Techno-economic and carbon-intensity assessment of lignin-methanol oil production for marine fuel applications

Abstract

Maritime fuel decarbonisation requires alternatives compatible with emerging methanol bunkering infrastructure, yet few lignin-derived routes have been assessed at process scale under transparent economic and carbon-intensity metrics. This study evaluates lignin-methanol oil (LiMO) - a blend of crude lignin oil from mild thermolytic solvolysis with methanol - as a methanol-compatible marine fuel pathway. A chemical process flowsheet model was developed for production of 25 wt% LiMO at 200 C, with techno-economic analysis across technical lignin (Protobind) and pseudo-waste lignin scenarios at pilot and commercial scale. Minimum selling price (MSP), carbon intensity and energy return on investment (EROI) were quantified under UK cost and emission-factor assumptions. MSP was estimated at GBP 15-21/GJ and carbon intensity at 94-105 kgCO2e/GJ; methanol dominated both cost and emissions because it serves as solvent and major fuel component. Tenfold scale-up reduced MSP by only GBP 0.37-0.65/GJ, reflecting OPEX dominance by methanol and feedstock. Waste lignin improved EROI toward unity (maximum 1.04), but most scenarios remained below net energy breakeven. LiMO is technically viable but should be framed as a methanol-enhancing or biomethanol-extending blend rather than a standalone low-carbon fuel. Meaningful improvement requires higher solvolysis yield, heat integration, char valorisation and access to low-carbon methanol and heat.