Conversion and storage of solar energy in the forms of liquid fuel and electricity in a hybrid energy storage system using methanol and phase change materials

Abstract

The utilization of solar-assisted hybrid energy systems is an appropriate way to generate green power. To this aim, an innovative hybrid charging/discharging system comprised of solar dish collectors, methanol synthesis unit, power cycles, and carbon dioxide liquefaction process as well as phase change materials, is introduced and thermodynamically assessed. An ammonia/water absorption refrigeration cycle is applied for the carbon dioxide liquefaction process. The proposed structure is simulated by using HYSYS, TRNSYS, and MATLAB, and a thermodynamics framework is conducted to assess the integrated system performance. The proposed structure successfully produces 8.449 kg/s and 11.49 kg/s of methanol liquid carbon dioxide, respectively. Energy analysis of this integrated system indicates that, the overall thermal efficiency of the charging and discharging modes are 0.8486 and 0.4076, respectively. The results of exergy evaluation reveal that the largest exergy destruction in the charging and discharging modes are related to collectors with 34.07% and reactors with 56.58%, respectively. In addition, the overall exergy efficiency of the charging and discharging cycles are 57.11% and 42.32%, respectively. A comparison between the proposed system and similar works show that the energy efficiencies of the power cycles are higher than similar studies. Finally, sensitivity analyses on the influence of various parameters such as useful energy collected by collectors, stored heat of phase change materials, solar collector thermal efficiency, irreversibility, and exergy efficiency in the cycle and collector are performed.