Earlier this year, it was revealed that more than 1,000 maritime vessels are now operating with batteries on board, providing either all-electric or hybrid propulsion. This is a significant milestone in the maritime industry’s journey towards decarbonising the sector and, while it is still far from the finish line of fully net-zero operations, the move towards electrification is gaining pace, with hybridisation emerging as the most viable near-term solution for large vessels to decarbonise.

Although there are multiple projects ongoing to explore the feasibility of charging while at sea, currently, the vast majority of vessels require onshore based power to recharge their batteries, presenting a number of challenges across various maritime industries. Space at ports is at an absolute premium and, realistically, for larger vessels using current common battery technologies, the length of time it takes to recharge will cause issues in the long-term. For example, Brittany Ferries is currently introducing a first of its kind LNG-electric hybrid vessel across some of its England to France routes that requires 12 megawatt hours of energy to fully recharge. Even with a marine-grade megawatt charging system, it would require over 12 hours downtime and significant demand on the national grid to complete a full recharge.

The majority of the 1,000 fully or partially battery powered maritime vessels that are currently in operation are smaller tugboats, ferries or offshore support vessels. As well as reducing greenhouse gas (GHG) emissions, battery power improves powertrain energy efficiency, reduces noise, and increases vessel response time. The benefits are clear, but the full electrification of larger vessels is significantly more complex. Norway’s Norled, for instance, is currently operating a fully battery powered passenger ferry for its 20-minute crossing between ports. However, there are significant challenges associated with scaling this technology to manage longer journeys. The sheer weight of the batteries required to power these ships would negatively impact vessel efficiency, limit vital space for passengers and/or freight and the batteries would also take an unviable amount of time to recharge.
While innovators seek out solutions to unlock the full electrification of larger vessels, the best opportunity for larger cargo and cruise ships operators to significantly reduce their emissions and combat the rising prices of fuel is by utilising a hybrid system. Hybridisation allows vessels to combine traditional internal combustion engine propulsion with battery power, enabling improved operational flexibility and reduced emissions.

A study from DNV GL reveals that, for ferries, a hybrid battery system could provide fuel-cost savings of between 10 to 30 per cent, with a payback timeframe of just three to five years. A reduction in fuel consumption also achieves GHG emission reduction too, in some cases, up to 20%. Importantly, no charging infrastructure is required to achieve these benefits, resulting in an easy to adopt, yet significant step forward in decarbonising larger vessel operations. These savings stem from the opportunity to not oversize combustion engines on large vessels to cater for brief power surges, which leads to inefficient low-load operations. Hybrid battery systems can better handle these peak demands, allowing for the use of smaller engines that run more efficiently at high loads.
So why hasn’t the industry embraced vessel hybridisation more widely?

There are, of course, costs associated with the initial process of retrofitting a hybrid system on a ship, although these costs generally can be recouped through fuel savings across a short-to-medium timeframe. Perhaps the biggest barrier towards wide-spread hybridisation of the maritime industry is that current mainstay battery technologies cannot deliver the performance required to effectively hybridise large ships.

However, there are new battery technologies that are already being embraced by other industries that can deliver the performance required by hybrid vessels.

Standard lithium-ion batteries utilised in passenger vehicles cannot meet the needs of heavy-duty vehicles due to limitations on energy density, safety concerns, and the slow speed at which they charge. The battery anode is the limiting factor when it comes to addressing these limitations and one innovative technology that addresses these limitations is Echion Technologies’ niobium-based anode material, XNO®. When applied in heavy-duty applications, XNO®, enables rapid charging in less than 10 minutes, extended cycle life of more than 10,000 cycles, and market-leading safety attributes. It is also able to deliver high power in extreme temperature and humidity conditions, making it a viable option for ships that operate in polar regions and areas with extreme heat.

In order to hybridise larger ships using current LTO batteries, the required cell units would be prohibitively large to operators. By using an alternative battery chemistry which offers a higher energy density, combined with the fast-charging and safety benefits of LTO, the cells can take up less space and don’t need to be installed with excessive energy capacity to achieve the power required for the application. Installing cells with higher power density in charge and discharge means smaller battery packs can be used instead, making more space is available for driving economic output. In this space, XNO® can deliver market leading energy density under such power conditions.

The maritime industry has an opportunity to move the dial towards achieving its target of net-zero operations by 2050 by embracing hybridisation. However, to do so effectively, it must look beyond current widely used battery technologies and explore the use of unique chemistries that are able to meet the unique demands of large ships.
Source: By David Keating, Sales and Marketing Director, Echion Technologies