As the industry implements its strategy for cutting greenhouse gas (GHG) emissions, manufacturers are beginning to develop main propulsion engines and auxiliary generators to burn alternative fuels
Shipowners will need to invest in zero-carbon fuels as the industry implements its strategy for cutting greenhouse gas (GHG) emissions, with manufacturers beginning to develop main propulsion engines and auxiliary generators to burn alternative fuels.
Of the contenders for the most likely fuel for neutral- or zero-carbon ship propulsion, ammonia was seen as the best long-term solution by a panel of experts during Riviera Maritime Media’s Maritime Air Pollution, Europe virtual conference on 21 October.
During the fourth session of presentations, a shipowner, naval architect and engine manufacturer agreed ammonia will become a usable option for shipping.
The panel included MAN Energy Solutions director of new technologies in the two-stroke promotion department Kjeld Aabo, who said this development resulted from interest in the shipping industry to test ammonia-fuelled propulsion.
“Ammonia’s storage and transportation is easier,” he said. “The market has said go for ammonia – and that is our next goal.”
MAN announced on 21 October it is leading a consortium in Denmark to develop ammonia-fuelled two-stroke engines by 2024.
Joining MAN in the Danish-funded AEngine project will be fuel supplier Eltronic FuelTech, the Technical University of Denmark (DTU); and class society DNV GL.
This project aims to demonstrate a large marine engine running on ammonia at MAN’s test facility, Research Centre Copenhagen. There will be three stages: concept development and initial design, design of an ammonia fuel-supply system and finally full-scale testing in Denmark.
Mr Aabo said ammonia could be stored at moderately low temperatures of -33ºC and supplied at a pressure of 70 bars. It has specific energy of 18.6 MJ/kg and energy density of 11.5 MJ/L.
This means ammonia does not have the same storage challenges as LNG or hydrogen.
Shipowners and design
Some forward-looking shipowners are considering ways to use ammonia on their assets, most likely newbuildings, but with potential for retrofits.
DFDS head of innovation and partnerships Jakob Steffensen said his company was considering ammonia for its long-term environmental strategy of cutting GHG.
“Ammonia will be a winner going forward – it has good potential as we can feed it into engines or fuel cells,” he said. “But it will be very expensive to retrofit ships, so this will be for newbuildings only.”
Mr Steffensen said the shipping industry needs to act together to develop alternative fuels. “We need a global level playing field with global rules to manoeuvre in,” he said.
DFDS is especially interested in burning fuels produced using renewable energy and/or biomass.
“Today we are measuring [carbon footprints] from tank to wake, but we need to measure well-to-wake,” said Mr Steffensen. “We need to run on green versions of fuels and not black versions.”
He was referring to the majority of ammonia produced through reforming natural gas for fertiliser. “We will need to eventually produce fuel from green resources,” he added.
On the back of interest from owners, a naval architect on the panel cited recent work in developing designs for ammonia-powered ships.
NETSCo vice president Jan Flores told attendees existing IMO Type B tanks can be used to store ammonia on board ships. He highlighted a use case involving a barge in the US with a prismatic Type B tank on board for transporting ammonia.
“Ammonia is very efficient as a hydrogen carrier,” said Mr Flores. “It is less challenging and class societies have regulations for its storage and transportation.”
Its application includes injecting hydrogen or ammonia into diesel burning engines, using ammonia as a direct fuel into ship engines, or directly fed into solid-oxide fuel cells.
Ammonia could also be used with polymer electrolyte membrane fuel cells, which will require cracking the NH3 molecule to extract hydrogen, which is 85% efficient said Mr Flores.
In conclusion, Mr Steffensen said for full industry adoption, a key challenge for the industry is to produce green fuels, such as ammonia, from renewable resources at commercial costs that are similar to current heavy fuel oil prices.
Riviera’s Maritime Air Pollution, Europe, conference continues on 22 October with sessions covering the role of ports in decarbonising the industry and the technical aspects of installation and managing emissions abatement technology - use this link for more details and to register to attend.
Use this link to view other virtual conferences and webinar weeks Riviera is hosting during Q4 2020