ABSTRACT
Background .......................................................................................................... 112 Evolving Motivations for Bulk Energy Storage .............................................. 113 System Operation ................................................................................................ 115 Suitable Geologies for CAES ............................................................................. 117
Salt Geology .................................................................................................... 118 Hard Rock ........................................................................................................ 120 Porous Rock .................................................................................................... 120
Existing and Proposed CAES Plants ................................................................ 123 Huntorf ............................................................................................................ 123 McIntosh .......................................................................................................... 125 Norton .............................................................................................................. 126 Iowa Stored Energy Park ............................................................................... 126 Proposed Systems in Texas ........................................................................... 126
CAES Operation and Performance ................................................................... 127 Ramping, Switching and Part-Load Operation ......................................... 127 Constant Volume and Constant Pressure ................................................... 129 Cavern Size ...................................................................................................... 130 Performance Indices for CAES Systems ..................................................... 133
Heat Rate..................................................................................................... 133 Charging Electricity Ratio ........................................................................ 134
Toward a Single CAES Performance Index ..................................................... 135 Primary Energy Efˆciency ............................................................................ 135 Round-Trip Efˆciency .................................................................................... 136
Additional Approaches ...................................................................................... 137 Advanced Technology Options ......................................................................... 138 Conclusions .......................................................................................................... 142 References ............................................................................................................. 143 Appendix: Storage Volume Requirement ........................................................ 147 Case 1: Constant Cavern Pressure .................................................................... 150 Case 2: Variable Cavern Pressure and Variable Turbine Inlet Pressure ...... 150 Case 3: Variable Cavern Pressure and Constant Turbine Inlet Pressure ..... 152
Compressed air energy storage (CAES) is a low cost technology for storing large quantities of electrical energy in the form of high-pressure air. It is one of the few energy storage technologies suitable for long duration (tens of hours), utility scale (hundreds to thousands of megawatts) applications. Several other energy storage technologies such as £ywheels and ultracapacitors can provide short duration services related to power quality and stabilization but are not cost effective options for load shifting and wind generation support [1,2].
