The FlexiFuel project, funded by the German Federal Ministry for Economic Affairs and Climate Action under grant number 03SX473B, was launched in 2018 with the goal of developing automated fuel‑system solutions for the next generation of maritime fuels. The consortium, led by MAN Energy Solutions SE, brought together a range of research and industry partners to investigate the compatibility and performance of emerging fuels in marine engines. The project ran through 2024, with an early start, a pause caused by the COVID‑19 pandemic, and a cost‑neutral extension in 2020 that allowed the work to be completed on schedule.

The technical work focused on a series of engine tests that examined how different fuel blends behaved in a marine diesel engine and a dual‑fuel (DF) configuration. Initial trials in 2018 used two fuels in a standard marine diesel engine; the results showed that the supplied fuels could be combusted without any observable operational issues, confirming their suitability for marine use. Building on this, the team conducted dual‑fuel experiments with B100 biodiesel as a pilot oil. These tests demonstrated that the engine could handle the biodiesel blend without compromising combustion stability or engine integrity.

Subsequent work shifted to a single‑cylinder DF test rig in Augsburg, where two biodiesel variants were evaluated as pilot fuels. The experiments confirmed that both biodiesel blends were compatible with the DF system, and no adverse effects on engine performance were detected. The project also explored a diesel‑methanol mixture, anticipating future environmental regulations aimed at improving CO₂ balances. Unfortunately, during the methanol trials a critical failure of the water‑brake system prevented the full set of planned tests. Only ignition‑testing of various diesel‑methanol blends could be completed in the laboratory, leaving the full performance assessment incomplete. No specific quantitative performance metrics were reported for any of the fuel blends, but the available data consistently indicated that the fuels could be used without measurable degradation of engine operation.

Throughout the project, the consortium maintained a focus on fuel‑adaptable control strategies and the development of drop‑in fuel solutions. The research contributed to a better understanding of how emerging marine fuels interact with existing engine technologies and highlighted the need for robust fuel‑system automation to accommodate future regulatory changes. The findings were disseminated through several publications, and additional papers were planned for release following the project’s conclusion.

In terms of collaboration, MAN Energy Solutions served as the project coordinator, overseeing the overall strategy, data integration, and reporting. Other partners, while not named in the report, were responsible for specific experimental work, data analysis, and the development of control algorithms. The project’s timeline was adjusted in response to the pandemic, with a pause in 2020 and a subsequent extension that allowed the consortium to reallocate tasks after the withdrawal of a coordinating partner. Despite these challenges, the project achieved its core objectives, demonstrating the feasibility of using biodiesel and diesel‑methanol blends in marine engines and laying the groundwork for future automated fuel‑system technologies.