Electrochemical hydrogen compression toward operation in hydrogen distribution systems

Hydrogen will be a key component of a zero-emission energy system, enhancing resilience and aiding in decarbonizing hard-to-abate sectors. For mid-term hydrogen distribution and storage, blending hydrogen into the natural gas grid presents a viable option that necessitates decentralized compression and separation technologies, as hydrogen must be compressed to achieve competitive volumetric energy density. Existing technologies, such as mechanical compression and pressure swing adsorption, are not well suited for distributed hydrogen compression and separation and often entail high footprints and capital costs. Electrochemical hydrogen compression is an evolving technology combining separation and compression, delivering high hydrogen purity and operational flexibility. This thesis aims to advance electrochemical hydrogen compression applicability in natural gas mixtures by increasing process robustness against impurities and reducing costs through innovative reactor design. Low- and high-temperature electrochemical hydrogen compressor (EHC) systems are compared in this work, assessing their performance and poisoning tolerance in the presence of single impurities (CO2, CO, NH3, H2S) at natural gas concentrations. In the low-temperature EHC, detrimental performance reductions due to impurities were observed. With impurity/hydrogen mixtures, the high-temperature EHC demonstrated stable operation, minimal potential increase, and higher product gas purity compared to the low-temperature EHC. However, diluting the H2S/ hydrogen feed with methane resulted in severe potential oscillations. Several mitigation strategies were implemented to address H2S poisoning in the high-temperature EHC, with repetitive cyclic voltammetry proving the most effective and efficient. Furthermore, an innovative tubular reactor design was developed alongside a 2D numerical model. This work established a proof-of-concept for the tubular EHC design. The modelling results indicated the process competitiveness of EHC technology compared to state-of-the-art separation and compression methods, highlighting its potential for integration into future hydrogen distribution systems. This research demonstrates the capability of high-temperature EHCs to simultaneously compress and separate hydrogen from natural gas mixtures containing critical impurities. By developing innovative reactor designs and demonstrating effective mitigation strategies for poisoning effects, this work advances EHC technology, paving the way for its integration into hydrogen distribution systems.