The world availability of non-wood lignocellulosic biomass for the production of cellulosic ethanol and potential pretreatments for the enhancement of enzymatic saccharification

Non-wood lignocellulosic biomass is abundantly available, low cost, easy to process and consists of a short growth and harvest period; therefore, it is introduced as a potential feedstock biomass for bioethanol production. Common non-wood lignocellulosic biomasses are categorised into agricultural residues, native and non-wood plant fibres. The potential of non-wood lignocellulosic biomass as a resource for cellulosic ethanol production are determined and, analyzed in the context of their chemical composition, fibre production yield, total cellulose availability as well as the enzymatic saccharification efficiency after pretreatment. Based on the obtained data, agricultural residues show significant advantages in all contexts over other non-wood lignocellulosic biomasses. Moreover, pretreatment plays an important role in enhancing the enzymatic accessibility and hydrolysability of non-wood biomass. This review found that various pretreatments could be applied to enhance the enzymatic hydrolysability of different biomasses; however the major factors that vary the effectiveness of particular pretreatment on improving of different biomass hydrolysability have not been clearly highlighted. In addition, even though enzymatic saccharification of pretreated biomass is mainly highlighted in most of the cellulosic ethanol studies to evaluate the improvement of biomass hydrolysability, this data is unable to show the total glucose that obtained from the untreated biomass directly. In this study, the importance of total glucose yield is emphasized and it is calculated from various research data by multiplying the solid recovery yield by the enzymatic saccharification yield of the pretreated biomass, as it presents the percentage of the total glucose that could be converted directly from the original biomass. This work verifies that besides enzymatic saccharification yield, the solid recovery yield is also one of the major factors to be identified in cellulosic ethanol study.