Description of need
It is expected that many countries and industries will import hydrogen (e.g. for the production of steel), and that this hydrogen may arrive in the form of ammonia (NH3). There is a need for cost-effective, scalable, efficient systems to convert that ammonia back into hydrogen.
Problem severity (1-10)
8
Who has this need
Unclear who is the customer. Shipping port authorities? Entities that sell hydrogen? Need to research this.
Total addressable market (TAM)
Large
Solutions today, and their shortcomings
Potentially relevant capabilities
Work in Yogesh (Yogi) Surendranath’s lab
References
Background Research
- Ammonia cracking typically requires temperatures in the 700-1000 ºC range.
- Table 9 in [yousefiriziGreenHydrogenProduction2022] has a summary of various ammonia decomposition reactors.
- Key metrics appear to be:
- Conversion %
- Throughput
- Efficiency
- Membrane reactors are a common approach. Several kinds of membranes have been proposed (see Figure 25)
- The rare catalyst materials are an issue. There’s an interest in using Fe, Co, and Ni.
- What temperature is required?
- There’s an interest in using plasmas, electron beams, RF, etc. to
- https://arpa-e.energy.gov/sites/default/files/documents/files/REFUEL_ProgramOverview.pdf:
Cracking of ammonia is well known and is already a commercial process. In spite of high cracking temperature and expensive catalysts it is considered as viable option for hydrogen delivery.41 Recently, it has been reported that inexpensive alkali metal amides may replace or reduce loading of platinum group metal (PGM)-based catalysts and substantially reduce the cracking temperature.42 Another potential approach to H2 generation from CNLFs is electrolysis. For example, ammonia oxidation to H2 has a low potential (0.06V) and therefore has much lower energy requirements (1.55 kWh/kg H2) compared to water electrolysis.43 Several approaches to liquid NH3 electrolysis have been demonstrated44 but the development of more effective electrocatalysts and cell designs is necessary.
- Criteria:
- Yield
- Purity
- Less expensive catalysts
- Modularity (e.g. for refueling stations)
