Bioconversion of lignocellulosic waste into bioethanol: Process development and optimization – A review

The continuous growth in global population has significantly increased energy demand, leading to the rapid depletion of fossil fuel reserves and environmental issues such as climate change. The combustion of fossil fuels is a major source of greenhouse gas emissions, raising serious environmental and energy security concerns. At the same time, industrial development and urbanization have intensified the need for alternative energy sources that are both sustainable and economically viable. Renewable energy, particularly bioenergy has emerged as a promising solution. Among various biofuels, bioethanol is considered as one of the most widely produced and utilized fuel worldwide due to its clean-burning properties, safety, and environmental benefits. Bioethanol is increasingly viewed as a strategic alternative to conventional liquid fuels but the raw materials that are being used to obtain first generation bioethanol are typically food crops raises ethical and logistical concerns regarding global food supply. Hence, in recent years there has been growing interest in second-generation bioethanol derived from lignocellulosic biomass, which includes agricultural residues, forestry waste, and other non-food plant materials, as this feedstock is abundant, renewable, and inexpensive, making it an attractive option. However, the conversion of lignocellulosic biomass to ethanol presents significant technical challenges due to its complex structure and the presence of lignin, which resists enzymatic breakdown. These challenges have hindered the large-scale commercial production of bioethanol. Nevertheless, substantial research and technological developments are underway to overcome these barriers and make the process more efficient and economically feasible. This review aims to highlight the technological details that are being applied for the conversion of biomass waste into biofuels. This review focuses on the provision of updated information on current use of existing conversion techniques, various processes and current advancements in lignocellulosic bioethanol production, with a focus on improving and optimizing the process of the conversion of biomass into fermentable sugars and ultimately, sustainable bioethanol fuel.