French marine engine manufacturer Nanni has developed a high-speed dual-fuel engine capable of running on methanol and diesel, following a collaboration with Swedish engineering firm ScandiNAOS AB.

The engine, based on a 6-litre John Deere platform and designed for use as a generator set, underwent testing in late 2025 at a laboratory in the presence of a representative from classification society RINA (Registro Italiano Navale). The tests were conducted according to International Association of Classification Societies (IACS) standards.

According to Nanni, the dual-fuel system allows the engine to operate on a fuel blend of approximately 30% diesel and 70% methanol on an energy basis, adding that 60-70% of conventional diesel fuel can be replaced with methanol while maintaining engine performance.

The development forms part of Nanni's Life Mystic project, which aims to reduce diesel consumption and associated emissions in response to the International Maritime Organization's requirements for reductions in atmospheric exhaust emissions.

ScandiNAOS AB was commissioned to develop the dual-fuel conversion kit, which includes methanol-specific engine control units (ECUs), a redesigned air intake manifold equipped with methanol injectors, and a double-walled methanol fuel rail designed to meet maritime safety requirements.

The system is designed to automatically switch back to diesel operation when the methanol tank is empty, without interrupting engine operation.

Test results showed that the proportion of energy derived from methanol ranged from 50% to 75%. According to Nanni, carbon monoxide (CO) and hydrocarbon (HC) emissions were reduced by 95-99%, while nitrogen oxide (NOx) emissions decreased by 65% across most load conditions. Particulate matter was also lower following conversion to methanol.

The transition between single-fuel and dual-fuel modes during operation was described as smooth and seamless, with full power output maintained in both diesel and dual-fuel modes.

Nanni, founded in 1952, manufactures marine engines and generator sets for recreational and commercial vessels. The company operates production facilities in France and Italy.

ScandiNAOS AB, based in Gothenburg, Sweden, specialises in the design of ships and maritime transport systems, with recent focus on the integration of alternative fuels including methanol. The company was founded in 2005.