GEA at the SMM in Hamburg: Full speed ahead with solutions for the maritime energy transition and digital transformation

Ammonia - promising alternative for shipping

Due to worldwide efforts to stop global warming, the shipping industry is also on the lookout for alternative fuels or energy sources. The International Maritime Organization (IMO) has set a goal of reducing total annual greenhouse gas (GHG) emissions by at least 50 percent by 2050 compared to the levels emitted in 2008.

This goal cannot be achieved by further improvements in the efficiency of ship propulsion systems alone. The use of alternative energy sources is necessary. Renewable energy can be generated as electrical energy by wind turbines, solar cells or hydroelectric power plants. Not only from GEA's point of view, the conversion of the generated electricity into hydrogen by an electrolysis plant is the most promising way.

According to the current state of the art, storing hydrogen on board ships would require pressure vessels with pressures in the range of 350 bar and more. However, due to the low density of hydrogen, a too large tank volume would be required. Cooling the hydrogen to -253 °C would allow it to be stored in liquid form, but this requires energy for cooling and energy to maintain this low level while it is stored on board. Alternatively, hydrogen can be converted to ammonia.

Ammonia only needs to be cooled down to -33 °C to store it in liquid form under atmospheric pressure. Of course, permanent cooling energy is also required here to keep the temperature down, as well as good thermal insulation of the tanks to minimize heat input from the environment into the tank. However, proven technologies are available for this purpose: Liquefied natural gas (LNG) is already used on board hundreds of ships today. Here, the temperature must be -162 °C to keep it liquid at ambient temperature. Handling and storing a substance at -33 °C is far less demanding than handling and storing a substance at -162 °C. A growing community is convinced that using ammonia as an energy source is an attractive option for bringing energy on board.

Global production of ammonia is estimated at more than 140 million tons per year. This figure shows that the handling of ammonia is well understood worldwide. It is now transported all over the world by truck, rail and, of course, by ship. Thus, the storage of ammonia in larger quantities on board ships is also a proven technology. Since the current production of ammonia also produces CO₂, the above-described way of producing ammonia based on green energy is necessary for its future use as an energy carrier.

In addition, ammonia can also be used on board of ships as a hydrogen carrier for hydrogen fuel cells or for direct use in ammonia fuel cells, which are currently under development.