Cruise ships are the biggest and mightiest sea-going vessels available in the shipping industry at present. Unlike the cargo ships, these carry passengers for entertainment and transport across the water bodies. Hence, the common question of how much fuel does a cruise ship use arises often.
The primary requirement of these cruise vessels is passenger safety and engagement. In such conditions, their maintenance stoppages will be minimum and with high safety awareness.
Moreover, the tightening of regulation under Annex VI of MARPOL and IMO guidelines monitor these ships regularly. Any extra emissions can get them in trouble as they tour some of the most sensitive tourist destinations.
The size difference of these sailing giants also decides their fuel utility and efficiency. The biggest cruise ship at 360 meters long consumes almost double the fuel of an average vessel. Hence, fuel quality, grade, and engine efficiency are important for knowing how much fuel does a cruise ship use.
In the article, we discuss the consumption figures of these modern luxury sailing hotels. Moreover, we also consider the changes in the propulsion technology affecting fuel consumption and storage.
Factors Deciding the Fuel Consumption of Cruise Ships
A ship’s fuel consumption depends on several factors varying from its structure to carriage capacity. Meanwhile, cruise liners have only one cargo, with the highest value amongst all, the human life! To approximate an ideal fuel consumption outline, the crew accounts for several changes.
Cruise vessels mostly dwell around the coastal areas with occasional visits to the deep ocean. A major reason for this is that passengers want to indulge in the onboard and shore enjoyment together. Hence, once the vessel route comes through, the bunker estimations go underway.
This will include the port stays, sailing conditions, and carriage capacity too. If the engine department has information of rough weather, the same is taken into account for surplus bunkers.
Engine Generation and Consumption Characteristics
It becomes important for the crew onboard to know the engine characteristics. For example, a third-generation engine and its performance between eco speed to full load vary considerably. This means every engine will have a unique consumption chart depending on these characteristics.
Makers such as MAN B&W, Sulzer, Mitsubishi, etc. include these curves within their manuals. Since the cruise ships follow similar patterns of sailing without load variation, the calculations are steady.
Modern cruise vessels hit speeds of 22 to 24.5 knots during their international voyages regularly. This means their operation in the range of 85% load and above is quite frequent too. Under such conditions, the consumption increases more than 40% of the eco speed performance.
Meanwhile, sailing on the coastal edges mostly uses eco or low-speed movement. This means a balance of speed variation limits the excessive burning of fuel. It also makes sure the vessel complies with the emission regulations within the region.
The cruise ship draughts have a lesser variation in comparison to the cargo ships available. Hence, the load parameters do not necessarily depend on it but rather the weather conditions. With a relatively higher draught, the propeller performance varies significantly with the changing sea conditions.
This means the load parameter of the cruise ship will rather be a dynamic factor than static. Most owners always provide their ships with surplus bunkers for safe navigation under such conditions.
Ship Size and Construction
The size and construction parameters of the ship are static factors for its lifetime. These considerations are always present in the accounting of the engine performance too.
It means that a steady correction factor is available for the consumption chart concerning these points. Therefore, correcting the bunker figures with these coefficients will give the correct bunker values.
Propulsion Types and their Fuels for Cruise Ships
After considering the design and performance factors, the nature of propulsion is the next big step. The changing propulsion design and source decide how much fuel does a cruise ship use.
Conventional Diesel Propulsion
After the arrival of 0.5%, sulfur content regulation under MARPOL, diesel engines faces significant changes. The big reason for this change is the change in specific gravity of the fuel under usage in the engine.
Consumption of Fuel (Metric Tons) = Consumption of Fuel (meter cube) X Specific Gravity of the fuel
The blended oils and the VLSFO fuel have significantly less density, making its volume go higher. Hence, the bunkering team takes consideration of the same while fueling estimations.
The traditional cruise ships rely heavily on diesel (less than 0.1% sulfur) for their propulsion. The power system on board, including the generators and the boilers, also operate on this fuel.
In the electric propulsion systems, the main engine does not utilize any driving fuel. This lowers the consumption significantly in comparison to the standard diesel propulsion. The big sets of alternators produce the power that is useful to drive heavyweight electric motors.
Most electric propulsion cruise ships have a twin-screw or triple-screw propeller design. Hence, a reduction in load uses the propeller ability accordingly.
Shaft generators are also useful in lowering the consumption with the production of electrical power. This removes the auxiliary machinery out of the picture while sailing, reducing the fuel consumption.
To eliminate the demerits of diesel fuel, modern cruise ships are using LNG propulsion. The storage of LNG and its usage parameters differ from that of any other available fuels. Its higher calorific value also has a great effect on the fuel efficiency of the engines.
However, the LNG compatible ships have a trademark LNG engine onboard. Cruises with standard engines can’t burn this fuel for propulsion power. In addition, the refrigeration system and inert gas regulation change considerably with LNG as a bunker.
Consumption Figures for Cruise Ships
After considering all these factors, it is easier to understand how much fuel a cruise ship uses. While the individual ships differ on their size and design, generic figures will help you out.
Large Size Cruise Vessels
With all the above considerations, cruise ships over 300 meters in size consume 200+ MT of fuel. The figures at 85% and above load go as high as 235 to 250 MT of fuel per day. It includes the power generation system for the generators available onboard.
The boilers firing for steam generation also use the same grade of fuel. However, 80% of the fuel and more goes mainly into the propulsion of the ship.
The fuel consumption for such ships reduced to 150MT when operating in the eco speed range. Moreover, it goes down further when the vessel is manoeuvring near the visiting ports.
On average, these vessels go from 7.5 MT to 20 MT during the port stays. The significant difference also includes the passenger behaviour of visiting the shores, resulting in lower power usage.
Moderate Size Cruise Vessels
For cruises varying between 150 to 250 meters, the fuel usage goes down fast. This takes into account their short voyages as well as shorter port stays. These typical sizes range between 140 to 180 MT of their 85% and above rated loads of fuel consumption.
Hence, these vessels can give you speeds of 20 knots and more with such consumption. Meanwhile, like their larger sisters, the medium-size cruises also have manoeuvring requirements. Under such conditions, the fuel usage is lesser as well.
The consumptions drop to an average of 120 to 135 MT per day for loads between 60 to 85%. Moreover, the figure also goes below 100 MT if the vessel has a near-port drifting schedule.
Smaller Passenger Vessels
The declining trend continues for the passenger capacity and the size of cruises. It reflects in the fact that smaller passenger carriers typically use 100 to 120 MT of fuel.
The figures do not ascertain a consumption guarantee but reflect the observation trends. These trends include the calculation of Specific Fuel Oil Consumption for Power requirements. The highest consumptions go in the maintenance of 5- and 7-star facilities onboard for the passengers.
Specific Consumption for Energy Generation
The specific consumption of fuel for power generation at the European cruise terminals is available. It shows the fuel consumption per hour and the KW requirement for the port operations. These figures vary significantly at sea where all entertainment sources are driven by shipboard power.
Comparisons With Cargo Ships
Cruise ships consume a lot more fuel in comparison to the average cargo vessel. However, this stands as an exception to the large container ships that also have higher consumption limits. Therefore, this needs one to understand how much fuel a cruise ship uses and why it is relatively high.
Nature of Profit
Cruise Ships rely on passenger pleasure for their profit and turnover. Hence, the power requirements onboard ships are extremely high and diverse in usage. This needs multiple auxiliary engines and power systems for the upkeep.
The consumptions are even higher than a standard 5-star hotel on land. Hence, the power generation fuel requirements onboard cruises are almost 10 times a standard bulk carrier. This also includes auxiliary services like steam generation and boiler operations.
A traditional tanker or bulk carrier has long-distance voyages with steady speed. These values range between 12 to 14 knots, with delivery dates and design considerations being important.
The same does not stand true for cruises and container ships, where speed is of paramount importance. These beasts move as fast as 24 to 26 knots at a given time. With such high speed, the specific fuel oil consumption goes way over the bar.
It also means a large amount of energy is important to maintain these speed and power requirements. Hence, the fuel consumption almost quadruples itself than a standard bulk vessel.
Fuel Storage on Cruise Ships
Cruise Ships rely heavily on their external appearance to attract more people towards them. This restricts the fuel storage options for the crew on board the ship and its monitoring too. These factors also account for the safety of the passengers under operating conditions.
The cruise ships have a bottom-heavy design when it comes to bulk fuel storage. However, the tanks are not cumulative but distributive across the length. This accounts for the dynamic stability and also uses less space for higher passenger capacity.
Monitoring of fuel levels across all tanks is important for these ships for regular updates. In addition, the hectic nature of work and safety aspects need mandatory remote gauges on each tank. All these gauges direct back the readings to the control room for the engine crew monitoring ability.
Settling and Service Tanks
Very rare do cruise ships rely on the fuel of lower quality for power generation. This means the purpose of the settling tank is to mostly separate water (if any) from the standard diesel fuel. The general bunkers for cruise vessels are high-quality and expensive to adhere to the coastal regulations.
The service tanks provide a direct inlet to the propulsion engine or generator engine. The supply system has fine filters, temperature regulating elements, and other fine instruments.
Since bunkering mostly proceeds before the voyage or during port visits, safety remains important. Moreover, the nature of cruise ships makes them even more aware of the possible hazards. The LNG bunker uses the standard coupling at the selective terminals available globally.
Cruise Ship Fuel Usage
With such changing fuel consumption patterns, cruise ships use a high share of fuel in shipping. The changing regulations are also dictating the adaptability of these ships to use electric propulsion. Modern vessels also use dual propulsion, using both electric and fuel resources.
However, the changing market is shifting fast towards the LNG sources for propulsion. Therefore, the vast spread of terminals for LNG refuelling will considerably reduce these figures for the cruise liners.
The use of LNG will drastically change the question of how much fuel does a cruise ship use. It reduces the specific consumption figures for power generation at sea from 0.30 to 0.15 kg/kWh. Hence, the evolving fuel option produces a cleaner and cost-efficient alternative to the cruise industry.
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- Engineering Department Onboard Cruise Ships: A Detailed Guide
- Video: Why Are Cruise Ships White?
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