370 / 2018-07-30 02:37:30

Green Gas Production in an Integrated Circular Bioenergy System

全体主题 > 生物质燃气

Typically energy in transport comprises approximately 40% of final energy consumption. Transport energy is the least decarbonised, compared to electricity and heat. The European Union has capped first generation biofuels to 3.8% of energy in transport by 2030 thus advanced biofuels from renewable feedstocks must be developed, with a target of 6.8% set for 2030. Green gas (such as biomethane) has the potential to qualify as an Ultra-Low Emission transport fuel. However, the optimal system to produce sustainable transport biofuel has yet to be defined. Biogas can be produced through anaerobic digestion and upgraded to biomethane. The conventional anaerobic digestion may suffer from two drawbacks: (1) Vulnerable to many environmental factors; and (2) Digestate generated after digestion still has a great amount of unutilised energy. In this study, a combined system including the concepts of cascading bioenergy and circular bioeconomy have been proposed. The integrated system includes four modular systems: (1) Feedstocks optimisation and pretreatment; (2) Enhanced anaerobic digestion through addition of pyrochar; (3) Upgrading of biogas to biomethane through Power to Gas; (4) Pyrochar production through controlled pyrolysis of solid anaerobic digestate. The advantages of such system include: (1) Improved biomethane yield and production rate, allowing for higher organic loading rate; and (2) Enhanced total energy recovery through integration of solid digestate pyrolysis. The preliminary results demonstrated that as compared to conventional anaerobic digestion, the integrated system enhanced biomethane yield by 25%, peak biomethane production rate by 20%, and reduced lag-phase time by 48%.