Integrated e-Methanol and Drop-in Fuels Hydrothermal Liquefaction Platform─Techno-Economic and GHG Emissions Assessment for Grid-Connected Plants under Flexible BECCU(S) Operation

This study examines the combined production of drop-in fuels and methanol using hydrothermal liquefaction (HTL) as a technological basis in the context of bioenergy and power-to-X (PtX) applications. Given the increasing need for flexibility in a system dominated by fluctuating renewable power, we evaluated flexible methanol operation as a strategy to harness global greenhouse gas (GHG) emissions in a grid-connected HTL setup. In this operation, the biogenic CO₂ destination is alternated between methanol synthesis bioenergy with carbon capture and utilization and combined underground storage depending on the hourly electricity price and grid carbon intensity. The results indicate that the strategy has potential to maintain the average fuel carbon intensity within the 65% GHG reduction threshold set by the renewable energy directive III at a minimum methanol price of 870 EUR/t. This approach could facilitate implementation as it does not require dedicated renewable power generation and hydrogen storage, potentially decreasing costs compared to semi-islands and off-grid PtX systems.