南方能源建设 (Mar 2023)
Concept Research of Compressed Air Energy Storage Power Plant Coupled with Pumped Hydro Storage
Abstract
[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.
Keywords
