New battery-hydrogen tugboat for Japanese ports

An electric tugboat with towing power of 50 tons driven by a combination battery – hydrogen fuel cell system has been announced by E5Lab and Tokyo Kisen, Japan’s largest tugboat manufacturer.

E5Lab is the company that also introduced the world’s first electrically powered bunker oil carrier in March and this is the world’s second full size electric tugboat. The first was developed by Damen shipyards and commissioned by the Ports of Auckland  in August.

Battery – hydrogen powers two 1500kW azimuths

schematic showing how the battery-hydrogen motors link to shore power and an emergency LNG generatorThe Japanese tug has two 1,500 kW azimuthing drives for its main propulsion, and the system is called the  “e5 powertrain platform”. It’s a bit difficult to sort through the translations from the Japanese, and no specifications have been released on the size of the lithium-ion batteries or fuel cells, but there is a description of how it works. The battery is the main power source and a hydrogen fuel cell the auxiliary source. Not that speed matters a whole bunch with a tugboat, but it has a service speed of 14 knots.

It appears that the tug is recharged from shore, but also has a LNG (Liquid Natural Gas) generator for emergencies.


To quote from the press release:

Fully electrified powertrains can adopt the most suitable energy sources (lithium-ion battery, hydrogen fuel cell, all solid-state battery, LNG generators, etc.) in accordance with technological progress. In the future, it will be possible to achieve zero emissions in combination with renewable energy.

The first two tugs will be deployed in the harbours of Yokoshima and Kawasaki. Regarding the carbon emissions from shore power, it is difficult to know by city, but less than 20% of Japanese electricity is generated from renewable sources, according to Wikipedia. Until the Fukushima disaster in 2010 nuclear plants supplied 25% of the country’s electricity, but that is now less than 2% and the nuclear shortfall was made up by fossil fuel sources. Coal now makes up 34% of the grid, natural gas 39% and oil 9%.

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