| dc.description.abstract | The expanding global demand for transportation fuels and stringent governmental pollution policies have prompted energy supplier investment in the development of renewable energy technologies. Bioethanol is a renewable, market-competitive petroleum additive, produced from the fermentation of plant-derived sugars. First generation ethanol is produced from the fermentation of edible hexoses, whilst second generation ethanol is produced from the saccharification of inedible lignocellulosic fractions of waste plant residues. Due to the recalcitrant nature of lignocellulose, second generation ethanol production requires intensive biomass thermochemical pre-treatment, which incurs significant capital and operating expenditure. Ensiling is an alternative, low-technology route to ethanol, and requires two steps: Primary ensiling, which produces first generation ethanol, and Secondary ensiling, which produces second generation ethanol. Although ensiling associated industrial costs are lower, the process produces significantly reduced ethanol yields in comparison to thermochemical pre-treatment. Therefore, increasing ensiling ethanol production whilst maintaining low technology associated costs is paramount to making it an economically competitive technology.
In this investigation, the optimisation of six ensiling components, biomass cultivar, lignocellulosic degrading enzyme, fermenting yeast species, operating temperature, and process contamination control were explored for increased ethanol production efficiency. The data collected from this study suggests that the use of Sorghum bicolor cultivar Topper 76-6, addition of cellulolytic enzyme CTec3 at half the conventional industrial dose, employment of yeast Saccharomyces cerevisae strain C6 FUEL, the antibiotic Lactrol, and an operating temperature of 30 ˚C, increased second generation ethanol production efficiency. A novel, 'Consolidated' ensiling approach, which combined production of both first and second generation ethanol in a one-step reaction, was then developed. Utilisation of the determined optimal conditions in Consolidated ensiling resulted in increased ethanol production, decreased process contamination, and the potential to decrease ensiling associated industrial costs in comparison to the two-step Primary - Secondary ensiling process previously employed in industry. | en_GB |
