Environmental Footprints of the Catalytic Pyrolysis of Pine Needles through Integration of a Nickel-Decorated Chemically Modified Biochar Catalyst

Abstract

The current study presents the life cycle analysis (LCA) of a biochar-catalyzed pyrolysis-based biorefinery system. Noncondensable gases (NCGs), produced as a coproduct, have been recycled back to the system, while biochar produced was employed for catalyst preparation, to visualize a biorefinery model. Results showed the considerable environmental impact of the process, in particular of the catalyst and energy sources utilized during the process. Matching up with the LCA metrics, both single parameter and Monte Carlo uncertainty analyses also revealed the high sensitivity of the obtained impacts for the impregnating chemical (i.e., ZnCl2, H3PO4, and NaOH) employed during catalyst preparation. Among different processes, the Ni/BC-H3PO4 catalyzed process with NCG recycling has emerged as the best possible case with the lowest environmental emissions (GWP ≈ 0.109 kg CO2 equivalent) and low cumulative energy demand (∼2.47 MJ) together with high process efficacy and productivity. Furthermore, sustaining process energy needs with varieties of different sources advocates for renewable sources (more specifically hydropower) over nonrenewable sources of energy. The study highlights the hotspots of the current technology, envisaging ways of reducing emissions through clean/renewable energy sources as well as utilizing less impact-causing intermediate materials, and thus, acting like a building stone in creating a base toward the vision of achieving net zero emissions.