Technologies integration towards bio-fuels production: A state-of-the-art review

Abstract

Biomass is concerned as a most promising alternative energy resource. There are a number of biomass utilization technologies, most of which can be classified to either biological technology or thermo-chemical technology. Both have their specific bottleneck problems. Individual technology is currently almost reaching the ceiling, and technologies integration is thus proposed to make up drawbacks of individual technology with synergy effect. Technologies integration towards bio-fuels production include integration of biological technologies (e.g. algae cultivation from anaerobic digestate, secondary digestion of anaerobic digestate, anaerobic digestion of aerobic digestate, etc.), integration of thermo-chemical technologies (e.g. hydrodeoxygenation of bio-oils, steam reforming of fast bio-oils, cascade pyrolysis, etc.), and integration of biological technologies with thermo-chemical technologies (e.g. gasification of anaerobic digestate, pyrolysis of anaerobic digestate, carbonization of anaerobic digestate etc.). a comprehensive review concerning the state-of-the-art conceptual designs of technologies integration as well as their performances is urgently needed. Accordingly, this paper critically reviews: (1) State-of-the-art conceptual designs of integrated bio-fuel production systems; (2) Overall evaluation of different integrated technologies; (3) Insightful discussion on the future perspectives in this field. Concerning carbon conversion as an overall indicator for the performance of different technologies, it was found that the average carbon conversions were 70.71%, 75.29%, and 70.44% for integration of biological technologies, integration of thermo-chemical technologies, and integration of biological technologies with thermo-chemical technologies, respectively. This review is hoped to be beneficial for promoting future development of integrated bio-fuels production technologies.