The global energy storage industry gained significant momentum in 2015, as records were broken for deployed and new announced project capacity around the world. Despite the substantial growth, the complexity of integrating new resources into existing networks highlights the challenges still ahead for the growing industry. The industry continued to see an increasing number of technologies deployed in 2015, including advanced battery and electromechanical storage technologies. It also benefited more from economies of scale in both manufacturing and the actual deployment of systems. According to Navigant Research, lithium ion (Li-ion) batteries remain the leading form of storage for new projects worldwide, accounting for around 51.2% of newly announced energy storage system (ESS) capacity and 85.6% of deployed ESS power capacity in 2015. Li-ion batteries are the most popular technology for the growing distributed energy storage system (DESS) and behind-the-meter (BTM) market segments. These systems accounted for an estimated 12.0% of new system capacity announced in 2015, the highest percentage of any year on record. While market activity picked up in a number of regions during 2015, North America remains the largest market for newly announced ESSs. An estimated 1,653.5 MW of new ESSs were announced worldwide in 2015, with around 33.8% of this new capacity coming from North America. This Navigant Research report provides a comprehensive resource of global energy storage projects. The Tracker includes a database of 1,119 projects (encompassing at least 43,305 individual systems) and tracks the country, region, market segment, capacity, status, technology vendor, systems integrator, applications, funding, investment, and key milestones of each project. In addition, the report includes an analysis of the technology choice within each major region for energy storage, analysis of the leading regions for energy storage capacity and projects, and market share analysis for technology vendors for deployed projects and projects in the pipeline.