Production of bioethanol from napier grass (pennisetum purpureum)

Abstract

Bioethanol from lignocellulosic biomass and agricultural waste is a way to turn waste into added value that will solve the problem of food competition and waste management and provide a cost-effective alternative solution in the energy sector. Napier grass is a highly productive and effective lignocellulosic biomass, which is an important substrate of the secondgeneration biofuels. In addition, several processes are required in the production of ethanol from lignocellulosic materials; thus, fermentation can shorten the production process. This experimental research utilizes cellulase enzyme and Saccharomyces cerevisiae (baker’s yeast) in majorly two steps of hydrolysis and fermentation to produce bioethanol from napier grass using separate hydrolysis and fermentation (SHF) technology. To improve ethanol yield, napier grass was pretreated with 2M sodium hydroxide solution in a 0.75:1 (w/v) mixing ratio. An orthogonal experimental design was employed to optimize the napier grass content, optimal conditions for cellulase enzymatic action provided, yeast loading, and incubation time for maximum bioethanol production. The optimal fermentation condition was 21.56 g of napier grass, 8.00 g yeast loading, and 43 hours incubation time, which gave a bioethanol yield of 285.14g/kg of napier grass. The novelty of this research lies in the use of cellulase enzymes and S. cerevisiae to produce bioethanol from napier grass with the maximum bioethanol yield.