Direct use of ammonia

Two basic ways of using ammonia directly to generate electricity and heat are being investigated:

• Conversion of ammonia in solid oxide fuel cell (SOFC) systems
  These systems enable high electrical efficiencies and are already available on the market for conventional fuels such as natural gas. However, the switch to the carbon-free fuel ammonia requires an adaptation of the system concept. To a limited extent, ammonia can be converted directly in the cell and used to provide electrical energy - this has advantages for system complexity, heat management and thus the achievable efficiency. Nevertheless, a cracker is required to at least partially break down ammonia into hydrogen and nitrogen before it enters the cell. Catalyst materials are being developed for this process step. Suitable cracking reactors are integrated into the SOFC system and suitable operating and heat integration concepts are developed and demonstrated.
  
  
• Engine combustion
  Ammonia has challenging ignition and combustion properties, which is why a suitable concept for fuel preparation, mixture formation and ignition is required. The combustion properties of ammonia can also be improved by adding hydrogen. The provision of hydrogen by means of a cracking reactor integrated into the engine is part of the concept under consideration. Engine exhaust gases are used to provide heat for the endothermic cracking step. This heat integration allows efficient operation of the developed engine. The development work is carried out on a 1-cylinder research engine. The suitability will be evaluated on the basis of the knowledge gained.

One disadvantage of using ammonia to generate energy is the unavoidable production of harmful nitrogen oxides (NOx) in both concepts. In order to comply with the relevant emission standards, exhaust gas aftertreatment is required - similar to conventional combustion engines. Part of the work is therefore the development, characterization and optimization of long-term stable catalyst materials for this specific application.

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