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Pathways To The Energy Future Of The Inland Waterways

August 21, 2023   The Waterways Journal

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“There is no single silver bullet or unicorn technology” for lowering emissions, said Gary Sarrat of Caterpillar Marine. Instead, there are many choices, each with trade-offs to consider.


Sarrat was speaking on “Sustainability Solutions for Marine Segments” at The American Waterways Operators’ Summer Safety Meeting in downtown St. Louis on August 16-17. The meeting featured several panels and presentations on green tech for the inland waterways, all packed with information. Mike Breslin, AWO’s director of safety and sustainability, introduced panelists and speakers.

Sarrat noted that Caterpillar has increased its communications with its customers about its research and development efforts in green technologies and what they might mean for them.


Sarrat’s presentation covered Cat’s engine upgrades, services, electric and hybrid powertrains, lower-carbon-intensity fuels and regulated emissions. He said companies are getting more sophisticated about calculating their carbon cycles. “Just going to an alternative fuel doesn’t always mean fewer emissions,” he said. “Under some circumstances, methanol can have a carbon cycle with more carbon emissions than fossil fuels.”



Sarrat went over the pros and cons and tradeoffs of alternative fuels from biofuels and renewable diesel to methanol, liquid hydrogen, compressed hydrogen and battery-stored electricity. He explained the concept of “volumetric density,” or the amount of energy per equivalent volume. Hydrogen has zero carbon emissions but requires 10 times more volume than diesel for an equal amount of energy. Even liquefied hydrogen still requires five times the volume of diesel. It also requires a lot of energy to liquefy it and keep it cool, reducing its overall carbon efficiency.


European countries have been making major investments in hydrogen technology for marine uses.


Biofuels can have blend limits. Renewable diesel is a “drop-in” fuel that requires no engine modifications. Biodiesel doesn’t like water or high temperatures, however, and unless handled properly can grow algae. 


Methanol has half the volumetric efficiency of diesel—i.e., it takes only twice as much methanol to achieve the energy output of diesel and is liquid at ambient temperatures. In March 2022, Caterpillar announced that it is close to releasing dual-fuel versions of its 3500 series of marine engines that can run on methanol, Sarrat said. The 3500 series is Cat’s most popular marine engine platform and is used across a range of marine vessels. Cat will also release upgrade kits within five years for converting Tier 4 3500 engines to dual-fuel. Eventually Caterpillar will look at its other engine platforms as well.


Batteries require a robust ship-to-shore, land-based charging ecosystem. A potentially promising green technology pathway for the future might involve using land-based hydrogen facilities to charge shipboard batteries.

The control system is the most important part of any energy system, Sarrat said.

Battery Advantages

Ben Parrish, who is in charge of special projects and ESG initiatives at Kirby Marine—and a “40 Under 40” winner from the 2018 Inland Marine Expo—spoke on Kirby’s dual-fuel mv. Green Diamond, due to be christened within a few weeks. Its name came from a naming contest in which 755 entries were submitted by Kirby employees and design collaborators SanJac Marine and Stewart & Stevenson.

Its diesel-electric plant is supported by a battery bank. One of the big advantages of a battery-powered vessel is “instant torque without increasing speed,” said Parrish. Battery power is ideal for very low-speed and close-in maneuvering for that reason. Steersmen also get a broad power band with battery power. “We have a team that is timing the throttle now,” said Parrish. The throttle controls for battery power can be so sensitive that they have to be tested extensively with wheelmen to get them used to it and to calibrate the controls. Batteries can give two to three times the instant power of a conventional engine.


The Green Diamond has redundant power systems that can operate independently if needed with no loss of horsepower. When on battery the operation is quieter, although not completely quiet. Parrish showed a chart that illustrated how the battery can switch from discharging to recharging in different operational modes. While batteries need shore-based plug-in charging to optimize their use, that charging can be broken up into segments and doesn’t have to be continuous. Emissions savings can be 30 percent without charging, and up to 80 percent with dock charging.

Novel Fuels

Matt French, a territory operations manager for ADM, noted that American River Transportation Company (ARTCo) got involved in biofuels because parent company ADM makes them. ARTCo—which has operated for 51 years and currently has 29 linehaul boats and 53 fleet/harbor boats—began studying alternative drop-in fuels in 2003 on the mv. Mary Evelyn. It started its repower program 15 years ago by integrating biofuels into its fleet.


There are currently 59 biofuel production facilities in 29 states that made 2.087 million gallons last year, French said. He noted that their locations closely map the inland river system, since they are located where crops are grown and also take advantage of water transport when they can.  He said ARTCo did have some growing pains in learning to handle biofuels and renewable diesel. It built a shore-based blending facility with computerized blending and a flush cycle. Biofuels can have a detergent effect on piping and components.  Users may have to change filters more frequently at first, he said.


Last year, ADM had 5.5 million gallons of biofuel throughput. It is developing a load-out biofuel business for rail and trucking customers. French concluded by recommending EPA’s Smartway Program, which encourages companies to voluntarily enter their carbon data to benchmark themselves against other modes, companies and industries.

Ammonia To Hydrogen Promise

Sam Lewis, vice president of sustainability at Southern Devall, started out as a deckhand and races cars as a hobby. He spoke on his company’s collaboration with a startup company called Amogy, which has developed a proprietary portable ammonia “cracker” that releases the hydrogen in ammonia at point of use. Amogy, which has filed 12 patents related to its technology, makes a bold promise on its website: “This technology has the potential to revolutionize not only the transportation industry but the energy sector as a whole. … Amogy will enable the transportation industry to completely decarbonize by 2050, with additional applications in decarbonizing large-scale power and hydrogen generation.”


Lewis noted that ammonia, which is composed of three parts hydrogen to one part nitrogen, is the densest and most efficient way to transport and store hydrogen. The resulting hydrogen fuel has zero emissions, and the released nitrogen escapes into the atmosphere, which is 70 percent nitrogen. The proprietary cracker is located in a self-contained black box.


On June 22, Amogy announced that an unnamed maritime customer in Norway has signed a deal to buy four of Amogy’s crackers for shipboard use. “This is a major milestone on our road to commercialization, and I believe it will serve as an inspiration for other shipowners to follow,” said Christian Berg, managing director of Amogy Norway.


The concept is being tested in a pilot project for Southern Devall, a barge called DCBL 57 that is being built and tested at the Brooklyn Navy Yard. The promise of this fuel is especially important to Southern Devall, he said, because “we push ammonia.”


One issue with ammonia-to-hydrogen is that the process releases lots of heat, which must be dispersed. Hydrogen spaces must also be vented. Parrish noted that stack-like venting structures extending back on some prototype battery-powered boats are required by the Coast Guard. Since there is a 30-foot exclusion zone around areas where highly flammable hydrogen is stored, vents cannot be located close to other equipment, such as radars, that could generate a spark. The venting “stacks” are currently a limiting factor in the design of boats using hydrogen.


Another issue, Lewis said, is total lifecycle of the fuel cells. The heat that is generated by cracking ammonia can degrade fuel cell components, although progress is being made in materials durability.

“Batteries are the future,” said Lewis. Like other speakers, he cautioned, “Diesel engines won’t go away in my lifetime, and maybe not in my kids’ lifetimes—but they eventually will go away.”