Techno-economic analysis of screening metal hydride pairs for a 910 MWh_th thermal energy storage system

Matching of metal hydride pairs has a significant influence on performance of thermal energy storage (TES) system. This article conducts a complete techno-economic analysis of screening metal hydride pairs (MgH₂&LaNiAl and MgH₂&TiFeMn). A mathematical model is developed to calculate the energy consumption, which is solved by COMSOL Multiphysics v5.1. Firstly, thermodynamic matching is analyzed to judge the energy consumption qualitatively. Further, a cost model of thermal energy is established to estimate the energy consumption cost. It is found that the charging energy consumption cost of MgH₂&LaNiAl system is reduced to be zero due to a good thermodynamic matching, whereas that of MgH₂&TiFeMn system accounts for as high as 63.8% of the cycle energy consumption cost. Based on the life cycle economic analysis, matching of MgH₂&TiFeMn is considered to be a better selection due to a smaller levelized thermal storage cost (28 USD/kWh_th), where two major expenses are the capital cost and energy consumption cost, 74.3% and 19.3% respectively. Therefore, a matching principle is concluded that screening metal hydride pairs for TES should be considered in two ways: firstly, the hydrogen storage cost due to the expensive price of low temperature metal hydride; secondly, the thermodynamic matching, which determines the energy consumption cost.