Pumped thermal storage cycles with turbomachine speed control

Abstract

The present disclosure provides pumped thermal energy storage systems that can be used to store electrical energy. A pumped thermal energy storage system of the present disclosure can store energy by operating as a heat pump or refrigerator, whereby network input can be used to transfer heat from the cold side to the hot side. A working fluid of the system is capable of efficient heat exchange with heat storage fluids on a hot side of the system and on a cold side of the system. The system can extract energy by operating as a heat engine transferring heat from the hot side to the cold side, which can result in network output. Systems of the present disclosure can employ solar heating for improved storage efficiency.

1 . A method of controlling turbomachinery speed, the method comprising:
 in a closed cycle fluid path of a pumped thermal system having both heat engine mode and heat pump mode, operating the pumped thermal system in one of the heat engine mode and the heat pump mode, wherein operating the pumped thermal system in the heat engine mode includes circulating a working fluid through the closed cycle fluid path, in sequence, a compressor system, a recuperator heat exchanger system, a hot side heat exchanger system, a turbine system, the recupertor heat exchanger system, and a cold side heat exchanger system, and operating the pumped thermal in the heat pump mode includes circulating the working fluid through the closed cycle fluid path including, in sequence, the compressor system, the hot side heat exchanger system, the recuperator heat exchanger system, the turbine system, the cold side heat exchanger system, and returning through the recuperator heat exchanger system in the heat pump mode;   determining an increase in a shaft speed of the turbine system; and   responsive to the determination of the increase in the shaft speed of the turbine system, transferring a quantity of the working fluid from the closed cycle fluid path to an auxiliary working fluid tank.   
     
     
         2 . The method of  claim 1 , further comprising:
 responsive to the determination of the increase in the shaft speed of the turbine system, changing a flow rate of a hot side thermal storage (“HTS”) media through the hot side heat exchanger system, wherein the HTS media is in thermal contact with working fluid.   
     
     
         3 . The method of  claim 1 , further comprising:
 responsive to the determination of the increase in the shaft speed of the turbine system, changing a flow of a cold side thermal storage (“CTS”) media through the cold side heat exchanger system, wherein the CTS media is in thermal contact with working fluid.   
     
     
         4 . The method of  claim 1 , wherein transferring the quantity of the working fluid from the closed cycle fluid path to the auxiliary working fluid tank comprises actuating a valve in fluid connection with both a high pressure leg of the closed cycle fluid path and the auxiliary working fluid tank. 
     
     
         5 . A method of controlling turbomachinery speed, the method comprising:
 in a closed cycle fluid path of a pumped thermal system having both heat engine mode and heat pump mode, operating the pumped thermal system in one of the heat engine mode and the heat pump mode, wherein operating the pumped thermal system in the heat engine mode includes circulating a working fluid through the closed cycle fluid path, in sequence, a compressor system, a recuperator heat exchanger system, a hot side heat exchanger system, a turbine system, the recupertor heat exchanger system, and a cold side heat exchanger system, and operating the pumped thermal in the heat pump mode includes circulating the working fluid through the closed cycle fluid path including, in sequence, the compressor system, the hot side heat exchanger system, the recuperator heat exchanger system, the turbine system, the cold side heat exchanger system, and returning through the recuperator heat exchanger system in the heat pump mode;   determining a decrease in a shaft speed of the turbine system; and   responsive to the determination of the decrease in the shaft speed of the turbine system, transferring a quantity of the working fluid from an auxiliary working fluid tank to the closed cycle fluid path.   
     
     
         6 . The method of  claim 5 , further comprising:
 responsive to the determination of the decrease in the shaft speed of the turbine system, changing a flow of a hot side thermal storage (“HTS”) media through the hot side heat exchanger system, wherein the HTS media is in thermal contact with working fluid.   
     
     
         7 . The method of  claim 5 , further comprising:
 responsive to the determination of the increase in the shaft speed of the turbine system, changing a flow of a cold side thermal storage (“CTS”) media through the cold side heat exchanger system, wherein the CTS media is in thermal contact with working fluid.   
     
     
         8 . The method of  claim 5 , wherein transferring the quantity of the working fluid from the auxiliary working fluid tank to the closed cycle fluid path comprises actuating a valve in fluid connection with both a low pressure leg of the closed cycle fluid path and the auxiliary working fluid tank. 
     
     
         9 . A method of controlling turbomachinery speed, the method comprising:
 in a closed cycle fluid path of a pumped thermal system having both heat engine mode and heat pump mode, operating the pumped thermal system in one of the heat engine mode and the heat pump mode, wherein operating the pumped thermal system in the heat engine mode includes circulating a working fluid through the closed cycle fluid path, in sequence, a compressor system, a recuperator heat exchanger system, a hot side heat exchanger system, a turbine system, the recupertor heat exchanger system, and a cold side heat exchanger system, and operating the pumped thermal in the heat pump mode includes circulating the working fluid through the closed cycle fluid path including, in sequence, the compressor system, the hot side heat exchanger system, the recuperator heat exchanger system, the turbine system, the cold side heat exchanger system, and returning through the recuperator heat exchanger system in the heat pump mode;   determining a change in a shaft speed of the turbine system; and   responsive to the determination of the change in the shaft speed of the turbine system, transferring a quantity of the working fluid between an auxiliary working fluid tank and the closed cycle fluid path.   
     
     
         10 . The method of  claim 9 , further comprising:
 responsive to the determination of the change in the shaft speed of the turbine system, changing a flow of a hot side thermal storage (“HTS”) media through the hot side heat exchanger system, wherein the HTS media is in thermal contact with working fluid.   
     
     
         11 . The method of  claim 9 , further comprising:
 responsive to the determination of the change in the shaft speed of the turbine system, changing a flow of a cold side thermal storage (“CTS”) media through the cold side heat exchanger system, wherein the CTS media is in thermal contact with working fluid.   
     
     
         12 . The method of  claim 9 , wherein transferring the quantity of the working fluid between the auxiliary working fluid tank and the closed cycle fluid path comprises actuating a valve in fluid connection with both the closed cycle fluid path and the auxiliary working fluid tank. 
     
     
         13 . The method of  claim 9 , wherein determining a change in a shaft speed of the turbine system includes determining an increase in shaft speed, and
 wherein transferring a quantity of the working fluid between the auxiliary working fluid tank and the closed cycle fluid path, includes transferring the working fluid out from the closed cycle fluid path.   
     
     
         14 . The method of  claim 9 , wherein determining a change in a shaft speed of the turbine system includes determining a decrease in shaft speed, and
 wherein transferring a quantity of the working fluid between the auxiliary working fluid tank and the closed cycle fluid path, includes transferring the working fluid into the closed cycle fluid path.