Compression-free low-pressure boil-off gas utilization in LNG receiving terminals via solid oxide fuel cell integration

Conventional boil-off gas (BOG) management in LNG receiving terminals typically relies on high-pressure utilization pathways that require substantial gas compression, resulting in significant energy consumption and exergy destruction. This study proposes and evaluates a compression-free low-pressure BOG utilization strategy based on the direct integration of a solid oxide fuel cell (SOFC) system operating at approximately 1.2 bar. Using transient industrial operating data from an LNG receiving terminal, BOG generation behavior under realistic transfer operations is characterized, showing that BOG production is governed primarily by operational dynamics, with the flow rate increasing by approximately 160% from 11.25 to 29.35 t/h during dual-jetty operation. Thermodynamic analysis identifies compression as the dominant inefficiency in conventional pathways. The send-out gas (SOG) compression pathway requires 151% more power than the recondenser BOG-compression pathway (2.087 vs. 0.832 MW), primarily due to its substantially higher pressure ratio. By eliminating the need for compression, the proposed SOFC pathway avoids the conventional compression–decompression energy penalty and improves thermodynamic performance. Exergy analysis shows that the SOFC system achieves the highest exergy efficiency among the evaluated simple-cycle configurations (42.74%), increasing to 52.14% with steam-cycle integration. The techno-economic assessment indicates that SOFC systems provide the highest annual net operating benefit (36.1–90.8 MUSD/y), whereas gas engines exhibit more favorable investment performance with an IRR of approximately 11.2%. However, the economic viability of all configurations remains sensitive to CAPEX, electricity prices, operating conditions, and other market assumptions. The results demonstrate that direct low-pressure electrochemical conversion represents a promising alternative to conventional high-pressure BOG handling, highlighting the importance of cost reduction, waste-heat recovery, and LNG cold-energy integration for economically competitive next-generation LNG terminal designs.