In wireless sensor networks, grid-based clustering and routing schemes have attracted considerable attention due to their simplicity and feasibility. In this paper, we adopt a hexagonal tessellation approach and propose a Fast Hexagonal Clustering (FHC) algorithm for efficient data collection. The traffic load is intentionally concentrated at a small portion of Cluster Heads (CHs) and Convergence Points (CPs). In order to provide a steady and efficient energy supply for the nodes under our clustering scheme, a mobile energy replenishment approach is designed by using the Mobile Elements (MEs) to conduct wireless energy replenishment for the CPs. We construct an optimal route of the MEs for a better energy replenishment efficiency. Through extensive simulations, our scheme is demonstrated to outperform the best known clustering algorithms, in terms of both energy dissipation of data collection and energy replenishment.Index Terms-Wireless sensor networks, hexagonal grid-based clustering, mobile energy replenishment Globecom 2013 -Ad Hoc and Sensor Networking Symposium 978-1-4799-1353-4/13/$31.00 ©2013 IEEE