A novel coupled hydra-pneumatic energy storage system is proposed to improve the energy and power performance of the energy storage system in hybrid mining trucks. Based on four basic layouts, representing different energy conversion and storage approaches, of compressed air energy storage system and hydraulic energy storage system, a coupled layout is proposed for the hybrid mining truck application through a comparative study of the four basic layouts in this paper. Simulation and analysis results show that the coupled layout can effectively balance the power and energy performances of the pressure energy storage system. The total benefit of hybrid mining trucks with the coupled layout in ten years is increased by 9.7% as compared with the compressed air energy storage system, and by 91.2% as compared with the hydraulic energy storage system. Moreover, the weight and volume of the coupled layout are reduced by 15.4% and 24.8% as compared with the compressed air energy storage system, respectively, and by 83.1% and 92.8% as compared with the hydraulic energy storage system, respectively. (C) 2017 Elsevier Ltd. All rights reserved.