Nottingham University leads MariNH3, a program exploring ammonia-based engine concepts with the aim of decarbonising the marine sector.
The MariNH3 team hopes that by developing disruptive engine technology solutions with minimal energy consumption and fewer pollutants, the EPSRC-funded project will help push the maritime sector towards Net Zero and boost the strong powertrain sector in the UK.
Professor Alasdair Cairns, principal investigator of the project and director of University of Nottingham Powertrain Research Centerexplained that he believes the ‘real challenge’ for the shipping industry is retrofit.
Speak with The mechanicCairns said about 80 percent of the industry’s greenhouse gases come from the large commercial ships used to transport materials around the world, something that has historically been cheap and logical from an economic standpoint — but poses a huge environmental problem, he emphasized. †
“These large ships have engines that last up to 30 years. If you look at the timing of Net Zero … it will still be these big engines that are in use,” he said. “And the problem is, if you look at competing energy vectors like batteries or fuel cells, they just don’t have the energy density.”
MariNH3 hopes to solve this problem by exploring retrofit solutions that can address issues surrounding engine efficiency and pollutants. While Cairns describes that ammonia will play a key role in marine decarbonisation efforts, he acknowledged that the issue of NOx emissions needs to be addressed.
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“We need to reduce NOx emissions, and the technologies we’re looking at are what you would call ultra-low NOx combustion systems,” Cairns said. “There is a classic trade-off… as the thermal efficiency increases, unfortunately the NOx also goes up.
“The big problem with ammonia is that it is a very slow-burning fuel. It burns about five times slower under comparable conditions than conventional fossil fuels.”
Industry partners helping the team meet this challenge include: MAHLE powertrain† MAHLE’s new ‘Jet Ignition’ technology is a fast-burning combustion system currently used in Formula 1 engines, which the team aims to scale up and transfer to the marine environment, where the rapid combustion could run the engine under conditions where NOx could be generated. avoided or reduced.
Another UK company involved is: Dolphin-N2bringing its Split Cycle engine technology into the program, which the team hopes can serve as a long-term replacement solution to achieve diesel-like efficiency with ultra-low NOx.
While the industry is slowly moving towards dual-fuel technologies, where a secondary clean fuel supply is attached to the existing diesel engine, Cairns said, natural gas is still used, limiting efforts to limit decarbonization.
One idea from MariNH3 is that instead of using a small amount of diesel as a liquid spark plug to burn ammonia, a biodiesel or more sustainable renewable fuel could be used to completely decarbonize dual-fuelling, he added.
“Our goal is to develop the best technical solutions in parallel with the right adoption criteria and policies so that we ultimately develop technologies and policies that are ‘right first time’ and scale appropriately across the sea,” said Cairns.
“This framework is based on a ‘technology agnostic’ life cycle analysis approach to help us ensure we are properly positioning ammonia end-uses.”
