耦合抽水蓄能的压缩空气储能电站概念研究

目的]储能是发展新能源、实现碳达峰碳中和目标的基础条件,其中抽水蓄能是最主要的储能方式,但是抽水蓄能依赖地理条件,需要占用大量自然资源,优良的厂址资源十分有限。为了缓解抽水蓄能厂址资源需求与自然资源稀缺的矛盾,提出了一种耦合抽水蓄能的压缩空气储能系统,并从研究思路、概念方案和工程可行性进行分析,从而为抽水蓄能产业发展提供创新解决方案。方法]围绕提高能量密度,以减小水库容量、降低水库高度差为突破点,运用压缩空气排水的方法,将水泵水轮机替换为压缩机和膨胀机,下库改为封闭结构的承压容器。储能时,压缩机将空气压缩至高压充入下库,并推挤下库内的水至上库。释能时,水从上库返回下库,下库内的压缩空气被推挤出,并经膨胀机释放。这可使相同条件下抽水蓄能的能量转换量提高数倍。为了论证耦合抽水蓄能的压缩空气储能电站的储能效果,设置上、下库高度差300 m,按照低性能和高性能两套设备参数,对40 MW/200 MWh的概念方案进行热力学分析和储能效率计算。结果]结果表明:在低性能参数条件下,储能效率65.68%,在高性能参数条件下,储能效率70.81%;能量密度1.67 kWh/m³

Concept Research of Compressed Air Energy Storage Power Plant Coupled with Pumped Hydro Storage

  Introduction  Energy storage is the basic condition for the development of new energy and the realization of carbon neutrality, where the pumped hydro storage is the most important energy storage method. However, pumped hydro storage depends on geographical conditions and needs to occupy a lot of natural resources, and excellent site resources are very limited. In order to alleviate the contradiction between the demand for pumped hydro storage plant site resources and the scarcity of natural resources, a compressed air energy storage system coupled with pumped hydro storage is proposed and analyzed from the perspective of research idea, conceptual scheme and engineering feasibility so as to provide innovative solutions for the development of the pumped hydro storage industry.   Method  By focusing on the improvement of the energy storage density, with the reduction of the reservoir capacity and height difference as the breakthrough point, the method of water drainage with compressed air was adopted. The pump turbine was replaced with compressor and expander, and the upper reservoir was changed into a pressure vessel with closed structure. When storing energy, air compressed by the compressor to high pressure and then filled into the lower reservoir to push the water from the lower reservoir to the upper reservoir. When releasing energy, the water returned from the upper reservoir to the lower reservoir, and the compressed air in the lower reservoir was pushed out and released by the expander. This could increase the energy conversion quantity of pumped hydro storage by several times under the same conditions. In order to demonstrate the energy storage effect of the compressed air energy storage power plant coupled with pumped hydro storage, a height difference of 300 m was set between the upper and lower reservoirs, and the thermodynamic analysis and energy storage efficiency calculation of the conceptual scheme of 40 MW/200 MWh were carried out according to the two sets of equipment parameters with low performance and high performance.   Result  The results show that the energy storage efficiency is 65.68% under the condition of low performance parameters and 70.81% under the condition of high performance parameters; the energy density is 1.67 kWh/m3.   Conclusion  The compressed air energy storage system coupled with pumped hydro storage can greatly reduce the reservoir capacity or height difference, significantly reduce the site demand and enable the areas with limited development of pumped hydro storage to have development conditions. Besides, the key equipment are mature, and the unit cost is close to that of the conventional pumped hydro storage. Therefore, this kind of compressed air energy storage system is technically and economically feasible.