Electric tugs

by Gary Gimson

Electric tugs spark interest

Damen launches new tug type

It’s a dilemma facing many car buyers and it’s one that is set to exercise procurement departments at many port authorities, terminal operators and tug companies in the coming years; and that’s when or if to switch harbor towage from conventional to electric.

For would-be car buyers it’s agonizing over higher up-front pricing, range anxiety and worries about residue values as well as the easy availability of charging points; for those in the towage sector, it’s a slightly different calculation and one that has some pros and cons.

As has been covered in previous issues of Caribbean Maritime, the move to electric cargo-handling operations is already underway across the region and gaining pace. But there is now the possibility of operating battery-powered tugs and the first such vessel is currently on order.

New Zealand’s Ports of Auckland is the launch customer for Damen’s revolutionary new RSD-E Tug 2513, which is being built at the Damen Song Cam Shipyard in Vietnam. The RSD-E Tug 2513 will be a zero-emissions derivation of the IMO Tier III-ready RSD Tug 2513, introduced by Damen in 2018. And with the RSD-E Tug 2513 in-build, Damen is already working on offering zero-emission versions of its IMO Tier III-ready “Next Generation” tug series.

What makes this a pivotal event in the 220-year history of tugboats is that when launched, the RSD-E Tug 2513 will be the first, fully electric tug in existence with 70 tonnes of bollard pull. This potentially heralds a new era of emissions-free operations and marks a big step towards a more sustainable future in harbor and wider maritime operations.

Regional market

Caribbean Maritime spoke to Damen’s Caribbean Sales Manager, Bram van der Plas, about the new tug and whether there was a market in the region for such a vessel.

Damen declined to go into much detail about the additional up-front cost of an electric tug only saying that “every case is different”. But in general, the CAPEX of the electric zero emission Damen RSD-E tug 2513 is approximately twice that of a normal diesel driven Damen RSD 2513 tug. The tug builder does believe there are savings to be made; but admits these are more difficult to quantify. Explains van der Plas: “There are many variables. These relate not only to the price of utilities in a given country, but also to the port’s individual characteristics, vessel requirements, infrastructure etc, which make it very hard to calculate such figures.

What we can say, however, is that in the right circumstances there is scope over the lifecycle of a vessel for an electric operation to represent an equal or lower total cost of ownership than a conventional diesel tug. Examples of factors that are the basis for this are; Lower cost of energy to fuel the vessel, lower cost of maintenance due to no running hours on diesel engines. Aside from the financials though, there are numerous additional benefits to an electrical operation – increased sustainability associated with lower emissions and the need for fewer crew members on board and thus adding to the safety being two obvious examples.”

Then there’s operations anxiety to think about. Van der Plas dampens any concerns: “Everything ultimately depends on the operation itself. The Damen RSD-E tug is equipped with a battery capacity that is sufficient to perform at least two (un)berthing operations in an average harbor. During operations, the vessel is designed to operate at 70 tons bollard pull for a minimum of 30 minutes. Free sailing (at seven knots) the tug can operate for several hours. Also, two IMO Tier 3 compliant back-up/fire-fighting generator sets are installed for fire-fighting and other operations that require more autonomy. The Port of Auckland has opted to have a 1,500 kW charging system. This charges a vessel from empty to full in two hours.”

And when it comes to charging, van der Plas adds: “Damen’s approach is to take the role of integrator – or total solutions provider. We unburden our clients by taking responsibility for the entire process, not only shipbuilding – naturally this includes the charging infrastructure, though we manage the process along with a third party (see panel), specialised in this field.”

Possibilities

But there are some limitations. “Current technology enables Damen to build full-electric and hybrid vessels that operate relatively short, predictable sailing routes,” says van der Plas. “It is important to note that the viability of an electrically propelled dedicated harbor tug rests on two things – availability of affordable green/blue electricity and the right sailing profile. Due to the current possibilities in battery technology, the sailing profile of the operation determines whether or not the tug can sail on zero emission batteries alone or if the tug needs to rely on a reduced emissions hybrid propulsion. Power demand during max bollard pull is very high so is time-limited in order not to drain the batteries and leave some capacity for emergencies.

To summarize, the tug can perform the majority of its daily operations with zero emissions on batteries alone and only requires the help of the installed IMO Tier III certified generator set to perform incidental operations like fire-fighting and long operations when at relatively high speed and bollard pull.”

As to whether all this will work in Caribbean is open to question. Van der Plas is confident that local solutions can be found: “The Caribbean islands present great opportunities for renewably sourced utilities. Aside from Trinidad and Tobago, none of the islands have a domestic fossil fuel supply, which make energy costs relatively expensive. Additionally, the islands have a high amount of sunshine hours per day, which opens up possibilities for solar power – alongside an abundance of geothermal and wind power. But, basically, there is good potential for the Caribbean to take advantage of the natural, renewable energy sources at its disposal. That potential will hopefully see a cost reduction in the supply of electricity and water. When such an infrastructure is set up, a logical step would then be to add transport and work equipment (including vessels) powered by electricity.”

There’s also concerns about the weather and whether electric-powered tugs will be rendered idle as a result of a major hurricane and the storm’s probably negative impact on local power supplies? Van der Plas allays any such fears: “Two IMO Tier 3 compliant back-up/fire-fighting generator sets are installed to be able to perform towing assistance independent of the availability of shore power. Also, the generator sets can be used to charge the batteries when shore power is not available. Safety is paramount to us and to our customers, so it’s essential that the vessel can continue to sail under any circumstances.”

Clearly, Damen makes a compelling case for electric tugs but will potential customers in the Caribbean be persuaded of their merits? Or, as with many car buyers, will fear of the unknown and a natural tendency to stick to the familiar prevail? Time will tell.

Partnership

Damen Shipyards and Echandia have already announced a global partnership that combines Echandia’s DNV-Certified E-LTO energy systems and battery expertise with Damen’s tugboat experience.

Echandia’s E-LTO energy storage system (ESS) is a smart, highly scalable air-cooled modular design system based on Toshiba LTO cells - widely considered the best heavy-duty cell chemistry on the market. The 2.8 MWh ESS is specifically optimized for the RSD-E Tug application and will be type-certified by world-leading testing and certification organization, Bureau Veritas.

The Echandia-Damen partnership brings together sophisticated battery technology and deep skills in the shipyard industry with technology strategy and development to bring the next generation of electric tugboats to the global market.