CMB is working towards maritime hydrogen use through acquisitions, collaborations and new projects
A pioneering tug newbuilding project in Europe will be a forerunner for future hydrogen-fuelled harbour vessel operations, paving the way for a future generation of low-emissions port and inland waterway tugboats worldwide.
Belgium-headquartered shipping group Compagnie Maritime Belge (CMB) has partnered with the Port of Antwerp to build the world’s first hydrogen-powered tug. Hydrotug will be the first vessel in the 4,000-kW class to be powered by hydrogen-diesel dual fuel. Hydrotug is among several projects shipowner CMB has taken up that advance hydrogen use in ships.
Hydrogen is an extremely clean fuel – avoiding the carbon dioxide (CO2), sulphur and particulate matter (PM) emissions of fossil fuels – however, its storage can be problematic. If it is liquefied for transportation, it can be highly explosive and flammable. Known as a highly reactive gas, hydrogen’s use on board ships and as fuel for engines of 1-MW size represents unchartered territories.
Yet, through these announcements, CMB has shown its conviction that dual-fuel combustion engines are the way forward for shipping, favouring them over fuel cells. “Experience has shown that reciprocating engines burning hydrogen are a mature technology,” says CMB research and development manager Roy Campe.
He tells Tug Technology & Business that since LNG is already proven, much of the cryogenic technology can be leveraged while cutting carbon emissions. CMB developed Hydroville, a ferry in Antwerp burning hydrogen in the engine, launched in 2017. Hydrotug will use proven technology from engine to propeller, says Mr Campe.
A hydrogen organisation takes shape
Among CMB’s moves towards using hydrogen was acquiring Revolve Technologies Limited (RTL) in September. RTL has developed hydrogen combustion engines and systems for more than 10 years. Power ranges in the truck and van engines it has developed have been from 110 kW to 450 kW. RTL also developed the dual-fuel, diesel-hydrogen engines on board the CMB-owned Hydroville ferry.
The newly acquired business will be renamed CMB Revolve Technologies and remains based in Brentwood, UK. CMB Revolve Technologies will not only focus on CMB’s hydrogen projects, but continue to supply consultancy services to third-party customers in the automotive and marine industries.
CMB and Tsuneishi Facilities & Craft (TFC) have announced they will work together to build a passenger ferry powered by a dual-fuel hydrogen-diesel internal combustion main engine. After receiving regulatory approval, the ship will be built at TFC’s facilities in Onomichi, Japan and delivery is expected in 2021.
In 2018, Anglo Belgian Corporation Engines and CMB created BeHydro, a joint venture focused on developing, designing and marketing medium-speed hydrogen combustion engines (mono-fuel hydrogen and dual-fuel, hydrogen-diesel). BeHydro has announced it aims to commercially launch its first hydrogen medium-speed engine in 2020. Engines currently under development have a power range between 0.8 and 2.5 MW and are available in 6, 8, 12 and 16 cylinder configurations.
What research suggests
The results of a recent bench test by Anglo Belgian Corporation (ABC) on using hydrogen on a single cylinder engine were presented at the CIMAC Congress 19 held in Vancouver earlier this year in a paper titled ABC’s Dual-Fuel Engines Running on Renewable Fuels like Methanol and Hydrogen, by ABC development engineer Luc Mattheeuws, and chief executive and managing director Tim Berckmoes.
Hydrogen, as an explosive mixture, has 2.5 times less energy than natural gas, with less potential damage, and is liquid at -253°C causing storage issues. Dual-fuel engines constructed to use hydrogen have a diesel injector and a natural gas admission valve.
Hydrogen pre-ignites. It was found that at the same injection point, with the same compression, speed and load, pre-ignition always started at the same concentration of hydrogen. When boosting the air flow, the possible amount of hydrogen to inject also increased. But, pre-ignition still occurred due to the auto ignition temperature at that concentration.
Hydrogen can auto-ignite and as the testing was carried out on a single cylinder engine, it was not possible to increase the charge air pressure to avoid this. The test engine suffered from hot spots, or a local high concentration of hydrogen. Further testing was to involve increasing the intake air mass to see if this would prevent auto-ignition.
The nitrogen oxides (NOx) formation was comparable to diesel because of the high mass flow of intake air. NOx formation depends on the dilution rate of the hydrogen. Hydrogen’s flame velocity and rate of expansion is far higher than diesel, so heat release in the cylinder occurs earlier and this will also result in high NOx emissions. One way to reduce NOx emissions is to dilute the mixture, decreasing the flame velocity and therefore delaying the heat release.
CO2 was found to have a 60-85% reduction when tested with a higher boost pressure and PM/soot was significantly reduced. The test engine’s efficiency was comparable to diesel and is expected to be slightly higher when fully developed and designed.
Achieving optimum combustion
Revolve Technologies technical director Paul Turner says burning any fuel brings challenges. If the lambda (air-fuel ratio) reaches 1, there is a risk the incoming charge of hydrogen will undergo pre-ignition, which is similar to diesel combustion. “If you manage the air-fuel ratio, concentration of hydrogen and ensure the correct timing of the source of ignition, whether diesel pilot or spark, then hydrogen combustion can be smooth and efficient,” he says.
Hydrogen can burn with the same flame speed, rate of pressure change and NOx emissions as diesel, he adds. “The temperatures need not be higher. It is a myth that hydrogen always burns very hot,” Mr Turner says.
CMB’s preference for taking the engine route to hydrogen hinges on key factors including the cost of electrification and weight and reliability concerns if hydrogen were to be deployed through fuel cells. A further factor is the retrofitting option that would help transition the existing fleet with reciprocating engines.
Mr Turner says retrofitting involves a hydrogen fuel handling system, an injection system and combustion tuning to get the optimum injection tuning. In the case of dual-fuel engines, he says the mixing ratio can depend on the load. A dynamic engine would require the diesel-hydrogen ratio to continuously vary depending on the demands of the engine. A marine engine, on the other hand, is a steady state engine where the ratio only needs to change when the load changes.
In CMB’s perspective, storing the fuel is more technically and commercially challenging than burning it. But there are promising technologies on the horizon for hydrogen storage. “Hydrogen storage is not going to be a show-stopper,” says Mr Turner.
In the transition phase, dual-fuel engines are the solution, especially in retrofitting, he says. Mono-fuel does not pose a significant technological challenge, he says, adding the engine must be sized correctly. The bore size will have to be greater, but, the mean effective pressures would be lower. “Mono fuel would require a larger capacity engine but not necessarily larger in physical volume than a diesel engine,” Mr Turner says. A two-stroke engine would require direct injection.
Mr Turner says the fuel system should ensure any leak is quickly dissipated. He says the gas, if leaked, will travel up and spread quickly, at a speed of 20 m/s. “Ventilation, ventilation, ventilation. The installation should be designed to vent, not accumulate the gas. If you try and trap or contain the leak, you have a problem,” Mr Turner says.
Even in diesel, it is the hydrogen that burns, points out CMB’s Mr Campe. The carbon string is a storage mechanism for the hydrogen, a carrier and forms CO2, he adds. Hydrogen burning is fundamentally clean burning. Hydrotug will, however, have a catalyser and particulate filter for diesel burning, he adds. “We wanted to meet future emission standards for inland water vessels,” says Mr Campe.
Dual-fuel would not mean zero emissions. But in terms of cost, it can bring in a drastic reduction in carbon and other emissions at less cost, says Mr Campe. The cost factor comes in through storage. For mono-fuel, three times as much storage is required as dual, he adds.
Mr Campe says tests are ongoing on the 1-MW engine including in mono-fuel operation. Tests on V12 and V16 are also being carried out. “We found that NOx levels with mono fuel were at 0.2 g/kWh, which is one-tenth of Tier III mandates and achieved without after-treatment,” he says.
CMB’s Hydrotug will need high power for its towage operations and fire-fighting requirements. Dual-fuel operations means diesel would be available if the hydrogen tanks are empty or service is required. For CMB, which has a fleet of dry cargo, container and chemical tanker vessels, Hydrotug represents the next step as it moves the hydrogen project from kW to MW scale. The tug is scheduled for delivery in 2021 for operations in the busy Port of Antwerp, becoming a pioneer for others to follow.
Meanwhile, Vattenfall has signed a contract with Windcat Workboats to provide crew transfer vessels for the HollandseKust Zuid 1 and 2 offshore windfarm projects in the Dutch sector of the North Sea. Under the agreement, Vattenfall will be one of the first users of Windcat’s hydrogen-powered vessels, currently being developed. The IJmuiden-headquartered vessel operator is working with CMB Technologies to develop the vessels, which will be completed by the end of 2020.
New hydrogen-fuelled tug projects
CMB is among a select few early-adopters of hydrogen-fuelled tugboat projects. These include: