Battery power on board

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Words / Amy McLellanWords / Amy McLellanThe Havila Castor (Credit: Havilavoyages)
 

Propelled by a growing demand for cleaner energy, battery-powered vessels are moving stealthily forwards.

 

As much of the planet battles extreme heat and wildfires, there’s growing scrutiny of the climate-changing emissions generated by our modern carbon-dependent transportation systems. This includes the maritime industries, on which so much of our global prosperity and comfort depend. In a bid to decarbonize the industry, ship owners are exploring a range of fossil fuel alternatives, from cleaner-burning fuels to new forms of wind power. Battery-powered propulsion systems are also gaining in popularity.  

Just last month the energy storage system supplier Corvus Energy celebrated when Havila Kystruten`s passenger ship, Havila Castor, sailed the scenic Geiranger fjord in northern Norway on an 11-day zero-emission – and zero sound – trip using a 6.1Mwh battery system. Geir Bjørkeli, CEO of Corvus Energy, said it was a “big step for the decarbonization of shipping.” “This proves that technology is ready even for large ships to operate in zero-emission mode for longer periods of time,” he said.

Feedback from Havila technical personnel on board was that the battery performed beyond expectations. The energy storage systems along with all other environmental technologies on the ship reduce CO2 emissions by around 30% and NOx emissions by 90%. With the gradual blending of biogas, emissions of CO2 will be reduced to 50% in 2023 and 80% in 2024. 

Increased battery capacity

And battery size is about to undergo a step change. Last month Finnish technology group Wärtsilä announced it will supply its hybrid propulsion system for Stena RoRo’s three new RoPax vessels, two of which will have a battery capacity of 11.5 MWh, the largest hybrid vessels to date.  

OTR batteries 2 MRS3 V1.4 FINAL lighter Credit Leclanché

Three Stena RoRo vessels will be equipped with the latest generation Leclanché energy storage system – the Navius MRS-3. (Credit: Leclanché)

“The extensive battery size will allow the vessels to operate with full power, using both propellers and all thrusters to manoeuvre emissions-free in and out of ports, even in bad weather,” said Håkan Agnevall, president & CEO of Wärtsilä. “The built-in shore power solution will charge the batteries while berthed.”  

The combination of the hybrid propulsion system and shore power saves up to 15% GHG emissions compared to a conventional diesel mechanical propulsion system. Brittany Ferries will charter the ships, which will be capable of running on either LNG fuel or batteries, from Stena RoRo for its route between Portsmouth in the UK and the French ports of St Malo and Caen. The ferries, being built in China, will be delivered in 2024 and 2025. 

These ships represent a step up in size and capacity of battery ships to date. This will be essential if the technology is to break into the mainstream, and particularly if they are to break out of their current niche of short port-to-port coastal trips. “The main impediment to battery power on longer voyages is the limited energy density of current batteries,” explains Dr Peng Wu, Senior Mechanical Engineer at AqualisBraemar LOC. “Longer voyages mean more energy would need to be stored on board, given the reality that charging in the middle of the ocean is very unlikely. The system-level energy density of current battery systems means the vessels on longer voyages will likely have more volume and mass margins reserved for their power and propulsion systems, which could reduce their capacity for carrying cargo.” 

Resolving this would require breakthroughs in battery technology as well as improvements in optimized power, battery management systems and air lubrication. There will also need to be investment in charging infrastructure at port and offshore and modular power barges to charge the battery-powered ships.   

 

Battery failure

And, as with electric cars, there are safety issues that need to be addressed. Thermal runaway can cause battery rupture and explosion, while damage caused, for example, by a collision at sea could lead to a fire or explosion.  

“Failures such as over-charge, over-discharge or short-circuit of batteries can also lead to a disastrous situation,” said Dr Wu, who also highlighted the risk of thermal abuse, such as thermal shock or high local temperature, as possible safety issues for batteries in the marine environment.  

Battery cost is another issue, although this is expected to come down over time, but operational costs will be linked to local electricity prices and the battery’s cycle limit.  

“Typically, a ship would be operated for a couple of decades, and conventional diesel engines would be maintained and operated until the end of the ship’s life,” explained Dr Wu. “However, batteries would need to be replaced a few times throughout the ship’s life cycle.”  

Despite these challenges, there’s certainly increased investment in battery technology and battery energy storage systems for marine applications. Corvus Energy, for example, is opening a new factory in the state of Washington as a result of significant uptake in orders from the US maritime market. The new facility, with an annual capacity of 200 MWh of stored energy, is in addition to the company’s existing battery factories in Norway and Canada. 

AMY

Amy McLellan is a journalist and author. She was previously editor of Energy Day. Twitter  @AmyMcLellan2