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Table S1: Numerical values of the EIIs for the processes of Case I. Table S2: Numerical values of the EIIs for the processes of Case II. Table S3: Numerical values of the EIIs for the processes of Case III.

Among the approaches to facilitating negative CO2 emissions is biochar production. Biochar is generated in the pyrolysis of certain biomasses. In the pyrolysis process, carbon in the biomass is turned into a solid, porous, carbon-rich, and stable material that can be captured from the soil after a period of from a few decades to several centuries. In addition to this long-term carbon sequestration role, biochar is also beneficial for soil performance as it helps to restore soil fertility and improves the retention and diffusion of water and nutrients. This work presents a Life Cycle Assessment of different pyrolysis approaches for biochar production. Biomass pyrolysis is performed in a fixed-bed reactor, which operates at a mild temperature (550 °C). Biochar is obtained as solid product of the pyrolysis, but there are also liquid (bio-oil) and gaseous products (syngas). The pyrolysis gas is partly used to fulfil the energy demand of the pyrolysis process, which is highly endothermic. In the conventional approach, CO2 is produced during the combustion of syngas and emitted to the atmosphere. Another approach to facilitate CO2 capture and thus obtain more negative CO2 emissions in the pyrolysis process is burning syngas and bio-oil in a Chemical Looping Combustion unit. Life Cycle Assessment was performed of these approaches toward biomass pyrolysis to evaluate their environmental impact. The Chemical Looping Combustion approach significantly reduced the values of 7 of the 16 environmental impact indicators studied, along with the Global Warming Potential among them, it slightly increased the value of one indicator related to the use of fossil resources, and it maintained the values of the remaining 8 indicators. Environmental impact reduction occurs due to the avoidance of CO2 and NOx emissions with Chemical Looping Combustion. The CO2 balances of the different pyrolysis approaches with Chemical Looping Combustion configurations were compared with a base case, which

Among the approaches to facilitating negative CO2 emissions is biochar production. Biochar is generated in the pyrolysis of certain biomasses. In the pyrolysis process, carbon in the biomass is turned into a solid, porous, carbon-rich, and stable material that can be captured from the soil after a period of from a few decades to several centuries. In addition to this long-term carbon sequestration role, biochar is also beneficial for soil performance as it helps to restore soil fertility and improves the retention and diffusion of water and nutrients. This work presents a Life Cycle Assessment of different pyrolysis approaches for biochar production. Biomass pyrolysis is performed in a fixed-bed reactor, which operates at a mild temperature (550 °C). Biochar is obtained as solid product of the pyrolysis, but there are also liquid (bio-oil) and gaseous products (syngas). The pyrolysis gas is partly used to fulfil the energy demand of the pyrolysis process, which is highly endothermic. In the conventional approach, CO2 is produced during the combustion of syngas and emitted to the atmosphere. Another approach to facilitate CO2 capture and thus obtain more negative CO2 emissions in the pyrolysis process is burning syngas and bio-oil in a Chemical Looping Combustion unit. Life Cycle Assessment was performed of these approaches toward biomass pyrolysis to evaluate their environmental impact. The Chemical Looping Combustion approach significantly reduced the values of 7 of the 16 environmental impact indicators studied, along with the Global Warming Potential among them, it slightly increased the value of one indicator related to the use of fossil resources, and it maintained the values of the remaining 8 indicators. Environmental impact reduction occurs due to the avoidance of CO2 and NOx emissions with Chemical Looping Combustion. The CO2 balances of the different pyrolysis approache