Techno-economic evaluation of pulp and paper mill derived biochar, liquid and gaseous biofuel precursors: A British Columbia case study

Canada is home to one of the largest concentrations of pulp and paper (P&P) mills in the world. With declining demand for traditional P&P products and tightening environmental regulations, these mills are diversifying to produce a range of biorefinery products. Mill residue derived solid biochar, liquid and gaseous biofuel precursors are potential biorefinery products that can help mills sustain operations, as well as meet emission reduction targets in other "hard-to-decarbonize" industries such as petroleum refining and iron and steelmaking. This study undertook a techno-economic analysis of fast pyrolysis of wood residues to produce low-carbon intensity biofuels at operating P&P mills in British Columbia (BC). Aspen Plus (R) models for fast pyrolysis of wood residue with a novel three-stage quench and heat recovery were integrated into an Excel-based cost estimation tool, which was used to perform techno-economic analysis (TEA) for ablative and fluid-bed reactor configurations. The ablative case outperformed the fluid-bed case, under baseline conditions of 4 dry t/h capacity, 60 $/dry t wood residue, 800 $/t char, WCS crude and RNG pricing for the bio-oil and off-gas respectively. TEA showed a net present value (NPV) of USD 4.30 million, and a bio-oil minimum selling price (MSP) of 7.86 USD/GJ for the ablative pyrolysis case, while the fluid-bed case was unprofitable, requiring a bio-oil MSP of 23.47 USD/GJ. Lowering feedstock cost and increasing biochar and liquid price increased the profitability of both pyrolysis cases, whereas increasing throughput capacity increased profitability in the ablative case but lowered it in the fluid-bed case.