Techno-Economic Evaluation of Lignocellulosic Bio-Oil Processes

Sammanfattning

This master’s thesis evaluates the commercial-scale feasibility of two processes that upgrade lignocellulosic bio-oil: dewatering and derivatization upgrading (DDU) and green cooking and cleaning (GCC). Both processes aim to produce upgraded bio-oil suitable for co-processing in existing oil refineries, though they differ significantly in complexity. GCC includes the entire conversion from raw biomass to upgraded bio-oil, while DDU focus solely on upgrading an already produced pyrolysis oil. The process designs are based on an annual input of 100,000 tonne of biomass with estimated capital investments of $3.4 million for DDU and $38 million for GCC, which reflect their differing complexities. Both processes show potential for economic viability if a competitive sales price can be achieved. Currently, the estimated sales price for both exceeds $2200/tonne, which is more than twice that of other untreated biofuels, making market competitiveness the main barrier to economic viability. The energy demand varies significantly: DDU requires 900 MWh/tonne bio-oil, while GCC consumes 9400 MWh/tonne bio-oil, underscoring the need for energy savings in GCC. In both processes, reactants and solvents were identified as the primary cost drivers, indicating a shared limitation for economic feasibility and a key focus area for future development of upgrading processes. For GCC, transitioning from batch to continuous operation of the cooking shows significant potential for reducing both capital and operational costs. A continuous setup demonstrated economic viability at a sales price of $1500/tonne with only a slight decrease in expenses (~25 %). Cost reductions can be achieved through validation and optimization of the liquid-liquid extraction step, solvent recycling, and utility integration. For DDU, economic viability depends largely on reducing the cost of the derivatizing reactants. Exploring alternative, lower-cost reactants is therefore crucial. Additionally, technical validation and optimization of the fractionation column should be prioritized to reduce costs. In conclusion, both processes show potential for commercialization, if production costs are lowered through reactant substitution, improved material economy, and optimized feed ratios. Consumables remain the dominant cost driver, making their reduction is essential to achieve economically viable lignocellulosic bio-oil upgrading. Furthermore, as this is an early-stage assessment and the capital investment estimate excludes supporting infrastructure and carries a high degree of uncertainty due to multiple assumptions, it leads to a severe underestimation of the true investment required. A more detailed capital investment analysis is needed to provide a realistic and robust economic assessment.