A low-temperature glide cycle for pumped thermal energy storage
A low-temperature glide cycle for pumped thermal energy storage
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DOI：
10.1016/j.est.2021.103038
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发表时间：
2021-10
影响因子：
9.4
通讯作者：
A. Koen;Pau Farres-Antunez;J. Macnaghten;Alexander J. White
中科院分区：
文献类型：
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作者：
A. Koen;Pau Farres-Antunez;J. Macnaghten;Alexander J. White
抽水蓄能被认为是抽水蓄能计划的一种可能的替代方案，用于大规模储存电力，并促进可再生能源的进一步整合。本文提出了一种新的形式的泵送热能储存的热力学循环利用非共沸混合物所表现出的温度滑移。工作流体是直链烷烃的混合物，其被优化以在两相区域中获得接近恒定的有效热容。这使得能够以引起非常低的有效能损失同时还实现高循环功比的方式与存储流体进行热交换。这两个特征使循环能够在低温（0-100° C）下运行时获得可观的往返效率。所提出的分析构成了初步的热力学设计;通过全面优化，可以进一步提高性能。尽管如此，结果表明，大约50%的整体（电力到电力）往返效率应该可以用未加压的水作为存储流体来实现。还进行了初步成本估算，表明边际能源（资本）成本在15-45美元/千瓦时之间，取决于遏制类型。由于低温储存的低功率密度和高热功比，每单位功率容量的估计边际资本成本不太有利（1，300 - 2，900 $/kW），这意味着该系统最适合长期放电。
Pumped thermal energy storage is seen as a possible alternative to pumped-hydro schemes for storing electricity at large scale and facilitating increased integration of renewable sources. This paper presents a novel form of pumped thermal energy storage in which the thermodynamic cycle exploits the temperature glide exhibited by zeotropic mixtures. The working fluid is a blend of linear alkanes, optimised so as to obtain a near-constant effective heat capacity in the two-phase region. This enables heat exchange with the storage fluid in a manner that incurs very low exergetic losses whilst also achieving a high cycle work ratio. These two features allow the cycle to attain a respectable round-trip efficiency whilst operating at low temperature (0–100° C). The analysis presented constitutes a preliminary thermodynamic design; further improvements to performance may be possible with comprehensive optimisation. Nonetheless, the results show that an overall (electricity-to-electricity) round-trip efficiency of around 50% should be achievable with unpressurised water as the storage fluid. Initial cost estimates have also been undertaken, showing marginal energy (capital) costs in the range 15–45$/kWh e, depending on the type of containment. Due to the low power density and high heat-to-work ratio of low-temperature storage, the estimated marginal capital cost per unit power capacity is less favourable (1,300–2,900$/kW) implying the system is best-suited to long-duration discharge.