Advanced Industrial Heat Supply: H2 Infrastructure and Metal Hydride Synergies for increased Energy Efficiency

Abstract

Hydrogen is seen as a promising alternative to conventional industrial heat supply offering benefits in reducing carbon emissions and at the same time a potentially straight-forward transition from natural gas. Typically, the hydrogen supply pipeline operates at pressures above 30-35 bar (ps), while end-user consumption occurs at pressures below 6 bar (pc). This pressure ratio (ps/pc>5) presents a significant opportunity for efficient energy utilization. One such opportunity is integrating metal hydrides (MH) in hydrogen-based industrial processes to enhance energy efficiency by upgrading waste heat from various temperature levels. By integrating an MH system between the hydrogen supply pipeline and industrial processes, heat (ṁH2·ΔHMH) is added at elevated temperatures, while hydrogen is absorbed at supply pressures (ps). In a subsequent step, it releases the gas to the consumer at pc, utilizing heat from downstream processes at lower temperature. To ensure quasi-continuous operation, a dual-reactor setup is necessary: one reactor serves as a heat source while absorbing hydrogen, and the other supplies hydrogen to the combustion process, with their roles alternating. The actual temperature level is defined by the used MH whereas the reachable temperature lift depends on the available pressure ratio. This contribution will introduce the technology with the presentation of an experimental proof-of-concept (TRL 4) for low temperature/cooling applications. It will continue with a theoretical study about the integration of the system in industrial processes, providing system schematics and performance evaluations. As conclusion and outlook, we will discuss first ideas for future integration and application strategies to utilize synergies between hydrogen as energy carrier and reaction partner for thermochemical systems.