Compressed air energy system integrated with gas turbine

Abstract

An apparatus performs a power cycle involving expansion of compressed air utilizing high pressure (HP) and low pressure (LP) air turbines located upstream of a gas turbine. The power cycle involves heating of the compressed air prior to its expansion in the HP and LP air turbines. Taking into consideration fuel consumption to heat the compressed air, particular embodiments may result in a net production of electrical energy of ˜2.2-2.5x an amount of energy consumed by substantially isothermal air compression to produce the compressed air supply. Although pressure of the compressed air supply may vary over a range (e.g. as a compressed air storage unit is depleted), the gas turbine may run under almost constant conditions, facilitating its integration with the apparatus. The air turbines may operate at lower temperatures than the gas turbine, and they may include features of turbines employed to turbocharge large reciprocating engines.

1 - 17 . (canceled) 
     
     
         18 . A method comprising:
 flowing compressed air from a storage unit to an air heater;   flowing a combusted exhaust of a combustion gas turbine into the air heater while maintaining the compressed air separate;   flowing heated compressed air from the air heater to an air turbine; and   causing the combustion gas turbine to receive compressed air exclusively from an output of the air turbine.   
     
     
         19 . A method as in  claim 18  wherein the combustion gas turbine is configured to receive compressed air at normal inlet conditions, the method further comprising operating the air turbine to deliver the output at the normal inlet conditions. 
     
     
         20 . A method as in  claim 19  wherein operating the air turbine comprises expanding at a variable pressure ratio. 
     
     
         21 . A method as in  claim 19  wherein operating the air turbine comprises adjusting a nozzle vane to achieve an incidence angle of the heated compressed air on a blade of the air turbine. 
     
     
         22 . A method as in  claim 18  further comprising providing the combustion gas turbine as an existing gas turbine modified to avoid a compressor element. 
     
     
         23 . A method as in  claim 22  wherein the existing combustion gas turbine is modified to remove a compressor blade. 
     
     
         24 . A method as in  claim 18  wherein a combustor of the combustion gas turbine is caused to receive the compressed air directly from the air turbine. 
     
     
         25 . A method as in  claim 18  wherein the air turbine comprises a low pressure air turbine and the method further comprises flowing the heated compressed air to the low pressure air turbine via a high pressure air turbine. 
     
     
         26 . A method as in  claim 25  wherein the combustion gas turbine is configured to receive compressed air at normal inlet conditions, the method further comprising operating the low pressure air turbine to deliver the output at the normal inlet conditions. 
     
     
         27 . A method as in  claim 26  wherein operating the low pressure air turbine comprises expanding at a variable pressure ratio. 
     
     
         28 . A method as in  claim 26  wherein operating the low pressure air turbine comprises adjusting a nozzle vane to achieve an incidence angle of the heated compressed air on a blade of the low pressure air turbine. 
     
     
         29 . A method as in  claim 28  wherein the method further comprises operating the high pressure air turbine to expand at a variable pressure ratio. 
     
     
         30 . A method as in  claim 29  wherein operating the high pressure air turbine comprises adjusting a second nozzle vane. 
     
     
         31 . A method as in  claim 25  further comprising:
 sensing a pressure in the storage; and 
 bypassing the high pressure air turbine when a pressure within the storage falls below a predetermined value. 
 
     
     
         32 . A method as in  claim 25  further comprising generating electricity from the low pressure air turbine and from the high pressure air turbine. 
     
     
         33 . A method as in  claim 32  further comprising coupling the low pressure air turbine to a first generator and coupling the high pressure air turbine to a second generator. 
     
     
         34 . A method as in  claim 18  further comprising storing energy by compressing air using off-peak energy. 
     
     
         35 . A method as in  claim 18  further comprising storing energy by compressing air using energy provided by a renewable energy source. 
     
     
         36 . A method as in  claim 35  wherein the renewable energy source comprises wind. 
     
     
         37 . A method as in  claim 18  further comprising storing energy by compressing air utilizing heat exchange across a gas/liquid interface.