NOVELTY - The apparatus has a capsule containing phase change material, and comprising encapsulation material including a material that is chemically and physically distinct from the phase change material. The encapsulation material and the phase change material are selected to store and discharge thermal energy at temperatures of greater than 450 degrees Celsius without capsule failure. The capsule has an inner chamber containing the phase change material and a layer of encapsulation material placed onto a surface of the phase change material.    USE - Encapsulated phase change apparatus for storing thermal energy generated from energy source e.g. solar energy source, wind energy source, geothermal energy source and nuclear energy source (all claimed) in a solar industry.    ADVANTAGE - The encapsulation material and the phase change material are selected to store and discharge thermal energy at temperatures of greater than 450 degrees Celsius without capsule failure, so that the apparatus provides improved heat transfer fluids for thermal energy storage. The apparatus utilizes phase-change latent heat so as to increase thermal capacity, and offers energy storage at preselected high temperatures, thus improving plant thermodynamic efficiency with decrease in cost of electricity.    DETAILED DESCRIPTION - The phase change material comprises Zinc, stainless steel, mixture of magnesium chloride and sodium chloride eutectic salts, sodium nitrate, potassium nitrate, mixture of Sodium nitrate and potassium nitrate, magnesium chloride, mixture of magnesium chloride and sodium chloride, mixture of magnesium chloride and potassium chloride, and mixture of sodium chloride and potassium chloride. The encapsulation material comprises Nickel, carbon steel or stainless steel. The capsules are provided to form a thermal energy storage system fluid in thermal contact with the capsules. The fluid is selected from the group consisting of air, silicones, biphenyls, eutectic salt mixtures such as mixture of sodium nitrate and potassium nitrate, and mixture of sodium nitrate, potassium nitrate and lithium nitrate.    DESCRIPTION OF DRAWING(S) - The drawing shows a graph of temperature distribution of an exemplary cylindrical capsule.