opinion) t e s t from June 15, 1978 to September 15, 1978, i n which 232,000 g a l l o n s of gasohol were sold at f i v e s t a t i o n s (also o f f e r i n g unleaded regular) across the s t a t e . Results show: a) 67% of users reported improved performance (29% c i t e d increased m i l e a g e ) , b) three of every f i v e users were repeat customers, c) 90% o f users would purchase gasohol i f i t were a v a i l a b l e at most s t a t i o n s , d) gasohol o u t s o l d unleaded regular 3.9 to 1. Gasohol i s being used i n automobiles without m o d i f i c a t i o n . With normal precautions to maintain a moisture free blend during r e f i n i n g / m i x i n g , t r a n s p o r t a t i o n , and at the s e r v i c e s t a t i o n , the tendency of the e t h a n o l - g a s o l i n e mixture to undergo phase separat i o n can be minimized. The presence of alcohol in the gasoline increases the water tolerance of the g a s o l i n e . While only a maximum of a few parts per m i l l i o n of water w i l l mix f r e e l y with g a s o l i n e , a gasohol mixture w i l l t o l e r a t e nearly 0.25 percent



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water (depending on temperature) before phase separation takes place. Because most automobiles have some small percentage of water in t h e i r gas tanks, the use of anhydrous ethanol w i l l minimize phase separation problems. C e r t a i n minor d r i v e a b i l i t y problems can occur when using e t h a n o l - g a s o l i n e blends in engines which are set-up for optimum performance with g a s o l i n e . With gasohol, under c e r t a i n c o n d i t i o n s , d r i v e a b i l i t y problems may i n c l u d e : o Greater tendency of s t a l l i n g and stumbling during engine warm-up o Increased tendency towards h e s i t a t i o n during a c c e l e r a t i o n for l a t e model cars o Increased vapor lock tendency in hot c l i m a t e s or at high al t i t u d e Leaning of the a i r / f u e l r a t i o in a gasoline engine i s known to impair d r i v e a b i l i t y . D r i v e a b i l i t y problems r e s u l t i n g from a lean a i r fuel mixture can include increased engine s t a l l i n g and stumbling during engine warm-up, increased tendency to h e s i t a t e during a c c e l e r a t i o n , and increased tendency for engine surge during constant speed d r i v i n g . The use of ethanol in automotive fuel leans the a i r / f u e l mixture because the ethanol molecule contains oxygen, and increases the oxygen content in the engine combustion chamber. In l a t e model v e h i c l e s which are adjusted to run lean in order to minimize p o l l u t i o n , the f u r t h e r leaning induced by use of blends can cause d r i v e a b i l i t y problems. The same tendency i s not t y p i c a l l y present with o l d e r v e h i c l e s which have a r i c h e r i n i t i a l a i r / f u e l r a t i o . A q u a n t i t a t i v e measure of warm-up d r i v e a b i l i t y i s presented in the t e s t r e s u l t s of Figure 2. The r e s u l t s of these l i m i t e d t e s t s i n d i c a t e d that the use of a 10 percent by volume ethanol blend can be expected to degrade warm-up d r i v e a b i l i t y of standard ( i . e . , non-adjusted and non-modified) carbureted cars to a degree ranging from n e g l i g i b l e to pronounced (8). F u r t h e r , at 22 p e r cent e t h a n o l , warm-up d r i v e a b i l i t y was dTegraded s i g n i f i c a n t l y i n a l l three cars t e s t e d . The three cars were tested by a procedure which measures d r i v e a b i l i t y with a Total Weighted Demerit (TWD) value. (Higher values of TWD i n d i c a t e poorer engine d r i v e a b i l ity). Carburetor m o d i f i c a t i o n s performed to achieve an a i r / f u e l r a t i o for the blend which i s e q u i v a l e n t to s t r a i g h t gasoline w i l l r e s u l t in improved d r i v e a b i l i t y . For engines which are adjusted or modified to operate at e q u i v a l e n t a i r / f u e l r a t i o s , the fuel economy d i f f e r e n c e s between gasohol and gasoline are apparently n e g l i g i b l e . However, the leaning e f f e c t of ethanol may r e s u l t in fuel economy or exhaust emissions e f f e c t s ranging from s i g n i f i c a n t increases to s i g n i f i c a n t decreases, depending on the adjustment of the engine. An a n a l y s i s of state and p r i v a t e t e s t data received by DOE i n d i c a t e s that use of a 90/10 blend of unleaded regular g a s o l i n e and ethanol (compared to 100% unleaded regular) r e s u l t e d in s i m i l a r



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7001—

A B C

Base Gasoline 10 Vol. % Ethanol 22.2 Vol. % Ethanol

95% Confid Range

300

-A: B

A: B ^ C : CARBURETOR:

STANDARD

MOD-

STANDARD

: C :

STANDARD*

IFIED

IFIED BUICK6

MOD-

CHEVELLE 8

PINTO 4

'Exhaust 0g Sensor and Carburetor Feed-back Control

Figure 2.

Warm-up driveability in three cars with gasoline and gasoline blends



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miles per g a l l o n or a small increase in mileage by a majority of the v e h i c l e s t e s t e d . A s u b s t a n t i a l mileage increase or decrease was found with a very few v e h i c l e s . D i f f e r i n g r e s u l t s in mileage are a t t r i b u t a b l e to the d i f f e r i n g age, s i z e , c o n d i t i o n and adjustment, weather c o n d i t i o n s , and the d i f f e r i n g q u a l i t y of ethanol and gasoline employed. E f f e c t of the Use of Ethanol Gasoline Blends on Engine Emissions. On December 16, 1979, EPA approved use of gasohol under Section 211(f)(3) of the Clean A i r Act of 1977 and found that there was no s i g n i f i c a n t environmental r i s k associated with the continued use of gasohol. Furthermore, new emissions c o n t r o l systems, such as the "threeway c a t a l y s t with exhaust oxygen sensors for carburetion feedback for a i r - f u e l c o n t r o l , " have been shown to be equally e f f e c t i v e using e i t h e r g a s o l i n e or gasohol. EPA and the Department of Energy have conducted a cooperative gasohol t e s t i n g program to obtain and evaluate environmental impact d a t a . On the basis of these t e s t s , EPA concluded that the a d d i t i o n of 10% ethanol to g a s o l i n e (11): o s l i g h t l y decreases hydrocarbon emissions o s i g n i f i c a n t l y decreases carbon monoxide emissions o s l i g h t l y increases nitrogen oxides emissions o s u b s t a n t i a l l y increases evaporative hydrocarbon emissions The r e s u l t s to date have been g e n e r a l l y favorable with respect to the use of gasohol i n automobiles. However, in a recent t e c h n i c a l memorandum, the O f f i c e of Technology Assessment of the Congress of the United States stated that the "mixture o f observed emissions reductions and i n c r e a s e s , and the lack of extensive and c o n t r o l l e d emissions t e s t i n g , does not j u s t i f y a strong value judgment about the environmental e f f e c t of gasohol used in the general automobile population (although the majority of analysts have concluded that the net e f f e c t i s u n l i k e l y to be significant)"(12). CompatibiTTty of E t h a n o l - G a s o l i n e Blends with Automotive Fuel/Engine Systems. Experience with gasohol has i n d i c a t e d t h a t the solvent p r o p e r t i e s of ethanol loosen c o r r o s i o n and d i r t from the w a l l s of fuel tanks and fuel l i n e s of automobiles. This makes i t advisable to f l u s h and dry a l l storage tanks used with e t h a n o l - g a s o l i n e blends. V e h i c l e tanks, p a r t i c u l a r l y with older v e h i c l e s , should be flushed with ethanol or gasohol, and the fuel f i l t e r may require replacement a f t e r the f i r s t or second t a n k f u l . The use of neat ethanol or ethanol blends may p o t e n t i a l l y cause minor problems with c o r r o s i o n of metal fuel system m a t e r i a l s , p a r t i c u l a r l y aluminum, copper, i r o n , lead and z i n c . In a d d i t i o n , c l e a r polyamid, used in fuel systems for such items as fuel f i l t e r housings, has been reported to f a i l in s e r v i c e with ethanol blends.


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Conclusions Several c o n s i d e r a t i o n s i n the use of gasohol or e t h a n o l gasoline blends w i l l ensure w i d e- s cal e a p p l i c a t i o n and maximum b e n e f i t s to the United S t a t e s : o Small and l a r g e - s c a l e production of ethanol should be expanded u t i l i z i n g e x i s t i n g food crop surpluses as well as d i s t r e s s e d g r a i n s . o Ethanol plants should r e l y on lower u t i l i t y fuel sources rather than premium fuels such as natural gas or' p e t r o leum derived f u e l s . Lower u t i l i t y f u e l s may i n c l u d e c o a l , and renewable resources such as a g r i c u l t u r a l wastes (corn s t o v e r , bagasse) geothermal or s o l a r energy. o Phase separation of e t h a n o l - g a s o l i n e blends r e s u l t i n g from blend water content d i c t a t e s the use of anhydrous ethanol and that the blend d i s t r i b u t i o n system e x e r c i s e a d d i t i o n a l care to minimize water contamination o The d i f f e r e n c e s in fuel economy and exhaust emissions between a gasohol-type blend and s t r a i g h t gasoline are a t t r i b u t a b l e to ethanol changing the e f f e c t i v e a i r / f u e l r a t i o of standard engines. Equal performance can be achieved by adjusting the a i r / f u e l r a t i o to the equivalent value obtained with g a s o l i n e . o Research, development and t e s t i n g should continue t o : Identify new feedstocks with high alcohol y i e l d s A c c e l e r a t e the development o f feedstock c o l l e c t i o n and conversion technologies capable of using l o w - c o s t , waste feedstocks ( i n c l u d i n g c e l l u l o s i c m a t e r i a l s ) . Resolve the fuel consumption and exhaust emission impacts of e t h a n o l - g a s o l i n e blends. Remove the t e c h n i c a l and material c o n s t r a i n t s to the use of alcohol fuels in a l l highway and non-highway systems i n c l u d i n g diesel engines, t u r b i n e s and on-farm uses.


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Literature Cited 1. 2.


3. 4.

5. 6. 7. 8.

9. 10.

11.

12.

Lucke, C. E.; and Woodward, S. M. "Use of Alcohol and Gasoline in Farm Engines," USDA Farmers Bulletin, 1907, 277. "Fuels from Farms - A Guide to Small Scale Ethanol Production", Solar Energy Information Data Bank, for Department of Energy, February 1980. Marks, C.. "The Fuel Quality and Quantity Requirements of Future Automobiles", General Motors Corp., NPRA AM-77-31, March 1977. Balasubramaniam, M.; and Jenkins, R. "Automotive Fuel Requirements with Increasing Diesel Car Population and Implications to Refining Operation", TRW Energy Systems Planning Division, McLean, Virginia, PA-3885-22-1, February 1978. "The Report of the Alcohol Fuels Policy Review", U.S. Department of Energy, Washington, D.C., June 1979. "Grain Motor Fuel Alcohol Technical and Economic Assessment Study", Raphael Katzen Associates for U.S. Department of Energy, June 1979. "Ethanol Production from Biomass with Emphasis on Corn", College of Agriculture and Life Sciences, University of Wisconsin, Madison, September 1979. Nakaguchi, G. M.; and Keller, J. L. "Ethanol Fuel Modification for Highway Use", Final Report, Union Oil Company of California, for U.S. Department of Energy, 26 July 1979. Ecklund, E. E. "A Department of Energy View of Gasohol", Speech Delivered to American Gasohol Limited, New York, 1979. Bernhardt, I. W.; Lee, W., "Possibilities for Cost-Effective Use of Alcohol Fuels in Otto Engine-Powered Vehicles", Proceedings, International Symposium on Alcohol Fuel Technology, Methanol and Ethanol, November 21-23, 1977. "Analysis of Gasohol Fleet Data to Characterize the Impact of Gasohol on Tailpipe and Evaporative Emissions", U.S. Environmental Protection Agency, Technical Support Branch, Mobile Source Enforcement Division, December 1979. "Gasohol--A Technical Memorandum", Office of Technology Assessment, September 1979, 69 p., Available from Superintendent of Documents, U.S. Government Printing Office, Stock No. 052-003-00706-1.

RECEIVED

February 23,

1981.


Monohydric Alcohols - American Chemical Society

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