Matching energy storage to small island electricity systems : a case study of the Azores

Abstract

Island economies rely almost entirely on imported diesel and fuel oil to supply their energy needs, resulting in significant economic and environmental costs. In recognition of the benefits of clean energy development, many islands are pursuing ambitious goals for renewable energy. For example, the Azores Islands of Portugal have set a goal to achieve 75% renewable energy by 2018. Despite significant environmental and economic benefits, however, the introduction of renewable energy sources introduces new operating challenges to island power systems, including intermittent and uncertain generation patterns. This research investigates energy storage on small island power systems under scenarios of increasing penetrations of variable-output wind. The analysis applies a least-cost unit commitment model to three Azores island networks (Sdo Miguel, Faial and Flores), in order to determine expected cost savings from introducing energy storage onto those systems. Modeling results indicate that renewable energy coupled with energy storage can produce significant savings in operating costs on island electricity systems- above those levels achieved from renewable generation alone. Furthermore, the research suggests that storage power (in terms of available megawatts for discharging energy) is more critical than storage capacity (megawatt-hours of available storage) for achieving costs savings and clean energy goals. The largest impacts from storage will come from relatively small-sized storage installations, above which there is a diminishing return from storage.