[originally published in RealClear Energy]

This summer, Americans are setting sail. Post-pandemic cruise bookings have soared in the past few years and many travelers are finding their sea legs for the first time — 27% of cruise passengers over the past two years have been first-time customers.

With this surge in popularity, it is worth considering the environmental impact of cruise ships (beyond endless shrimp buffets). Traditional cruises that run on fossil fuels produce far more greenhouse gas emissions than cars or planes. One study found that 63 Carnival Cruise ships emitted 43% more sulfur oxides than all 291 million cars in Europe in 2022.

Thankfully, recent cruise ship innovations are changing these statistics for the better. It has become increasingly clear that low carbon liquid transportation fuels like advanced biofuels are the future of cruise ship travel and marine shipping.

In January, Royal Caribbean Cruises unveiled the Icon of the Seas, the largest cruise ship in the world. At 250,800 gross tons and capacity for 5,610 passengers and 2,350 crew, at first glance the ship should be an environmental nightmare. Yet, in line with the company’s net-zero by 2050 goal, the ship prioritizes sustainability in everything from an advanced waste and water management system to being the first cruise ship powered by liquefied natural gas (LNG).

LNG produces about 25% less carbon emissions than traditional maritime fuels. These lowered emissions are something to celebrate, but they’re even more important in the context of the future of maritime fuel. By prioritizing low-carbon fuel, Royal Caribbean Cruises has taken a serious step towards eventually transitioning to biofuels and advanced biofuels. Already last September, Royal Caribbean’s Symphony of the Seas became the first ship in the cruise industry to successfully test and use a biofuel blend.

Advanced biofuels are manufactured from non-food biomass and are mandated to achieve at least a 50% reduction in emissions, although many reduce emissions by as much as 80%. They will play a significant role in decarbonizing large transportation vehicles that cannot be easily electrified like planes, trains, and, of course, ships. Indeed, while cruise ships are the maritime vessels that the average person is more familiar with, the marine shipping business is also booming, and ships are only getting larger. Many major shipping companies have already taken steps to address these increased emissions, such as Maersk ordering methane-powered vessels last year, but there is still more that can be achieved by using advanced biofuels.

Further, amid global instability that’s causing ships to take different, longer routes, it’s important that Congress prioritize policy support for low carbon renewable maritime fuels under the Renewable Fuel Standard program, which shapes how low carbon fuels are produced and used in America. Greater policy support for this program will help maritime vessels, like cruise ships, transition faster to low carbon fuels, and it will incentivize domestic production of low carbon fuels to help our country build immunity to global supply shortages and price fluctuations.

The Icon of the Seas is a perfect example of an all-of-the-above emission reduction strategy. While LNG does not reduce emissions as much as advanced biofuels do, it is a promising first step towards using more energy efficient advanced biofuels. Similarly, the marine shipping industry cannot solely pursue electrification efforts that will take decades to scale when advanced biofuels can imminently start reducing emissions by as much as 80%.

The vast majority of the maritime industry has committed to being net zero by 2050. Policy makers must support this effort by crafting smart policy that supports the production and encourages the adoption of advanced biofuels and make cruising a guilt-free pleasure.

Michael McAdams is the president of the Advanced Biofuels Association.