In the context of advocating a green and low-carbon era, ocean energy, as a renewable strategic resource, is an important part of planning and building a new energy system. Triboelectric nanogenerator (TENG) arrays provide feasible and efficient routes for large-scale harvesting of ocean energy. In previous work, a spherical rolling-structured TENG with three-dimensional (3D) electrodes based on rolling motion of dielectric pellets was designed and fabricated for effectively harvesting low-frequency water wave energy. In this work, the external shape of the scalable rolling-structured TENG (SR-TENG) and internal filling amount of pellets were mainly optimized, achieving an average power density of 10.08 W∙m⁻³ under regular triggering. In actual water waves, the SR-TENG can deliver a maximum peak power density of 80.29 W∙m⁻³ and an average power density of 6.02 W∙m⁻³, which are much greater than those of most water wave-driven TENGs. Finally, through a power management, an SR-TENG array with eight units was demonstrated to successfully power portable electronic devices for monitoring the marine environment. The SR-TENGs could promote the development and utilization of ocean blue energy, providing a new paradigm for realizing the carbon neutrality goal.