| || || Ethanol as fuel -- Fiji|
| || || Ethanol production from selected cassava varieties in Fiji and testing of ethanol-petrol fuel blends |
Author: Bijay, Pritika
Institution: University of the South Pacific.
Subject: Ethanol as fuel -- Fiji , Cassava -- Processing
Call No.: Pac TP 339 .B54 2013
Copyright:20-40% of this thesis may be copied without the authors written permission
Abstract: Ethanol production from renewable resources has received worldwide attention due to increasing petroleum shortage. One such renewable resource that has been identified is cassava starch, which can be extracted from root crop cassava (Manihot esculenta (Crantz)) and is readily available in Fiji. Ethanol may be used as a fuel for spark-ignition engines either in its original form, or as blends with petrol. The most feasible way of expanding the use of ethanol as a fuel, however, is by using ethanolpetrol blends in vehicles already on the road, without the need to modify the engines. The main objective of this study was to produce ethanol from some of the locally available cassava varieties in Fiji, and to test the operation of spark ignition (SI) engines on various ethanol-petrol blends. Starch was extracted from the roots of ten different cassava varieties available at two different research stations in Fiji using the sedimentation technique, and the yields were determined. In the case of Koronivia Research Station (KRS) the variety Nadelei had the highest starch yield (23.1 %) whereas Coci had the highest starch yield (23.3 %) for Dobuilevu Research Station (DRS). The extracted starch was then used to produce ethanol via the technique of Simultaneous Saccharification and Fermentation (SSF), with the yeast Saccharomyces cerevisiae being used as the fermentation agent. Ethanol yield was in the range of 0.35-0.40 L of ethanol per kg of starch and 0.35-0.41 L of ethanol per kg of starch for KRS and DRS respectively. Ethanol-petrol blends, E10, E15 and E20 were prepared from alcohol with varying degrees of water content. It was found that 96 % ethanol could be used to prepare blends that did not phase separate at temperatures typical of the tropics. The prepared blends were tested on a SI engine for engine efficiency, fuel consumption and exhaust emissions. An increase in fuel consumption was noted as the engine load was increased and also as the ethanol content in petrol was increased. The latter effect was identified as being due to the lower gross calorific value (GCV) of ethanol as compared to petrol. Hence, as the ethanol fraction in ethanol-petrol iv blend increased, the GCV decreased, and as a result more fuel was required. At maximum load, there is a decrease in carbon monoxide (CO) emission by 34, 61 and 78 % with the E10, E15 and E20 blends respectively when compared to petrol. Reductions in exhaust emissions of hydrocarbons (HC) by approximately 10, 30, and 34 % were noted for E10, E15, and E20 blends respectively at maximum engine loadings. Reductions were also observed in carbon dioxide (CO2) emissions at maximum engine load for E10 (7 %), E15 (17 %) and E20 (20 %) when compared to petrol.