Hybrid propulsion system for ships – Wärtsilä HY

Wärtsilä HY is an integrated hybrid propulsion system that combines engines, energy storage and an intelligent Energy Management System (EMS) in one coordinated solution. Rather than simply adding batteries to an existing arrangement, it manages engines and batteries as one system so engines run at optimal load while batteries absorb load fluctuations. It is offered for newbuild and retrofit projects.

Key components

• Propulsion engine
• Power drives for PTO/PTI/PTH (shaft generator via PTO/PTI gearbox charges batteries or boosts propulsion)
• Energy storage system (ESS) for fast load fluctuations, peak shaving and silent, emission-free operation in port
• Optional fuel cells
• Energy Management System (EMS) controlling energy flow between all power sources and protecting battery lifetime

Configurations

• Diesel-mechanical with PTO/PTI/PTH
• Diesel-electric with DC hub architectures
• Shore power/charging integration

EMS functions

• Battery as spinning reserve instead of an extra running genset (e.g. in DP or confined waters)
• Green mode with zero exhaust emissions from battery power
• Engine start-and-stop at low load
• Instant load taking while engines ramp up
• Cold system start-up from battery
• Peak shaving and power boost (engines and batteries together)
• Automatic power backup
• Charging control within the allowed C rate

Operating modes

• Mechanical mode: main engine drives the propeller, auxiliary genset supplies hotel load; system fallback mode
• Hybrid mode: main engine drives the propeller and PTO for hotel load, with the ESS providing peak shaving, load taking and backup; typical sailing mode
• Electric mode: auxiliary genset powers the PTI for slow-speed navigation and manoeuvring, with the ESS in peak shaving mode

Performance

• Up to 10–15% fuel savings in transit
• 25–40% fuel reduction in DP standby
• Supports EU ETS and FuelEU Maritime compliance and improved CII/EEXI ratings

Applications

Ferries, tugs, merchant ships and offshore vessels.