High energy density powertrains are being investigated for use in high performance offshore lifeboats
The Marine industry is facing the same challenges as other industries to meet sustainability targets and reduce its dependence on fossil fuels. However, unlike road transport, some parts of the maritime sector don’t have the option of converting to battery electric propulsion.
To help overcome these challenges for lifeboats, MAHLE Powertrain is leading a project to develop sustainable propulsion solutions for retrofit to high performance marine vessels where battery and other electrified technologies may not prove practical. The collaboration with the Royal National Lifeboat Institution (RNLI), the University of Nottingham and Clean Air Power will initially target search and rescue vessels.
Clean Air Power is providing the critical fuel injection system and the University of Nottingham is home to the renowned Powertrain Research Centre, where fuel storage assessment and testing is taking place. In addition, Hybrid Marine Power will act as a consultant, providing legislative impact analysis alongside their experience of marine safety standards and the wider industry.
To find out more about the project and the technology behind it, we spoke with Jonathan Hall, Head of Research and Advanced Engineering at MAHLE Powertrain.
The marine industry is heavily reliant on diesel fuel as it has high energy density, low hazard and is easy to transport and store with a well established distribution network. However, continued use of the fuel doesn’t allow organisations such as the RNLI to meet the carbon reduction targets.
According to Victoria Limbrick, Carbon & Energy Manager, RNLI, the organisation has committed to eliminating or reducing impacts on the environment and to become a low-carbon, climate-resilient organisation.
“Fuel for our lifeboats, rescue watercraft and logistics vehicles accounts for around 57 per cent of our total energy use,” she says.
Converting to battery power is an option that is being adopted in some sectors of the marine industry but this isn’t viable for use on lifeboats. The low energy density and high weight of current battery technologies, coupled with the need to quickly replenish for the next mission, means that alternative green propulsion solutions are required.
“The current and predicted future state of battery technology alone can’t offer the range and performance required by the RNLI at an acceptable weight for retrofit to its lifeboats,” explains Hall.
At the core of the consortium’s project is MAHLE’s Jet Ignition (MJI) technology, optimised for hydrogen combustion under the name HyJet. This enables the ignition of sustainable fuels in clean combustion engines.
The HyJet project will begin by analysing usage data collected from the RNLI’s vessels during real-world operation to establish the fleet requirements and to help identify the optimum approach for clean operation. This technology-agnostic approach will also consider the issue of on-board fuel storage and refuelling, critical to deployment in an emergency setting, and will also assess the impact on vessel safety standards and regulatory compliance.
According to Jonathan Hall, the use of powertrain simulation tools was an important aspect of this initial study of examining energy storage, fuel systems and the available alternatives of ammonia, methanol and hydrogen.
The characteristics and performance of these alternative fuels is being examined in the post-simulation stage of the project on a single representative engine at the Powertrain Research Centre in Nottingham University.
“We have data on the use of ammonia and now we can examine methanol and hydrogen. This is all done on the same engine so we can perform side-by-side comparisons,” says Hall.
Looking at all the alternatives in this way is important to ensure MAHLE understands the limitations of each fuel and informs the user of the best direction to take.
Victoria Limbrick says the HyJet project offers an exciting opportunity to investigate and learn about potential solutions that could help meet our challenging sustainability targets and to fulfil our ambition to move away from fossil fuels.
Jet Ignition Technology
The HyJet project is reliant on MAHLE’s Jet Ignition (MJI) technology, which consists of a small pre-chamber which can be fitted into the cylinder head of the engine. Combustion is initiated in this pre-chamber, with the resulting hot combustion gas forced through small orifices into the main combustion chamber as a series of jets which quickly and uniformly ignite the remaining mixture. This ensures clean, efficient combustion throughout the main chamber with little or no pollutants such as nitrogen oxides, even when operating with lean hydrogen mixtures or other sustainable fuels that are well beyond the capability of traditional spark ignition systems.
Hall explains to us that the use of hydrogen relies on having a very lean mixture in order to achieve low NOx emissions. However, the leaner the mixture, the harder it is to ignite. This is why MJI technology is used. The system uses a pre-chamber, which enriches the mixture to ignite it before being jetted out to create even combustion within the main chamber.
In its “active” configuration, which is applicable to the lifeboat application, the MJI technology achieves almost diesel-like efficiency.
Meeting Sustainability Targets
As Hall explains, all of the fuel alternatives that are being investigated have their own challenges including toxicity, availability, transport and logistics. Supporting infrastructure for all of the alternatives involves some dependence on other agencies, such as ports, as well as local availability.
All aspects of the fuel system including the powertrain technology, logistics and infrastructure need to be in place to meet the sustainability targets the marine industry is striving to achieve over the next ten years.
Engine Test Facility
The Powertrain Research Centre at the University of Nottingham is an important test-bed for the development of fuel technology that can eliminate the need for diesel in off-highway power applications.
The facility is used for projects in which the transition to more sustainable power presents significant challenges. These include the marine, mining and construction industries.
According to Hall, these sectors have demanding energy and utilisation requirements and are often in hazardous environments far from a power grid connection, making them difficult to electrify.
“Exploring other power sources such as ammonia or hydrogen has considerable potential, especially because there’s the opportunity to decarbonise the large numbers of vehicles and equipment already in operation and using diesel,” he says.