Integrating large amounts of wind power in energy systems poses balancing challenges due to the variable and only partly predictable nature of wind. The challenges cover different time scales from intra-hour, intra-day/day-ahead to several days and seasonal level. Along with flexible electricity demand options, various electricity storage technologies are being discussed as candidates for contributing to large-scale wind power integration and these also differ in terms of the time scales at which they can operate. In this paper, using the case of Western Denmark in 2025 with an expected 57% wind power penetration, wind power impacts on different time scales are analysed. Results show consecutive negative and high net load period lengths indicating a significant potential for flexibility measures capable of charging/activating demand and discharging/inactivating demand in periods of 1 h to one day. The analysis suggests a lower but also significant potential for flexibility measures charging/activating demand in periods of several days. In addition, the results indicate a physical potential for seasonal electricity storage. In the study, a number of large-scale electricity storage technologies - batteries, flow batteries, compressed air energy storage, electrolysis combined with fuel cells, and electric vehicles are moreover categorised with respect to the time scales at which they are suited to support wind power integration. While all of these technologies are assessed suitable for intra-hour and intra-day/day-ahead power balancing only some are found suited for responding to several days with high/low net loads and even fewer for seasonal balancing. (C) 2011 Elsevier Ltd. All rights reserved.