Perspectivas exergéticas sobre la licuefacción hidrotérmica de microalgas: un estudio de caso con Chlorella sp.

Eduardo Andrés Aguilar Vasquez; Angel Darío González Delgado

doi:10.21803/ingecana.6.6.976

Authors

Eduardo Andrés Aguilar Vasquez Universidad de Cartagena https://orcid.org/0000-0003-1744-1622
Angel Darío González Delgado Universidad de Cartagena https://orcid.org/0000-0001-8100-8888

DOI:

https://doi.org/10.21803/ingecana.6.6.976

Keywords:

Biocrude, Bioenergy, Exergy, Hydrothermal liquefaction, Microalgae

Abstract

Introduction: Recently, microalgae have emerged as a promising biomaterial for biofuel production; however, despite its efficiency, hydrothermal liquefaction (HTL) faces significant technical challenges at the industrial scale, particularly due to its high energy demand, which limits its viability and commercialization. Objective: This study conducted an exergy analysis of the biocrude production process from wet algae via hydrothermal liquefaction (HTL) using Computer-Aided Process Engineering (CAPE) tools, with the aim of evaluating energy performance, identifying irreversibilities,
and proposing process improvements. Method: The exergy analysis was performed based on operational data and extended mass and energy balances, determining the physical and chemical exergy of each process stream, as well as the exergy associated with industrial utilities. From the exergy balance, the overall process efficiency and the local efficiencies of each unit were evaluated, allowing the identification of low-performance critical points. Additionally, an exergy resilience analysis was applied to propose improvements for underperforming units. Results: The results showed an overall exergy efficiency of 24%, indicating poor performance, with total irreversibilities of 111,000 MJ/h, mainly due to heat losses and chemical transformations (83%). Most process units exhibited high efficiencies (>85%), except for the biocrude cooling stage, which showed a critical efficiency of 9%. The resilience analysis indicated that overall efficiency could increase up to 84% through the integrated valorization of process residues—including residual gas, biochar, and wastewater—optimizing exergy use and reducing
potential environmental impacts. Furthermore, energy integration was identified as a key strategy to recover heat from hot process streams. Conclusions: The analysis demonstrated that the HTL process requires significant optimizations to become thermodynamically viable for biofuel production. In addition, incorporating the refining stage is necessary for a comprehensive assessment of process performance, and adopting a biorefinery approach could provide substantial technical benefits.

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