Techno-economic and life cycle analysis of hydrothermal liquefaction: a case study on Shorea sawdust

This study investigates the economic and environmental viability of hydrothermal liquefaction (HTL) of Shorea sawdust for ethanol production. This research was conducted in three stages: a laboratory analysis using high-performance liquid chromatography (HPLC) to examine the HTL aqueous phase (AP), a techno-economic analysis (TEA) to assess the capital costs and payback period and a life cycle analysis (LCA) to evaluate the environmental impact and cumulative energy demand over a 20-year lifespan. HPLC analysis of the AP revealed significant saccharide depolymerisation, with AP rich in C5 and C6 sugars and ethanol. TEA results suggest that a commercial-scale HTL would require a capital cost of USD 7.59 million, with 54% of these costs attributed to direct plant establishment and a payback period of 16.2 years. Integrating an ethanol production unit could enhance profitability, potentially generating USD 348.05 million in revenue and reducing the minimum fuel selling price for the produced ethanol to USD 37.75 per ton of oil equivalent. However, LCA results highlight substantial environmental challenges, with transportation-related energy demand and ethanol fermentation contributing to negative impacts. While HTL shows economic promise, its sustainability is hindered by energy consumption and transportation emissions, underscoring the need for further technological advancements and process optimisations.