Kirby christens first plug-in diesel hybrid electric towboat in U.S.

The U.S.'s first plug-in hybrid electric inland towboat, the M/V Green Diamond. (Credit: Kirby)

On August 25, Kirby Inland Marine christened the first plug-in diesel hybrid electric towboat in the U.S., the M/V Green Diamond, on the water in Channelview, Texas. Following the ceremony, the vessel will be time chartered by Shell Trading (US) Company, which will use the boat to push barges throughout the Houston port region. Shell Energy Solutions is providing electrical power to charge the vessel’s battery system. Kirby Inland Marine is a subsidiary of Houston-based Kirby Corporation (NYSE: KEX).

“We are excited to be the first to market with a plug-in hybrid inland towing vessel,” said Christian O’Neil, president of Kirby Inland Marine. “Barge transportation is already the cleanest and greenest way to move a wide variety of cargoes in America, and we are working to make it cleaner and greener. Our customers who are focused on reducing their emissions want more efficient options. This solution is available today.”

The 73-foot, 6-inch M/V Green Diamond has a beam of 30 feet, a depth of 11 feet and a draft 9 feet, 6 inches. Propulsion is provided by two 575 KW Danfoss electric motors that can be driven either by the Corvus Orca series battery system, which provides 1,243 KWH of power, or, if needed, onboard Caterpillar generators.

The M/V Green Diamond hybrid system works by combining the diesel generators with batteries to deliver efficient power to the vessel through a centralized Power Management System. The vessel has been designed and constructed by San Jac Marine, LLC, Kirby’s shipyard in Channelview. Stewart & Stevenson Manufacturing Technologies, another Kirby company, designed and installed the power management, control and propulsion systems.

Charging System

A Shell New Energies US-owned charging system, supplied by Zinus Solutions, will be used for dockside charging of the battery system, allowing the vessel to operate on trips within the Houston area without ever needing to start the generators. According to Kirby’s modeling, when operating on shore supplied power, the fuel use can be reduced by almost 80%, resulting in an estimated 88-95% reduction in emissions of nitrous oxides, carbon monoxide and hydrocarbons. Engine run time can be reduced between 93 and 98% compared to a conventional inland towing vessel. When in hybrid mode with the generators running, the boat is expected to have an estimated 27% reduction in emissions compared to a conventional towing vessel.

“The plug-in hybrid design offers numerous advantages for towboats in certain trades,” said Mitch Jones, vice president of San Jac Marine. “We are already looking at building follow-on vessels.”

Stewart & Stevenson Executive Vice President Chad Joost added, “As a leader in electric fracturing equipment, Stewart & Stevenson already has a proven track record of high horsepower electric systems that save energy and reduce emissions in the oilfield. We were able to adapt that patented technology to the marine environment and enable this vessel to operate on shore power and charge the batteries while on dock, then get underway on battery power. On extended trips, the generators will be used to supply power to the motors and charge the batteries. All of this happens seamlessly through Stewart and Stevenson’s power management system.”

“We expect the Green Diamond, with its unique ‘Eco-Tug’ logo, to be a fixture in the Port of Houston for years to come,” O’Neil concluded.

The towboat has been built to operate more quietly and with more available power than a conventional vessel of its class, with reduced maintenance down time (anticipated 30-40% savings in maintenance costs) and significant fuel and emission savings (fuel savings of up to 80% over a conventional vessel). The towboat can achieve full charge in six hours.

Christening Ceremony

O’Neil opened the christening ceremony, with special remarks by Kirby Corporation President and CEO David Grzebinski. Shell’s Senior Vice President and Global Head of Shipping & Maritime Karrie Trauth, a Marine Log Top Women in Maritime awardee, gave remarks on behalf of Shell, who provided the charging station for the vessel.

Taylor Dickerson, who is vice president – project management office for Kirby, christened the vessel with a customary bottle of champagne.

“The christening of the M/V Green Diamond is a significant milestone in Kirby’s history and marks our commitment to investing in cleaner transportation options to benefit our customers and overall environment,” said Dickerson.  “I was humbled and honored to be selected to christen the vessel and will remember it as one of the pinnacles of my career.”