Marine Sector Turns to Ammonia to Decarbonize Shipping

The shipping industry is charting a new route toward cutting
fossil fuel use in ocean-going vessels: ammonia.

To date, no ammonia-fueled ships have been built, but that’s
not stopping companies including Equinor, MAN Energy Solutions and
Wärtsilä from rushing to help bring ammonia-fueled ships to

Moves to adapt engines and ship designs to ammonia fuel are
driven by a 2018 International Maritime Organisation (IMO)
commitment to cut international shipping’s annual greenhouse gas
emissions by at least 50 percent by 2050, compared to 2008

“Making the target a reality means getting commercially viable
deep-sea zero-emission vessels into operation by 2030,” said
Katharine Palmer, global head of sustainability at Lloyd’s
Register, the maritime classification society.

“Fully decarbonizing the shipping sector presents a
significant challenge,” she added. “It has the potential to be
among the most disruptive transitions that shipping has had to deal
with but also to provide significant opportunity for the

Moving away from fossil fuels in shipping will require different
approaches according to the type of vessel involved, experts
believe. Commuter ferries such as those plying waters in
Washington State
are already moving towards battery power.

Elsewhere, compressed or liquified
green hydrogen
could be an option for ships that are able to
refuelregularly. However, for vessels that spend days or weeks at
sea, such as tankers, super trawlers or cargo ships, the size of
the fuel tanks needed for hydrogen would be prohibitive.

Another possibility is for the industry to rely on synthetic
diesel or other carbon fuels produced using renewable energy. Here,
though, the problem is cost.

Synthetic diesel would cost approximately twice as much as green
hydrogen in terms of energy on a megajoule-per-megajoule basis,
said Niels de Vries, lead naval architect at C-Job Naval Architects
of the Netherlands.

Green ammonia’s manageable drawbacks

Green ammonia, which requires less storage volume than hydrogen
and is cheaper to make than synthetic carbon fuels, seems like a
handy compromise. But as a fuel it is still far from ideal.

Although more energy-dense than hydrogen, ammonia still occupies
significantly more space than diesel for the same amount of
propulsion. New vessel designs might be able to accommodate this,
but retrofitted ships could end up losing a fair amount of space in
the hold.

Wärtsilä is already testing an ammonia engine. (Credit:

Other problems with ammonia are that it is toxic, could emit
polluting nitrogen oxides throughout the fuel cycle and, as
produced today, is still far from carbon neutral. Nevertheless,
proponents claim that none of these drawbacks is fatal for its

“We have experience already with burning all sorts of fuels
and mixing them in all sorts of interesting ways,†said Peter
Kirkeby, a technical promotion and support specialist at MAN Energy
Solutions, which is developing a two-stroke vessel engine that can
run on ammonia.

“Yes, it will be a challenge. But it’s also something we can

Ammonia engines on the way

Kirkeby said MAN Energy Solutions was expecting to have a
two-stroke ammonia engine ready to deliver in the first quarter of
2024. By Q1 2025, the company also aims to offer retrofit
conversions to allow existing two-stroke engines to use

Separately, the Finnish marine-to-energy giant Wärtsilä is
working on four-stroke engine designs.

As well as hoping for field tests from 2022, “Wärtsilä is
developing ammonia storage and supply systems as part of the

EU project ShipFC
to install ammonia fuel cells on Eidesvik
Offshore’s supply vessel Viking Energy by 2023,†said the
company in a statement.

After its conversion, Viking Energy is expected to become the
first carbon-free ammonia-powered vessel in the world. Equinor will
be using it for supply operations on the Norwegian continental
shelf, as part of moves to cut supply-chain emissions.

The ship is expected to be a sign of things to come in the
shipping industry, but insiders concede it would take a lot more
than technical innovation to shift the sector away from fossil

“Zero-carbon fuels are significantly more expensive than
conventional fuels,†noted Hege Rognø, manager for low-carbon
technologies at Equinor. “For fuel producers to scale up
production a market needs to exist, but a market will not appear
before the fuel is available.â€

And beyond this chicken-and-egg situation, she said, “As
shipping to a large degree is international, the legislation also
needs to be adjusted and aligned internationally. What the IMO
decides will be important for how quickly the shipping industry
will decarbonize.â€

Source: FS – GreenTech Media
Marine Sector Turns to Ammonia to Decarbonize