Characterization, activation, and life cycle analysis of rice husk biochar

Rice husk is generated in abundance in India, and requires efficient utilization for sustainable management of agricultural residues. Traditionally, farmers burn rice husks, which leads to environmental degradation. Biochar production offers an effective waste management solution, mitigating climate change concerns. For a thorough characterization, modification, and assessment on environmental impacts of biochar, a study on production of rice husk biochar using vacuum pyrolysis at three different temperatures, followed by chemical activation with KOH was carried out. Lifecycle assessment (LCA) of biochar and activated biochar was conducted using SimaPro software TRACI 2.1 method. Highest yield of biochar of 33.75%, was observed at 500°C. The activated rice husk biochar produced at 700°C had calorific value of 23.13 MJ kg^-1, surface area of 334.71 m² g^-1 and pore volume of 1.15 cm³ g^-1. The global warming potential and ozone layer depletion for activated biochar production was found to be 24.3 tonnes of CO_2eq and 0.728 × 10^-3 kg CFC-11_eq, respectively. Recycling of 50% KOH can reduce greenhouse gas emissions by 16.3% and cumulative energy demand (CED) from 92 to 75.1 MWh for Re (KOH). Higher pyrolysis temperatures had significant environmental impact due to generation of higher proportion of syngas, which reduced biochar production.