PRODUCTION OF BIOETHANOL AS AN ALTERNATIVE SOURCE...

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PRODUCTION OF BIOETHANOL AS AN ALTERNATIVE SOURCE OF

FUEL USING CASSAVA AND YAM PEELS AS RAW MATERIALS

ADIOTOMRE K.O. Department of Chemical Engineering,

Delta State University, Abraka, Nigeria

Email: [email protected]

ABSTRACT This project work is based on the production of bioethanol as an alternative source of fuel using cassava and yam peels as raw materials. The Bioethanol was produced by fermentation of the Cassava and yam

peels with the aid of the enzymes Zymomonas mobilis and Saccharomyces cerevisiae at 28⁰C for 5 days. The fermented liquid was distilled at 78⁰C and the quantity of bioethanol was determined. The use of Glocophylum seplarium and Pleurotus ostreatus for hydrolysis of the peels and Zymomonas mobillis and Saccharomyces cerevisiae for fermentation of 20g of cassava and yam peels yielded a peak mass and percentage yield(concentration) of 26.5g/cm

3 (12.2%) and 20.1g/cm

3 (9.3%) respectively. When 35g of

substrate was used, cassava peels produced a mass of 42.6g/cm3 (18.6%) and yam peels produced a mass

28.1g/cm3

(12.3%) of bioethanol. When 50g of substrate was used, cassava and yam peels produced a mass of 55.2g/cm

3 (23%) and 46.6g/cm

3 (19.3%) of bioethanol. This study reveals that bioethanol can be

produced from cassava and yam peels with maximum yield from cassava peels as a result of the presence of higher starch content when Gloeophylum saplarium, Pleurotus ostreatus, Zymomonas mobillis and Saccharomyces cerevisiae are used. Keywords: Bioethanol, fuel, cassava peels, yam peels.

INTRODUCTION Bioethanol is a volatile, flammable, colorless liquid made by fermenting and distilling starch crops. It is a sustainable and renewable form of energy from Agricultural feedstock. These feedstock include waste straw, milk, rice, beetroot, recently grape, banana and dates, sugar cane, potatoes, corn, cassava and yam etc. aside fermentation process, bioethanol can be manufactured by the chemical reaction of ethylene with steam. Bioethanol is used in cosmetic, thermometer, used as solvent, as a preservative and most importantly, as a motor fuel (additive for gasoline) (FAO 2005-2008). These indispensable uses of bioethanol have led to a high demand for the product but the feedstock (cassava, yam, potatoes, sugar cane, and cereals) used for the first generation biofuels are also used in the food industries. This dichotomy has raised an inevitable tension between the production of food and bioethanol (O.K Achi, P.I. Akubor 2000). It is on this basis that this project researches on production of bioethanol from yam and cassava peelings as waste product is being carried out to mitigate the stem competitive demand of Agricultural feedstock for bioethanol production since these feedstock used as food are not even sufficient for the healthy stay of Africans. Bioethanol is a microbiological way of converting simple sugar into ethanol and carbon (IV) oxide. The process for achieving this involves the following methods:

(1) Enzyme hydrolysis (2) Acid hydrolysis (3) Fermentation (4) Distillation

Bioethanol as a renewable energy source could substitute petrol in function in its purest form for moving vehicles. One of the environmental advantages of bioethanol is that it reduces pollution emission 80-90% to 40-60% of 2

nd generation bio fuel. This is due to its complete combustion when bioethanol is blended

International Journal of Innovative Scientific & Engineering

Technologies Research 3(2):28-44, April-June 2015

© SEAHI PUBLICATIONS, 2015 www.seahipaj.org ISSN: 2360-896X

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with gasoline, i.e, combination of fuel mixture. (Londo et al, 2009). Bioethanol fuel trends are widely sold in the United State. The most common blend is 10% (E10) bioethanol and 90% petrol. Vehicle engines require no modification to run on 10% bioethanol and 90% petrol (E10) and vehicle warranties are unaffected also (Davies 2006). Bioethanol is the only liquid transportation fuels that do not contribute to greenhouse effect. Bioethanol is classified into first generation bioethanol, second generation bioethanol and lastly third generation bioethanol. Cassava and yam (peelings) used in this research project fall into the second generation bioethanol because they are made from waste of cassava and yam which make it harder to extract the required bioethanol. The use of classical or GMO yeast strains such as Saccharomyces cerevisiae, Aspergillus niger and mucromucedo are general use for the production of first generation bioethanol. With the help of technology, bioethanol and other domestic forms of energy production has become economically viable and feasible (Londo et al, 2010). The high productivity yield, and availability of yam and cassava (peeling) especially, along with its ability to grow on marginal soils, requiring a minimum labor, management and costs, have placed them on a higher choice among the candidates for bioethanol production (Ziska Dixon, Karltun et al, 2009).The peels of cassava contains cyanogenic glycosides in high concentration making it poisonous if consumed. Using this as a feedstock in bioethanol production, gives it a sense of usefulness in the economic sector (fermont et al, 2008). The non- food parts of cassava and yam (peelings) play a very significant role in the production of energy since they produce relatively high amount of biomass, and are easily hydrolysable and having a high content of dye matter (Kosugi et al, 2009).

Aims and objectives of study The aim of this work is to produce bioethanol as an alternative source of fuel to fossil fuel like gasoline from waste materials. And also to compare between biofuel produced from cassava and yam peels.

Scope of Study This research work involves the collection of cassava and yam peeling from farms and homes respectively. Thereafter an analysis test was made to determine physical and chemical properties of cassava and yam peelings for the production of bioethanol as fuel. In all the specific properties in bioethanol that may enable it to be used as alternative fuel or used to mix gasoline for purpose of modifications and increase quantity in order to meet market needs.

Relevance of Study This study enables us to know the importance of bioethanol as it could be used as a substitute for petrol in motor vehicle in its purest form or when blended with petrol. This work is also of great importance in that it produces fuel that is environmentally friendly and cheap.

MATERIALS AND METHOD

Sample Collection All the samples were collected in the various restaurants in Yanga market in Oleh and Iduoma farm area in Irri, all in Isoko South L.G.A Delta State. The second sample (cassava peels) was collected from farmers in Iduoma farm area during harvesting and peeling.

Adiotomre …. Int. J. Inno. Scientific & Eng. Tech. Res. 3(2):28--44, 2015

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Table 1: Material and Equipment

S/N Material Source Remark 1. Dry active

yeast 20g College of Basic Medical Science Delta State University, Abraka

They are dry active yeast Agglomerates of Dehydrated cells of saccharomyces cerevisiae. The properties of active yeast are characterized by electron microscopy and mechanical analysis after exposure of the powders to various level of relative humidity.

2. Yeast Extract: 20g

Affamefune Biomedical Consult (Analytical/Research) Laboratory

Yeast Extract Autolysed yeast produces yeast extract. Autolysis of yeast cells is by addition of a high concentration salt solution ( sodium chloride) or use of solvent such as ethyl acetate

3. Sodium Hydroxide: 1.0g

Affamefune Biomedical Consult (Analytical/Research) Laboratory

Sodium Hydrogen. The aqueous sodium hydroxide react with alcohol to form C-O

- Na

+ and water. The

ethoxide ion will react with water reforming the alcohol.

4. Deionized Water: 55.56m

Biochemistry Laboratory Delta State university Abraka.

Deionized Water. Absolute alcohol has a tendency to absorb water and the first few drop of water added to the bioethanol form H-bonds, with the release of heat.

5. Hydrochloric Acid 0.1m

Chemistry laboratory, Delta State University Abraka

Hydrochloric acid 200ml of 1molar of hydrochloric acid was mixed with the starch

6. Buffer solution (P

H 4-10)

Chemistry Laboratory, Delta State University Abraka

Preparation is mixing a weak acid and a salt of its conjugate base in solution

List of Equipment And Standard Calibration 1. Spectrophotometer -wavelength band (320-1050) 2. Laboratory Incubator -+5-65⁰C

3. Autoclave or pressure Pot-0-138 gauge MmHg, 0-0.25⁰C 4. Digital Constant Temperature Tank -0-100⁰C 5. Digital Constant Temperature tank: Model HH-6 china.

Used to heat the mixture to 78⁰C for the commencement of bio-ethanol production Simple Distillation Apparatus 1. Round Bottom Flask: Pyrex England 500 ml. it serves as a container, containing the mixture inside the incubator 2. Thermometer: Used in reading the various temperatures of the mixture 3. Liebig condenser: Used in condensing the vapor during distillation process to liquid (bio-ethanol) 4. Volumetric flask (1000ml) 5. Conical flask 500ml, 250ml 6. Beaker 7. Test tubes and Rack 8. Burette 3.3 Procedure

Enzymes Hydrolysis of Cassava Peels Different quantities of the substrates (ground yam peels and cassava peels) were weighed into separate 500ml conical flasks, carried in quadruple (i.e., 20g each in four different conical flask 35g each in another set of four conical flask, and 50gram in another four different conical flask). Sterile distilled water was added to make up to the mark and the flask was plunged with sterile cotton wool wrapped in


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aluminum foil to avoid contaminations. The mixtures were sterilized in an auto clave at 121⁰C for 15minutes, allowed to cool and sterile distilled water was aseptically added to make up to the mark again. Freshly harvested cell of Gloeophyllum sepiarium was inoculated into a set of 20gram, 35gram and 50gram of each substrate mixture under aseptic condition. Pleurotus ostreatus was also added into another set of flask containing the mixture, while the other set serves as control for the two substrates.

The flasks were covered and where then incubated at room temperature (28⁰C) for seven days. The flasks were shaken at interval to produce a homogenous solution and even distribution of the organisms in the substrates mixture. The mixtures were separately filtered after seven days using NOI WHATMAN filter paper. Acid Hydrolysis of Yam Peels 200g of yam was soaked with deionized water. With the aid of a sieve, the starch content from the yam peels was gotten and allowed to settle down. 200ml of one molar solution of hydrochloric acid (HCL) was mixed with the starch.

The mixture was autoclave at 121⁰C for 15 minutes, heated and allowed to cool. After 15minutes the mixture was tested, if there was conversion of starch to reducing sugar using iodine which gave a deep blue coloration indicating the presence of reducing sugar. The PH was also tested using the PH paper or PH meter. The standard PH range for the mixture was 4-6

Fermentation of Yam Peels The supernatant from the above hydrolysis process were transferred into another set of conical flask correctly labeled, covered, and autoclaved at 121⁰C for 15minutes and allowed to cool. Freshly harvested cells of Zymomonas mobillis were aseptically added into a set of flasks containing the hydrolyzed supernatants (20g, 35g, and 50g supernatants) and Zaccharomyces cerevisiae was also added into another set of hydrolyzed supernatant. The two organisms were combined into the third set of the hydrolyzed supernatant, while the control still served as control. The flasks were corked using cotton wool, shaken

and incubated at room temperature (28⁰C) for five days. The flasks were shaken at interval to produce a homogenous solution and even distribution of the organisms in the substrate mixture.

Distillation of Yam Peels This was carried out using distillation apparatus (set up). The fermented liquid was transferred into a round bottom flask and placed on a heating mantle fixed to a distillation column enclosed in running tap water. Another flask was fixed to the other end of the distillation column and the ethanol was collected at

78⁰C at an interval of 28minutes.

RESULTS AND DISCUSSION Results from tables 2 – 4 showed the average quantity of Bioethanol produced from 20g, 35g and 50g of yam peels to be 16.8ml, 18.9ml and 30ml respectively. Also, from figures 1 - 3 the graph showed that there was an increase in the quantity of Bioethanol produced as the substrate increased i.e. 20g, 35g, and 50g. The peak of production of Bioethanol for the three different grams (20g. 35g and 50g) of yam peels were recorded in the 196 minutes, producing 25 ml, 35 ml and 58 ml respectively. Also from tables 5- 6, the peak of quantity of bioethanol produced from 20g, 35g, and 50g of cassava peels are 33ml, 53ml, and 69ml, respectively. The consistent increase in bioethanol production from the graphs (figs. 1-3 and figs 4-6), started decreasing from 197 to 254 minutes. This fall in bioethanol production was due to the depletion of the starch content in the yam and cassava peels during the distillation process. The results also showed that the bioethanol produced from cassava peels was more than that produced from yam peels, indicating that there is higher concentration of starch content in cassava peels than yam peels. The quantity of bioethanol produced from yam peels, is in contrast with Oyeleke et al [23], who reported a peak production of bioethanol from sweet potato peels to be higher than that of yam peels in his experiment when Aspergillus Niger was used as the enzyme of fermentation. In his experiment, the same gram of (20g, 35g and 50g) of sweet potato peels were used as yam peels in this project, and the peak production of sweet potato peels were 23ml, 30ml and 48ml respectively while that of yam peels were lower and they were 22ml, 29ml and 45ml respectively in his experiment. But in


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this project, where Gloeophylum Sepiarum and Pleurotus ostreatus were used as enzymes for hydrolysis and Zymomonas mobilis and Saccharomyces Cerevisiae as enzymes for fermentation, the production of bioethanol from yam peels was noted to be higher than that stated in Oyeleke et al experiment. This could be due to the powerful and potent bioethanol producing enzymes used in this project work.

Table 2: Volume of Bioethanol Produced (ml) for 20g of Yam peels

TIME(mins) 28 56 84 112 140 168 196 224 254

Volume of Bioethanol Produced

ml) 8 12 14 15 17 22 25 20 18

Table 3: Volume of Bioethanol Produced (ml) for 35g of yam peels

TIME( mins) 28 56 84 112 140 168 196 224 254

Volume of Bioethanol Produced (ml) 10 11 14 17 21 28 35 20 14

Table 4: Volume of Bioethanol Produced (ml) for 50g of Yam peels.

Fig 1: A Plot of Volume of Bioethanol produced (ml) for 20g yam peels against Time (mins)

0

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(m

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Time (mins) 28 56 84 112 140 168 196 224 254

Volume of Bioethanol of Produced (ml) 14 17 21 30 44 53 58 40 20


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Fig 2: A plot of Volume of Bioethanol produced (ml) for 35g yam peels against Time (mins)

Fig 3: A plot of Volume of Bioethanol produced (ml) for 50g yam peels against Time (mins)

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Table 5: Volume of Bioethanol Produced (ml) for 20g of cassava peels.

Time(mins) 28 56 84 112 140 168 196 224 254

Volume of Bioethanol Produced in (ml)

10 12 13 16 20 27 33 18 15


Time (mins) 28 56 84 112 140 168 196 224 254

Volume of Bioethanol Produced in (ml)

13 15 18 25 28 42 53 42 18


Time (mins) 28 56 84 112 140 168 196 224 254

Volume of Bioethanol Produced in (ml) 15 18 23 32 35 58 69 47 20

Fig 4: A plot of volume of Bioethanol produced (ml) for 20g Cassava Peels against Time (mins)

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Fig 5: A plot of Volume of Bioethanol produced (ml) for 35g Cassava Peels against Time (mins)

Fig 6: A plot of Volume of Bioethanol (ml) for 50g Cassava Peels against Time (mins)

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Table 8: Concentration yield of Bioethanol (%) for 20g of Yam peels.

Time(mins) 28 56 84 112 140 168 196 224 254

Conc. yield of Bioethanol (%) 3.0 4.4 5.2 5.6 6.3 8.1 9.3 7.4 6.7

Table 9: Concentration yield of Bioethanol (%) for 35g of yam peels.

Time (mins) 28 56 84 112 140 168 196 224 254


Table 10: Concentration yield of Bioethanol (%) for 50g 0f Yam peels.

Time (mins) 28 56 84 112 140 168 196 224 254


Fig 7: A plot of Concentration yield of Bioethanol (%) for 20g of Yam peels against Time (mins)

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Fig 8: A plot of Concentration yield of Bioethanol (%) for 35g of Yam Peels against Time

Fig 9: A plot of Concentration yield of Bioethanol (%) for 50g of Yam Peels against Time

Table 11: Concentration yield of Bioethanol (%) for 20g cassava Peels. Time (mins) 28 56 84 112 140 168 196 224 254


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Table 12: Concentration yield of Bioethanol (%) for 35g of Cassava Peels

Time (mins) 28 56 84 112 140 168 196 224 254


Table 13: Concentration yield of Bioethanol (%) for 50g of Cassava Peels.

Time (mins) 28 56 84 112 140 168 196 224 254


Fig 10: A plot of Concentration yield of Bioethanol (%) for 20g of Cassava Peels against Time

(mins)

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Fig 11: A plot of Concentration yield of Bioethanol (%) for 35g of Cassava Peels against Time

(mins)

Fig 12: A plot of Concentration yield of Bioethanol (%) for 50g of Cassava peels against Time

(mins)

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Table 14 Variation of Volume of Bioethanol produced (ml) for 50g of Yam Peels with Temperature

(0C)

Temperature (0C) 78 81 83 85 87 89 91 93 96


Fig 13: A plot of Volume of Bioethanol produced (ml) for 50g Yam Peels against Temperature (

0C)

Table 15: Variation of Volume of Bioethanol for 50g of Cassava Peels with Temperature (0C)

Temperature (0C) 78 81 83 85 87 89 91 93 96


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Fig 14: A plot of Volume of Bioethanol for (ml) 50g Cassava Peels against Temperature (

0C)

From tables 7-9, the average percentage concentration bioethanol yield for 20g, 35g and 50g of yam peels were 6.2%, 6.5% and 11.7% respectively, while that of the cassava peels were 6.7%, 9.9% and 11.8% as shown in tables 10, 11 and 12 respectively. The graph in figs 7, 8 and 9 showed a steady rise in percentage concentration from 3% - 9.3%, 3.5 – 12.3% and 4.7 – 19.3% for yam peels respectively in the 28minutes in which the bioethanol production began till 196minutes in which the peak of percentage concentration bioethanol yield was obtained. After this time (196minutes) the graph began to fall between 224 -254 minutes reducing the percentage concentration yield from 7.4% - 6.7%, 7% -4.9% and 16.3% - 13.3% for yam peels respectively, while for cassava peels, the fall in the graph was from 6.7% -5.6%, 14.7% - 6.3% and 15.7% - 6.7% in figs 10, 11 and 12 respectively. The average bioethanol concentration yield of 6.2%, 6.5% and 11.7% for the yam peels and 6.7%, 9.9% and 11.8% of cassava peels produced in this project is less than the average bioethanol yield (concentration) reported by Agunlejika et al. [1] who reported an average bioethanol concentration yield of 16% from spoilt mangoes. This difference in the percentage concentration could be due to the large

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quantities of spoilt mangoes used in Agunleka’s experiment since increase in the quantity of substrate causes a proportional increase in percentage concentration of bioethanol as shown in this project. Also, the large quantities of spoilt mangoes used by Agunleka’s experiment seem to contain more starch than the just 135g of yam and cassava peels used in this project. The percentage concentration of bioethanol in this project also disagreed with Oyeleke et al. [21] who reported an average bioethanol yield (concentration) of 17.6% from spoilt fruits

From fig 13, production of bioethanol from 50g of yam peels began at 78⁰C with the production of 14 ml of the quantity of bioethanol. The production continued to increase as the temperature increase from 78⁰C

to 91⁰C with a peak production of 58ml. After this temperature (91⁰C), the quantity of bioethanol began to decrease indicating the depletion of bioethanol in the solution after heating the solution for a period of 180minutes. Also, for the 50g of cassava peels in figure 14, 15ml of bioethanol was produced at a temperature of 78⁰C. Bioethanol production increased to a peak of 69ml at a temperature of 91⁰C and began to decrease

from 47 – 20ml at a temperature of 93 - 96⁰C. The drop in the bioethanol production inspite of the increase in temperature indicated the depletion of the bioethanol in the solution after much heating. The result of the study confirmed that bioethanol can be produced from cassava and yam peels which are agricultural wastes. More bioethanol was produced from cassava peels than yam peels, thus making cassava peels a better alternative to yam peels, as well as spoilt fruits. The uses of cassava and yam peels are worthwhile venture for bioethanol production; considering their low cost, lesser need in food production and as means of controlling environmental pollution thus making bioethanol production economical and environmentally friendly.

Properties of Tested Bioethanol As Compared To Petrol A summary of results of bioethanol and petrol fuel properties data for the tested fuels are presented in Table 16. The average values of density for the tested bioethanol were found to vary from 0.7334 kg/l for E10 to 0.74192 kg/l for E25. They were found 1.003%, 1.006%, 1.013% and 1.015%, higher than petrol

fuel E10, E15, E20 and E25 respectively, which had a density of 0.7313 kg/l at 15.7⁰C. The API gravity of bioethanol/petrol blends varied between 61.4 to 59.2 degrees. The petrol API gravity was lighter being 62.7 degrees. The heavier weight of blends and petrol implied greater horsepower, less hazards but higher cost of transportation. In general the densities and API gravity are within the range that can be handled by internal combustion engine.

Table 16: Properties of Tested Fuels

Fuel Density, Kg/L @ 15.6

API gravity

Viscosity, Mm

2/sec

@38

Flash point,

(⁰C)

Fire point,

(⁰C)

Gross Heat content

Pour point,

(⁰C)

Gasoline 0.7313 62.7 0.4872 28.7 25 43500 Above 8

E10 0.7334 61.4 0.5266 29 31 41900 Above 8

E15 0.7357 60.8 0.5562 29.4 31.1 41025 Above 8 E20 0.74072 59.5 0.6044 29.5 31.2 40000 Above 8

E25 0.74192 59.2 0.6048 29.6 31.8 39375 Above 8

The kinematic viscosity values for the bioethanol/petrol blends (i.e. E10, E15, E20, E25) were found to be 1.08%, 1.14%, 1.24% and 1.32% more viscous than petrol fuel (0.4872mm

2/sec)..

From the results it appeared that the flash point for E10, E15 and E20 and E25 were 29, 29.4, 29.5 and

29.6⁰C respectively. The fire points were found to be 31, 31.1, 31.2, and 31.8⁰C respectively The mean gross heat values for bioethanol/petrol blends decrease by 3.7%, 5.7%, 8%, 9.5% compared to petrol fuel ( 43500 kJ/kg) for E10, E15, E20, and E25 respectively. The decrease of heat values was due to the presence of bioethanol having lower heat value of 27000kJ/kg. From the result it appears that pour

point for the bioethanol/petrol blends were above 8⁰C and similar to petrol fuel


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CONCLUSION 1. As second generation biofuel, cassava and yam peels are considered to produce energy from gas-

liquid process. Due to low aromatic content and pure nature of the biofuel, the unhealthy gas pollution in our environment cause by petrol from the exhaust of vehicles, have been reduced to the lowest level because of bioethanol complete combustion in motor engines.

2. Motor vehicles will require no modification in bioethanol blend of 10%E10 bioethanol and 90% petrol to run in Nigeria’s roads, as this enhances the octane rating of the blended mixture, improving the fuel performance.

3. More bioethanol is produced when the hydrolysis and fermentation process of the cassava and yam peels are done enzymatically rather than acid hydrolysis (hydrochloric acid or sulfuric acid). Also the risk of acid corrosiveness is avoided when enzymes are use in the hydrolysis and fermentation process.

4. The cost of producing one liter of petrol is five times more than the cost of producing one liter of bioethanol from cassava and yam peels.

5. The use of pure bioethanol from cassava and yam peels reduce life cycle green house gas emission by 20% to 100%.

6. The bioethanol/petrol blend has been successfully tested as alternative fuel for spark ignition Engine up to 25% ratio without blend phase separation or engine modification.

7. Properties of bioethanol blend such as density, viscosity, cloud point, flash and fire point were found to be higher than petrol the API gravity and heat of combustion were lower compared to the fuel.

8. Bioethanol blend has a higher power and fuel consumption rate and a lesser exhausting temperature.

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