CO2 Energy Storage Research Articles

Thermodynamic analysis of a novel supercritical compressed carbon dioxide energy storage system through advanced exergy analysis

Abstract To reveal the sources of energy-saving potential of each component and compare the thermodynamic properties of the compressed air energy storage (CAES) system and the supercritical compressed CO2 energy storage (SC-CCES) system, most related works have been done using conventional exergy analysis. However, conventional exergy analysis cannot reveal the thermodynamic interactions among components. Therefore, conventional and advanced exergy analyses are applied to evaluating the CAES and SC-CCES performances in this paper. In addition, sensitivity investigations are conducted to evaluate the influence of decision variables on the performances of CAES and SC-CCES. The results show that the SC-CCES exergy efficiency is 57.02%, which is preferable and performs better than that of CAES (50.86%) and the interactions among different components are not strong since the endogenous exergy destruction rates of the components are larger than the exogenous exergy destruction rates in CAES and SC-CCES. Sensitivity analyses show that a larger efficiency of compressor, turbine, and combustor improves the SC-CCES and CAES performances. The effects of pressure drops in high pressure reservoir in SC-CCES are similar to those in storage cavern in CAES. Improving the performance of reservoir throttle valve itself is an effective way to improve the SC-CCES and CAES performances.

Thermodynamic analysis of a novel energy storage system based on compressed CO2fluid

Because of rapidly growing renewable power capacity, energy storage system is in urgent need to cope with the reliability and stability challenges. CO2 has already been selected as the working fluid, including thermo-electrical energy storage or electrothermal energy storage systems and compressed CO2 energy storage (CCES) systems. In this paper, a CCES system based on Brayton cycle with hot water as the heat storage medium is proposed and analyzed. Thermodynamic model of the system is established for energy and exergy analysis. Sensitivity analysis is then conducted to reveal effects of different parameters on system performances and pursue optimization potential. At a typical transcritical operation condition, round trip efficiency is 60% with energy density of 2.6 kWh/m3. And for the typical supercritical operation condition, the round trip efficiency can reach 71% with energy density of 23 kWh/m3. High round trip efficiency and energy density, which is comparable with those of compressed air energy storage systems, thermo-electrical energy storage (electrothermal energy storage) systems, and other CCES systems, lead to promising prospect of the proposed system. Copyright © 2017 John Wiley & Sons, Ltd.

Thermodynamic analysis of a compressed carbon dioxide energy storage system using two saline aquifers at different depths as storage reservoirs

Compressed air energy storage (CAES) is one of the leading large-scale energy storage technologies. However, low thermal efficiency and low energy storage density restrict its application. To improve the energy storage density, we propose a two-reservoir compressed CO2 energy storage system. We present here thermodynamic and parametric analyses of the performance of an idealized two-reservoir CO2 energy storage system under supercritical and transcritical conditions using a steady-state mathematical model. Results show that the transcritical compressed CO2 energy storage system has higher round-trip efficiency and exergy efficiency, and larger energy storage density than the supercritical compressed CO2 energy storage. However, the configuration of supercritical compressed CO2 energy storage is simpler, and the energy storage densities of the two systems are both higher than that of CAES, which is advantageous in terms of storage volume for a given power rating.

Thermodynamic analysis of a novel energy storage system with carbon dioxide as working fluid

Recently, energy storage system (ESS) with carbon dioxide (CO2) as working fluid has been proposed as a new method to deal with the application restrictions of Compressed Air Energy Storage (CAES) technology, such as dependence on geological formations and low energy storage density. A novel ESS named as Compressed CO2 Energy Storage (CCES) based on transcritical CO2 Brayton cycle is presented in this paper. The working principle of CCES system is introduced and thermodynamic model is established to assess the system performance. Parametric analysis is carried out to study the effect of some key parameters on system performance. Results show that the increase of turbine efficiency is more favorable for system optimization and the effect of minimum pressures on system performance is more significant compared with maximum pressures. A simple comparison of CCES system, liquid CO2 system and Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) system is conducted. It is shown that the system efficiency of CCES is lower than that of AA-CAES system but 4.05% higher than that of liquid CO2 system, while the energy density of CCES system is 2.8 times the value of AA-CAES system, which makes CCES a novel ESS with potential application.