In the breakneck quest for zero-carbon fuels, ammonia is emerging as a strong contender
It is one of the most widely used chemicals in the world. It is abundant – production levels approach 200M tonnes a year – and unlike some of the newer fuels on the horizon, it has the advantage of a long-established storage and transport infrastructure. And above all, it is a zero-carbon fuel, provided it is sourced renewably.
Ammonia is currently being cited as one of the fuels of the future for the shipping industry. Trade body Ammonia Energy Association believes the chemical has high potential in combustion engines, noting back in 2017: “Ammonia is emerging as an economically viable fuel for dual-fuel engines where it can be used as a substitute for natural gas.”
At that time though, critics pointed out there was no commercially available dual-fuel ammonia engine. Nor was there anything like an adequate bunkering system.
So what has changed in the last two years? “The maritime industry is learning about ammonia fast,” noted the association in its October annual review. “It is searching for a new bunker fuel and ammonia is one of the few options that can realistically deliver a 50% reduction in the sector’s greenhouse gas emissions by 2050.”
Quick off the mark, MAN Energy Solutions unveiled its ammonia-fuelled two-stroke concept engine in late 2018 and has budgeted US$5.7M to the further development of the project. Chairman Uwe Lauber has announced that the first ammonia engine could be in operation by early 2022.
When it is released, the engine will be based on MAN’s B&W dual-fuel ME-LGIP engine, which uses LPG. A two-stroke, it is suitable for large ocean-going vessels such as tankers, bulk carriers and container ships with engine sizes between 5-85MW. In short, a deep-sea alternative.
Further, the potential for retrofits opens up a huge market. According to MAN’s calculations, there are 3000 B&W engines that can in theory be converted to ammonia operation. Behind the scenes, at least one shipowner is trialling the fuel. And industry partnerships are tackling a variety of issues, including regulations.
Still, hurdles remain and ammonia must yet be accepted as a fuel under the IGC Code. However, MAN says it will probably start this process by seeking approval from a flag state, most likely Norway.
Even so, as Maersk chief operating officer Søren Toft warned recently, the absence of bunkering cannot be underestimated. “The main challenge is not at sea but on land,” he said, pointing out that it is relatively easy to reconfigure onboard technology.
But what are ammonia’s properties as a fuel? Apart from its environmental virtues, it is rated a high-octane fuel with “a high level of resistance to pre-ignition”, according to the Ammonia Energy Association. It can also be burned in an engine without producing any CO2 or carbon. And it can be stored as a liquid at minus 34C, or at normal temperatures at a pressure of about 10 bar.
On the minus side, not only does ammonia weigh twice as much as fuel oil, it requires three times the space to contain the same amount of energy. It is highly toxic and has caustic properties, posing problems in carriage and bunkering.
However, according to the Ammonia Energy Association, about 170 ships currently in operation are equipped to carry ammonia and about 40 of these cargo it on a regular basis.
And finally, ammonia is no stranger to the engineroom – the chemical has been used as a refrigerant for many years.