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Study: alcohol, biomethane and ammonia are the best-positioned fuels to reach zero net emissions for shipping; OPEX, not CAPEX challenge

A study by A.P. Moller - Maersk and Lloyds Register has found that the best opportunities for decarbonizing shipping lie in finding new sustainable energy sources. Based on market projections, the best positioned fuels for research and development into net zero fuels for shipping are alcohol, biomethane, and ammonia.

Energy efficiency has been and still is an important tool for Maersk to reduce CO2 emissions; efficiency measures have positioned Maersk 10% ahead of the industry average. However, achieving net zero requires a total shift in the way deep sea vessels are propelled. The shipping industry needs to introduce carbon-neutral propulsion fuels and new technologies.

The main challenge is not at sea but on land. Technology changes inside the vessels are minor when compared to the massive innovative solutions and fuel transformation that must be found to produce and distribute sustainable energy sources on a global scale. We need to have a commercially viable carbon neutral vessel in service 11 years from now.

—Søren Toft, Maersk Chief Operating Officer

The joint study evaluates the interplay between economic performance of zero-emission vessels (ZEVs), technology readiness of fuels, associated machinery configurations, as well as safety and environmental considerations, all in the context of the wider energy system and the dependable production of future fuels.

The study also found that the most relevant carbon neutral fuel configurations have relatively similar cost projections so initial modelling cannot yet determine clear winners purely from a cost point of view.

It is too early to rule anything out completely, but we are confident that these three are the right places to start. Consequently, we will spend 80% of our focus on this working hypothesis and will keep the remaining 20% to look at other options.

—Søren Toft

The next decade requires industry collaboration as shipping considers its decarbonization options and looks closely at the potential of fuels like alcohol, biomethane and ammonia. This joint modeling exercise between Lloyd’s Register and Maersk indicates that shipowners must invest for fuel flexibility and it is also clear that this transition presents more of an operating expenditure rather than capital expenditure challenge.

—LR CEO Alastair Marsh

The additional price to build a ship with new fuel tanks, modified engines and fuel supply systems is a very small element of the total cost of operation, as the additional CAPEX cost is divided over the lifetime of the ship but given the potential impact of future fuel prices on operating costs, shipowners must invest in flexibility—for example, designing a ship which can run on one fuel today and later be retrofitted to run on an alternate fuel.

—Katharine Palmer, LR global head of sustainability, who led the study on behalf of the classification society

Alcohols (ethanol & methanol) are not a highly toxic liquid with various possible production pathways directly from biomass and/or via renewable hydrogen combined with carbon from either biomass or carbon capture. Existing solutions for handling the low flash point and for burning alcohols are well proven. Ethanol and methanol are fully mixable in the vessel’s bunker tanks, creating bunkering flexibility.

However, the transition of the industry towards alcohol-based solutions is yet to be defined. Biomethane on the other hand has a potential smooth transition given existing technology and infrastructure. The challenge however is methane slip—the emission of unburned methane along the entire supply chain.

Ammonia is truly carbon free and can be produced from renewable electricity. The energy conversion rate of this system is higher than that of biomaterial-based systems, but the production pathway cannot tap into potential energy sources as e.g. waste biomass. The main challenge for ammonia is that it is highly toxic and even small accidents can create major risks to the crew and the environment. The transition from current to future applications is also a huge challenge for ammonia.

According to Maersk and Lloyds Register, batteries and fuel cells are unlikely to have an immediate role in propelling commercially viable carbon-neutral deep-sea vessels.

Shipping is responsible for 2-3% of global greenhouse gas (GHG) emissions, so the industry has significant potential to help create a carbon-neutral economy by 2050. Maersk is determined to play its part by leading the development and scaling of future solutions.



The problem with shipping is that it is international and thus difficult to enforce regulations. Even if Maersk obey the rules, it will be very hard to get a decent compliance rate.
IMO, the easiest would be methane (bio or otherwise), but they point out the "methane slip" problem which should really be called "methane leak" problem.

Steve Reynolds

Why not nuclear?

Paul Wittwer

Coal, oil and gas comprise around 40% of maritime trade so the demise of that part of shipping alone would result in a huge reduction of it's emissions. Ammonia is already shipped all over the world so I don't see a problem with using it as fuel with the proper precautions.
I see hydrogen, split from ammonia using membrane technology, fueling Solid Oxide fuel cells, generating electricity for High Temperature Superconductor motors for future shipping. Hopefully, the same technology will replace fossil fuels in aviation even sooner.


@Steve, I think the safety requirements would make it too expensive.
+ if you got hijacked, you would have a larger problem.
Better to keep it on land - I have no personal objection to nuclear, although many do.


here's a link.
(I haven't read it)


The main challenge for ammonia is that it is highly toxic ...
I remember someone favoring this was opposing methanol for being toxic.

Roger Pham

Just use Hydrogen directly, either in combustion engine or in fuel cell.


LNG/DME with SOFCs can power ocean going ships more cleanly.


A nuclear-powered ship has no reason to run slow enough for hijackers to be able to board.  It can avoid pirate-rich areas like various straits in Malaysia/Indonesia because it doesn't have to pick the shortest path to save fuel and time; it can just go at maximum speed most of the time.

On top of this, a nuclear powered ship can easily have a much lower "mission weight" than one carrying thousands of tons of bunker fuel, and thus carry more cargo.

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