Techno-economic analysis of I-CAES systems to increase dispatchability of wind power

Abstract

The variability of energy production from renewable sources remains the main issue hampering their larger penetration in current energy grids. While batteries have been proven to work well in many applications, their cost and environmental footprint are opening room for alternative systems. In this study, the innovative isothermal compressed air energy storage (I-CAES) system proposed by Sadaat et al. in 2014 is analyzed. In this system layout, a wind turbine is coupled with a CAES system through a hydraulic circuit including a liquid piston. The original work theorized the system and focused only on a preliminary verification under an energy perspective, using data referring to very short time series. In the present study, a long-term techno-economic analysis is performed to provide a more representative insight into the real feasibility of the proposed plant configuration. The analysis is carried out using yearly wind speed data and a 1-minute average approach, so as to correctly track the energy fluxes. A parametric analysis of the system, varying the size of the storage vessel and generator is performed to identify the optimal configuration. Finally, the overall performance is compared with that of a traditional standalone turbine. The effect of fluctuations in the energy price during the day is considered, as well as the impact of possible future scenarios, where traditional systems are penalized due to significant oscillations in power production. Results show that, despite the high compression and expansion efficiencies achieved through the liquid piston, the complexity of the system causes a significant reduction of total energy production affecting the economic performance, although interesting prospects can arise whenever constant-load off-grid users are about to be fed.