Energy and carbon LCA of high ligno-cellulosic biomass pyrolysis coupled with anaerobic digestion

The combination of thermo-chemical (pyrolysis) and biological (anaerobic digestion) pathways for the treatment of biomass can bring to a wider range of exploitable residual biomasses in anaerobic digestion, in particular the ones with a high content in lignin. A laboratory scale plant has been realized by the University of Bologna, and the energy and carbon balances of the system have been evaluated in this LCA study. Results show that the process can yield a net energy gain and reduce GHGs emissions, but further research is needed on some key parameters such as the energy required by the pyrolyzer and the biogas output from the anaerobic digester. The experimental process would allow for higher biogas yields, product diversification and other advantages for agro-energy industries and the environment. As for the carbon balance, a relevant contribution is given by carbon storage in biochar.