The global adoption of electrified shipping is on the rise, with a projected value of $14.2 billion for electrified ferries, tugboats, and cargo ships by 2030. As electric propulsion becomes increasingly popular, energy production companies are placing significant emphasis on energy storage and battery logistics.
Lithium manganese cobalt oxide – a viable option
A recent study highlights the availability of various lithium-ion battery chemistries for energy storage, with lithium manganese cobalt oxide emerging as a viable option for vessels. The demand for electrically powered ships is increasing, necessitating a sustainable and reliable lithium supply. Norway introduced the world’s first fully electric autonomous cargo vessel in 2021, equipped with eight lithium-ion batteries and drawing power from hydropower generation. However, the lack of charging infrastructure remains a challenge for electric propulsion. Companies like Stemmann-Technik are working on solutions, but dockside charging facilities are still scarce in ports. One innovative solution is the use of power buoys, which can provide shore power while vessels wait for berths or instructions. Additionally, supercapacitors and superconductors are being explored as alternative energy storage technologies in the maritime industry. While not yet widely used on ships, they offer unique characteristics that make them suitable for specialized applications such as peak demand supplementation, engine start, or dynamic positioning. Further research and development are underway to harness the full potential of these technologies in maritime energy storage.
Hybrid
Hybrid systems in maritime applications can be categorized into two configurations: series hybrid and parallel hybrid. Series hybrid systems utilize energy storage and electric motors to drive propellers, with diesel generators providing both propulsion and auxiliary power. The batteries can be charged through various sources like diesel generators, shore power, and renewable energy. Parallel hybrid systems combine conventional propulsion with diesel-electric systems, suitable for vessels with varying power demands. Examples include harbour assist and escort tugs that require high-power engines for specific operations. Hybrid mechanical-electrical systems are gaining popularity globally, with Norway delivering a diesel-electric hybrid catamaran in 2018. Washington State Ferries is converting 16 ferries to hybrid systems with substantial funding, while Maersk is piloting a marine battery system on the Maersk Cape Town container ship to enhance performance and reliability, along with a waste heat recovery system for battery charging. These advancements in hybrid technology aim to improve vessel efficiency and reduce environmental impact.
Battery (all electric)
Lithium-ion batteries are the preferred power source for all-electric vessels due to their high energy and power density, as well as their long life cycle. The three primary lithium-ion battery chemistries are nickel-manganese-cobalt (NMC), lithium-iron-phosphate (LFP), and lithium-titanate-oxide (LTO). NMC is the most commonly used chemistry due to its high specific energy. LFP and LTO offer extended life cycles and increased stability but have lower specific energies.
In Gee’s Bend, Alabama, the Gee’s Bend Ferry underwent a retrofit to 100% lithium-ion battery power, using two banks of 135 kWh batteries and new induction motors for propulsion. However, long-distance operations present challenges in terms of time under power and recharging capacity, limiting the energy storage capacity of onboard batteries. Companies like Asea Brown Boveri, EST-Floattech, and Fleetzero have developed ruggedized containerized battery systems to address these challenges, capable of withstanding the forces experienced onboard a vessel.
FleetZero, which secured $15.5 million in funding, aims to convert a vessel to run on its container batteries. Their strategy involves segmenting shipping routes into shorter trips, focusing on smaller ports, and implementing a battery-sharing scheme. These advancements in battery technology and innovative approaches aim to overcome the limitations of battery electric propulsion for long-distance vessels.
Charging stations
Electric operation is well-suited for vessels on shorter, fixed routes like ferries and tugboats due to simplified charging infrastructure needs. Battery packs can fully power these vessels for the entire journey, and predictable routes enable efficient deployment of shoreline charging infrastructure. Stemmann-Technik, a German energy storage company, specializes in designing onshore power supply systems for container vessels and ferries that can withstand tidal changes and vessel movement.
To alleviate traffic congestion in ports, offshore charging buoys are being explored. Maersk Supply Service and Ørsted are collaborating on a charging pilot buoy trial in 2023, taking place at one of Ørsted’s wind farms in the North Sea. The buoy, known as the Stillstrom prototype, will provide power to service operation vessels (SOVs) and crew transfer vessels (CTVs) operating at the wind farm. Charging buoys enable cold ironing while at anchor, and the reduction in emissions depends on the renewable source of power, such as wind or hydroelectricity, used by the buoy. These developments aim to enhance the charging options and emission reduction potential for electric vessels in maritime operations.
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Source: Work Boat
