Carbon Balance of a Waste Biomass Supply Chain: The Integration of a Pyrolysis-Based Valorization Process

Abstract

In the present work, the valorisation of waste biomass (olive wood) was analysed from an environmental standpoint. A process of thermo-catalytic reforming in which bio-char, bio-oil and syngas are produced, have been integrated to olive wood waste supply chain. In particular, the energy efficiency evaluation was carried out by solving energy and mass balances on the system. Furthermore, the capacity of the systems in energy-self- sustainability has been evaluated along with thermal recovery methods and different uses for the products obtained. The entire supply chain was examined in order to identify its optimal configuration, minimizing environmental charges. Environmental performance is assessed by considering greenhouse gases (GHGs) expressed in terms of CO2 equivalent as an indicator: this approach allows to define the supply chain incidence on the global warming relative to each of the phases involved in the process. In order to obtain the better configuration in terms of thermal and electrical power for the self-sustainability of the process, and also in terms of CO2 emission, different scenarios for the use of the products obtained by the process were evaluated. The results have shown that it is possible to self-sustain the process through the proper use of the products. The right combination of use of syngas, bio-oil and char allows to satisfy the thermal and electrical demands of the system by avoiding the use of the energy by the grid. In addition, the choice of the optimal configuration for the use of the products (e.g. use of gas in a cogeneration plant and use of char to field as fertilizer) allows reducing environmental impacts by reducing CO2 emissions and making the whole process eco-friendly.