There is no single solution – no miracle solution – that will reduce energy demands dramatically on cruise ships tomorrow, according to the classification society experts and cruise line executives interviewed by Cruise Industry News. Instead, the cruise lines should be looking at fuel savings from many aspects and work out their own best models. With the proper approach, savings of up to 30 to 40 percent can be reached.
Speed Equals Fuel “If you increase speed, fuel consumption goes up,” said Andrea Cogliolo, technical sector manager at RINA. “Diesel-electric ships are usually designed to operate at about 20 knots,” be said, “but the last two to three knots require nearly full power. If you reduce the medium speed of your fleet, you can reduce fuel consumption significantly. It comes down to good planning.”
There is more to gain looking at operational aspects than throwing money at new technology , according to Arne Haueng, principal consultant and energy management practice manager at Det Norske Veritas. “Besides,” he said, “the demand for certain ship types is so great today that many yards have no choice but to use yesterday’s technologies to build faster and (for them) more profitably. As a consequence, a substantial number of ships being built today are constructed with ‘old’ technology,” he said.
Ship management, however, has traditionally not been very focused on saving fuel, according to Haueng, so their efforts often end up falling short of the initial objectives. He mentioned the increased use of silicone hull paint as one example. “Companies are willing to spend three to four times more on silicone anti-fouling paint, but they are rarely able to document the savings,” he said. “When other variables are added, including the condition of the propeller, wind and current, how do they know if the paint is really contributing to saving fuel?”
Another example of investments that may not be optimized is expensive weather routing equipment, which Haueng said is often only used at 20 to 30 percent of their functionality.
“If you can manage the technical side better and monitor fuel consumption as well as retrofit new technology, there are savings to be had on all ships,” said Zabi Bazari, technical manager of ship energy and marine consulting services at Lloyd’s Register. More savings can be gained by reducing the amount of fuel that is “lost” as sludge, which is usually from 0.8 to 1 percent, Bazari said.
All machinery should be looked at, according to Bazari, who noted that ships often run two or three units for redundancy, while one might do the job. The different engine manufacturers produce powerplants that are similar, according to the classification societies, usually within a 1 to 3 percent difference in fuel consumption. Over time, fuel consumption and maintenance costs tend to be same.
Meanwhile engine room automation systems are designed for the safety of the ship first and foremost and only secondarily for achieving energy savings, according to Cogliolo. Thus, the systems are geared to run three engines instead of two, he said, and while fuel usage is monitored, fuel efficiency is not – up to now no one asked for it, he added.
Another factor that plays in is environmental concerns. “If you reduce the combustion temperature you reduce the amount of NOx generated, but you also reduce the efficiency of the engines, which means they need to burn more fuel,” said Cogliolo.
And on the hotel side, he said significant savings can be obtained from the HV AC system and lighting. HV AC consumes some 40 percent of the hotel load, Bazari said, and is typically not very efficient, consisting of hundreds of fans and treating the air by cooling it down, taking out the humidity and beating it up again to an acceptable temperature.
Future
Work is underway on fuel cells with a 500 kW test project, but it will take another five to 10 years before a cruise-ship application will be financially attractive, according to Dr. Pierre Sames at Germanischer Lloyd. “In pure economic terms, a fuel cell bas higher energy efficiency than a diesel engine,” he said. “In the future, the fuel is not likely to be hydrogen. Instead it can be a gas or a liquid synthetic fuel. We obviously know how to handle liquid fuels aboard ships. Pressurized gas tanks, however, are difficult to design into a ship environment.”
Solar power may be less attractive, at least for the foreseeable future. “Solar applications can presently produce 150 watts per square meter,” said Sames. “Even if you covered an entire large crude carrier with solar panels, you would only produce 2.5 MW.” Nuclear power is attractive from a price point of view and ice breakers and submarines have been operating incident free for a long time, be said. One problem is public perception among passengers; another is the fact that few ports allow nuclear-powered ships to dock.
Trade Off
“We have energy savings and development teams in place both on the corporate and brand levels,” said Micky Arison, chairman and CEO of Carnival Corporation. “We have done whatever we can to minimize fuel consumption and will do more over time. We have discussed everything, including studying a wind-power concept.”
According to Richard Fain, chairman and CEO of Royal Caribbean Cruises, there is no silver bullet. “We have looked at fuel cells and different kinds of diesel engines,” he said, “but have not seen anything that would be viable in the near term.”
As for efforts to reduce fuel consumption, there is always a trade off, Arison said. “For instance, you can design a ship to be more aerodynamic, but lose earnings power. You can also consume less fuel by just going to one port and staying there. But if you cannot sell the cruise, it does not do you much good.”
