Types of Fuel Used by Cruise Ships: From Heavy Fuel Oil to Liquefied Natural Gas

Cruise ships have traditionally relied on various types of fuels, primarily marine diesel oil (MDO) and heavy fuel oil (HFO). However, as environmental regulations have tightened and concerns over sustainability have risen, many cruise lines are now exploring alternative fuel options such as liquefied natural gas (LNG).

Traditional Fuel Types

One of the most common traditional fuels used in cruise ships is marine diesel oil (MDO), which is a blend of fuel oil and diesel fuel. MDO is favored for its relatively low sulfur content and good efficiency. Another fuel used by cruise ships is heavy fuel oil (HFO), which is thicker and less refined than MDO. HFO is a cheaper option but has a higher sulfur content, leading to increased emissions and environmental concerns. Many cruise ships have been transitioning away from HFO due to regulatory pressures.

New Developments: Liquefied Natural Gas (LNG)

In recent years, some cruise lines have started to explore alternative fuels such as liquefied natural gas (LNG). LNG is produced from natural gas and is known for its lower emissions and greater environmental friendliness. According to the Cruise Line International Association, 63% of ships on order from January 2024 to December 2028 are expected to be powered by LNG. This shift towards LNG is driven by both regulatory requirements and the growing demand for cleaner energy sources.

Why Gasoline or Petrol is Not Used

Gasoline (petrol) is not typically used in large cruise ships due to several factors. Firstly, the costs of storing and maintaining gasoline are higher compared to other fuel options. Additionally, gasoline is less stable and has a shorter shelf life than other fuels, which makes it less practical for long-term use on a large vessel. Safety is also a significant concern, as gasoline is highly volatile and explosive, posing a higher risk of fire and explosions compared to diesel.

The traditional practice is to use number-6 bunker oil (also known as heavy fuel oil) or simply heavy fuel oil for large ships. Diesel oil is also commonly used. These fuels are challenging to burn, especially the heavier oils, which makes them safer to handle and store. Diesel engines require fuel oils for lubrication, which is an additional factor to consider.

Special Regulations and Considerations for Fuel Usage

There are specific regulations for the sulfur content of fuels used in shipping. Heavy fuel oil with a sulfur content of less than 0.5% is required globally, while less than 0.1% is required in restricted or special areas like SECA (Sulfur Emission Control Areas) or ECA (Emission Control Areas).

Moderate and high-speed diesel engines in cruise ships are typically designed to use heavy fuel oil and diesel oil, regardless of whether they are two-stroke or four-stroke engines. Cruise ships are generally fitted with medium-speed diesel engines, which are specifically engineered for these types of fuels, ensuring efficient and reliable operation.

Conclusion and Future Outlook

As the industry continues to prioritize sustainability and environmental responsibility, it is likely that the use of LNG and other renewable energy sources will increase in the future. The 'chicken and egg' problem linked to the availability of suitable petrol-fuelled engines and the associated safety concerns will likely drive the ongoing transition towards cleaner and safer fuel options.

Given the current trends and the increasing demand for eco-friendly shipping, it is essential for cruise ship operators to continue exploring and adopting alternative fuels. This shift not only helps address environmental concerns but also aligns with the evolving expectations of consumers and regulatory bodies.