the temperature and pressure range where it’s decomposed again. In the diesel cycle, which is the one we use, you have very good control over this.”
This is how it could be done: burning ammonia generates nitrous oxide emissions inside a certain pressure and temperature window during the combustion process.
The final challenge has been to adapt the well-established two-stroke engine system to ammonia without changing the fundamentally good things about it. “We have to make it a very simple system that can also handle ammonia – meaning that it is modular enough to allow for easy troubleshooting and for crews to have straightforward maintenance procedures even though the fuel is a toxic substance.”
to detect leaks. “This is a common standard for all alternative fuels,” explains Christos Chryssakis, Business Development Manager and Alternative Fuels Expert at DNV. Additional solutions such as double block and bleed valves ensure that systems can be separated for maintenance.
“Our class rules for ammonia are based on experience with ammonia as a refrigerant and as cargo. We are constantly updating these rules, as ongoing research offers further insights into the necessary margins to ensure that systems are not only safe but also practical in their handling,” says Chryssakis. “Carrying out risk assessments on the first designs for ammonia-fuelled vessels will be an important next step.”
The MAN Energy Solutions test bed plays a crucial role in the development of ammonia combustion technology, which, while carbon-free, must ensure safety and avoid corrosion.
Ammonia tankers ideal first users
Looking ahead, the first engines will likely be installed on ammonia tankers. Currently there are about 200 gas tankers that can take ammonia as cargo and typically 40 of them are deployed with ammonia cargo at any point in time. These kinds of vessels could be ideal candidates as they already have the fuel as cargo and crews with experience in handling ammonia. Other segments such as bulk carriers and containerships could follow suit. DNV expects the first ammonia-fuelled vessels to hit the water in the second half of this decade, but large-scale uptake of this technology is not expected until the early 2030s.
The safety of ammonia systems and operational procedures is at the top of the agenda in DNV’s work on this fuel. In the AEngine joint development project, DNV is handling the safety aspects and will be performing risk assessments with regard to hazard identification (HAZID), hazard and operability (HAZOP) and failure mode and effect analysis (FMEA).
Safety: Mitigating ammonia toxicity
DNV class rules for ammonia as ship fuel were published in July 2021, paving the way for technology development. They include provisions for storing, handling and bunkering ammonia on board. Some of the aspects to consider here include the use of toxicity zones and venting masts in specific locations.
The engine technology itself would be fitted with double wall piping, so that the pipe containing ammonia is surrounded by a ventilated space, making it easy
60 | The Report • June 2022 • Issue 100
Looking beyond operations on board ammonia-fuelled vessels, DNV recently completed studies on ammonia bunkering operations in the Ports of Amsterdam and Oslo, examining the potential ramifications of a large ammonia leak in ports. “We looked at worst-case scenarios, including the implications of leaks in the port-side supply infrastructure and on a bunker vessel. The Port of Oslo lies in a residential area – so the stakes are particularly high here,” explains Chryssakis.
“We defined external safety zones and risk-reduction measures, looking at the radius which would be affected by an ammonia leak. For the Port of Oslo, we found that in principle using a bunkering vessel with refrigerated ammonia would come with an acceptable risk level, because the residential area in Oslo would not be affected by a leak. But there is still work to be done to ensure safe handling on board.”
“There are many parts to this puzzle and it’s essential that we have them all in place for ammonia to safely enter the marine fuel market,” says Hendrik Brinks. “We will need rigorous safety procedures, the inclusion of ammonia in international regulations as well as engine designs that control harmful emissions and allow for straightforward maintenance protocols. And of course, highly skilled crews that are trained to handle ammonia and green ammonia in sufficient supply. Only then can ammonia reach its full potential as one of the most promising green fuels
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