LNG-fuelled and hybrid tug designs are ready if owners are driven to invest through subsidies, government funding or regulation
Naval architects have designed tugs with hybrid propulsion or dual-fuel engines that lower emissions and fuel consumption for owners. Limited numbers of these types of tugboat have been ordered, so a change in the shipping industry’s desire to cut emissions in ports is needed before fleets of greener tugs are ordered.
Damen Shipyards has designed and built tugs with hybrid propulsion and dual-fuel engines for the last five years.
Damen product manager for tugs Dirk Degroote said tug operators should record fuel consumption to estimate gaseous emissions and provide this information to regulators. This would demonstrate the measures that owners have already initiated to reduce pollution.
“It will take a very long time to replace these with greener tugs and there would need to be sustainable and viable business before anything happens”
“Less than 1% of tugs are greener than conventional tugs,” he said. “It will take a very long time to replace these with greener tugs and there would need to be sustainable and viable business before anything happens.”
He asked what the tug industry was willing to do to introduce greener tugs. “There needs to be a change in mindset,” Mr Degroote said. “It will be a mixture of buying new tugs and dealing with existing tugs through better assessment of emissions.”
He thinks governments need to offer subsidies to get newbuild and conversion hybrid and green tug projects underway. But, tugs also need to be viable for commercial requirements, so “there needs to be an economic case,” he said.
One way that designers can assist is to include facilities for energy storage devices that could be leased and replaced. “Then there is less upfront investment,” said Mr Degroote. But he asked what happens to batteries after they are removed from tugs. “Would there be a second life for these batteries?”
Another way naval architects can assist owners is to design tugs with IMO Tier II compliance that have enough engineroom and deck space for future conversion to IMO Tier III. “Owners could buy now and upgrade perhaps in three years’ time,” he suggested. “There are greener vessel designs available – it is possible to reduce emissions.”
Damen has designed and built tugs with hybrid propulsion including the latest to be delivered, Fregate, built to a Damen WID Tug 2915 design and to Bureau Veritas class. Dutch Dredging and Iskes Towage & Salvage jointly invested in this multipurpose tug for operations for in the ports of Cayenne and Kourou in French Guiana.
Robert Allan has provided designs for LNG-fuelled tugs, three of which are operating in Norway, and for hybrid propulsion tugboats. It uses computers to help create these designs and test their hydrodynamic performance.
Its naval architects also co-operate with classification societies to design LNG facilities and associated pipework and with manufacturers of dual-fuel engines. Robert Allan manager of project development Jim Hyslop thinks one of the biggest challenges in designing these tugs is the lack of deck space they have for adequate LNG storage.
Another challenge for owners considering LNG-fuelled tugs is finding the refuelling infrastructure in port. On the commercial side, it is the higher capital expenditure required to construct dual-fuel tugs.
“There is a financial burden on owners and technology burden on designers”
“There is a financial burden on owners and technology burden on designers,” said Mr Hyslop. This is why less than 15 LNG-fuelled tugs have been built so far worldwide, and why owners consider hybrid propulsion and engines with selective catalytic reduction (SCR) units for treating NOx emissions first.
There should be a return on investment for the higher costs of greener tugs, when set against those with conventional propulsion, in terms of lower fuel costs. However, Mr Hyslop thinks this is not enough for owners to order in bulk. “There is not an economic case for reducing emissions,” he said. “Legislators will need to drive our industry into reducing emissions.”
A legislative push and/or subsidies for green propulsion are the best ways forward for better environmental operations in the towage and ports sector. Mr Hyslop described two examples where this has already occurred.
He said tugs with hybrid propulsion have operated in California, US, for more than six years due to funding by port authorities in Los Angeles and Long Beach. In 2011, Foss Maritime converted the propulsion on 2005-built tug Campbell Foss into a hybrid system, an industry first at the time, to operate in these ports. A sister tug with hybrid propulsion was also operated in these ports.
In November 2018, Foss transferred Campbell Foss, a Dolphin-class tug, to Anchorage, Alaska, where it was renamed Bering Wind and is operated by subsidiary Cook Inlet Tug & Barge. Bering Wind is powered by two Series II Caterpillar main engines and twin Rolls Royce US 205 fixed pitch Z-drives. It also has a Marathon generator set that delivers 125 kW of power for the diesel-electric hybrid service.
During Q1 2019, shipbuilder Nichols Brothers Boat Builders expects to deliver a new tractor tug with Rolls-Royce hybrid propulsion to Baydelta Maritime for operations in container terminals in the US west coast.
Elsewhere in the US, tug owners have ordered vessels with propulsion systems that comply with the most stringent emissions regulations from the Environmental Protection Agency (EPA). The latest of these tugs to be delivered, Samantha S for Shaver Transportation, meets EPA Tier 4 requirements for operations in the Colombia River. It was built by Diversified Marine Inc to a Jensen Maritime design and ABS class.
Mr Hyslop also highlighted that Østensjø Rederi operates three LNG-fuelled azimuth reverse tractor tugs – Audax, Dux and Pax – at Equinor’s LNG production plant and export terminal on Melkoya Island, near Hammerfest in northern Norway.
These Robert Allan-designed and Bureau Veritas-classed tugs provide towage, escort and berthing services to LNG carriers operating at the export terminal. They needed to be LNG-fuelled because of a mandate from the Norwegian Government and the needs of the terminal to reduce emissions.
If there are no subsidies, upfront funding or legislative push, then owners need to lobby regulators or find commercial methods to facilitate capital expenditure in greener tugs.
US designers for EPA Tier 4
In the US, shipyards are constructing more tugs to EPA Tier 4 from designers such as Guarino & Cox. Alabama-based Master Boat Builders has used designs from this naval architect for articulated tug-barge (ATB) units, such as Cape Lookout, delivered in Q3 2018.
Castleman Maritime designed tugs for ATBs that Conrad Shipyards built for Vane Brothers. Two of these – Assateague and Chincoteague – were delivered in 2018, while a third tug Wachapreague is due to enter service in Q1 2019. These are Tier 4, 3,300-kW tugs that drive 80,000-barrel capacity petroleum barges.
CT Marine designed Z-drive tugs for Marquette Transportation, which were built by C&C Marine and Repair in the US. The latest of these, Jerry Jarrett, was delivered in September 2018 to join sister tugs, Chris Reeves and Cindy L. Erickson, which are already in service.
C&C Marine formed Hyperion Marine Engineering Group, which merged with Ocean Tug & Barge Engineering (OT&BE) in October 2018. This amalgamated naval architecture and marine engineering for inland and offshore tugs and barges.
All Hyperion’s ATB designs begin with a 3D model which is used to produce 2D drawings for shipyards, owners and class. By using 3D models, naval architects can identify potential conflicts and resolve them before construction begins. Hyperion uses 3D ship design packages such as Ship Constructor, Nupas Cadmatic and Catia for creating and adapting these models. OT&BE has design expertise in the offshore, oceangoing and inland towage sectors.
Jensen Maritime has become a main designer of tugs operating on the US west coast. In 2018, it supplied tugboat designs to Foss Maritime for constructing up to 10 escort tugs by Nichols Brother Boat Builders. These tugs will be based on an adapted Valor tugboat design and will comply with EPA Tier 4.
Jim Hyslop and Dirk Degroote were speaking as panellists at the European Tugowners Association conference in London, in November 2018.
Jim Hyslop has worked for Robert Allan since 1992 and is now project development manager. He has a diploma in naval architecture and shipbuilding technology from the Newfoundland and Labrador Institute of Fisheries and Marine Technology.