Battery-powered tankers to go into service in Japan

Japanese shipping company Asahi Tanker unveiled its new first-of-its-kind fully electric vessel “e5 tanker”. The vessel is the first of two all-electric vessels to be built from the e5 Lab initiative and is expected to go into service in bunkering operations in Tokyo Bay by 2022.

The name of the ship stands for the five core values of the project and its green initiative: electrification, evolution, environment, efficiency, and economics. 

The e5 aims to help Japan’s shipping industry tackle carbon dioxide emissions and air pollution produced by ships. Asahi Tanker has announced that the e5 tanker will produce zero emissions of CO2, NOX, SOx and other gasses that have a high environmental impact. In addition, reduced noise and vibration will create a more comfortable work environment for the crew members and limit noise pollution in the bay and its surroundings.

Further, the vessel will make its battery power available to emergency services in the case of a natural disaster in Tokyo. This idea was originally proposed by e5 Lab and Asahi Tanker.


Kawasaki Heavy Industries (KHI) was awarded the contract for the ship’s propulsion system which will be combined with the 3,480kwh Orca Energy storage system (ESS), developed by Corvus Energy, to power the e5. KHI has been manufacturing engines for more than 140 years. In response to stricter, highly regulated guidelines that call for engines to have a reduced environmental impact, the company have been working towards developing greener engines powered by cleaner fuels.

Corvus Energy was primarily selected to provide the e5’s ESS because of the previous relationship KHI have with the company. “Our first contact with e5 was about three or four years ago,” says KHI manager Ohno Tatsuya.

The ship will incorporate two 1,740-kWh Orca ESS lithium-ion batteries which will power the motors of the e5. Corvus Energy CEO Geir Bjørkeli says the company are enthusiastic to work on this project due to its important environmental impact. 

Corvus is very enthusiastic about the launch of this pilot project in Japan because we see a great opportunity for this,” he explains. “Japan have climate high up on the political agenda but also in public opinion. We are very pleased to be able to contribute to clean air and a future in Tokyo Bay.” 

The benefits of battery power

Although there are many green fuel alternatives ranging from hydrogen, biodiesel and biofuels, running a ship with battery power comes with environmental and operational benefits. Batteries were selected to power the e5 for several reasons.The vessel needed to have charging capability and holding capability, battery was the solution that could give zero emissions,” Bjørkeli says. 

Battery power results in a quieter, smoother experience for crew members as well as a scentless environment compared to ships that run on fossil fuels.

The alternative could have been green hydrogen but, for this kind of energy demand and operating profile, batteries were the right solution for us to achieve zero emissions.” said Bjørkeli.

The choice also took into consideration Japan’s younger population which may have reservations when it comes to working on tankers due to the volume of demanding labour. Batteries are considered to require less maintenance and manual labour to keep them running.

Nowadays in Japan, the crew in areas such as Tokyo Bay become older and the younger people do not want to work in a ship because it is a tough job, if you use a battery power propulsion system, compared to the conventional engine system, you don’t need as many engineers to keep them running.” Tatsuya explains.

The introduction of the e5 into Tokyo Bay is hoped to not only showcase the effective use of battery power but also to highlight the positive environmental impact that the ship has on the area. 

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