Design of Biochar Based Adsorber (Bio-Sorb) for Direct Carbon Capture

The most widespread human-caused greenhouse gas is carbon dioxide (CO₂). The automotive sector significantly contributes to CO₂ emissions in the atmosphere due to the usage of fossil fuels, which is challenging to decarbonize. In addition, emissions from agricultural waste yield billions of tonnes of CO₂ equivalent globally. These emissions results in an increase in the global average temperature. Direct carbon capture (DCC) technology eliminates CO₂ from source and is predicted to achieve a net-zero carbon world when used on a wide scale. The sustainable and cost-effective CO₂ collection by DCC has been achieved through the characteristics of the materials, high CO₂ selectivity, regeneration performance, and appropriate design. Biochar is known for its richness in carbon and low-cost material made from various biomass wastes and exhibited favorable surface characteristics (porous nature, high surface area, and pore volume) for an effective and sustainable CO₂ adsorbent. The aim of this work is to investigate the potential of biochar derived from Saudi Arabia's agricultural waste for CO₂ capture. The biochar-CO₂ adsorber (biosorb) system is designed and tested for direct carbon capture for sustainable mitigation of climate change. The CO₂ adsorber design results demonstrated that in order to achieve maximum CO2 adsorption the most appropriate design parameter are gas flowrate (100 mL/min) and, biochar particle size (0.35 mm), and temperature (25°C). The breakthrough adsorption results indicated 70% of CO₂ was removed by biochar at the breakthrough time (102 min) and 5g of biochar saturated at 420 min. The adsorption capacity of biochar at breakthrough and saturated time is 5.1g/g CO₂ and 21g/g. The biochar-adsorber system was designed for the direct capture of CO₂ (concentration 2500 mg/L) and gas flow rate of 1000 m³/day. The biochar adsorber system should of size (height= 230.87 cm and diameter= 124.99 cm) with a minimum carbon requirement of 840.20 kg of biochar and a biochar saturation time of 1.73 days. The total amount of CO₂ adsorbed onto biochar using one large-scale biochar adsorber system is estimated to be 1000.18 ton/per. The final prototype of direct carbon capture system-design contains three main sections supported with (<0.5 µm mesh, fan, sensor, silica gel, and fibric filter).