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Carnival Mardi Gras will be one of the first ships sailing in the United States to use LNG fuel.

There are a lot of topics related to efforts that the cruise industry is making to "go green" and while some such as banning straws and single-use plastics are easy ... the fuel that runs these giant ships is not so clear. While there are currently no LNG or hybrid-powered ships planned for service on the west coast currently, we are home to four environmentally sensitive areas that are playing a global leadership role with reducing greenhouse gas emissions on cruise ships. This includes Alaska, Hawaii, California, and British Columbia who led the way by mandating the use of scrubbers and are now progressing to improve on that as well.

Ultimately, that's one reason why west coast cruises can be significantly more expensive than Caribbean ones but personally I feel like the effort and expense is a positive one.

Fundamentally, all cruise ships today burn fossil fuels in a diesel engine that generates electrical energy to power the ship. This includes the propellers, lights, casino games, and even the environmental systems such as desalinization. In the past, cruise ships, like freighters used Heavy Fuel Oil (HFO) because it is as much as 30% cheaper compared to alternatives. Most cruise ships still do in various parts of the world, though many use a blend in their diesel engines. HFO - also referred to as bunker fuel in it's lowest quality form, is terrible for the environment but it is cheap, stable, and plentiful. It is essentially a tar-like byproduct of what remains after other petrol products are removed during distillation such as kerosene, diesel, and gasoline.

While California has mandated since 2009 that ships operating within its territorial waters use Marine Gas Oil (MGO) and scrubbers to further reduce emissions - the need to improve continues to accelerate. The cruise industry is now looking to the future for what will ultimately replace HFO as well as MGO. Unfortunately, the answer isn't an easy one.

To add an additional layer of complexity, unlike your personal automobile, a vehicle that Americans typically hold on to for between 4 and 7 years - a cruise ship can operate for 30-50 years if maintained properly. Additionally, the research and design phase for new cruise ships can take five or even more than 10 years before it finally floats out from the shipyard. Unfortunately, that means that technologies we consider cutting edge today - might have only been a dream when the ship's design phase began. It also means that decisions on what fuel to use and when to switch to something new like LNG will have an impact on the environment for decades to come.

One of the biggest issues with cruise ships - just as it is with cars is emissions of Green House Gasses. These are the compounds such as methane and carbon that ultimately help trap heat in the atmosphere and are contributing to the warming trend that we refer to as "climate change". While certainly there are lots of other environmental topics of importance to the cruise industry, this is certainly the biggest. 

Out here on the West Coast, we are privileged to have some of the world's most sensitive marine environments. This includes Alaska, Hawaii, and the Sea of Cortez. Unlike other parts of the world where the cruise industry has more leeway, Canada and the United States - California especially is taking a leadership role with reducing emissions and making cruising more environmentally sustainable. Ultimately though there are now tough world-wide regulations that will impact the industry no matter where the ships happen to be.

Everyone that I speak with about this topic agrees that Heavy Fuel Oil is a bad choice for the environment. While some vessels have switched over to lighter fuels, most large cruise ships have chosen to mitigate some of its impacts today by installing scrubbers. 

What Are Scrubbers on Cruise Ships?

Essentially, scrubbers being used on cruise ships help reduce emissions of sulfur and other pollutants released by the combustion of HFO so that they can be disposed of, rather than blown out into the air. The United Nations has enacted legislation that went into effect this year mandating a reduction in sulfur emissions to 0.5%. While the shipping industry is switching over to lighter fuels, most cruise lines chose to install scrubbers as a "cheaper" alternative. Installing scrubbers still represents a $5 million or more investment per ship, so cheap is a relative term. Carnival Corporation goes more into how these work on its Advanced Air Quality Systems website. They estimate that by the end of 2020, AAQS Systems (scrubbers) will be installed on 85% of its fleet.

States such as Hawaii and California though have enacted legislation that bans the use of scrubbers as a means to offset emissions from HFO. Instead, ships must use low-sulfur fuels such as MGO or LNG while in California and Hawaiian territorial waters. Other regions have enacted similar laws, as well as regulating how, if, and where vessels may discharge washwater from exhaust gas scrubbing. This helps reduce the opportunity for ship operators to simply shift from dumping sulfur into the air and instead dump it into the water.

So, while cruise lines have a technological solution for the short term in most areas, ultimately the solution is to find a new fuel source.

Alternative Fuels For Cruise Ships - LNG Leads The Way

Just like with the automotive industry, alternative fuel options is a hot topic for cruise ship designers. Most look forward to the day when Hydrogen Fuel Cell technology and other zero-emissions technology is practical at scale. Unfortunately, while hydrogen fuel has a very clean combustion process the creation of hydrogen for use in a vessel as large as a cruise ship still requires massive amounts of energy, the costs are prohibitively high, and most of the ports don't have refueling facilities available.

This leaves us with an intermediate step of what to use now, while hydrogen research continues.

Some cruise lines have been very vocal about their views and ultimately their choices. For instance, Viking's Founder and CEO Torstein Hagen expressed his thoughts very clearly during an interview recently talking about the new Viking Expeditions ships and why they chose MFO over LNG. In his perspective, LNG is only a short term solution and while it virtually eliminates carbon, the methane given off is a worse greenhouse gas than carbon dioxide. Instead, he prefers that Viking focus on engine efficiency resulting in reducing overall fuel consumption and long term solutions such as hydrogen. Other cruise lines such as Carnival Corporation (owner of nine different brands) are going "all in" on LNG or Liquified Natural Gas.

This fuel is extracted during petroleum and coal operations and then chilled to -260 degrees so that it can be transported in liquid form. It is safe to transport since the fuel can only burn when mixed with small amounts of air, and that also means the risk of spillage is less of an issue than oil in terms of water pollution. Large ports such as those in Los Angeles, Long Beach, and Tacoma already have LNG facilities for freighters though not for cruising. Port Canaveral and Miami's new Cruise Terminal F, however, will be ready for LNG powered cruise ships.

Currently, there are more than 9 ships on order and two already in service that will be powered by LNG from Carnival Corporation, including the Carnival Mardi Gras. Mardi Gras will be the first LNG-powered ship in North America.

Hurtigruten's new vessels will be a combination of LNG and battery-powered, plus they are converting other ships as possible so that their entire fleet will be hybrid-powered by next year. Other lines including Royal Caribbean, TUI, Disney, MSC, Norwegian Yacht Voyages, and Ponant also have LNG ships on order. In a 2018 interview though, Norwegian Cruise Line's Present Andy Stewart said that their new Project Leonardo class ships will not be using alternative fuels.

The challenge with LNG is that it is a transition fuel and ultimately not the solution for eliminating the significant negative impact that cruising has on the environment. The problem is that with today's LNG combustion technology for marine engines, is that about 2% of methane does not burn during combustion. Instead, it passes into the atmosphere. As a greenhouse gas, methane is approximately 30 times more potent in trapping heat in the atmosphere than CO2. While work is being done to make LNG-powered engines more efficient, this number looks sensational and offsets the carbon reduction benefits.

LNG Is a Transition Step; Not All Greenhouse Gasses Are Equal

Ultimately LNG as a fuel source is a transition step that some companies will choose to take - while others wait and see and then make a change in the future. However, even though companies such as Carnival are aggressively promoting the benefits of LNG, it is clear that they understand this isn't the end of the discussion. Additionally, while LNG certainly has significant benefits compared to HFO, the issue of methane remains. I talked with Carnival Corporation's Tom Strang - SVP of Maritime Affairs and a LNG expert about this last week and he shared an important fact that is sometimes ignored.

While carbon and methane are both released into the atmosphere and they are both greenhouse gasses, methane stays in the air for about 12 years before breaking down, whereas carbon can stay there for thousands. So, while menthane might be a more potent greenhouse gas as Viking's Tor cited - it will break down more rapidly instead of building up over thousands of years.

While neither gas is good, the benefit from the reduction of carbon with LNG can be seen as a priority. Carnival Corporation's Strang went on to share that when both are taken together, the overall savings in terms of Global Warming Potential (GWP) is around 12-15% with LNG vs the 28% savings in carbon emissions alone. With that in mind, it seems like LNG is a pretty good alternative. In his words, "It is better to take action now, rather than wait until a better solution is available".

What Does The Future Look Like For Cruise Ship Fuels?

Ultimately competition is good and all parties seem to be pushing forward in the right direction. Even though some are being more aggressive, the sheer amount of research and development being done here is staggering. For instance, Carnival is also investing in efforts to use hydrogen fuel cells and batteries so that when the time is right, they will be ready for the future. Even with brands like Carnival Corporation on one side and Viking and Norwegian on the other, both sides seem dedicated to ultimately embracing a carbon-free future for marine transportation.

As someone who loves cruising, I recognize that global travel has a significant environmental impact.

However, it is refreshing that some of the world's best minds are hard at work developing solutions for today as well as tomorrow. It can be challenging sometimes - especially for new cruises - to hear these competing points of view and process them since it can be scary not understanding the full picture.

Few people want to destroy the earth during a vacation so I encourage you to do what you can in your personal life to reduce your footprint. This could involve asking your travel agent to purchase carbon credits to offset the cruise and airfare or it could be as basic as taking a hike or kayaking expedition on your next cruise instead of doing an ATV tour. Ultimately though, the fuel being used is only one part of the equation and most of the other elements are things that are up to you to do. We'll talk more about those in the future!

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James Hills

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James is an avid fan of all types of cruising but especially enjoys exploring the Pacific coastal regions since it perfectly captures the elements that he is passionate about, including natural beauty, conservation, opportunities to explore new cultures, and meeting some fantastic new people too.