Techno-economic and environmental assessment of inclusive, context-specific, and capability-sensitive agrarian biohubs for marine biofuels in Spain, Colombia, and Namibia using field residues

Abstract

This study presents a novel bottom-up approach to co-design inclusive biohubs based on field residues, namely olive tree pruning, coffee pulp, and acacia bush in Spain, Colombia, and Namibia, respectively, to produce “drop-in” marine biofuels (MBF) via hydrothermal liquefaction (HTL). The economic feasibility and environmental footprint of the designed biohubs are investigated through a detailed techno-economic and attributional-environmental life cycle assessment. This study introduces an early-stage, context-specific, capability-sensitive, and stakeholder-inclusive approach to conceptual design by integrating process simulations, process economics, and life-cycle environmental assessment. The outcomes indicate that an MBF yield of 5–10 wt% is achievable at a production cost of 1.2–3.9 EUR/kgbiocrude. The upgrading costs were estimated between 0.12 and 0.90 EUR/kgbio-oil, resulting in a minimum fuel selling price (MFSP) of 0.94–4.45 EUR/kgMBF, after fractionation, which is 1.05 to 5.50 times (without carbon credits) that of the current fossil marine fuel (0.8–0.9 EUR/kgMGO). After mass allocation, the greenhouse gas (GHG) emissions of the derived MBF were estimated in the range of −43.4 to 10.9 g-CO2 eq./MJmarine biofuel, thereby indicating an immense potential to reduce global warming impacts. A sensitivity analysis showed that i) At smaller scales, the MFSP is found to be more sensitive to the HTL equipment costs than to feedstock prices; ii) The process economics could be improved through technological advancement and scale-up, and iii) Contextual factors plays crucial role in process design and sustainability of the biofuels. This study concludes that the proposed approach will aid in improving acceptability and in achieving global commercial-scale deployment of the bioeconomy.