Shipowners face a breakneck round of retrofits to incorporate a new generation of clean-fuelled engines
The Bremerhaven ferry earns its keep plying the route across the Weser River in Germany for 16 hours a day, seven days a week. Carrying 900,000 passengers and many vehicles a year, the ferry connects the seaside city of Bremerhaven and the town of Blexen; both lie on the edge of the North Sea, an environmentally sensitive area.
After 20 years of reliable service, in late 2019 the ferry’s engines were replaced with two new MTU Series 4000 units – the 8V4000M63 system delivering 850 kw of power. The Bremerhaven’s sister ship, Nordenham, has already been retrofitted with the same engine.
The old engines were not so much worn out as outdated. Their replacements are synthetically fuelled to comply with the increasingly stringent requirements of the local authorities. Obtained from natural gas, the fuel is known as gas-to-liquid (GTL). It contains fewer carbon compounds and is richer in oxygen than conventional diesel; the result is less CO2 released during combustion.
“That is a big plus for local emissions,” says Jörg Stelter, chief operating officer of the ferry company Weser Fähre, noting fuel consumption is the same as for normal diesel and the engines do not require extra modifications.
According to MTU sales engineer Christian Prinz, the fuel has other virtues. “The maintenance requirements of these propulsion systems are potentially lower because GTL burns more cleanly,” he says. “Given the number of operating hours, this is an economical argument as well as an ecological one.”
Along with the retrofit, the ferries were equipped with MTU’s automation system, Blue Vision, that manages the operation of the propulsion system.
The OECD’s International Transport Forum (ITF) would approve of this and other retrofits that are either in progress or planned for the world’s hard-working ferries, many of which operate in highly populated, environmentally sensitive areas. As the organisation noted in its latest report: “Using only currently known technologies, [the industry] can already eliminate annual shipping CO2 emissions equal to those of 185 coal-fired power plants.”
And cleaner-fuelled engines are a big part of these known technologies. As the ITF explains: “Alternative fuels and renewable energy can deliver much of the required reductions [and] advanced biofuels are already available, albeit in limited quantities.”
In a slap on the wrist for IMO, the ITF believes the organisation should take concrete steps to increase the use of greener fuels. “Incentives for promoting the uptake of alternative fuels deserve more attention,” it argues. “For the moment, discussions at the IMO focus mostly on measures to make ship design and the operation of vessels more energy efficient [but] working out effective mechanisms to accelerate the transition to alternative ship fuels should be pursued in parallel.” And the ITF singles out the importance of low-carbon fuel standards along the same lines as those already applying in road transport.
Under pressure from organisations like the ITF and local authorities such as those in Bremerhaven, the industry faces a busy decade or more of emissions-mandated retrofits. As engine manufacturers fall over themselves to produce Tier 4-compliant power packs and related cleaner technology, ship operators will find themselves obliged to seize every opportunity to make their vessels more environmentally friendly.
ICE is nice
For the foreseeable future the internal combustion engine (ICE) will be the way to go, predicted Wärtsilä in a late-2019 white paper entitled Synthetic fuels: supporting Wärtsilä’s vision of a 100% renewable energy future: “If the industry really wants to address emissions, the consensus is that the internal combustion engine still offers the most realistic emissions-reduction potential.”
The compelling argument for ICE propulsion is that the infrastructure already exists to support it, which dramatically cuts the cost of environmental compliance. This would tip the scales in favour of LNG. According to Wärtsilä’s long-term vision, a “defossilised future” could see fossil-fuel LNG eventually being replaced by bio-LNG and finally synthetic LNG, thus making the most of the current infrastructure that has developed over the last decade.
Wärtsilä calculates that the cost of synthetic LNG in 2030 would be the same or less than that of competing alternative fuels. “This, combined with the world’s decade-long experience with marine LNG fuel, makes it a safe and reliable bet,” the study says. “Bear in mind that other alternative fuels would take between 10 and 20 years to be accepted by marine classification societies, not to mention the time required to develop infrastructure and bunkering facilities.”
A fact that is often forgotten in the enthusiasm for alternative propulsion systems is the all-round capability of ICE power packs. As Wärtsilä points out, they have the flexibility to burn most combustible substances. And they are growing cleaner almost by the month. Although methane leakage during production and combustion remains a bugbear with LNG – because methane is 28 times more potent than CO2 – a lot of companies are working on it.
Unveiled in late 2018, the Wärtsilä 14 firmly belongs in the new generation. “The market is rapidly changing,” says Janne Klemola, product director for Wärtsilä Marine. “And customers demand that we maximise the overall performance of the whole solution, improve safety and advance environmental sustainability.”
Developed from the outset in collaboration with Switzerland-based Liebherr Group, which specialises in land-based large engines, the Wärtsilä 14 could be described as a petite powerhouse. Extremely versatile, it comes in 12- and 16-cylinder configurations, with a power output between 755 and 1340 kwm in mechanical propulsion and 675–1155 kwe in auxiliary generation and diesel-electric propulsion.
“There is a huge business potential for such an engine in this power range,” judges Mr Klemola, citing tugs, fishing boats and smaller seagoing vessels. But the engine is also designed to add auxiliary power for merchant ships like container carriers or tankers – in short, any vessel that requires small high-speed, environmentally compliant power packs.
Wärtsilä’s own HY Tug 40 is an example. Using cleaner fuels at the lower end of the power range, the shallow-draft tug is installed with two of the engines, plus a hybrid propulsion system that delivers flexible operating modes, such as one for zero emissions.
“The industry is moving towards cleaner and lighter fuels, so the time is right for the high-speed Wärtsilä 14,” Mr Klemola says. “One major innovation is the digital fuel injection system, which is optimised to operate on marine distillate fuel oils.”
Looking ahead, within a decade the ultimate retrofit for a vessel at work today may be an engine that can run on bio-LNG. This is because bio-LNG can be produced from practically any kind of feedstock, including manure and forest residue in an example of the circular economy at work. When bio-LNG comes available in volume, ICE-based propulsion will have yet another lease of life.
Meantime, Wärtsilä says: “Today, the combustion engine with LNG is the only way to put a real dent in GHG emissions.”
Rapid refits are standard practice
The research vessel Polarstern, flagship of Germany’s Alfred Wegener Institute, is once again conducting research of global importance in the Arctic after being given a new lease of life following the kind of rapid-response retrofit that is becoming standard practice in the low-emission era.
The entire retrofit, which required the installation of two sets of shaft generator systems, was completed in 2018 and took just eight weeks. Both of the systems were assembled inside the vessel to minimise downtime and, to speed things up, some of the smaller projects were done at sea.
Retrofits on older vessels require careful planning, explains Wärtsilä’s Nam Nguyen, project manager for power conversion in Hamburg: “The project was planned in close contact with the customer in order to optimise the delivery time as well as shorten the commissioning phase.” It was Wärtsilä’s first installation of a 660V direct front-end converter application for a shaft generator without a transformer.
In January 2020 the vessel was engaged in research of the Arctic ecosystem.
New fuels drive shift to better engines
The emergence of a new generation of fuels will drive future engine retrofits, as authorities tighten regulations on emissions, particularly in environmentally sensitive areas. As the virtues of fuels that are variously called bio, synthetic or zero-carbon become increasingly apparent, ship operators will be under pressure to install power units specifically designed to run on them.
“There is a growing consensus that synthetic fuels are set to play an important part in mitigating climate change,” explains Wärtsilä’s senior manager for power-to-x, Tommi Rintamäki in a definitive study entitled Synthetic fuels: supporting Wärtsilä’s vision of a 100% renewable energy future. “What makes the possibility of generating fuel from excess CO2 such a compelling prospect is that it has the potential to create a circular carbon economy,” he says.
And because some types of synthetic fuels are already available, the clear implication is that the much-maligned internal combustion engine has many years ahead of it.
California’s Water Emergency Transportation Authority (WETA), which operates in the environmentally sensitive waters of San Francisco Bay, illustrates where things are heading. “Our ferry routes require high-speed, efficient and reliable operation with high-capacity vessels that meet the most stringent emission standards in the nation,” says WETA executive director Nina Rannells.
Thus, WETA opted for the kind of engines that will become de rigueur in the retrofit era. In early 2019, the company’s 44-m catamaran ferry Pyxis entered service with two Tier 4-compliant MTU engines from MTU’s Rolls-Royce series that meet the standards of the Environment Protection Agency (EPA). Both are scrubber-fitted, Series 4000 field test units that emit lower NOx, particulate and hydrocarbons. The 16-cylinder engines deliver 2,560 kw of power at 1,800 rpm. Maximum speed is 34 knots. Another ferry, Vela, was refitted in August and Lyra will get one of the new engines in early 2020.
In yet another example of the incremental improvement that manufacturers are making in climate-friendly engines, the Rolls-Royce units represent the latest advances in turbocharging, combustion and fuel injection that, combined with the scrubber system, slash 75% off NOx emissions compared to the outmoded EPA Tier 3 standards.
Until there is a widely applied Tier 5 standard, this type of internal combustion engine could be the future.