As the maritime industry works to decarbonise, electrification is proving to be one of the most practical and immediate solutions. Wärtsilä’s Torsten Büssow explains how batteries, hybrid propulsion, and alternative fuels together are shaping the fleet of the future.
Shipping is entering a decisive phase in its energy transition. Electrification, once confined to pilot projects and short-sea ferries, is now becoming a cornerstone of decarbonisation strategies across the maritime industry.
As regulation tightens and the pressure to reduce emissions intensifies, hybrid and fully electric propulsion systems are emerging as practical and powerful tools for cutting fuel use, lowering costs, and improving vessel performance. For many operators, the question is no longer whether to electrify, but how far to go.
Types of electric propulsion
"Broadly speaking, there are two types of electric propulsion in use today: hybrid and fully electric"
Broadly speaking, there are two types of electric propulsion in use today: hybrid and fully electric. Hybrid systems combine an energy storage system, typically a marine battery, with a conventional engine, reducing fuel consumption and emissions by up to 25% compared with a diesel-only vessel.
Fully electric vessels, by contrast, rely entirely on battery power. They are ideal for shorter routes or coastal operations where charging infrastructure is available. Because batteries are heavy, range remains a limiting factor, which is why hybrids continue to dominate longer voyages.
In both cases, the benefits extend beyond emissions. Battery-assisted propulsion reduces engine load fluctuations, cuts wear and tear, and allows machinery to operate at optimal efficiency. Maintenance costs fall, reliability improves, and vessels run more quietly and smoothly. The outcome is a leaner, more efficient ship with lower lifetime costs.
Pace of adoption
The pace of adoption is accelerating. Between 2019 and 2024, the number of hybrid and fully electric ships contracted globally rose by around 200%. This growth reflects a wider understanding that the industry cannot afford to wait for a single dominant future fuel before acting on decarbonisation.
Policy is also driving progress. The European Union’s FuelEU Maritime regulation will require ports to provide shore power to a minimum of 90% of container, passenger, and cruise vessels by 2030. Ships spending more than two hours alongside will be required to connect, which creates strong incentives for owners to invest in battery systems and hybrid propulsion.
Economics reinforce the same conclusion. As green fuels reach commercial scale, they will carry a higher cost than conventional fuels. Technologies that improve energy efficiency, such as hybrid systems and electric propulsion, will therefore be critical to keeping operations profitable while meeting decarbonisation goals.
Integrating systems
"Integrated installations are well suited to ferries, tugs, and offshore-support vessels"
Battery technology for ships is developing in several directions, with both integrated and containerised systems now common across the industry.
Integrated installations are well suited to ferries, tugs, and offshore-support vessels, while containerised, swappable modules are proving valuable for inland and short-sea operations where space and flexibility matter most.
Each battery string can be controlled separately, allowing power systems to scale with the vessel’s needs. Safety remains a central focus, and the latest designs now include early fire detection, isolation, and suppression as standard. Together, these measures have made marine batteries far more reliable and compliant with demanding maritime regulations.
Proven hardware and advanced energy management
Much of this progress comes from integration rather than cell production itself. Wärtsilä works closely with global battery suppliers to combine proven hardware with advanced energy management, testing, and lifecycle expertise.
The result is a new generation of propulsion systems that are safer, smarter, and better suited to the realities of modern shipping.
Infrastructure challenges
"Infrastructure remains a challenge, particularly the availability of charging capacity at ports"
Infrastructure remains a challenge, particularly the availability of charging capacity at ports. Many vessels will require fast DC charging, standardised connections, and in some cases onshore energy storage to avoid grid constraints.
Innovative concepts such as swappable battery containers, already in use on some European waterways, demonstrate how smart design can extend range and reduce downtime even where grid strength is limited.
Looking ahead, the most effective pathway will combine battery technology with engines capable of running on alternative fuels such as methanol, ethanol, or ammonia. As these fuels become more available, and more expensive, batteries will be essential in improving efficiency and reducing overall consumption.
Hybrid energy model
Electrification is no longer a niche solution. This hybrid energy model will allow shipowners to balance cost, sustainability, and operational flexibility. It represents the next stage of sustainable ship design, where energy storage, clean fuels, and smart power management combine to create cleaner, quieter, and more efficient vessels.
