Dual-Fuel Marine Engines

Dual-Fuel EnginesCourtesy CMB.tech, Volvo Penta

CMB.TECH and Volvo Penta integrated a dual-fuel engine’s electronic control units (ECUs) and the hydrogen injection system. In dual mode, the fuel map is instantly altered to the optimized calibration for diesel and hydrogen. If the system is inactive, the engine ECU switches back to diesel mapping.

Electric propulsion might be the preferred technology for reducing greenhouse gas emissions in the transportation sector, but it is by no means a panacea. Principals in high-fuel-consumption applications such as trucking, shipping, and commercial aviation are scouting possibilities for clean fuels with a much higher energy density than even the best batteries can offer. In this context and despite being highly flammable and explosive, hydrogen is the most frequently mentioned alternative, but it comes with its own challenges:

• The Department of Energy says 95% of the U.S.-produced hydrogen is made with natural gas reforming, which requires more energy than it yields.

• scaling up renewable energy production to generate hydrogen more sustainably through electrolysis, thermochemical, photoelectrochemical, photobiological water splitting, or microbial biomass conversion

• developing the infrastructure for effective and safe distribution and storage.

The Swedish engine and drivetrain manufacturer Volvo Penta and the Belgian industrial firm CMB.TECH announced a partnership to develop dual-fuel engines powered by either hydrogen or diesel, thus “establishing dual-fuel hydrogen technology as a low-carbon interim solution before suitable zero-emissions alternatives become viable,” according to a joint press release. Their combined effort has adapted Volvo Penta engines to run on a hydrogen and diesel solution using a conversion kit made by CMB.TECH. Both firms are working on pilot projects and small-scale industrialization of dual-fuel solutions for selected but undisclosed customers. “From the initial dual-fuel technology projects, we have seen reductions of CO2 emissions up to 80%,” said Roy Campe, chief technology officer at CMB.TECH. Design and testing of the hydrogen-injection system takes place at CMB.TECH’s technology and development facility in Brentwood, U.K.

“CMB.TECH and Volvo Penta have integrated the ECUs [electronic control units] of the engine and the hydrogen injection system,” Campe said, explaining the technology of reducing CO2 emissions in dual-fuel engines. “If we trigger the engine’s ECU to use the dual mode, the fuel map for diesel injection is altered instantly towards the optimized calibration for dual fuel. If CMB.TECH’s system is inactive, the engine ECU switches back to the original diesel mapping. The switch can happen automatically and is realized in 1x revolution of the engine. Only the sound of the engine is a bit different.”

About the fuel injection, he said, “Hydrogen is injected in the air-inlet manifold and is consequently aspirated into the combustion chamber. For the energy amount of the aspirated hydrogen, diesel can be displaced. By using less diesel, significant CO2 emission savings are realized, [as] hydrogen does not create any CO2 in a combustion engine.” It takes a lot of testing on a dynamometer and tweaking to operate dual-fuel engines safely and efficiently across the full range of power. “We need to avoid preignition [an early detonation of hydrogen] during operation, and we have to calibrate the engine for dual fuel with extra variables. At any time, we need to make sure that nitrogen oxide levels are the same or better compared to diesel-only mode,” Campe added.

“This dual-fuel approach will appeal to many of our customers [for] its ease of installation, maintenance, and use,” claims Volvo Penta president Heléne Mellquist, who also emphasized the potential of accelerating the “transition to more sustainable operations.” Another important aspect of this approach is reliability and flexibility, which help operators maintain productivity. That’s a top priority in the transportation business to hedge against technical or logistical problems—with hydrogen or other technologies like fuel cells—by using a proven and familiar backup fuel.

Dual-fuel-propulsion systems are not new. For many years, conversion kits have enabled cars to switch between fuels, like gasoline and natural gas, not for environmental concerns but to bypass high prices at the pump or supply shortages. In the marine sector, Raider Outboards in Titusville, Florida, builds submersible multifuel outboards that run on diesel, gasoline, or jet fuel for military and search-and-rescue missions (see “Military Grade,” PBB No. 179). What is new is the packaging as a bridge technology toward a greener future for a sector that relies heavily on hydrocarbons.

“Heavy-duty equipment, which is widely present in port areas, is ideally suited for dual-fuel technology,” said Volvo Penta’s business development director, Jakob Ursby. “Since heavy-duty applications are expensive, they are built for…a long lifetime. Having now an option for a no-regret technology is becoming a key aspect for ordering new equipment. Even when the hydrogen refueling is missing, they can still operate on diesel. As soon as the hydrogen infrastructure is there, one can start using this clean fuel.” Ursby said that the early focus will be on projects with Volvo Penta’s commercial marine engines on near-shore applications such as tugs and pilot boats and eventually on crew transfer vessels serving offshore wind farms. European ports, he said, have numerous projects on the drawing board related to hydrogen production, ranging from 20-MW electrolyzers to gigawatt-scale projects.

Near the port of Antwerp-Bruges, CMB.TECH built a marine hydrogen refueling station with an onsite electrolyzer for “green” hydrogen production, said Campe. Plans call for a mobile refueler to supply hydrogen to the ships and projects in the port, which Campe calls “a good solution in anticipation of the refueling stations, which will be developed as soon as the offtake of the hydrogen [i.e., the amount of hydrogen typically bought at the refueling station] is established.” The company also announced the arrival at Ostend of the first dual-fuel-engine tugboat, the HydroTug 1. It was built in Spain but will be finished by CMB.TECH to go into service at the port of Antwerp-Bruges in 2023.

Campe said that several dual-fuel engines are already operating in commercial applications as part of the pilot projects and that “controlled introduction of the technology” is under way in some niche markets. “Furthermore, we have initiated follow-up programs, and we’d like to gather further experience with after-sales [support] before we start selling worldwide.”

CMB.TECH, De Gerlachekaai 20, BE 2000 Antwerp, Belgium, tel. +32 3 247 59 11.

Volvo Penta AB, Gropegårdsgatan 11, 417 15 Göteborg, Sweden, tel. +46 31 660000.