Renewable energy storage system uses reinforced concrete pile foundation to store renewable energy generated by solar panels.The renewable energy is stored in the hollow section of pile foundation in the form of compressed air.The pile foundation

acting as a load-bearing structure of the upper structure

sustains not only the upper structure load

but also the soil reaction force and the compressed air pressure.However

concrete is prone to cracking under tensile stress

which leads to the limitation of energy storage performance and durability of reinforced concrete piles.In order to overcome these defects of traditional reinforced concrete energy piles

this paper studies the dual functions of various FRP（Fiber Reinforced Polymer）-concrete composite pile foundations as energy storage and load bearing structures.Considering the combined action of structural load

soil reaction and internal air pressure caused by compressed air thermodynamic circulation

the applicability of multiple forms of composite energy pile foundation system is analyzed by the finite element method.The study shows that the inner and outer FRP pipes can effectively improve the service performance and durability of piles

and the service reliability and durability of FRPC pipe piles are improved compared with that of reinforced concrete piles.