Guest Column: Dan Jackson

LNG is no longer creating the buzz, ammonia is

Ammonia is emerging as the likely front-runner in the fourth propulsion revolution in the maritime industry driven by the sector’s urgent need to decarbonize. According to the predictions from the International Energy Agency (IEA), it will account for around 45% of global energy demand for shipping in 2050.

As was the case with LNG, ammonia is faced with a chicken and egg dilemma both from the supply side and the creation of the necessary bunkering infrastructure to the very technology that would be installed on board ships. Nevertheless, engine manufacturer MAN Energy Solutions is confident that it would meet its target of developing a commercially viable, ammonia-powered marine engine by 2024. The engine would be intended for large, ocean-going containerships. Once the engine enters the market, the company plans to follow up on this breakthrough in 2025 by offering shipowners a retrofit package intended for existing maritime vessels. “We will make an ammonia-engine, one way or the other, that’s for sure,” Kjeld Aabo, Director of New Technology for two-stroke promotion at MAN Energy Solutions, confirmed in an interview. “It may be the fourth quarter of 2024, but that’s still our target and we do believe we can do that.”

The two-stroke engine being developed builds on the MAN B&W Dual-Fuel ME-LGIP Engine platform, which uses liquefied petroleum gas (LPG) as a low-emission fuel. The research and development activities are taking place at the 2 stroke headquarters and Research Center in Copenhagen, where multiple tests are being made to prove the technology works.

Economically viable

As a zero-carbon fuel, ammonia has an acceptable energy density and could be an economically viable option as it could be stored onboard vessels at a temperature of -33°C. There are two ways to produce carbon-free / neutral ammonia: via renewable sources such as hydrogen to get green ammonia or natural gas combined with CO2 capture to get blue ammonia.

The major issue when it comes to burning ammonia is its high toxicity, as its combustion may produce Nitrous oxide (N2O), which is a potent greenhouse gas. Hence the most important aspect to developing an ammonia-powered engine is making sure potential ammonia releases are prevented or minimized, and safe and quick handling of potential leakages is ensured.

“Testing of ammonia is different from other fuels being tested. It burns quite slowly, and you must have a lot of energy to ignite it. That means that it might have to run on a different amount of pilot oil, and we might even have to derate the engine. We don’t believe that we would have to opt for derating the engine, but quite frankly, it is the first time we operate a two-stroke engine on ammonia, so there might be some surprises. However, we are not in any way afraid that we cannot do it,” Aabo said.

Talking about overcoming the safety challenges in developing the engine, the deadline will be a tough one to achieve. Still, MAN Energy Solutions believes the target is realistic as there are no major bottlenecks to tackle.

Safety

“We have to ensure that the ammonia-burning engine is safe, and highly reliable. We also have to ensure that there is no N20 release, also known as laughing gas, which is a very harmful greenhouse gas. Furthermore, we need to make sure the ammonia slip is not too high in the exhaust gas. There will always be a little bit because that’s the way the process is. Finally, we need to make the engine compliant with Annex VI, Tier II, and III NOx Emission Standards and we know that actually, ammonia produces more NOx than diesel.”

Therefore, there will be a lot of things to consider when the company starts testing the technology in the beginning of 2022 on one of its big twostroke test engines. As explained, the engine is one part of the process, and MAN Energy Solutions is also working closely with classification societies in relation to the design of fuel components and the fuel gas supply systems.

“We are now going to Hazard 4 on the fuel gas supply system for the ammonia engine. This covers the ammonia tank all the way to the engine itself, including pumps, filters, as well as the gas valve trains that can ensure that the gas supply to the engine stops when the alarm sounds. We also need to ensure that when this happens, the system is in place to purge the piping with nitrogen, so pipes are cleaned from ammonia when you are operating on diesel or going into the harbour. We are working with DNV GL, ABS, BV and ClassNK on this,” Aabo noted.

“Last year, we hosted an event gathering 32 people from the industry for two full days. We looked at all the hazards that could arise from such a system.

Kjeld Aabo, Director of New Technology for two-stroke promotion. Photo by MAN Energy Solutions