MAN Energy: Ammonia fuel for marine engines

May 29, 2020 | Case Study

With the implementation of the International Maritime Organisation (IMO)'s 2050 roadmap, the shipping industry faces clear challenges in determining the best route to reduce emissions. Our forecasts highlight this challenge, with a plethora of alternative fuels, powertrains, and energy sources preventing a clear roadmap for shipping industry decarbonization. Shipping companies also have varying routes with different shipping infrastructures. The lack of a clear roadmap compounded by varying fueling demands within the shipping industry means the future fuel supply market may well be fragmented and without a single low- or zero-carbon fuel of choice. However, this fragmentation presents opportunities for individual players to dictate their own energy strategy by establishing supply chains based on their own requirements and for equipment manufacturers to find some measure of protection from competitors by owning a niche within the potentially inhomogeneous market. As a major marine sector engine manufacturer, MAN Energy Solutions is pursuing multiple decarbonization routes, including liquified natural gas.

Ammonia (NH₃) presents an additional route for shipping decarbonization. As a diesel engine fuel, NH₃ has clear benefits. When combusted, it emits virtually no CO₂, SOx, particulate matter, or unburned hydrocarbons, though a small amount of injected pilot fuel will produce some emissions. Furthermore, with a high combustion temperature of around 1,300 °C, and regulated by the injected pilot oil, ammonia gives stable and robust combustion. Additionally, ammonia has a higher volumetric energy density than liquid hydrogen, though less than hydrocarbon fuels. Ammonia can also be stored relatively easily, after liquefaction via compression to a pressure above 8.6 bar at ambient temperatures (though NH₃ is commonly stored at approximately 17 bar to keep it in the liquid phase if the temperature rises). Finally, from a supply chain perspective, NH₃ is a major industrial chemical used in fertilizer production, with established production capacity and transportation infrastructure. Yet ammonia is not a drop-in replacement for hydrocarbon fuels. Notably, it is toxicity and corrosiveness present clear operational challenges and would require significant capital expenses to support ammonia combustion, especially for retrofits.