We climb metal mesh stairs up to the cylinder heads and back down again. The test engines in the WinGD halls in Winterthur are the size of a holiday house. Stainless steel pipes are everywhere. Corrosive substances are being used here. In another hall, a tank is jacked up on an angular metal frame that fits into a container the size of a railway wagon or truck. ‘For safety reasons, we refrain from transferring the ammonia from the transport tank to our own tank,’ explains our guide through the halls, emphasising that the safety regulations of the city of Winterthur are strictly adhered to.

Photography is prohibited. The research that WinGD is conducting here is likely to be of interest to competitors. A film on a screen shows in slow motion what happens in a fraction of a second in the cylinder of a test engine: two substances are injected. One ignites and thus ignites the other. Diesel serves as the pilot fuel, while ammonia provides the power. In the future, it is intended to power ship engines. Since it does not ignite on its own in the cylinder, it needs a boost from diesel. ‘We have managed to reduce the diesel content to five percent,’ explains the engineer, who is showing the group of visitors around the factory halls, with a sense of pride.

New fuel – new problems

Fossil fuel consists mainly of atoms containing hydrogen (H) and carbon (C). Combustion produces water (H₂O) and the greenhouse gas carbon dioxide (CO₂). That is why alternatives are being sought.

Ammonia (NH3) contains no carbon and is being discussed as a zero-carbon marine fuel. However, ignition with diesel shows that the term ‘zero’ must be put into relativity. Ammonia-powered car engines, such as those being developed in China for Toyota, are said to produce 90 per cent less CO₂. This corresponds to the order of magnitude expected for cargo ships powered mainly by wind.

However, ammonia has a number of disadvantages:

• Ammonia is easier to handle than pure hydrogen. However, the production of ammonia requires more energy than is ultimately available on board.
• Ammonia is toxic, which requires protective measures for the crew.
• The combustion of ammonia also produces emissions:
  – Nitrogen oxides (NO, NO₂, collectively referred to as NO_X) are harmful to health and promote the formation of particulate matter. NOx acts as a fertiliser. Nitrogen input through the air affects ecosystems. ‘It can be noticed that the use of NH₃ in combustion engines has a relatively higher contribution to impact categories such as marine eutrophication and terrestrial eutrophication,’ according to a study by a Swedish university (Kanchiralla et al., 2023). Eutrophication means overfertilisation. Among other things, excessive algae growth leads to oxygen-depleted zones where all life dies.
  – Unburned ammonia also escapes in the exhaust gases. The authors of a study by the Massachusetts Institute of Technology expect emissions of 82 teragrams (82 million tonnes) of ammonia per year under current legislation. They expect over 600,000 premature deaths (Wong et al., 2024). They are therefore calling for strict ammonia emission controls.
  – The combustion of ammonia also produces nitrous oxide (N2O). This is a greenhouse gas that is around 270 times more potent than CO2. ‘We find that the tailpipe N2O emissions from ammonia-powered ships have climate
• impacts equivalent to 5.8% of current shipping CO₂ emissions.’ (Wong et al., 2024) The Swedish study also points to the problem of nitrous oxide emissions: ‘The amount of these emissions is still uncertain as the technology is immature and hence it is critical for NH3-fueled combustion engine systems to control the N₂O emissions to have climate impact reduction benefits.’ (Kanchiralla et al., 2023). ‘There is a hype around this fuel in shipping today. But if, and when, we make a shift to ammonia, it is to solve the problem of using fossil fuels, and at the moment it seems like we might end up creating more problems instead,’ explains Fayas Malik Kanchiralla (Naida Hakirevic Prevljak, 2024).
• Ammonia contains less than half the energy per volume found in methane, the main component of liquefied natural gas (LNG). This means that either tanks around two and a half times larger would be required on board, or ships would have to make more frequent stops to bunker. Added to this are the tanks for diesel as an ignition aid and as backup fuel in case the ammonia propulsion system fails.
• Green ammonia is converted green electricity. However, this is not produced without emissions. Mining for the necessary minerals and metals has an impact on the environment and climate. The new fuels are certainly an improvement on heavy fuel oil. However, when you consider the emissions from the production of the new green hydrogen-based fuels to their combustion on ships, it becomes clear that there is no such thing as an emission-free combustion engine. 

The lack of green electricity 

Until now, ammonia has been produced with hydrogen from fossil raw materials, for example as fertiliser. However, ammonia could only become less harmful to the climate than fossil fuels if the hydrogen were produced from water by electrolysis using green electricity. This presents two hurdles:

• In 2020, the global electrolysis capacity for green hydrogen was 0.3 gigawatts. The International Energy Agency (IEA) estimates that by 2050, capacity would have to be increased to 3600 gigawatts, i.e. twelve thousand times the current level (IEA 2024).
• A large container ship burns 3,900 tonnes of heavy fuel oil on its journey from Shanghai to Rotterdam, which corresponds to 8,400 tonnes of ammonia in terms of energy, according to calculations by Norwegian professor Jan Emblemsvåg. However, due to conversion losses, far more green electricity is needed to produce this amount of ammonia (Portnews, 2022). Commodities trader Trafigura estimates that replacing fossil-based marine fuels with green methanol or green ammonia alone would require ‘about 20 per cent of current global electricity production’ (Trafigura, n.d.). Emblemsvåg estimates that the green electricity requirement is 2.7 times the EU's current total electricity production (email communication dated 15 December 2023).
• The production of green electricity requires metals such as copper, nickel, aluminium, cobalt, lithium and rare earths. For copper alone, which we are familiar with, forecasts predict that production will not be able to meet demand in the future. This will put a brake on electricity production from renewable sources.

In other words, neither the electrolysis capacity nor the required amount of green electricity are likely to be available within the few years leading up to 2050. This is because it is not just about the needs of the shipping industry. Rather, there is competition for use: land and air transport, steel and fertiliser production and many other industrial sectors also need green hydrogen and green electricity if they are to become even remotely climate-neutral.

Electricity production from renewable sources has grown impressively in recent years. However, green energy is not yet being used as a substitute for fossil fuels, but rather as a supplement: consumption of fossil fuels continues to rise, albeit at a slower rate than energy from renewable sources (IEA, 2025).

‘The technology is ready, but the fuels are not.’

Back to the event at WinGD in Winterthur. The invitation came from the Swiss Ministry of Foreign Affairs, the Federal Department of Foreign Affairs (FDFA). Among those who attended were the Swiss Shipowners Association, the lobby association for the commodities trade Suissenégoce, the industry association Swissmem and a number of companies working on innovations in marine engines. It is to be regretted that the UN shipping organisation IMO has postponed its decision on concrete measures by a year, as this means uncertainty regarding upcoming investments. The representative of the Swiss Maritime Shipping Office emphasised that the Swiss delegation had advocated for the controversial Net-Zero Framework at the IMO meeting.

Several companies presented their work in short presentations. The following graphic was projected under the heading ‘Increasing demand in alternative fuel technology and infrastructure’.

Image

Foto: Daniel Haller

From the perspective of a company that develops such technology, the growing demand can be emphasised. However, from the perspective of increasingly rapid global warming, the data is sobering: if we exclude fossil fuels LNG and LPG (which we know as camping gas), as both produce CO₂, then just one-eighth of the tonnage ordered is powered by electricity, methanol (CH₄O), ammonia or hydrogen. Electric propulsion is only suitable for short distances, such as ferries, inland waterway vessels, tugs or harbour barges. Electricity is unsuitable for long-distance ocean-going traffic.

Most shipowners have opted for methanol. This too is questionable: ‘grey’ methanol from fossil sources is even more harmful to the climate than fossil fuels. ‘True climate benefit depends on verified green content and upstream production.,’ according to the portal shipuniverese.com, among others.

The conclusion projected in the conference room at WinGD by another company: ‘The technologies are ready. The fuels are not.’ In other words, the economic, political and social structures that have been made possible by cheap fossil fuels cannot be made climate-friendly simply by replacing fuels. Even nuclear propulsion, which Professor Emblemsvåg proposes in view of this impossibility, offers no way out.

This does not mean that technical innovation is useless in principle. The narrative that this is ‘THE SOLUTION’ may be appealing to hear, because it avoids uncomfortable discussions about the necessary transformation and suggests that everything can continue as before with a few technical tweaks. But there are no technical solutions for false structures such as overconsumption, waste or extreme social inequality.

References

Chalmers University of Technology (2024): Ammonia attracts the shipping industry, but researchers warn of its risks, https://www.sciencedaily.com/releases/2024/02/240205165910.htm 

IEA International Energy Agency (2025): Global Energy Review 2025, https://iea.blob.core.windows.net/assets/5b169aa1-bc88-4c96-b828-aaa50406ba80/GlobalEnergyReview2025.pdf 

IEA International Energy Agency (Juli 2022): Securing Clean Energy Technology Supply Chains, S. 9, https://iea.blob.core.windows.net/assets/0fe16228-521a-43d9-8da6-bbf08cc9f2b4/SecuringCleanEnergyTechnologySupplyChains.pdf 

Fayas Malik Kanchiralla, Selma Brynolf, Tobias Olsson, Joanne Ellis, Julia Hansson, Maria Grahn (2023): How do variations in ship operation impact the techno-economic feasibility and environmental performance of fossil-free fuels? A life cycle study, Gothenburg, Sweden, Chalmers University of Technology, Department of Mechanics and Maritime Sciences, https://www.sciencedirect.com/science/article/pii/S0306261923011376?via%3Dihub 

Portnews (2022): One large container ship would spend green energy corresponding to annual consumption of 139,000 households, https://www.worldports.org/one-large-container-ship-would-spend-green-energy-corresponding-to-annual-consumption-of-139000-households/ 

Naida Hakirevic Prevljak (2024): Switching to ammonia as marine fuel may create more problems than it solves, https://www.offshore-energy.biz/switching-to-ammonia-as-marine-fuel-may-create-more-problems-than-it-solves/ 

Carsten Schmidt (2024): Energiewende: Warum der Kupfermangel das eigentliche Problem der Klimaneutralität ist, Deutsche Wirtschaftsnachrichten 15.5.2024, https://deutsche-wirtschafts-nachrichten.de/708851/energiewende-warum-der-kupfermangel-das-eigentliche-problem-der-klimaneutralitaet-ist 

Trafigura (o.J.): A proposal for an IMO-led global shipping industry decarbonisation programme. https://www.maritimecyprus.com/wp-content/uploads/2020/09/Trafigura-proposal-for-decarbonisation.pdf 

Anthony Y H Wong, Noelle E Selin, Sebastian D Eastham, Christine Mounaïm-Roussell, Yiqi Zhang, Florian Allroggen (2024): Climate and air quality impact of using ammonia as an alternative shipping fuel. Centre for Global Change Science, Massachusetts Institute of Technology, Cambridge, MA, United States of America, https://iopscience.iop.org/article/10.1088/1748-9326/ad5d07/pdf