Landmark study examines decarbonization of U.S. inland waterways

Sept. 23 webinar to cover challenges, options for inland fleet

A landmark new report by Vanderbilt transportation and environmental engineers looks toward decarbonization of U.S. waterways and evaluates the potential for possible future propulsion technologies and alternative fuels to reduce carbon emissions.

The comprehensive study, the first to examine the U.S. inland waterway system through the lens of reducing greenhouse gas emissions, was done on behalf of the American Bureau of Shipping (ABS), a leading global provider of classification and technical advisory services to the marine and offshore industries. The research itself is a collaboration between the Vanderbilt Center for Transportation and Operational Resiliency and the Vanderbilt Climate Change Initiative.

“There has been a lot of work focused on decarbonizing the international and coastal shipping sector but much less focus on the inland river sector, in part because it is already one of the most sustainable ways to move freight,” said VCCI Director Leah Dundon, JD, ‘97, PhD ‘17, Director, Vanderbilt Climate Change Initiative.

Leah Dundon

“The inland river sector has some unique technical characteristics that present real challenges to successful decarbonization, but we are excited about some of the possibilities and pathways we identified in this report,” she said.


Paths to decarbonize inland waterway freight, plus unique challenges the goal presents for the sector, will be discussed at a webinar on September 23 that features experts from ABS, VECTOR, and VCCI.  The event, at 10 a.m., is free and open to the public. Registration is required

Presenters include VCCI Director Leah Dundon; Sotirios Mamalis, ABS, Global Sustainability Manager, Fuels and Technology; and David Sehrt, Consultant and Former Chief Engineering Officer at Ingram Barge Company. They will cover what regulations or incentives could drive change within the market, the look and operation of an electrified river towboat, and which alternative fuels would be best suited for the inland fleet. Download the full report.


In 2018, the UN International Maritime Organization set a goal to cut the maritime shipping industry’s greenhouse gas emissions by at least half by 2050. “While the greenhouse gas profile of the inland waterways is low compared to other shipping sectors, the need to decarbonize operations is growing more pressing all the time,” said Georgios Plevrakis, ABS Director Global Sustainability. “The sector faces unique challenges and limitations and will require a bespoke emissions approach, which is analyzed in this study with Vanderbilt University.”

“Electrification clearly offers smaller inland river vessels swift gains in CO2 reduction, but the report also explores the wider decarbonization landscape that will need to be navigated to put this sector on a sustainable footing,” Plevrakis said.

The inland waterway sector faces unique challenges to decarbonization that coastal and trans-ocean shipping do not. River depth and width, plus the lock system and lock sizes, limit vessel length and overall dimensions, weight, and draft. The maximum underwater depth for a tug and barge, for example, is 10 feet.

The research team found that electrifying larger river boats may not be feasible with current technology because of the large batteries required.  However, retrofitting certain smaller boats known as “fleet boats” could be accomplished in the near-term. Converting all fleet boats to electric propulsion is estimated to reduce total annual average industry diesel fuel consumption by approximately 20 percent, or 1,000 kilograms of CO2, depending on the fuel types used to generate electricity. Each of the 1,000 fleet boats uses about 100,000 gallons of marine diesel each year.

Outside of electrification, the potential for using alternative fuels is mixed. Biofuels and methanol present the most feasible options because they can be used in some existing marine engines and are supported by current infrastructure, according to the report. Biofuels also have energy density near to that of marine diesel, meaning existing fuel tank-size may be sufficient.

Ammonia, hydrogen, and liquefied natural gas—a fossil fuel with lower emissions than diesel—have substantially lower comparative energy density than marine diesel, which would require significantly larger tank volumes. Existing tanks could not be used at all.

The report includes a case study and naval architect renderings of a retrofitted, weighted and balanced electrified boat.

“We are excited about some of the possibilities and pathways identified in this report. For example, we are hopeful that a pilot project based on river fleet boat electrification can be accomplished in the near term, which would inform scalability potential and cost, as well as further research needs,” Dundon said. “These types of grand challenges can’t be undertaken alone—they require input and insight from a broad range of skill sets and expertise, so Vanderbilt was extremely pleased to collaborate with ABS on this project.”

The study includes analyses of historic and projected cargo tonnage, feasibility of alternative fuel options, and current market conditions. Decarbonization of the inland waterway sector likely will require regulatory or market-based incentives, the authors said.

Download the report, Decarbonization of the Inland Waterway Sector in the United States

Register for the Sept. 16 webinar