Solar energy is an intermittent resource, and thus an energy storage system is required for practical applications of the collected solar irradiance. This work deals with the integration of a thermo-chemical energy storage (TCES) system based on the calcium looping (CaL) process with a concentrated solar tower power (CSP) plant. The objective of this work is the integration of a conventional 320 MWe Rankine cycle with a direct calcination for energy harvesting. Particularly, this work addresses the use of CO₂ as the working fluid of a compressed-gas energy storage (CGES) system for hybrid energy storage with the CaL process. The hybrid TC/CG-ES (thermo-chemical/compressed-gas energy storage) system can increase the competitiveness of the CSP with respect to conventional fossil-based power plants leading to a reduction in CO₂ emissions. The thermal integration with the calcium looping (CaL) system is optimized by means of the pinch analysis methodology. The obtained results show a reduction in the electrical efficiency of about four percentage points with respect to the conventional Rankine power cycle without the CSP unit: the net electrical efficiency reduces from 43.7% to 39.5% while the global (thermal and electrical) efficiency of the plant reaches the peak value of 51.5% when low enthalpy energy is recovered (e.g., district heating network, district cooling network). This paper highlights the importance of the thermochemical CaO based material. With a conversion of CaO to CaCO₃ of 80% the storage efficiency is defined as the ratio of the energy released during the carbonation and the CO₂ expansion to the energy collected by the solar field and required during the CO₂ compression, which is 87.3%.

中文翻译：

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创新的钙循环工艺辅助的太阳能兰金循环作为储能系统

太阳能是一种间歇性资源，因此对于实际应用所收集的太阳辐照度需要能量存储系统。这项工作涉及基于钙循环（CaL）工艺的热化学能量存储（TCES）系统与集中式太阳能塔式发电（CSP）厂的集成。这项工作的目标是将常规的320 MWe朗肯循环与直接煅烧相结合以收集能量。特别是，这项工作解决了CO ₂的使用作为压缩气体能量存储（CGES）系统的工作流体，用于与CaL工艺进行混合能量存储。混合TC / CG-ES（热化学/压缩气体能量存储）系统可以提高CSP相对于传统化石燃料发电厂的竞争力，从而减少CO ₂排放。通过收缩分析方法优化了与钙环化（CaL）系统的热集成。获得的结果表明，相对于不带CSP单元的常规兰金功率循环，电效率降低了约四个百分点：净电效率从43.7％降低到39.5％，而电热效率的整体（热和电）效率回收低焓能量（例如区域供热网络，区域供冷网络）后，发电厂的峰值达到51.5％。本文强调了热化学CaO基材料的重要性。当CaO转化为CaCO ₃达到80％时，存储效率定义为碳酸化过程中释放的能量与CO ₂的比率膨胀到太阳能场收集的能量，以及压缩CO ₂所需的能量，即87.3％。