A Review of Life Cycle Assessment (LCA) of Bioethanol from Lignocellulosic Biomass

Abstract

Liquid biofuels are widely recognized alternatives to fossil fuel not only to combat the global warming potential, but also to reduce the reliance on fossil fuels to facilitate economic development. The production and use of lignocellulosic liquid biofuel have been emphasized because it is highly reproducible and does not compete with food. This study summarizes the LCA studies on lignocellulosic ethanol produced from various biomass resources focusing on energy balance, greenhouse gas (GHG) emission and other impact categories, and the production cost to discuss their potential environmental and socioeconomic impacts. Numerous efforts have been made to evaluate the life cycle of lignocellulosic ethanol with LCA methodologies and deals with feedstock, energy paths, conversion technologies, allocation methods, utilization of by-products etc. to determine the environmental impacts as well as the production cost. The environmental benefits are reported in most of the studies except for few examples. A wide variation was observed in the reported production cost of ethanol, which is dependent on the feedstock, conversion technologies, allocation methods and plant sizes. Onsite enzymes production/purchase appeared to be the main hotspot, demands a vigorous study to improve their productivity and reduce costs. Another promising alternative for compensating production costs seem to be the generation of valuable coproducts and integration of ethanol production processes (ethanol and energy). Reviewed literature indicates that despite the environmental benefits of ethanol produced from lignocellulosic biomass, its economic viability remains doubtful at present, even if highly optimistic assumptions are made for the cost calculation, especially in the case of enzyme. Hence, the biotechnological revolution is must for the sustainability of bioethanol, especially in the field of enzymes and microorganisms. Moreover, the adaptation of innovative technologies and renewable energy policy may help limit costs, but careful consideration of land use changes and soil quality is required to avoid any loss of productivity.

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