The cruise industry, in fact the maritime industry as a whole, is at a crossroads as environmental concerns drive global regulations and the search for cleaner and more sustainable fuel alternatives.
Today, the incumbent fuel used by an overwhelmingly vast majority of ships is heavy fuel oil or marine grade diesel oil. If you heat your house with an oil burning furnace, the oil used there is similar but the marine grade is even darker and thicker.
One solution that’s gaining momentum is the adoption of liquefied natural gas (LNG), more specifically what’s known as ‘methane’, as a ship’s fuel. In this blog post, we’ll delve into the world of LNG as a maritime fuel, exploring its benefits, challenges, and its potential to reshape the industry’s ecological footprint.
LNG: A Clean and Viable Alternative
Liquefied natural gas, or LNG, is a clear, odorless liquid created by cooling natural gas to around -162°C (-260°F). This process reduces its volume by about 600 times, making it far easier to store and transport.
When used as a marine fuel, LNG brings several environmental and operational advantages.
LNG produces far lower emissions of sulfur oxides (SOx), nitrogen oxides (NOx), and particulate matter compared to conventional marine fuels. This means cleaner air, less environmental harm, and progress toward global emissions reduction goals.
It also has a smaller carbon footprint. While not zero-carbon, LNG generates fewer greenhouse gas emissions thanks to methane’s lower carbon-to-hydrogen ratio, resulting in less CO₂ when burned.
For ship operators facing increasingly strict emissions regulations from the International Maritime Organization (IMO), LNG’s cleaner profile makes it an attractive compliance option.
There’s even a bonus benefit—LNG-powered engines tend to run more quietly than traditional engines, leading to calmer, quieter operations at sea and in port.
While LNG cuts emissions, it’s not 100% carbon-neutral. Methane leaks (or methane slip) can occur throughout its lifecycle, especially in older or low-pressure engine systems. Depending on engine and handling, this can diminish the climate benefits. It’s why newer ships have a few additional skinny funnels built into their superstructure now.
Infrastructure Challenges and Investments
The transition to LNG as a maritime fuel isn’t without its challenges. One significant hurdle, in my opinion the largest single factor, is the need for a robust LNG infrastructure. This includes LNG bunkering facilities at ports to provide ships with the necessary fuel supply. While some major ports around the world have started to develop LNG bunkering infrastructure, further investment is required to ensure widespread availability.
In the United States, where a vast majority of ships currently bunker (the maritime term for ‘to refuel’), there are certain rules regarding the vessels that would be used to transport the LNG from refinery to ship. Each ship requires around 3,000m3 per ship, roughly every other week. In recent years, the United States has emerged as one of, if not the (depends on the year), producers and exporters of LNG. Therefore reliably procuring the quantity required won’t be a challenge. The challenge comes from the lack of specialized ships that can carry this super-cooled, highly-pressurized product. Unfortunately the thousands of US-built barges already out there can’t be retrofitted with the equipment to store LNG. New ones had to be built.
Additionally, the retrofitting or construction of the cruise ships themselves to accommodate LNG fuel systems involves significant upfront costs. However, these costs may be offset by potential fuel savings over the long term, as LNG prices are generally more stable than traditional marine fuels, which are subject to fluctuations in global oil markets.
Innovation in Maritime Engineering
The adoption of LNG as a ship’s fuel has led to innovation in maritime engineering and vessel design. LNG-fueled engines require modifications to accommodate the fuel’s specific properties, such as its lower energy density compared to conventional fuels. Dual-fuel engines, which can switch between LNG and diesel, offer flexibility and redundancy in fuel supply.
Some LNG-powered vessels also incorporate advanced technologies like re-liquefaction systems, which allow the ship to utilize boil-off gas (the gas that vaporizes from the LNG) as an additional source of fuel, maximizing energy efficiency.
A Glimpse into the Future
The growing interest in LNG as a maritime fuel signals a positive shift toward cleaner and more sustainable shipping practices. As the industry continues to evolve, advancements in LNG technology, infrastructure development, and collaboration between stakeholders will play pivotal roles in ensuring its successful integration.
While LNG presents a promising pathway to reducing maritime emissions, it’s important to recognize that it’s just one step on the journey toward a carbon-neutral shipping industry. Continued research, investment, and the exploration of alternative fuels and propulsion technologies will be key to achieving the ultimate goal of a greener and more environmentally responsible maritime sector.
In the end, the adoption of LNG as a ship’s fuel is not just a technological advancement; it’s a commitment to safeguarding the oceans, the air, and the communities that depend on a thriving maritime industry.