This works investigates a new type of spherical heat storage tank. A passively moving plate is fixed at the tank axis to increase the discharge flow rate without thermocline layer. The dynamic mesh Remeshing technique is activated to update the computational domain during the plate movement. The passive pitching of the submerged plate is due to the fluid-dynamic loads that acting on the plate during the discharging process. This makes it possible to prevent the mixture between hot and cold water regardless to the inlet flow rate. The present model is a single half-spherical tank used to achieve both energy storage and delivery. A comparative analysis between tanks with typical diffusers and the new moving plate model is provided. The comparison of the computational results with the available experimental data showed a good agreement. Examinations of the vortices interactions and the accompanying temperature contours indicate that the suggested model has height stratification efficiency while the other models are affected by thermal gradient and flow mixing.