Green tugs serving green ports

Kotug's 'RT Adriaan' was Europe's first true hybrid tug
Kotug's 'RT Adriaan' was Europe's first true hybrid tug
The world's first LNG-powered tugs 'Borgoy' and 'Bokn' are working for Statoil
The world's first LNG-powered tugs 'Borgoy' and 'Bokn' are working for Statoil
Three dual fuel tugs are being built in Spain for Norwegian owner Østensjø Rederi AS
Three dual fuel tugs are being built in Spain for Norwegian owner Østensjø Rederi AS
Peter Barker
Peter Barker
Robert Allan Ltd has taken a fresh look at the layout for its LNG-powered tug proposal
Robert Allan Ltd has taken a fresh look at the layout for its LNG-powered tug proposal

Green ships are sailing the oceans, green ports are handling their cargoes, but the towing industry is not allowing itself to be left out. The age of the green tug has arrived, writes Peter Barker, marine writer and photographer.

Readers of GreenPort will be aware of the new container terminals at Rotterdam’s Maasvlakte 2 development, where the opportunity is being taken to ensure best possible solutions are included to protect the environment. Here was not a case of upgrading existing terminals, but the opportunity to make the phase ‘state-of-the-art’ absolute, factored in from the start including the latest sustainable energy technology.

And what about shipping itself? Environmental impacts are not restricted to emissions but it is here where IMO regulations are influencing how the shipping world will operate in the future, the EU planning to go further with emissions regulations covering existing shipping trading into and out of, and between European ports.

And for tugs?

But what are the implications for the towage industry, specifically the ship-handling sector, a vital part of the marine infrastructure of most ports? Technical details surrounding emissions regulations run to hundreds of pages and GreenPort asked IMO about the implications of existing and proposed regulations for the towage industry. It is a complex area but relevant points are that emission regulations apply to ships of 400GT and above. Other regulations include the requirement to have an International Energy Efficiency (IEE) certificate and to provide an energy efficiency management plan.

It is difficult applying the Energy Efficiency Design index (EEDI) framework to new tugs when calculating “transport work” a product of a ship’s capacity and its design/reference speed, factors which cannot be readily defined for service ships. Also, the administration (flag state) may establish rules to ensure their own environmental standards are met, in other words it would be up to the national authorities. As mentioned it is a complex area.

So where do existing tug operations fit in, and what must owners consider when choosing to go down the green road? Bigger ships mean bigger tugs and with increasing requirements for terminal escort provision at LNG and offshore installations many tugs of note are now above the 400GT mark.

There are choices

When defining a green tug, current options are typically hybrid (diesel/electric/battery), LNG-fuelled, or dual fuel (LNG/diesel). All have the advantage of fuel savings and a reduction of emissions over conventional tugs. In 2012, Rotterdam based tug owner Kotug refitted its Rotortug RT Adriaan to become Europe’s first true hybrid tug with early reports of fuel reductions of 15% and emission reductions of 44% hydrocarbon, 33% NOx, and 38% SOx.

Reducing emissions is one advantage for tugs operating in built-up urban areas but the main advantage of hybrids is the ability to match the machinery’s most efficient power settings with its operational profile. A tug’s maximum power will be influenced by the worst case scenario during its normal (or not so normal) working day, but while it may have to deliver that power at a moment’s notice it is typically only required for as little as 2% of its working life. Mostly it will be operating at slow speed and low load condition, perhaps steaming leisurely from its berth to meet the ship. This wide range of required power results in machinery often operating at less than efficient settings.

Typical hybrid arrangements offer direct mechanical, electric motor or battery with various combinations of all three to suit the operating circumstances. The goal is to provide energy as efficiently as possible and includes the added bonus of reduced maintenance costs, lower running hours and lower on-board noise levels.

LNG horses for courses

Various factors influence the choice of LNG as fuel, one important consideration being the availability of adequate re-fuelling arrangements, permanent LNG bunkering facilities are currently few and far between. LNG suits fixed routes where such facilities can be established with Norwegian fjord ferries and platform supply vessels operating long-term charters two examples of where Norway is ahead with development of LNG-fuelled marine transport.

In 2014, Norwegian tug owner Buksér og Berging took delivery of the world’s first LNG-powered tugs Borgøy and Bokn from Turkey’s Sanmar Shipyard, built for operation at Statoil’s Kårstø gas plant. Rolls-Royce provided the machinery package and a reduction of sulphur and particulate matter emissions to almost zero, along with CO2 emission reductions of 26% and NOx of 80 to 90% have been reported.

The refuelling conundrum may be about to change however as more LNG import terminals make gas available as a transportation fuel either direct to LNG-powered vessels or LNG bunkering barges and road tankers. Rotterdam has a large ship handling tug fleet and developments at the port’s Gate LNG Terminal is an example of where choices between LNG and hybrid tugs could be influenced over time.

Gate LNG is developing a small harbour basin and breakbulk terminal adjacent to their existing terminal allowing LNG distribution for small-scale use with up to 280 berthing slots per year. The use of LNG is expected to grow as the new emissions regulations take effect and with LNG powering of inland barges at an embryonic stage, potential from this market could in the longer term have far-reaching implications for facilities such as Gate LNG, something that will perhaps be on the radar of owners of ship handling tugs in Rotterdam and elsewhere.

Going down the green tug road

Still in Rotterdam, the green tug story is currently going down the hybrid road. After Kotug’s trail-blazing with the RT Adriaan, they have committed further to hybrids with recent delivery of four hybrid Rotortugs. Designed by Canadian naval architects Robert Allan Ltd in conjunction with Kotug and Rotortug BV, two were built in Hong Kong, and two, RT Evolution and RT Emotion at Damen Shipyards’ Gdynia facility, both are currently operating in Rotterdam. Building on the experience of the RT Adriaan they provide various combinations of propulsion via batteries, diesel mechanical and electric motor dependent on the operational requirement.

Damen’s popular ASD 2810 ship handling tug is now getting the hybrid treatment following delivery of the Bernardus for another Dutch company, Iskes Towage & Salvage, a number of other hybrid ASD 2810s are now also on order. US based Foss Maritime’s Z-drive tractor Carolyn Dorothy became the world’s first hybrid tug when introduced in 2009, later followed by a second vessel Campbell Foss.

Following Buksér og Berging’s pioneering pair, another Norwegian order has followed with the recent contract from Østensjø Rederi AS for three powerful dual-fuel (LNG and marine gas oil) escort tugs to operate at Statoil’s Melkøya LNG facility. Designed by Robert Allan Ltd the trio are being built by Spanish shipbuilder Astilleros Gondán SA.

Robert Allan Ltd is taking the LNG tug concept further with the latest addition to their stable, the RANGLer class. A downside with LNG is the large space required for the gas storage tank and associated systems potentially restricting range and endurance. It has instead revisited the layout of the vessel starting with recognition that as ASD tugs operate mostly over the bow, the afterdeck becomes largely redundant. This area was considered an ideal location for the accommodation, freeing up traditional accommodation areas below main deck for an LNG fuel module.

The future

Summing up, current green tug activity is mainly concentrated in Europe. Word is spreading however. Wärtsilä, already active in the area of green energy solutions, recently announced it wasproviding propulsion systems for the Middle East’s first LNG green tug to be built by Drydocks World. China is also exploring the green tug road with Rolls-Royce providing machinery for two LNG-powered escort tugs for Chinese state oil company, CNOOC.

Just a few years ago, every green tug in operation or planned could have been explored here in detail. Not now, developments are happening fast. With ship-handling tugs often matched for specific locations much depends on local factors including emission regulations, fuel availability and operating profiles.

International and local regulations are a major factor driving green tug developments in Europe but much more is to be gained than just being forced into action by regulation with ‘big win’ potential from reduced operating costs and other benefits.

At this stage of development none of it comes cheap of course and it is the major tug owners, designers, shipyards and machinery suppliers who are able to pioneer the emerging phenomenon of the green tug. The towage industry has seen unbelievable progress with vessel designs in recent decades, there can be no doubt this trend will continue as green tugs become regular sights in ports worldwide.


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