Battery boats are mainly suitable for short trips

Electrification of the maritime sector

The shipping industry is one of the biggest polluters in the world. But electrifying it is complex. Yet electric ships can certainly contribute to a cleaner maritime sector.

Shipping is not the cleanest means of transportation. Fortunately, more and more marine batteries are emerging, allowing the sector to become electrified. You mainly see them on “workboats”, i.e. tugboats and crane barges. But more and more river boats and passenger ferries used in public transport are also equipped with electric propulsion. In the meantime, a large part of the electrification is already being actualized in inland and maritime navigation. Most of these commercial vessels rely on hybrid systems, in which the batteries run on hydrogen in combination with a diesel generator or even a fuel cell. This contributes significantly to the reduction of CO emissions2.

The very first ship that ever sailed electrically was the submarine. She was also the only ship that benefited from the weight of the batteries. The batteries provided the energy as well as the necessary ballast to be able to dive.

Long-haul distances

“The problem with the maritime sector and, to a lesser extent, inland navigation, is due to long distances, which means that you have to carry so many batteries on board that you have much less room left for cargo”, explains Jelle Meindertsma. , Sales Manager at EST-Floattech. This company from the Dutch town of Badhoevedorp works on the design, assembly and certification of marine battery systems. It also involves a battery management system, the metal battery case and the installation of power and data cables.

The base – the lithium batteries – come from a supplier in South Korea. Lithium cells are housed in modules that can be installed in ships as complete systems. A battery system is composed of several modules equipped with a battery management system. In the photo accompanying this story, for example, you can see 52 modules. If you were to open a module, you would see that it is made up of 14 lithium cells.


EST-Floatetech was launched ten years ago as a start-up with a team of three people and today employs 40 people, in addition to having five vacancies. “Currently, we mainly supply small and medium-sized commercial vessels.”

At first, the company mainly supplied large yachts. Meindertsma describes entering the battery room of such a ship as quite an impressive experience. “You walk between the cabinets and all you can hear is a hum. It’s really very different from walking into an average machine room. There’s a lot of noise and stench in these. Comfort is really important on a yacht. As the person on board you want peace and quiet around you. A buzzing diesel generator in the port of Monaco is not what you want then. Especially if there is still has a lot of diesel fumes. In such cases, electrification is very attractive,” says Meindertsma. “It was actually the first industry in shipping where lithium battery technology was adopted.”


Ferries then followed this trend to North West European ports (Oslo, Stockholm, Gothenburg, Hamburg and Kiel). Electric water taxis are already circulating in the Dutch city of Rotterdam. Soon, the water buses will also be electric. The IJ ferries in Amsterdam are also equipped with batteries. The batteries are recharged with a diesel generator (hybrid) or an electrical outlet. In all-electric ferry services on shorter journeys, you’ll find that charging takes place during breaks. A tour boat often has enough capacity for a whole day’s sailing and recharging takes place at night.

Port charges

Electric and hybrid navigation is encouraged by the ports through the collection of lower port charges, on the one hand. This is already done in Rotterdam. Meindertsma: ,, In the near future, ports will start saying: “You will not be allowed to enter without an energy label. This trend has already started in the cruise market.

As fast as things are moving in the aforementioned sectors, things are moving just as slowly in inland navigation and especially maritime navigation. It has everything to do with the volume and weight of the batteries, and the enormous distances covered by these ships. A container ship from Shanghai to Glasgow travels a long time before docking anywhere.

“If you want to continue to run such a ship on electricity, you need a huge amount of space for the batteries. If you were to do that, you would need so much space on the ship that you couldn’t take anything else with you,” says Syb ten Cate Hoedemaker, director of the Norwegian Maritime Battery Forum platform, which has 60 members (shipyards, shipowners and battery suppliers).

ocean vessels

However, six hundred ocean-going ships in the world are already sailing on electricity or hybrid power today. This represents approximately 0.5% of the entire world fleet. Some of these vessels are equipped with batteries from EST-Floattech. To overcome the problem of the enormous weight of the batteries, it is especially the smallest ships that are eligible for electrification. These do not make a full voyage at once, but call at various ports to load and unload goods. The batteries can then also be recharged at these times.

Short trips

According to Meindertsma, fully electric propulsion is particularly suitable for boats that always sail short distances and operate locally or on fixed routes, such as excursion boats, cruise ships or working boats in a port. Inland vessels or container ships that travel longer distances are much less suitable for electric propulsion, but can very well benefit from a battery system in a hybrid configuration.

For example, EST-Floatetech recently supplied a battery system for an inshore vessel. “This ship sails on a very specific fixed route where it is not allowed to transmit anything in a certain area, explains Meindertsma. be penetrated with electric propulsion. As this is a fixed port, a recharging facility has also been built for the vessel. This is important, otherwise you will be charging the batteries with a diesel generator and moving those emissions to the sea. “

Burning batteries

What is partly holding back the maritime sector in the transition from fossil fuels to electric propulsion is the question of safety. Shipping companies shudder at the thought of batteries starting to smolder, smoke or, worse, burn in the middle of the ocean. You can throw a burning electric car into the emergency lane, but just try to save a burning ship.

Syb ten Cate Hoedemaker of the Maritime Battery Forum wants to dispel any fear of burning batteries on ships. “I understand the horror of a fire in the open sea. But the chances of that happening are really extremely slim,” he says. “The fire would be limited to 1 cell. Which burns in a controlled manner if need be. marine battery must conform to strict requirements otherwise it is not permitted to be used on a vessel.Part of this certification relates to fire safety.Cells must be isolated from each other in such a way that a chain reaction can never happen.

A marine battery system weighs around 10 kilograms per kWh and will last around 10 years. Fireproof systems require the use of additional equipment, which costs weight, space and money. Battery management software ensures the battery operates within safe parameters and does not overheat. If things go unexpectedly wrong, the hardware kicks in and shuts down the system like a fuse box. The requirements for lithium batteries on land are less stringent.

Hybrid powertrains

The majority of vessels are not suitable for running on batteries alone. The energy density is not high enough for that. On the other hand, every type of boat can benefit from using a battery in a hybrid propulsion system. At the moment this is mainly done in combination with diesel generators, but it should move in the future to systems using alternative fuels such as hydrogen, ammonia or methanol.

“At the moment, battery development is leveling off a bit,” says Meindertsma. “We seem to have reached the upper limit of the capabilities of lithium battery technology. A new super battery basically needs to be invented.

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