Small LTO batteries produce sizeable operating savings for merchant vessels

For shipowners looking at battery systems, installed megawatt-hours are only part of the story. How frequently the batteries are used and what they allow the rest of the power plant to stop doing can matter more.

In merchant shipping, the business case for batteries does not necessarily depend on installing a large battery energy storage system. A relatively small battery may create value by making the existing machinery work less.

These three examples illustrate the point:

Car Carrier

On a car carrier in maneuvering operations, auxiliary generators operate at roughly 20% load while providing spinning reserve alongside a shaft generator. Replacing that mechanical reserve with a battery allows the auxiliary generators to be stopped during normal operation. This gives a 45% reduction in auxiliary generator running hours and fuel savings of 6%, while retaining redundancy and blackout protection.

Tanker

A second case involves a large tanker with three 1.4 MW auxiliary generators and an average electrical demand of 0.6 MW. An 830 kWh Echandia battery system cycling between charging and discharging allows the generator to run at 80–90% load while charging. It also allows the generator to reduce load or shut down while the battery supplies demand. This gives fuel savings of about 8% and a return on investment of less than three years. Under the stated cycling regime, it also gives an estimated 25-year battery life.

Container Ship

A third example uses a 250 kWh battery system on a container ship for both peak shaving and spinning reserve during maneuvering, berthing, idle periods and sailing. The estimated payback period here is about three years.

Learn more about how batteries can reduce fuel consumption and generator running hours in our white paper.