Compressed air energy storage with T100 microturbines: Dynamic analysis and operational constraints

The aim of this paper is the dynamic analysis of a small-size second-generation Compressed Air Energy Storage (CAES) system. It consists of a recuperated T100 micro gas turbine, an intercooled two-stage reciprocating compressor and an artificial tank for air storage. The possibility of including an innovative air expander before the injection into the turbine is also investigated. Starting from background on design and management optimization, this work proposes dynamic simulations and definition of operational constraints, not considered in previous publications. These represent significant results to extend the system range (producing efficiency and cost benefits), avoiding risks and failures in prototypes as well as in commercial applications. Following a section with calculations motivating the activity from an economic point of view, the interaction of the T100 integrated with the CAES system is analysed through a validated dynamic model. Close attention is paid to the discharging of the air storage vessel because the increment of mass flow at the turbine expander can lead to surge margin decrease and thermal stresses, especially during dynamic operations. Consequently, maximum limits for the air injection are obtained and different operational strategies are considered to ensure safe operation during the system dynamics, enlarging the application range or proposing modifications in the control system.