Ports of Auckland has signed a contract which will see New Zealand become the first country to have a fully electric port tug in operation.
The contract for the tug was with Dutch company Damen Shipyards. 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," said Tony Gibson, CEO of Ports of Auckland. "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 we 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."
"Luckily for us," said Gibson "Allan doesn't give up. He and Marine Technical Superintendent Rob Willighagen kept talking to manufacturers, kept suggesting ways to solve problems, and 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," he added.
Damen design and proposal engineer Tugs Marc Baken takes up the story. “We looked into the request and we saw that it was technically possible. The next step was to consider the feasibility of full electrical operation from a business perspective.” For this, Damen took data from the operational performance of Ports of Auckland’s existing ASD Tug 2411 and was able to work out what the battery requirements would be for the RSD-E Tug 2513.
As is usual of the Dutch shipbuilder’s approach, Damen’s role in the development and construction of the RSD-E Tug 2513 extends beyond shipbuilding. Damen is involved in the entire process, from start to finish. “This involves working to our philosophy of modularization and standardisation,” said Baken. “Taking proven components already in the marketplace and applying them to the vessel, for reliable efficiency.”
This includes, for example, the charging station, which is based on technology that has already demonstrated it credentials in the automotive industry. A simple system, it features four cables on the vessel being connected to the station. Once connected, the 1.5MW charger takes just two hours to fully charge RSD-E Tug 2513.
The tug has high levels of redundancy in its power systems. The electrical system has built-in redundancy, with the batteries arranged in strings; if one battery in a string fails, the others simply carry on the work. To ensure absolute safety – of utmost importance in shipping – the tug also has two 1000kW generator sets. They provide enough power for the tug to operate at 40 tonnes bollard pull in the event of an electrical system failure or if the vessel needs to operate beyond its battery capacity.
To be clear though, this is not a hybrid system. In normal operation, the generators will not be used as the vessel and its battery system has been designed to meet the port’s normal operational needs. Gibson said "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. Our new e-tug 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. This is just what we need."
"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. 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 we pay more up front, over the life of the tug we'll save around NZ$12 million in operating costs, making our electric tug cheaper in the long term," he added.
Like Damen, Ports of Auckland and New Zealand as a nation are committed to sustainability. Already around 40% of primary energy generated in the country comes from renewable sources, including 80% of electricity, which comes primarily from hydropower and geothermal power.
Auckland Mayor Phil Goff said, "Commissioning the world's first fully electric large tug represents a strong commitment by Auckland and its port to reducing carbon emissions and achieving our carbon zero target. It's great for the environment, reducing pollution in the city centre and cutting back carbon emissions. The life of the tug is around 25 years. By going electric now, we save 25 years of diesel pollution and a net reduction in costs of around NZ$2.5 million because it is so much cheaper to operate."