EXCLUSIVE: Doubts over deepsea electrification

The Maritime Battery Forum, an industry body that has focused on electrification for 10 years, recently estimated that there are already 94 cargo ships with a battery system installed. About 17% of these are inland cargo ships, 64% are coastal cargo ships, and 19% are ocean-going cargo ships.

“We are seeing batteries on container ships, general cargo, bulk carriers, vehicle carriers, and tankers,” says Syb ten Cate Hoedemaker, managing director of the Maritime Battery Forum. “It is not limited to specific ship types, but depending on their operational profile and onboard equipment they can use batteries for different purposes. The hybrid arrangement varies from just batteries to increase the efficiency of the hotel loads to a mild form of hybrid propulsion. Only with the vehicle carriers do we see some plug-in hybrid options coming now.”

One example is the Grimaldi Group roro Eco Malta, one of 12 vessels in the series built by Jinling Shipyard. During port stays, the Eco Malta can cut emissions to zero by using electricity stored in its 5MWh lithium batteries. The batteries are recharged whilst sailing from shaft generators and 350m2 of solar panels. March 2024 saw first steel cut on Grimaldi Group’s Grande Shanghai, the first of 10 ammonia-ready car carriers that will also include battery systems, along with shore power connection.

Battery saving possibillities 

Back in November 2021, UECC took delivery of the world’s first dual-fuel LNG battery hybrid vehicle carrier, Auto Advance. The battery technology was supplied by Finland’s WE Tech, incorporating a battery package from Corvus Energy that is charged by a permanent magnet, directly driven shaft generator or dual-fuelled generators. The energy storage system provides power to the main switchboard with a DC link for power distribution to enable peak shaving for the main engine and auxiliaries. Only two auxiliaries are required as the energy storage system and shaft generator provide spinning reserve and therefore eliminate the need for another genset.

Hoedemaker says the biggest challenge to greater adoption is the cost: for the battery systems themselves and for their integration in hybrid propulsion systems, but maybe even more so the industries’ perception of cost. If you just look at the CAPEX when installing batteries, he says, then a diesel-powered ship will look a lot more interesting. But if you look at the OPEX and TCO, then batteries suddenly become more interesting economically. Recalling a presentation at the forum’s recent WATTS UP conference, he says: “Physically, there will be more possible on batteries than expected, but there are definitely limitations to how far you can go on batteries. The more likely solution is hybrid propulsion in combination with whatever type of fuel will be optimal for the specific vessel and route.”

Decreasing battery prices, increasing fuel prices, more strict regulation regarding emission, and incentives such as the EU ETS will make major change possible. Battery prices are slowly declining again after a period of stability or even slight increase. However, the adoption of batteries and the size of batteries that get installed on ships is significantly increasing; this will push the price further down, he says.

“The discussions we are hearing are not about convincing people to install batteries, they are about sharing experience on how to do it in the best way. To me this is a major change.”

Battery backup

WinGD’s Markus Wenig, chairman of CIMAC’s WG 20 that is developing hybrid system design principles standards for system integration, also sees change, with car carriers as frontrunners. “While battery size may vary (500kWh (NYK) – 5MWh (Grimaldi)) the ratio of ship transient/port manoeuvring time will support the case for battery hybrid vessels. For example, you could have two identical ship designs but depending on the trading scheme (i.e. number of ports approached per trip) a battery would either be economically sensible or not.

“Generally speaking, any technology that causes (or any vessel that faces) a more transient operational profile would support the application of additional energy storage systems on board. For example, when using wing or rotor sails for covering a significant portion of the required propulsion power any sudden change of wind conditions would pose quite some challenges to the conventional propulsion system. In such cases an energy storage could help to stabilize operation and allow the main engine to operate more efficiently.”

In the end, says Wenig, it’s all about the cost-benefit ratio (Capex, Opex, TCO). “In an idealised environment, theoretical studies may assess the potential of full electrification, but each technology has to be compared to its competition. Assuming that the overall goal would be the defossilisation of maritime transport, there are other potentially more attractive solutions (in terms of cost-benefit ratio) such as internal combustion engines fuelled by ammonia. In fact, this technology would offer an interesting application case together with shaft generator and fuel cells covering the auxiliary load demand in port and manoeuvring.”

Depending on a vessel’s operational profile, battery technology will help make propulsion systems more efficient and increase safety and availability, regardless of the fuel used. “This understanding still needs to grow, so major change in that sense will hopefully happen when the first big owner has recognised the value,” says Wenig.

Electrification coming online 

While on a high-level there is a regulatory push towards more efficient propulsion systems, he says there is still some misalignment of requirements for hybridised systems. “For example: As for the redundancy of battery systems in propulsion system design ABS requires at least two independent battery systems to be provided and located in separate spaces. Whereas RINA asks generally for the same but additionally each battery space should have the capacity sufficient for the intended operation of the ship. This is obviously a much taller order. From the perspective of the system integrator removing such hurdles would definitely help.”

Also holding the industry back, says Wenig, is cost “prejudice”, unawareness of application cases and the potential of electrical energy storage, hesitance to move from a purely mechanical to a more electrically-infused world. “For the past 100 years we had Diesel propulsion only, and within the last decade we introduced and revived a plethora of new propulsion and existing system technologies (gas engines, hybridized propulsion systems, air lubrication systems, wind assisted propulsion, etc.),” says Wenig. So, a fast-changing environment meets a historically slow-changing industry.

Still, orders placed in the last few months provide further evidence that change is happening. In April, Corvus Energy announced it has been selected by HAF Power Solutions to supply energy storage systems for an energy subsea construction vessel to be built for REM Offshore. The new vessel will be the first vessel to perform heavy construction work in offshore wind and the subsea market with net zero emissions, as it will be equipped with dual-fuel methanol engines and a 1.7MWh battery system. The batteries will be used for spinning reserve and peak shaving as well as to regenerate power from the operation of offshore lifting equipment onboard the vessel.

The design and technology will provide flexibility and efficiency as well as high redundancy, says Ronny Pål Kvalsvik, chief commercial officer, Rem Offshore. “We anticipate significant improvements in energy consumption as well as a reduction in operational costs, while also contributing to a greener future for the maritime sector. Increased battery capacity is needed to optimize the system. When using an alternative fuel such as methanol, batteries play an even more important role as the response time for dual-fuel engines is slow. Increased energy storage capacity will allow us to more fully leverage the energy efficiency benefits of battery power, including the ability to regenerate energy from mission equipment onboard.”

“Up until now, battery packs have often been sized to a minimum to enable spinning reserve for 10 minutes. Adding more battery capacity unlocks the potential to gain increased value from the battery system,” says Pål Ove Husøy, VP of sales at Corvus Energy. It increases the value of the batteries by enabling them to be used in all operational modes as well as to improve the balancing of the entire power management system to reduce fuel consumption.

In May 2024, Kongsberg Maritime announced it has been chosen to supply hybrid electrical systems for three new 3,600 TEU LNG-powered container ships being built at Philly Shipyard for Matson Navigation Company. The integrated systems from Kongsberg Maritime will make the most efficient use of energy on board, including power generated from the main shaft and the battery system, which provide additional emission-free energy in peak load conditions.

“Owners, faced with higher fuel costs, want vessels that use less energy, so there is a shift towards more electrification and battery-hybrid solutions,” said Lisa Edvardsen Haugan, president, Kongsberg Maritime, as the company celebrated 50 years of vessel design in April. “The most significant driver impacting how we design ships today is sustainability.”