LNG is proving popular within the cruise sector and fuel-cell tests are returning favourable results; despite this, more scrubber retrofits are expected post 2020
The use of alternative fuels and methods of propulsion are quickly growing within the cruise sector as the 2020 low-sulphur cap draws near and efforts to decarbonise the maritime industry increase.
Carnival Corp has introduced its LNG-propelled AIDAnova – the first cruise ship to be propelled by LNG – and this will soon be joined by new LNG dual-fuelled vessel Costa Smeralda.
Discussing these vessels, Carnival senior vice president maritime affairs Tom Strang explains: “The LNG system of Costa Smeralda is almost identical to AIDAnova, which was delivered at the end of last year and whose operational experience has been excellent.”
Like AIDAnova, the intention for Costa Smeralda is to run continuously on LNG, says Mr Strang. Marine gas oil is deployed as a back-up in case the LNG supply chain is disrupted and to meet safe return to port requirements. It is also deployed as the pilot fuel for the LNG, but less than 1% is used.
Mr Strang says: “Our operational experience to date would say that it is up in the very high 90s in terms of percentage of time running on LNG. On occasion the engines switch to MGO, but generally speaking this is very infrequent and there are times that we have to burn MGO to move it through the tank system.”
Costa Smeralda features three type C LNG tanks, four dual-fuel MaK/Caterpillar engines and has been fully designed in accordance with the IGF code.
“While she is quite typical of the design of LNG-fuelled vessels you are seeing out there, she is a little bit different because of the use of the three tanks,” says Mr Strang. He explains this number was chosen because of both the space available and also the capacity of LNG required (3,600 m3).
Mr Strang adds: “She will normally operate at 0.7 bars and the safety valves will lift on the tanks at 4.5 bars. The biggest challenge when it comes to LNG-fuelled vessels is integrating the tank design, piping and bunkering into the ship.”
Caterpillar/MaK worked with the Meyer Turku shipyard to develop the LNG system. Mr Strang says: “Meyer had the capability to build the tanks and these were built in the Rostock yard, where the middle section of the ship was built.” The shipyard has built tanks before for LNG carriers and, says Mr Strang, has the necessary expertise and experience.
The ship will be bunkered ship-to-ship. Carnival Corp entered into a strategic partnership with Shell in 2016 to develop bunkering for both AIDAnova and Costa Smeralda. Costa Smeralda will be bunkered in Barcelona every two weeks, as it will be on an itinerary in the western Mediterranean.
Mr Strang says: “The whole bunkering process is similar to bunkering for conventional fuels, but because it is new to the industry and ports, there is a lot more oversight provided. Together with our bunker supplier Shell, we have developed a full risk mitigation process.”
He says that Carnival Corp is using a standard bunkering system on board, with hoses connecting the bunker vessel and cruise ship.
One notable challenge the team had to overcome involved the large overhanging lifeboats on the cruise ships. Mr Strang explains: “With conventional coastal-type LNG tankers that are being converted into bunkering operations, we do have some challenges with the lifeboats and need to use a pontoon between the ship and bunker vessel.”
The operational experience being gained from AIDAnova is important as Carnival Corp has 10 LNG-fuelled ships on order, while LNG-fuelled vessels make up some 44% of the global cruise ship orderbook.
Mr Strang sums up: “As we move forward on the decarbonisation journey, we see LNG particularly and then maybe liquid bio-methane becoming increasingly part of this pathway.”
Alongside alternative fuels, scrubbers are a popular choice among the cruise ship sector. The DNV GL Alternative Fuels Insight database shows that, overall, the number of ships with scrubbers installed in service or on order quadrupled to 3,021 this year compared to 2018. Out of the 3,756 ships with scrubbers in service or on order heading into 2020, nearly 10% are passenger ships, including ropax vessels and cruise. Some 10% of the passenger ship fleet will have scrubbers, while the corresponding figure for all ships is likely to be nearly half of that.
Big cruise companies Carnival Cruise and Royal Caribbean have both installed scrubbers in their fleet and Exhaust Gas Cleaning Systems Association chairman Nick Confuorto says in terms of net scrubber installations, while container ships may lead, in terms of coverage within the fleet, passenger ships are number one.
Being early adopters, the scrubber retrofit market among passenger vessels may have run its course for the time being, while the newbuild market is expected to hold its ground. Indeed, Mr Confuorto confirms retrofit orders from big companies have started to taper off.
But this could change; scrubber suppliers predict that once the price of low-sulphur fuels stabilise in the market, the payback period for scrubbers will turn out to be lower than expected. This would spur another wave of scrubber retrofits, including in passenger ships. "For cruise ships specifically, there are plenty of new orders to be won,” says Wärtsilä’s director of exhaust cleaning Sigurd Jenssen. “Opportunities still exist for retrofit projects, since some companies have been waiting until the very last moment to decide which option suits them best."
Piloting a world-first fuel-cell system
Carnival Corp’s AIDA Cruises brand is to pilot the world’s first fuel-cell system designed to power large passenger vessels.
As early as 2021, AIDA Cruises will trial this technology on AIDAnova, becoming the cruise industry’s first brand to trial fuel cells on a large cruise ship.
The research project, named Pa-X-ell2, is designed to develop fuel cells powered by hydrogen derived from methanol, with the potential to supply power to cruise ships at even lower emissions levels than LNG. Designed by Freudenberg Sealing Technologies, the fuel cells are expected to have a longer lifecycle than those currently being developed for automobiles, with early trials on land showing a lifespan of over 35,000 operating hours.
Funded by Germany’s Federal Ministry of Transport and Digital Infrastructure, the Pa-X-ell2 research project will include AIDA Cruises, represented by Carnival Corp’s Hamburg-based Carnival Maritime GmbH, Freudenberg Sealing Technologies, and the Meyer Werft shipyard, among other partners.
The brand recently signed an agreement to install a first-of-its-kind lithium-ion battery power system on its AIDAperla ship in 2020. This will be the world’s largest battery storage system on a passenger ship, capable of generating a total output of 10 MWh to help electrify the ship’s propulsion and operation.