Characterization of an ettringite-based thermochemical energy storage material in an open-mode reactor

Abstract The mismatch between renewable energy supply and demand requires energy storage technologies to work out the dilemma. In the thermal energy field, ettringite-based energy storage seems to be a good solution thanks to its high energy density and low material cost. It can store excess solar energy to meet the heating and domestic hot water demand in buildings. Therefore, the current work experimentally examines the energetic performance of an ettringite-based material made of commercial cements. The TG-DSC analysis shows the energy storage capacity of the investigated material is as high as 282 kWh/m3 original hydrated materials. Besides, the laboratory reactor tests prove the charging temperature is as low as 55–65°C for ettringite. Under operating conditions, the average energy-releasing power during the full period is about 33.3 W/kg while the maximum power is about 915 W/kg original hydrated materials, which are significantly higher than most materials from the literature. The best volumetric energy-releasing density and the corresponding prototype storage density of the fixed-bed obtained are 176 kWh/m3 original hydrated materials and 104 kWh/m3, respectively.