In the ferry sector, what was once a rarity is now becoming commonplace.
“If you look at new ferries globally, and specifically in North America, we’re seeing the majority of them being designed and constructed to be hybrid electric,” said Ed Schwarz, head of marine solutions sales for the U.S. and Canada at Siemens Energy. “It’s the rare exception, now, that’s mechanical.”
Increasingly, owners and operators of working vessels are exploring opportunities to adopt electric-diesel hybrid propulsion systems, eying the opportunity to reduce emissions and save on maintenance costs, among other benefits.
Of all commercial vessel types, ferries are arguably best suited for hybridization and electrification due to their design characteristics and operational profiles that typically consist of short, repeated routes. And while today’s fully electric propulsion systems do not suffice for many routes and vessel types, hybrid systems can often meet their needs and are usually less challenging to integrate. Steel-hulled, double-ended road ferries, which are typically longer, wider and operate on defined routes, are perfect candidates, Schwarz said.
“These ferries tend to have a lot of space below deck plates, allowing for additional equipment… You don’t need to wait for the next technology evolution. Existing hybrid technology fits well to the ferry design,” Schwarz said. “A lot of the hybridization is based on operational profile, so having one that is very well defined for the life of a vessel can make it well suited for hybridization.”
In recent years, the shift toward hybrid ferry propulsion has accelerated, driven by factors such as technological advancements, political incentives, increased availability of grant funding for green projects, and growing market acceptance. Additionally, many ferry operators are government agencies with their own decarbonization mandates. The nation’s largest ferry operator, Washington State Ferries, for example, is currently working toward transitioning its fleet to hybrid-electric propulsion to reduce emissions and improve sustainability. San Francisco Bay Ferry, which has said it will no longer order vessels with conventional diesel propulsion, is developing a new fleet of fully electric passenger ferries.
IN OPERATION
Beyond their green advantage, electric-diesel hybrid propulsion systems present many operational benefits, as has been seen by the Texas Department of Transportation (TxDOT) aboard its new 293'x66'x16' double-ended hybrid ferry, Esperanza “Hope” Andrade, which entered service in 2024 on the 2.7-mile route connecting Galveston Island with the Bolivar Peninsula. The vessel was designed by The Shearer Group Inc., Houston, and built by Gulf Island Fabricators, Houma, La.
The 495-passenger, 70-car ferry is outfitted with four EPA Tier 3 Caterpillar C18 diesel engines, each rated at 596 kW, two 1,200-kW Siemens Energy electric propulsion motors, and a pair of Voith Schneider Propeller 26RS units with custom blades. All are overseen by Siemens Energy’s BlueDrive PLUSC power and propulsion system. Siemens Energy’s BlueVault energy storage system (ESS) uses lithium-ion batteries, with a total of 1.44 MW-hours of energy storage. The ESS is charged by the diesels and can store surplus power while the ferry is operating and dispatches it on demand.
“The top reason for choosing hybrid propulsion was safety,” said Danny Perez, a public information officer with TxDOT. “The redundancy that hybrid provided in the way of propulsion and hotel load was extraordinary. The choices of running on engines only, in hybrid mode, or battery alone mode for 30 minutes gives us the utmost flexibility and knowledge that we should be able to get our vessels back to homeport in the event of propulsion emergencies… The runtime to return to our homeport is well within the range for battery-alone mode if needed at any point in our route.”
In addition, the ferry delivers fuels savings and helps TxDOT to reduce its carbon footprint. “We anticipate fuel savings due to the hybrid nature of this vessel as well as using smaller more efficient engines that meet Tier 3 compliance without the expense of urea injection required by larger Tier 4 engines,” Perez said. “Depending upon weather and sea current conditions, our fuel savings ranges from 10 gals. to 15 gals. per operational hour. Extrapolating out for a year represents a savings of $180,000 per year. Going from below-tier EMD 645 roots blower main engines in our older ferries to Tier 3 Caterpillar C18 engines represents a huge reduction in emissions.”
On board the Esperanza “Hope” Andrade, the technology supplied by Siemens Energy is key to unlocking further efficiencies. The Siemens Energy BlueDrive, like the ferry’s batteries, is based on a direct-current (DC) system, which makes power integration and distribution through the DC network easier, Schwarz said, noting Siemens Energy has protections and input circuits that make the system safe and redundant.
“Automation software runs behind the system to ensure all the engines are coming on and off as they need to, that the power is being distributed, the power management system that’s talking to the whole system, making sure that we’re evenly distributing loads, making sure that the batteries are in a good safe place when we talk about charging and dissipating power,” Schwarz said.
Currently, no shoreside charging infrastructure is in place to support the Esperanza “Hope” Andrade. “When infrastructure is available for charging, the [onboard] system has the ability to accommodate that,” Schwarz said.
IN BUILD
In North Kingstown, R.I., Senesco Marine is currently building an electric-diesel hybrid ferry, Battery Steele, for Casco Bay Lines, which provides ferry service throughout Casco Bay from Portland, Maine. The double-ended ferry was designed by Elliott Bay Design Group (EBDG) and features hybrid propulsion and automation systems supplied by ABB.
Nick Mavodones, operations manager at Casco Bay Lines, said the operator evaluated several propulsion system types, including diesel mechanical and diesel hybrid assist, before selecting an electric-diesel hybrid setup utilizing electric motors for propulsion, energy storage for primary power and onboard generators for backup power.
“We looked at capital costs, operational costs, system reliability, system serviceability, and operability,” Mavodones said. “We also considered environmental impacts associated with the operating system and what the passenger experience would be from a noise, vibration, and air quality experience while at berth… Ultimately, the electric-diesel hybrid option provided the best overall operational cost benefit as well as a superior environmental and passenger experience.”
The move from a twin-screw, single-ended ferry to a single-screw, double-ended ferry with a propeller at each will allow Casco Bay Lines to realize the full benefits of the hybrid propulsion system. “It became clear the responsiveness offered by the electric motors and this technology offered a better potential experience for our crews and passengers,” Mavodones said.
In addition, the Battery Steele’s route to and from Peaks Island, Maine, is short enough that the vessel will be able to operate a complete round trip on battery power and recharge fully at the berth in Portland. “The electric grid infrastructure near the terminal was such that a major upgrade of the grid to support a rapid charger would not be necessary, and the selection of an automated rapid charger would allow us to charge in a timely fashion and meet the demanding schedule of 17 round trips per day during our busy season,” Mavodones said. “The back-up diesel generators would assist in the event there is ever an issue with the grid or the energy storage system and to assist in managing costs during electrical peak-demand periods to avoid high demand charges when the electrical grid is near capacity.”
The biggest drawback of the propulsion system, Mavodones said, turned out to be the upfront cost, which Casco Bay Lines was able to overcome with the help of grant funding from the Federal Transit Administration (FTA), the Maritime Administration (MARAD) and the State of Maine through its Department of Transportation.
Unforeseen challenges have caused the build program to fall behind schedule. “Given that this technology is relatively new to the shipbuilding industry, there have been challenges associated with securing adequate engineering and labor support for the more complex and extensive electrical systems associated with this work,” Mavodones said.
A lack of U.S. suppliers for several key components has also caused difficulties. When the project’s original ESS manufacturer, Spear Power Systems, Grandview, Mo., decided to cease marine battery production, Casco Bay Lines was forced to find a replacement. Corvus Energy, which opened a factory in Bellingham, Wash. in 2023, was able to step in as the new supplier, but the switch required the propulsion system to be reengineered.
“There have been challenges to comply with Buy America requirements associated with the federal funding sources secured for the work. As this technology becomes more common in the U.S., additional domestic supply outlets should become available to help with this issue,” Mavodones said.
Casco Bay Lines anticipates Battery Steele will be delivered in the fall and operational before year’s end. When the new ferry enters service, cost savings will follow, Mavodones said. “We expect to save approximately $100,000 in operating costs per year that will help to maintain lower ticket prices for our customers,” he said. “These savings will be obtained through lower energy costs and lower maintenance costs associated with the system.”
A GROWING FLEET
The new TxDOT and Casco Bay Lines vessels are part of a growing fleet of hybrid ferries in the U.S.
In addition to the Battery Steele, Senesco Marine is also building a 250-passenger, 23-car diesel-electric ferry for the Maine State Ferry Service. The 154'x38' Capt. Almer Dinsmore, designed by Gilbert Associates, is a hybrid sister vessel to the Capt. Richard G. Spear, which was built in 2021. The new ferry was christened in Nov. 2024 and slated to enter service this year. The ferry features a BAE Systems HybriGen power and propulsion system, with a pair of 600-hp Caterpillar C-18 diesels, 150-hp electric boost motors, two Caterpillar 9.3 generators and battery banks from Spear Power Systems. Karl Senner LLC. supplied the Reintjes hybrid gearboxes.
A pair of hybrid ferries built by Derecktor Shipyards, Mamaroneck, N.Y., was recently christened for Chatham Area Transit. The 65' aluminum catamarans, Juliette Gordon Low II and Susie King Taylor II, will operate on short, continuous routes between three local landings in Savannah, Ga. The vessels are designed to transport up to 149 passengers at a top speed of 11 knots using BAE Systems HybriGen Power and Marine Jet Power Ultrajet 305 dual waterjets, making them the first hybrid ferries in the U.S. with waterjet propulsion. Each ferry is equipped with a pair of Cummins 6.7L marine diesel generators, BAE HDS 200 integrated starter generator, and 308 kWh XALT lithium-ion batteries.
A 190' ferry being built by Conrad Shipyard LLC, based in Morgan City, La., will be the first hybrid-electric ferry for New York City. The new EBDG-designed Governors Island ferry will feature a propulsion system offering the flexibility to operate on either zero-emission, battery-only power or a battery-assisted hybrid with diesel backup. The ferry will replace the 1,000-hp diesel-electric Lt. Samuel S. Coursen, which was commissioned by the Army in 1956.
