Methods of hot and cold side charging in thermal energy storage systems

A method comprising:

• storing a cold thermal storage (“CTS”) medium inside a first cold storage tank at a first temperature above an ambient temperature of atmospheric air;
• pre-cooling the CTS medium below the first temperature via heat exchange with the atmospheric air;
• cooling the CTS medium from the ambient temperature to a second temperature below the ambient temperature by flowing the CTS medium from the first cold storage tank through a cold side heat exchanger within which the CTS medium exchanges heat with a working fluid, wherein the working fluid circulates through a pumped thermal system, wherein the pumped thermal system is configured to operate in a refrigerator cycle in which energy is stored in the pumped thermal system and a heat engine cycle in which energy is discharged from the pumped thermal system, wherein the pumped thermal system comprises a closed cycle comprising, in sequence, a compressor, a hot side heat exchanger, a turbine, and the cold side heat exchanger, and wherein the working fluid flows through, in sequence and in the same direction, the compressor, the hot side heat exchanger, the turbine, and the cold side heat exchanger when the pumped thermal system operates in the refrigerator cycle and when the pumped thermal system operates in the heat engine cycle;
• and
• storing the CTS medium in a second cold storage tank.

A method comprising:

• storing a hot thermal storage (“HTS”) medium inside a first hot storage tank at a first temperature;
• pre-heating the HTS medium from the first temperature to an intermediate temperature by flowing the HTS medium through a first heat exchanger, wherein the HTS medium exchanges heat with an intermediate thermal storage (“ITS”) medium flowing through the first heat exchanger;
• heating the HTS medium from the intermediate temperature to a second temperature by flowing the HTS medium from the first heat exchanger through an element configured to transfer external thermal energy to the HTS medium;
• storing the HTS medium in a second hot storage tank;
• circulating a working fluid through, in sequence, a compressor, a hot side heat exchanger, a turbine, and a cold side heat exchanger, wherein the working fluid circulates through a pumped thermal system that is configured to operate in a charging mode in which energy is stored in the pumped thermal system and a discharging mode in which energy is discharged from the pumped thermal system, and wherein the working fluid flows through, in sequence and in the same direction, the compressor, the hot side heat exchanger, the turbine, and the cold side heat exchanger when the pumped thermal system operates in the charging mode and when the pumped thermal system operates in the discharging mode.