TITANIUM HYDRIDE FOR HIGH-TEMPERATURE THERMAL-ENERGY STORAGE IN SOLAR-THERMAL POWER-STATIONS

Titanium forms relatively stable hydrides (TiH2 and TiH) that allow fo r high operating temperatures (650-750-degrees-C) at low pressures (0. 1-1 MPa). These conditions are advantageous for thermal energy storage applications where high working temperatures are required. Under prac tical conditions, up to about 1.05 wt. % of hydrogen can be reversibly absorbed by titanium, which means an energy storage capacity of nearl y 0.9 MJ/kg Ti. The possibility of using titanium hydride to improve t he efficiency of solar-thermal power stations is investigated. Present ly a small-scale solar power station employing a nickel-doped magnesiu m hydride short-term thermal energy store is being developed. The oper ating temperature of this material is limited to less than 500-degrees -C, at which high working pressures of up to 10 MPa must be withstood. The hydriding and dehydriding behavior of titanium powder between 650 and 730-degrees-C has been investigated; experimental results are pre sented. Calculated data for solar power systems with a titanium hydrid e store and a magnesium hydride store are compared.