Marine batteries are gaining attention not only as a propulsion alternative for ferries and short-sea routes, but also as a tool for improving generator efficiency on larger merchant vessels — a use case that battery technology company Echandia says could deliver measurable fuel savings.

The underlying challenge is one of system design. Marine power systems are conventionally sized for peak demand and redundancy, which in practice can mean multiple generators running well below their most efficient operating point during normal conditions. According to Echandia, four-stroke generators operating below roughly 40% load can face a fuel-consumption penalty of 10–15% compared with running nearer their optimum load.

The problem is compounded when vessels keep additional generators running as spinning reserve — a precaution against sudden load changes or equipment failure that adds to fuel burn without contributing to productive output.

Echandia claims that integrating a battery system into the vessel’s power architecture changes this dynamic. A battery can respond rapidly to sudden demand increases or a generator trip, providing reserve capacity electrically. This, the company says, allows fewer engines to run during normal operation.

Batteries can also absorb short-duration power peaks and variations in hotel and auxiliary loads, enabling generators to operate at a steadier — and generally higher — average load rather than continuously chasing fluctuations.

Echandia estimates that battery-supported generator optimisation can reduce fuel consumption from auxiliary four-stroke generator sets by around 10–15%, depending on vessel type and operating profile.

The company points to operational data from a 15,000-TEU containership to illustrate the potential. According to those figures, the vessel’s auxiliary engines consumed approximately 245 g/kWh at low load, compared with 217 g/kWh at optimum load — a difference of around 28 g/kWh.

Echandia has published a white paper examining how battery integration can reduce both fuel consumption and generator running hours across different vessel types.