16/11/2021
How ammonia could decarbonise shipping
Andy Extance discovers why the compound best known as a fertiliser is a surprising candidate to power enormous container ships
In a giant warehouse in Copenhagen, Denmark, sits a 500-tonne engine, each revolution of its crankshaft moving the world nearer a revolution that could clean up international shipping. There, in the research centre of engine designer MAN Energy Solutions, the only clue to that transformation is invisible. MAN provides designs to heavy industry conglomerates, primarily in Asia, to make container ship and tanker engines that ‘are in 50% of all world trade’ according to the company’s principal promotion manager, Peter Kirkeby. ‘We are in very deep talks with the market continuously,’ Kirkeby says. ‘There’s a need for a fuel that doesn’t carry carbon.’
If you follow the world’s decarbonisation plans, you might expect the carbon-free fuel that they are testing to be hydrogen, but near this engine you might occasionally be able to smell that you’re wrong. MAN Energy Solutions’ huge test engine is burning a substance that some chemists might even be surprised to hear could be a transportation fuel – ammonia. The gas is very easy for humans to detect by smell, says Kirkeby – and toxic. MAN Energy Solutions is currently determining how to get it into engines safely. ‘Part of the difficulty here is to engineer a system where you do not have any leaks,’ Kirkeby explains. ‘And if you do, you can detect them, and you don’t panic, you will not have an emission of ammonia to an engine room where people work and make their living. To get it from a tank to the engine and keep it at a safe level, that is no simple task.’
The test engine now features safety and supply systems suited to ammonia, but otherwise looks like most other large two-stroke marine engines. MAN Energy Solutions will start to use it in tests burning ammonia as fuel in 2022. A further key landmark on ammonia’s voyage will come in 2024, when the company hopes to deliver its first engine that can burn either ammonia or conventional oil fuel. Ammonia burns less well than oil-based fuels, but Kirkeby stresses that these enormous engines in container ships are well suited to dealing with this challenge through brute force. ‘We can contain a lot of pressure and deal with high temperature,’ he says. ‘It will handle a lot of abuse.’