Definition of the Regulation Strategy of an A-CAES Power Generation Train Through Dynamic Modeling

The need for large-scale energy storage becomes pivotal as the global energy landscape shifts toward renewables. Adiabatic Compressed Air Energy Storage (A-CAES) has recently emerged as a promising alternative among various energy storage technologies. Compared to traditional systems, in A-CAES, the heat generated during air compression is stored and reused during the expansion phase, thus eliminating the need for external fuel. Custom-made caverns may also be used to overcome geographical limitations and enable isobaric air compression and expansion to keep the process's maximum pressure constant, granting turbomachinery the highest efficiency. A-CAES must provide fast response times to provide maximum market revenue opportunity. This poses challenges in the turbomachinery design process as, besides unconventional flow conditions, it is subordinated to meet the performance requirements while keeping under control transient phenomena occurring during operational and safety maneuvers. This paper analyzes the dynamic response of a Hydrostor's A-CAES to support the expanders' design. Focusing on its expansion train, different transient scenarios, from train startup to emergency shutdown, are investigated to define a suitable plant and control architecture. The paper will describe an identified solution to allow the train to start in about 10–15min. A regulation strategy aimed at keeping below acceptable limits the exhausts' temperature increase caused by ventilation losses will also be presented. Ultimately, emergency stop scenarios will be discussed, also accounting for the behavior of the turbomachinery driven by ageing, evidencing the results' dependency on the specific control strategy adopted.