Hi-CAES: High Performance Compressed Air Energy Storage Elevated through High-Temperature Thermal Storage

压缩空气储能(CAES)利用压缩机在有多余电力的情况下产生加压空气，然后将加压空气储存在储气罐中，并在需要时通过涡轮机释放出来发电。与其他储能技术相比，CAES具有规模大、持续时间长、成本低等特点。然而，它的低往返能效(目前运行中最好的CAES电厂的往返效率为60.2%)和低能量密度引起了商业部署的主要担忧。将电转化为热并通过储热来储存热量是一项相对成熟和高效的技术；但通过(传统的和有机的)朗肯循环、热电发电机和最近提出的热光电技术，将储存的热能转化为电能的能效较低(不到40%)。该项目旨在开发一种Hi-CAES技术，将CAES与高温储能(HTES)相结合，以实现高能量转换效率、高能量和功率密度以及操作灵活性。该技术使用HTES来提高CAES的电价，并利用压缩空气将高温热能转换为电能--压缩空气是一种自然工质。这项拟议的技术预计将使CAES的电效率提高到70%以上，整体能效提高到90%以上，并增加供暖和制冷的能源供应。所提出的Hi-CAES还将显著提高存储能量密度和系统功率。同时，该技术可以将储存的热能转化为电能，比现有的热电储能技术具有更高的能量转换效率和更低的系统成本。HTES与CAES的集成，可以在充放电过程中极大地提高系统的动态特性和操作灵活性。这将使Hi-CAES处于更好的财务状况，因为它可以通过某些高市场价值的快速响应电网平衡服务产生收入。该项目的目标是通过与HTES系统的集成，显著提高CAES的效率和能量密度。这项研究将解决实现Hi-CAES系统的技术和科学挑战，以及深度电力系统脱碳的社会挑战。

Compressed Air Energy Storage (CAES) uses compressors to produce pressurised air while excessive power is available; the pressurised air is then stored in air reservoirs and will be released via a turbine to generate electricity when needed. Compared with other energy storage technologies, CAES has some highly attractive features including large scale, long duration, and low cost. However, its low round trip energy efficiency (the best CAES plant currently in operation has a 60.2% round trip efficiency) and low energy density cause major concerns for commercial deployment. The conversion of electricity to heat and storing the heat via thermal storage is a relatively mature and a highly efficient technology; but the conversion of the stored thermal energy back to electricity has a low energy efficiency (less than 40%) through (conventional and organic) Rankine cycles, thermoelectric generators, and recently proposed thermophotovoltaics. The project aims to develop a Hi-CAES technology, which integrates the CAES with high-temperature thermal energy storage (HTES) to achieve high energy conversion efficiency, high energy and power density, and operation flexibility. The technology uses HTES to elevate CAES power rate and also convert high-temperature thermal energy to electricity using compressed air - a natural working fluid. The proposed technology is expected to increase CAES's electricity-to-electricity efficiency to over 70% and overall energy efficiency to over 90% with additional energy supply for heating and cooling. The proposed Hi-CAES will also increase the storage energy density and system power rate significantly. Meanwhile, the technology can convert the stored thermal energy into electrical power with a much higher energy conversion efficiency and lower system cost than current thermoelectrical energy storage technologies. With the integration of HTES with CAES, the system dynamic characteristics and operation flexibility can be much improved in terms of charging and discharging processes. This will place Hi-CAES in a better financial position as it can generate revenue through certain high market value fast response grid balance service. The goal of the project is to improve both the CAES efficiency and energy density considerably through the integration with a HTES system. The research will address the technical and scientifically challenges for realisation of the Hi-CAES system and societal challenges of deep power system decarbonisation.