THE NEW tug, a Damen RSD-E Tug 2513 to be delivered in 2021, will have a 70 tonne bollard pull, the same as the port’s strongest diesel tug Hauraki, also built by Damen.

“In 2016 we set ourselves the goal of being zero emission by 2040,” Tony Gibson, CEO of Ports of Auckland said.

“We set this goal because we recognise that urgent action is needed on climate change, and we wanted to be part of the solution. However, setting that goal created a tough challenge. We have a lot of heavy equipment, like tugs, and in 2016 there were no zero emission options.”

When the port first looked into buying an electric tug in 2016, there was nothing on the market, said Allan D’Souza, Ports of Auckland’s general manager marine, engineering and general wharf operations.

“We talked to several manufacturers about building a battery powered tug. They told us we were dreaming. Hybrid tugs were possible, they said, but not battery. No way,” he said.

“Luckily for us,” said Mr Gibson “Allan doesn’t give up. He and marine technical superintendent Rob Willighagen kept talking to manufacturers, kept suggesting ways to solve problems.”

Eventually they found a partner willing to take on the challenge, Damen Shipyards.

“I would like to acknowledge Damen for their work on this project since 2016. They have invested a significant amount of time and money to develop this innovative vessel.

“In the fight against climate change, partnerships are important, and Damen have been a great partner,” Mr Gibson said.

The life of the tug is around 25 years. By going electric now, the port will save 25 years of diesel pollution and a net reduction in costs of around $2.5m because it is so much cheaper to operate.


The port’s current 70-tonne bollard pull tug Hauraki uses around 120 litres of diesel per hour. In 2019 it consumed 190,926 litres of diesel equating to 514.33 tCO2e.

The energy rating of the e-tug’s batteries is 2800 kWh – that’s the same as 70 Nissan Leafs (based on a 40kW Leaf battery). Based on the Hauraki 2019 diesel consumption/number of ship pulls it is expected the electric tug will use approximately 501,685 kWh to operate in the same way, this equates to 49.02 tCO2e, which would mean an annual saving of 465.31 tCO2e.

In future, the port hopes to use 100% renewable energy, which would reduce emissions to zero. As its tugs account for approximately 10% of its total scope 1 emissions and approximately 8% of its total gross scope 1,2 & 3 emissions, replacing all our tugs represents a significant reduction in the port’s carbon footprint.

“It was important to us that a new electric tug should be able to carry out normal port operations, just like our existing diesel tugs,” Mr Gibson said.

The new e-tug will have dimensions of 6 metre draft and a length of 24.73 metres and have two azimuth thrusters with 3 metre diameter props. It will be able to do three to four shipping moves on a full charge, or around three to four hours work (one shipping move takes an hour on average). A fast charge will take about two hours.

“One of the other hurdles we had to get over was cost. The purchase price of this tug is significant, at roughly double that of a diesel tug, and that is an important consideration for a business that needs to make a profit,” Mr Gibons said.

“However, we are prepared to wear that up-front cost because our commitment to reduce emissions has to be more than just words.”

Fortunately, the cost of operating an electric tug is less than a third of the cost of running a diesel tug. So while the port pays more up front, over the life of the tug it will save around $12m in operating costs, making the electric tug cheaper in the long term.

View the Ports of Auckland video here:

‘Zero-emission’ ship powered only by battery
In other news, Nagasaki-based Oshima Shipbuilding Co Ltd has built an automatic ship powered only by a battery.

The ship, e-Oshima, is a zero-emission vessel that uses a storage battery not only to provide a driving power but also supply power to communication, navigation and wireless devices, lighting equipment, air-conditioning systems and all the other devices used at the time of sailing.

The propulsion system of the vessel uses GS Yuasa Corp’s large-capacity lithium-ion (Li-ion) storage battery as a main power-supply device and includes a control device that protects the Li-ion battery in multiple ways. The nominal voltage and rated capacity of the system are 622V and 590kWh (14 modules connected in series x 10 modules connected in parallel x 2, each module consists of 12 cells), respectively.

The maximum capacity of the vessel is 50 people, and it can carry a large-size bus and four passenger cars at the same time. Its length and weight are 35 metres and 340 tonnes, respectively.