(Article originally published in January / February 2021 issue.)
When battery hybrid power first hit the maritime industry in the early 2010s, it was billed as a great way to make diesel ferries and work boats more economical. The value proposition was straightforward and, depending on the application, saved 10 to 20 percent fuel. That’s still a major benefit, but hybrid performance has proven to be much more than an efficiency enhancer for the existing technology. For the transition beyond diesel, hybrid is an essential tool for electrification, fuel cell performance and the transition to carbon-free shipping.
Battery hybrid propulsion is ideal for stop-and-go duty cycles, and ferries are strong candidates. Ferry companies in Europe, North America and Asia have been testing and using hybrid propulsion systems for almost a decade, starting with the Scottish Ro / Pax ferry Hallaig in 2013. The technology has caught on with passenger ships of all sizes through to the 3,200 dwt Color Hybrid, a Ro / Pax ferry operated by Color Line between Norway and Sweden.
Scandinavian ferry companies have pioneered the adoption of battery hybrid systems, but North Americans are fast catching up. Washington State Ferries plans to use plug-in hybrids on most routes by 2040, and the project is well underway. The state has ordered a number of new battery hybrid ferries from Vigor Industrial, the power systems of which will be provided by ABB. With financial support from the US Maritime Administration, one of the largest existing ferries is being converted from a diesel-electric configuration to a battery hybrid system.
Casco Bay Lines, a not-for-profit ferry operator in Portland, Maine, recently completed the design for a new battery hybrid ferry for the route to Peaks Island, a small community east of the downtown waterfront. The current ferry is nearing the end of its useful life and the operator has worked with the Elliott Bay Design Group (EBDG) on the best option for a replacement. They opted for a plug-in hybrid propulsion system that charges at the pier on the Portland side of the route.
Ferries are ideal for plug-in hybrid technology, says EBDG boss John Waterhouse, the longtime dean of American ferry design. These ships have a predictable duty cycle and their regular routes and fixed terminals are perfect for installing charging infrastructure.
“Hybrid is way behind the early stages of ferry rollout and we thank our friends in Norway who took the lead in developing and deploying it,” says Waterhouse. “Operators can think of this as a mature technology and a viable option for their fleet. Perhaps the real question is whether you want to be the last to use it.”
According to the Getting to Zero Coalition, domestic vessels such as ferries, tugs and OSVs play an important role in efforts to reduce shipping carbon emissions. Reducing domestic shipping emissions by just 15 percent could reduce the greenhouse gas footprint of the entire shipping industry by three percent by 2030. That may not sound like a lot, but the coalition says that early steps (even small ones) are essential to get the process of decarbonization started.
Hybrid propulsion is a great option for these classes of ships, and it’s a bigger step than you might think to get to zero. Every hybrid ship has a large battery pack, and if this is large enough, the ship can be converted to run fully electrically with a diesel engine as ballast. “You can order a hybrid ship today that cuts your fuel consumption immediately. Then you can set up a charging infrastructure on land in the future and run the same ship with plug-in electricity,” says John Waterhouse of the EBDG.
For the new plug-in hybrid from Casco Bay Lines, mains electricity will be the primary energy supply from day one, blurring the line between battery hybrid and battery electricity. “They intend to be working on batteries almost 100 percent of the time,” says Bruce Strupp, senior account manager at ABB Marine & Ports, the systems integrator for the Casco Bay project. “They have generator sets on board in case they lose power at the dock or have to go to a shipyard.”
Hydrogen fuel cells can have an important advantage over battery-electric designs on routes that are difficult to electrify due to their length or limited network capacity. Due to the higher energy density of hydrogen fuel, the designer can bring more of it on board for a long journey. However, fuel cells have one drawback: it takes a while for the throttle to move, especially with solid oxide fuel cells, which work well with ammonia and other hydrogen-based fuels. A battery pack can smooth out this gas lag by instantly delivering power when needed to maneuver, so the fuel cell has time to catch up. Given this synergy between battery power and fuel cell power, today’s battery hybrid ships are excellent candidates for fuel cell retrofitting in the future, and many will be designed with this upgrade in mind. Stay tuned, says Strupp, because fuel cells are likely to be an accessible commercial option in the next five years.
Wind power decarbonize
In the offshore windship sector, the charterers are wind farm developers and work every day on the decarbonization of the global power supply. It is no surprise that they are actively interested in decarbonising their own supply chain, including the fleets of their service ships. As an interim solution, the battery hybrid drive fits the requirements exactly: the motors offer enough range for transits to and from the location, and the stored battery power can be used to hold and loiter around stations in order to save fuel and reduce wear and tear.
This combination is an attractive solution for the UK-based crew transfer operator CWind, a division of the Global Marine Group. In collaboration with the wind farm developer Orsted and the naval architect ESNA, CWind set out to build a super-fast, super-efficient and unique ship. The new Crew Transfer Ship (CTV) CWind Pioneer combines a hybrid powertrain with the design of a surface effects ship (SES) – a hovercraft with catamaran hulls instead of a rubber apron. At first glance, the CWind Pioneer looks like a standard catamaran, but when its electric fan turns on, it rises out of the water at a cruising speed of over 40 knots.
CWind Pioneer is the only SES ship in the world with a hybrid propulsion, and Ian Douglas, CEO of Global Marine Group, says a hybrid-SES combo is ideal for offshore wind. “The ship can only run slowly with the battery on the switch-on and switch-off pad. This is a crucial factor in reducing emissions when waiting for technicians from offshore wind towers. We no longer have idle engines and we no longer have any maintenance problems with us working engines. ” at low power, “says Douglas.” The results have been extremely positive. What is not to like about a CTV that can travel more than 40 knots on less fuel than a traditional ship? “
The extra speed and fuel consumption translate into greater range, and CWind hopes ships like CWind Pioneer will be able to compete against larger and more expensive service operations vessels (SOVs) that are the industry standard for remote locations are banks. Hybrid performance is also making great strides with SOV operators. Edda Wind, owned by Wilhelmsen / Østensjø, has ordered a fleet of six SOVs with hybrid drives that will later be converted to hydrogen.
A shipbuilding boom is just beginning in the emerging US offshore wind segment, and rumors suggest that hybrid propulsion could become a standard feature. With an expected market size of more than 200 ships of all sizes, it is a rare opportunity to incorporate new technology into an entire fleet. “I think that with these new offshore wind support vessels, there will be some form of hybridization and energy storage on every one,” says Bruce Strupp of ABB.
Crowley Maritime, headquartered in Jacksonville, is one of the most active US shipowners in the sector, and interest from wind farm developers is growing – especially in hybrid options. “Every time we see a quote request for an offshore windship, the developer wants to understand how we can reduce emissions, including options for hybrid, battery and fuel cell power,” said Coulston Van Gundy, director of commercial operations at Crowley. “They want to be future proof as much as possible, with containerized or modular solutions that can be changed later as technology advances.”
Efficient work boats
While offshore oil and gas has been a quiet sector for new build in recent years, the OSV market has been receptive to battery hybrid retrofits and hybrid power is ideally suited for the cyclical operation of an offshore vessel. Energy stored during a transit can be used for maneuvering or stationing, reducing the time the engines have to run under light loads – their least efficient and most atrocious operating condition. Eidesvik started the hybrid OSV trend with the Viking Queen in 2015 and has converted seven ships so far. Last year, Harvey Gulf retrofitted a Wärtsilä battery system for its LNG dual-fuel OSV Harvey Energy, making it the world’s first LNG battery hybrid offshore ship.
Tugs place greater demands on battery space and cooling requirements, but hybrid solutions are now used on several larger tugs – many of them by the tug experts at Robert Allan Ltd. – and interest is growing. In the US tug market, “hybrid” can also mean a ship with a diesel main engine, diesel generators and an electrically assisted axle drive. Examples include the Rolls-Royce powered port tug Delta Theresa, the Cat powered port tug Ralph, and the Canal Marine designed tug Michigan. Although they don’t come with batteries, all three are designed to use the most efficient combination of engines for the job at hand, reducing fuel consumption and maintenance costs.
“Hybrid” has an evolving meaning, but it plays an essential role in achieving zero emissions – a role that is expected to grow with the green power mainstream. If there is a flexible transition technology for ships on the water, this could be just the thing. Takeout for owners? “Don’t be afraid to think about it and ask lots of questions,” says John Waterhouse of the EMCDDA. “So you can customize the ship design and operations so that they fit together.”
The opinions expressed here are those of the author and not necessarily those of the Maritime Executive.