Decarbonizing ferries: Technological innovation and electrification

With IMO decarbonization targets becoming more ambitious, and social and political pressure building, each sector of the maritime industry needs to examine the most practical and cost-efficient ways of reducing greenhouse gas emissions. For ferries, electrification and battery power are high on the agenda.

Electrification and battery power perfect fit for ferries

“Ferries are the perfect segment for electrification and battery power,” says Hans Eivind Siewers, Segment Director of Passenger Ships and RoRo at DNV. “Short, regular routes between the same ports makes it easier to charge regularly and reduces the need for large batteries.”

Three new technologies have emerged in recent years which are expected to have an impact on the ferries market. For all, the development has been facilitated by recent technological developments, most notably improvements in the energy density of batteries. Two of these innovations are based on hydrofoiling, an established technology which is making a comeback due to energy efficiency gains.

Hydrofoiling: Back to the future with Fast Foil Ferry

Hydrofoil technology – where a foil lifts the vessel up from the water as it gathers speed – was popular in the 1970s due to passenger comfort and high speeds, but this was eventually sidelined due to poor fuel and energy consumption. However, over the past few years, advancements in high strength and lightweight composite materials, gains in hydrofoiling technology and – most importantly – increases in the energy density of batteries have reopened the door to this technology.

Collaborative innovation: Developing a fully electric Fast Foil Ferry

In 2020, Kitsap Transit (a public transit agency serving Kitsap County, Washington, part of the Seattle metropolitan area), Foil Ferry LLC (a collaboration between Anacortes-based Bieker Boats and Seattle naval architecture firm Glosten) and Washington Maritime Blue received a Federal Transit Administration innovation grant to develop a proof-of-concept design for a fully electric Fast Foil Ferry. This has led to the delivery of a preliminary design for a high-speed hydrofoil passenger ferry, aided by DNV-led studies around shoreside infrastructure and permitting requirements and economic and environmental impacts.

Decarbonization just one advantage of Fast Foil Ferry

“These ferries use around one-third of the energy of conventional fast ferries and have zero local emissions,” says Cassidy Fisher, Programme Director of Washington Maritime Blue, which is coordinating the Fast Foil Ferry project. “They produce negligible waves as the hulls fly above the water’s surface. This is important for protecting sensitive shorelines such as those along Rich Passage, Washington, which makes up a significant portion of the Bremerton–Seattle route.”

With a cruising speed of 30 knots (around 55 km/h), the ferries have a range of about 30 nautical miles. This means they will be able to complete one full round trip on the proposed Bremerton to Seattle commuter route without recharging.

Financial benefits make the business case for Fast Foil Ferry

Besides the extensive list of advantages, including reduced motion compared to non-foiling hulls, providing passengers with a more comfortable ride, reduced noise, and the hope that increased ferry traffic will result in fewer cars on the roads of Washington State, the Fast Foil Ferry will also deliver significant savings to its operators.

“We have estimated a 35% reduction in annual operating costs compared to conventional diesel-powered ferries, mainly due to energy savings, although this depends on the price of diesel,” continues Fisher. “Alongside the decarbonization benefits, this is a strong business case and removes any significant barriers to further development.”

The project is aiming to secure another USD 4 million in federal funding so it can advance and complete the design development stage, while full-scale trials, construction and deployment, and the development of shoreside infrastructure will require another USD 18 million in funding.

Hydrofoiling also gaining traction in Sweden

The rebirth of hydrofoiling technology is also gathering steam across the Atlantic Ocean. Following the launch of two hydrofoil leisure vessels, Swedish company Candela is now developing the Candela P-12 ferry, with the first prototype set for launch in late 2023.

The Candela P-12 will have a similar cruising speed to the Fast Foil Ferry and shares other benefits, such as near-zero wake. With a range of around 60 nautical miles, this vessel is also benefitting from gains in battery density. Like the project in Seattle, the Candela P-12 will have close to zero local emissions and is expected to benefit from an estimated 50% reduction in operating costs, partially thanks to significant energy reductions compared to conventional vessels.

Candela benefits from DNV’s Technology Qualification process

Because the Candela P-12 is a novel technology, existing rules and regulations, which are normally prescriptive, have not been sufficient to support its technological development. The company, therefore, utilized DNV’s Technology Qualification (TQ) process as it advanced the P-12 from concept to prototype. The TQ process provides a framework for the technological innovation of novel technologies, like the Candela P-12, by providing assurance of their safety, reliability and profitability, and improving confidence at different stages of the development process.

With this process now nearing completion, the first P-12 Shuttle will be launched at the end of 2023 with plans to enter Stockholm city’s fleet of public transportation ferries in 2024 as a pilot on one of its main routes.

From LNG to battery power

In Uruguay, ferry operator Buquebus is preparing to start operating the largest battery-powered ship in the world. Currently under construction at Tasmania-based shipbuilder Incat, the 130-metre ship will have a battery capacity of over 40 MWh, almost four times the capacity of any battery-powered vessel constructed before.

Following the success of the DNV-classed HSC Francisco Papa, Incat’s first LNG vessel delivered to Buquebus in 2013, the new DNV-classed vessel was originally planned to run on LNG. This was switched to electric/battery propulsion after Robert Clifford, founder of Incat, showed Buquebus his plans for a new electric/battery-powered ship.

“Our President Mr. Lopez Mena asked Incat if it was possible to use the electric propulsion on our future vessel,” explains Gerardo Babini, Technical Manager, Buquebus. “After a couple of weeks of weight and speed calculations, Incat came back to us and said it would be possible.”

Taking battery power to the next level

A key decision for Buquebus has been what kind of batteries would be on board the vessel and how much these would weigh.

Norwegian company Corvus Energy was selected by Wärtsilä, the electrical system integrator for the vessel, to supply the batteries. Corvus’ latest innovation – the lightweight, high-density Dolphin NextGen battery, which is the result of the company’s four-year project Blue Whale ESS – will be utilized for the Buquebus ferry, enabling the vessel to fulfil a longer route without weighing it down.

The longest battery-powered route in the world

The aluminium-constructed ferry is intended to operate between Montevideo in Uruguay and Buenos Aires in Argentina, making this the longest battery-powered route in the world. It will have enough capacity for 2,100 passengers and crew, 225 cars and a 2,000-square-metre duty-free shop, all on one level. With Buquebus favouring a lighter weight vessel – and therefore fewer batteries – the company decided that charging would take place on both ends of the route. This requires collaboration with a wider group of actors.

Progressing charging infrastructure collaboration

“Following meetings with technical and commercial officers from electrical companies in Argentina and Uruguay where we had to seek answers around charging stations and operations, these companies confirmed that charging operations were possible,” says Babini. “Now we are working with port authorities on details like locations for transforming stations, rectifiers and charging towers.

The future of ferries is battery-powered

While the Buquebus ferry is very different in design to the two hydrofoil vessels, all of these technologies showcase the key role that electrical/battery power can play in the decarbonization of shipping. This is likely to increase, particularly in the ferry industry, as battery technology develops even further.

“These technologies are all extremely exciting and impressive, but we can expect so much more from battery power over the next ten years,” says Hans Eivind Siewers. “Improvements in density will extend ranges, opening up longer routes and reducing the reliance on scarce carbon-neutral fuels. This will contribute greatly to shipping’s quest to reach net-zero by 2050.

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