Adjusting Marine Lubes for Ammonia Fuels


Adjusting Marine Lubes for Ammonia Fuels
The Ammonia 2-4 project represents an important step towards commercial ship engine concepts after early combustion tests with ammonia fuel blends. © Wärtsilä Corporation

As marine engine manufacturers develop equipment that can run on ammonia, it has become clear they will require modified lubricant formulations to address issues such as ammonia’s different corrosive action and its impact on common elastomer seals, a speaker said at an online webinar earlier this month.

Although ammonia as a gas is not itself harmful to marine lubricants, ship engine original equipment manufacturers noted key differences in the way ammonia affects the engine, compared to other ship engine fuels, Trevor Gauntlett, CEO and principal consultant of United Kingdom-based Trevor Gauntlett Consulting, said Sept. 1 during a webinar, “Marine lubrication and ammonia-fueled engines,” hosted by Riviera Maritime Media.

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“Its mode of corrosive action is different from the combustion acids we would normally discuss when we’re discussing how a lubricant has to protect a marine engine of any type,” Gauntlett said. Because ammonia is corrosive to metals, he noted, OEMs are likely to restrict the amounts of metals such as copper, nickel and yellow metals in engines and in associated control systems – anything the ammonia may come in contact with.

“But the lubricant is still going to have to protect – they’re not going to remove everything,” Gauntlett added. “Maybe they can replace some yellow metal components, but probably not everything.”

Ammonia is also aggressive to many common elastomer seals, he pointed out.

“It’s possible the lubricants may have to counteract that effect on existing elastomer types,” he said. “The first move to address any kind of problem OEMs are going to take is to try to eliminate the problem. So we may see new elastomer types used in certain parts of the engines, and therefore there’s going to be a compatibility issue for the lubricant with the new elastomers. Which probably or may not be commonly used in any kind of combustion engine at the moment.”

Re-formulation of the lubricant may then be necessary to ensure its compatible with the new elastomers, he said.

The first ammonia-fueled ship engines are expected to reach the market in around 2024.

Gauntlett said that one key initial challenge will be that as the first ammonia-fueled engines go into service, many ship owners, operators and perhaps even lubricant manufacturers will likely not have gotten much experience yet in their operation. Such experience is necessary for setting key parameters on what makes for good operation under such circumstances. Setting out specifications for what constitutes fuel-grade ammonia will also be critical, he added.

“It’s highly likely ammonia-fueled engines will require modified formulations” such as a rebalancing of existing componentry, he said.

On the seals side, the move to different elastomers could bring about the need for new lubricant additives.

“Not necessarily completely new chemicals, but chemicals that haven’t been used routinely in marine engine oils,” he said. “Certainly, additive suppliers are going to be very carefully looking through their portfolios in different application areas – have we already got some data that helps us to make decisions about existing molecules that we have in our portfolio?”