Assessment of sustainable biochar production for carbon abatement from vineyard residues

In the present work ripped vines (Vitis vinifera) from the winery industry were pyrolyzed at 550 °C in a pilot plant reactor. Characterization of biomass and pyrolysis co-products was carried out. Mass and energy balances were determined in order to find out whether or not a self-sustainable process was achievable for this biomass by burning the gas and liquid co-products. The energy content in these co-products was 5.52 MJ/kgfeedstock and the surplus energy after meeting the energy demand for the process was about 2.73 MJ/kgfeedstock. A mobile and self-sustainable demonstration scale pyrolysis reactor was designed and manufactured based on the findings of the experimentation in the pilot plant reactor. The mobile reactor is self-sustainable, with capacity up to 60 kg/h of ripped vines' wood with little pre-treatment, reaches high working temperatures (up to 800 °C) and has a biochar yield between 25 and 35% depending on pyrolysis conditions. The produced biochar in the mobile pyrolyzer meets the heavy metals content for the class B and C in Spanish legislation on fertilizers and those of the International Biochar Initiative for international and European limits. Using the mobile reactor to produce biochar and applying it at the biomass source (avoiding the biomass and biochar transportation) could lead to a carbon footprint reduction of ≈18 g of CO2eq per bottle of wine or 125.4 tCO2eq/yr.