System-level analysis of energy efficiency in a Power-to-Ammonia-to-Hydrogen Cycle : a case study

Abstract

This thesis assesses the energy efficiency of a Power-to-Ammonia-to-Hydrogen (P2A2H) chain, where electricity is converted to hydrogen via electrolysis, then synthesized to ammonia, stored and transported, and, finally, reconverted to hydrogen through cracking and purification processes. A thermodynamically consistent and simplified model was used on a 1 kg delivered hydrogen basis with the use of literature data for the specific electricity consumption for each stage of the chain.

The obtained values for the central case indicate a total electricity demand of 59.45 kWh per kilogram of hydrogen delivered that corresponds to 56% (LHV) round-trip efficiency and lies within the range of 50 – 60% range, reported for similar systems. The most dominant energy consuming stages are water electrolysis and ammonia cracking, while other processes combined showed only a minor contribution. The transparent and stage-resolved framework is the main innovation, which combines process breakdown with a systematic sensitivity analysis and comparison of alternative hydrogen carriers, clearly highlighting electrolysis efficiency and cracking energy demand as the key levers for improving P2A2H efficiency. The results, interpreted in the context of current large-scale projects such as NEOM, H2Global and Project Yuri, position chain as a medium efficiency, but logistically an attractive option for long distance renewable hydrogen transport and provide a practical benchmark for future technology and system development.