Such hybrid power systems help reduce operational costs as they make the best possible use of Hawaii’s sun-soaked and windy weather, while storing excess energy for later. In addition, battery storage is used for peak shaving, frequency regulation, reducing curtailments, and ramping/spinning reserves.
Peak shaving — when storage is used to lower peaks in demand — is the second most common application for such systems on Hawaii. Shifting portions of electricity demand from peak hours to other times of day also reduces the need for higher-cost, seldom-used generation capacity to be dispatched, which helps reduce wholesale electricity prices.
Averting costly HFP peaking plants
Without battery storage, Hawaiian utilities would have to rely on fast-ramp fossil power sources to back up renewables. Traditionally utilities used petroleum-, heavy fuel oil (HFO)- and coal-fired peaking power units, despite their high emissions intensity. Energy storage is virtually emissions free, helping to lower Hawaii’s carbon footprint.
Batteries are characterized by two metrics: power capacity and energy capacity. Power capacity is the maximum instantaneous amount of power that can be produced on a continuous basis. Energy capacity is the total amount of energy that can be stored or discharged by the battery.