TRB Session Looks Toward Maritime Decarbonization Options For Greener Future

Maritime companies have a lot of options when it comes to choosing how to save money on fuel costs and work toward greater environmental sustainability.

Several of those options were discussed as part of “Decarbonization Challenges and Opportunities in Marine Transportation,” a lectern session that was part of the recent Transportation Research Board’s annual conference.

Held virtually over the past two weeks, the TRB conference is normally the world’s the largest gathering of transportation research professionals. The TRB is part of the Academies of Sciences, Engineering and Medicine.

Panelists at the session on decarbonization included those from academia and government.

Bryan Comer, marine program lead for the International Council on Clean Transportation, talked about a study monitoring carbon emissions from ships from 2012 to 2018, showing that international shipping emissions grew from 5.6 percent to 8.6 percent during that time. The study combined AIS data with ship registry information to calculate fuel consumption and emissions.

Comer noted that as liquefied natural gas (LNG) has gained popularity as a marine fuel, vessels are producing more methane emissions, what is known as “methane slip.” Methane emissions grew 150 percent during the study period, Comer said. He added that the data shows that about one-quarter of new cargo ship builds are now LNG-fueled, and about half of new cruise ship capacity will be LNG fueled. Meanwhile, he said, demand for shipping fossil fuels is expected to decrease over time.

Comer talked at length about various greenhouse gas emissions and International Maritime Organization (IMO) goals.

“We must be very careful about the source of biofuels,” he said, adding that in the long –term, he doesn’t see LNG as a climate solution for ships as the most popular LNG-fueled vessels also have the most carbon slip.
However, he said, batteries and hybrid fuel cell systems do show some promise, especially for vessels on fixed, short-duration routes such as ferries and harbor craft.

“No matter what type or size, all ships can take measures,” Comer said.

Michael Carter, acting associate administrator for environment and compliance at the U.S. Maritime Administration (MarAd), talked about the work MarAd has done to promote environmental sustainability. That includes producing the popular Energy Efficiency Guide, Liquefied Natural Gas Bunkering Study and, most recently, looking at battery and hybrid applications.

“Clearly there are a number of challenges that remain,” Carter said, adding that cost was one of them.

He added that there is no one magic bullet when it comes to finding an environmentally friendly solution that meets mariners’ needs and that eliminating fossil fuels in the immediate future appears unrealistic.

“I think we’re going to need to push forward with baby steps,” he said.

He also urged attendees to keep in mind that ships can have useful lives of 30 or more years, meaning decarbonization won’t come fast, that a new build can cost $100 million or more depending on size, that space is at a premium, that ships are confined spaces where safety must remain paramount and that fuel is one of the biggest cost factors for operating vessels.

Also, he said, when retrofitting or modifying vessels, it is important to keep in mind that in addition to capital and labor costs, there is a cost to lost time while a vessel is in drydock.

The U.S. system of ports should also be considered, Carter said, noting that in the United States, ports are often landlords with many independent operators over whom the port has limited influence, and they don’t control what happens beyond their boundaries. Ports often have little space for expansion, limited funding for expanding infrastructure such as storage and bunkering fuels and operate under very strict security rules. Additionally, he said, fueling facilities must be available in multiple locations both domestically and internationally.

Pete Devlin of the U.S. Department of Energy’s Hydrogen and Fuel Cell Technologies Office said fuel cells with LH2 storage show promise in competing with low-sulfur diesel and LNG on ferries and tugs if cost targets are met. Fuel cell vessels s could compete with diesel engine vessels with short range routes and variable power loads, she said. Container ships, meanwhile, are constrained by on-board hydrogen storage volume requirements.