Manufacturers are offering IMO Tier III options for main diesel engines after new regulations in emission control areas came into force January 2021
With the changing regulation landscape, manufacturers have developed engine packages for IMO Tier III requirements that came into force in 2021. These environmentally friendly main engines will be increasingly ordered alongside selective catalytic reaction (SCR) technology as owners invest in IMO Tier III-compliant tugs, regardless of whether they operate in emissions control areas.
Owners in North America are already operating tugs with engines compliant with US Environmental Protection Agency (EPA) Tier 4 emissions requirements. European owners have started to follow with tugs ready for European Union and IMO emissions requirements.
At the start of 2021, Caterpillar launched a high-performance marine engine with a new sequential air system and IMO Tier III options with an SCR. Its additions to the Cat C32B engine series now come with a triple-turbo version for commercial and recreational vessel applications.
These were built from the Cat C32 series that includes C32 Acert, which comes with EPA Tier 4 and IMO Tier III options. Caterpillar also offers the C32B 2025 MHP engine with 2,025 mechanical horse power (1,490 kW), and its Cat C32B Triple Turbo 2,433 MHP (1,790 kW) with a rated engine speed of 2,300 rpm.
This engine has an updated cooling system and a new sequential, triple-turbo air system, delivering faster response and better performance. An environmentally friendly option includes an SCR for NOx removal. Otherwise, C32B Triple Turbo complies with EPA Tier 3 Recreational and IMO II emissions regulations. The first of these engines will be available in Q4 2021. In the meantime, more tug newbuildings are being delivered with Cat 3512E main engines compliant with EPA Tier 4 and IMO Tier III emissions.
These engines are being supplied to the US Navy’s YT 808-class tugs, under construction at Dakota Creek Industries’ shipyard. These 27.4-m tugs will be the first vessels in the US Navy’s fleet to be EPA Tier 4-compliant. Each tug will be fitted with a pair of Caterpillar 3512E engines, rated at 1,350 kW each, to drive two Schottel SRP 340 fixed-pitch Z-drive thrusters. These provide the YT 808-class tugs with a top speed of 12.5 knots and an anticipated bollard pull of 40 tonnes.
Cummins’ EPA Tier 4 and IMO Tier III engines for tugs are in the QSK38 series with power ranging from 746 to 1,119 kW. Based on Cummins’ KTA38 range, these were developed for US inland waterway applications. For environmental compliance, QSK38 comes with SCR exhaust aftertreatment.
These V-12 cylinder, 4-stroke diesel engines have improved idle stability and reduced noise and vibration due to Cummins’ modular common rail fuel system. They have displacement of 37.7 litres, a bore and stroke of 159 mm by 159 mm and a counter-clockwise facing flywheel. QSK38’s engine weight of 4,850 kg is increased by another 420 kg by the SCR.
In 2020, Seaspan International repowered one of its 1974-built harbour tugs, Seaspan Cavalier. Its old IMO Tier I Cummins KTA38 diesels were pulled out and a new set of Tier II, KTA38s went in. Seaspan Cavalier and two sister tugs tow fuel and general cargo barges along the British Columbia coast, Canada.
Seaspan port engineer Kevin Tweedy explains how these engines were changed. “We cut a 2.1-2.4 m hole in the tug’s port side and install both starboard and port engines through that,” he says.
The same place is used each time the engine is replaced, with the old welds being cut in both the hull plate and framing to ensure the structural integrity of the hull.
“Putting it back together we do a sealing weld from the inside first, then clean the weld from the outside before doing a second sealing weld from the outside,” Mr Tweedy explains.
These new engines are coupled to the tug’s Lufkin RLS 3614 gears, with 6.987:1 reduction. They turn three-blade 200 by 179-cm propellers in nozzles. “The props are in good shape,” says Mr Tweedy, “but we will send them to Osborn Propellers for a tune up, crack testing and pitch checks, as well as weld fill in way of cavitation and balancing.”
The transition from Tier I to Tier II required some minor piping and electrical modifications. Seaspan Cavalier maintains its 27-tonne bollard pull after the repower.
EU Stage V engines
Volvo Penta introduced new engines in its D16 range for IMO Tier III and European Union’s Stage V marine emissions requirements for inland waterways. These are part of the company’s investment in sustainable solutions to significantly reduce emissions, says Volvo Penta chief executive Helene Mellquist. She introduces this new range as Volvo Penta unveiled its digitalisation strategy and focus on sustainability, automation, electrification and connectivity.
The range includes an upgraded D16 engine available in packages for marine engines and gensets to IMO Tier III compliance. These are in-line six-cylinder, 16.1-ltr, charge air-cooled marine diesel engines which use a high-pressure unit injector system, overhead camshaft and a twin-entry turbocharger. D16 engines have increased power up to 635 kW for heavy-duty operations and 560 kW for continuous operations.
Volvo Penta chief technology officer Peter Granqvist says this D16 has better fuel injection, for higher productivity and durability of engines. “It is a massive upgrade on engine platform,” he says. “The important thing for us is to keep delivering and performing with the best of today’s propulsion and power solutions.”
D16 engines come with high torque at low revolutions for powerful manoeuvring and rapid acceleration. The torque rise enables a high load capacity and improved fuel economy.
Dual-fuel engines for a low-carbon future
At the Engines for now and the future webinar, during Riviera’s Maritime Air Pollution Asia Webinar Week in December 2020, experts discussed changes in engine technology and what is in store for the near future.
Shipping industry’s fuel mix will have to change to meet IMO’s 2050 emissions reductions goals, said WinGD general manager for global sales Carmelo Cartalemi. He said the industry has both an upstream problem – a lack of infrastructure, availability and fuel cost, and a downstream problem – the need to upgrade technology, safety and regulation challenges regarding new fuels.
WinGD expects fuel-flexible engines to be the future. “By nature, they can burn any kind of fuel” said Mr Cartalemi adding “that is what our R&D is focused on, the engine for new fuel.” Most flexible engines will be dual-fuel at least, with the fuel injection system adapted to new fuels, with gas and diesel as the most common in tug enginerooms.
Wärtsilä Marine director for power supply product management Lars Anderson said the internal combustion engine can be decarbonised in the future with fuels derived from renewable electricity or biomass.
Production of green hydrogen is the starting point for more transportable fuels, such as ammonia or methanol. “Dual-fuel engines can run on all next-generation fuels,” Mr Anderson said.
At present, biofuels are the only available green fuels, with bunkering for hydrogen and ammonia severely limited. “We have a long way to go,” said Mr Anderson. “Waiting for 100% hydrogen and ammonia will take too long,” he said.
Liquid hydrogen requires a bunkering volume 4.5 times that of diesel fuel for the same energy content with the figure for ammonia and methanol at 2.6.
In addition, these new fuels bring design and safety challenges related to cryogenic storage, the flammable nature of hydrogen, and toxicity in the case of ammonia, making them complicated for use on tugs.
Instead, the strategy mooted was to promote LNG in the near future and blend in BioLNG and synthetic LNG. Mr Anderson added that Wärtsilä has a solution to reduce methane slip, a major environmental issue with gas-fuelled engines.
MAN Energy Solutions offers several dual-fuel engines capable of retrofits to use LNG, ethane, methanol and LPG. The company’s director of new technologies Kjeld Aabo said MAN had developed a design to make retrofits easier.
“We add on the extra equipment for the dual-fuel parts. The cover is changed because we have extra valves. We have a gas distribution block and double-walled piping,” he said.
Mr Aabo said hydrogen is the leading non-carbon option for vessels running on four-stroke engines, but ammonia would also be an option.
MAN leads a consortium in Denmark to develop ammonia-fuelled engines and will begin testing one in 2021. Ammonia can be stored at the moderately low temperature of -33ºC and supplied at a pressure of 70 bars, and does not have the same storage challenges as LNG or hydrogen.
Alternative fuels will be driven by a range of factors including installation costs, climate impact, regulation and fuel costs. On fuel costs Mr Aabo admitted, “We do not know what will happen there. It is something which is controlled by others.”
Mr Cartalemi said the shift to new fuel should be driven by regulation. “The prices of new fuels are speculative. To compete with fossil fuel there has to be some kind of carbon tax or incentive, otherwise the shift will take longer and be difficult. The majority of global shipping – medium-sized companies – need to be driven by regulation,” said Mr Cartalemi.
Agreement opens Chinese market for MTU engines
Rolls-Royce Power Systems has reached a breakthrough in the Chinese marine market to supply its MTU Series 2000 and 4000 engines for workboats and passenger vessels.
It has secured multi-party strategic partnerships with two shipyards building vessels for domestic and export markets.
These agreements will see MTU engines supplied to vessel building projects in Jianglong Shipyard and Aulong Shipyard. Jianglong Shipyard is China’s leading designer and manufacturer of aluminium hull high-speed vessels. Aulong Shipyard is a joint venture of Austal and Jianglong.
MTU engines were supplied to several tugs completed during 2020 including tugboat Cyathea, built by Turkish shipyard Bogazici to a Robert Allan design for Compagnie Maritime Chambon.
Cyathea sailed more than 10,000 nautical miles from Turkey to Nouméa, in French overseas territory New Caledonia, in 55 days in H2 2020. It has two 12-cylinder MTU 4000 M63 engines, each with output of 1,500 kW at 1,800 rpm, giving a cruising speed of 13 knots.
MTU Singapore and Australian distributor Penske Power Systems will provide regular service to Cyathea’s engines. This tug will be monitored by MTU’s remote service platform.
Another set of MTU engines were installed in German harbour tug Peter Wessels. This was built by Damen Shipyards in the Netherlands for Louis Meyer who sold it to Emder Schlepp-Betriebe (ESB).
Peter Wessels has a pair of 16-cylinder MTU Series 4000 engines with total output of 3,680 kW. It became the strongest tug of ESB’s fleet of five tugs in Emden, with 63 tonnes of bollard pull.
Engines overhauled on Irish Mainport tugs
UK-based marine engineering specialist Royston overhauled engines on two tugs and an offshore support vessel (OSV) owned by Cork-based Irish Mainport Holdings in 2020. Engineers worked on two Niigata 6L28BXE main engines on board 37-m tugboat Celtic Rebel. This saw the removal and inspection of two units, overhaul of the fuel injection equipment and 12,000-hour overhaul on two NHP30 turbochargers.
Royston also reconditioned two Cummins KTA38 propulsion engines on board tugboat Mainport Kells in 2020 before it was sold to French owners, replacing 12-cylinder heads with service exchange heads as part of the 50,000 running hours service of the main port engine.
Royston engineers also reconditioned two Bergen KRM9 main engines on board 66-m offshore support vessel Ocean Spey as part of a planned maintenance programme. This was during refurbish docking of this 2000-built vessel in Cork Dockyard, Ireland.
The servicing involved the engines being disassembled to install overhauled cylinder heads, fuel pumps and injectors.
Valves, pistons and connecting rods, cylinder liners, bearing blocks and crankshaft were also checked, and essential repair and replacement work carried out before reassembly and inspection of the engines.
Yanmar unveils new vessel controls
Yanmar Marine International introduced new vessel control systems in November 2020 for its common rail marine diesel engines. Its VC20 controls single, twin and triple engine installations, with simplified electrical management and dedicated control modes.
It can control commercial diesel engines JH-CR, 4LV, 8LV and 6LY-CR series and Yanmar’s 2020-launched 6LF and 6LT powerboat engine line. It can also control Vetus bow thrusters. VC20 comes with joystick controls, JC10A for sterndrive applications and JC20A for inboard applications. It enables up to four helm stations networked on a multi-station configuration. VC20 displays can be synchronised and auto-dimmed for low light operations.