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Located on the south coast of Alaska, Kodiak Island is home to the United States’ largest Coast Guard base, the nation’s third most productive fishing port and 3,000 of the famous, namesake Kodiak bears. The residents of the island rely on the Kodiak Electric Association (KEA) to generate and distribute power safely and reliably. In 2007, KEA set a goal to produce 95 percent of energy sales from cost-effective renewable power resources by the year 2020 to reduce their reliance on diesel fuel and lower the cost of generation to its customers.
KEA operates an isolated grid system with a peak load of approximately 27 megawatt (MW) and a minimum load of 11 MW. The main power source comes from two 11.5 MW hydroelectric turbine generators located at the island’s Terror Lake. KEA also operates four independent diesel generation facilities totaling 33 MW of available capacity. In 2009, KEA added 4.5 MW of wind power with the completion of phase I of the Pillar Mountain Wind Project.
For phase II, KEA’s goal meant doubling the wind project’s capacity to 9 MW. Given the inherent intermittency of wind power, KEA performed a detailed study to investigate the possible impact that adding 4.5 MW of wind would have on grid reliability. While the hydroelectric facility provided an excellent source of clean energy, it was not responsive enough to maintain grid frequency in the event of a sudden loss of wind power. In order to maintain the same level of reliable power delivery to its customers, KEA faced the unfavorable prospect of bringing more diesel generators online to provide frequency regulation and spinning reserves during high wind generating hours.
However, this additional diesel generation would require curtailing available wind power and consuming more diesel fuel – effectively increasing the cost of delivered energy and diluting the percentage of energy sales from renewable resources.
Not satisfied with the idea of increasing wind capacity only to run more diesel generators, KEA set out to find a more efficient solution. After investigating various technologies and companies, KEA selected Younicos to design, build, install and commission an integrated 3 MW battery-based energy storage system to provide robust and reliable frequency regulation – enabling the full 9 MW clean promise of the Pillar Mountain Wind Project to be delivered to its customers.
Darron Scott, President/CEO of KEA
Since its commissioning in November 2012, the Younicos ESS has successfully responded to over 250,000 frequency events – an average of approximately 180 events per day. This fast-acting, accurate response has helped to avoid multiple potential power losses and in some cases, prevented island-wide blackouts due to sudden drops in grid frequency.
Younicos ESS allows KEA to take full advantage of the 9 MW of wind capacity without increasing diesel fuel consumption. Overall, phase I and phase II of the wind project, coupled with the addition of the ESS, has allowed KEA to deliver 114 million kWh of wind energy and save 8 million gallons of diesel fuel – delivering on its commitment to reliable, affordable and renewable power for its customers.
of wind capacity without increasing diesel fuel consumption
of wind energy – save 8 million gallons of diesel fuel
of real power within 50 milliseconds whenever the grid frequency drops below 59.8 Hz
The Younicos Energy Storage System (ESS) is comprised of two 1.5 MW power conversion systems (PCS) each paired with 15 minutes of advanced lead acid energy storage – all seamlessly integrated with the grid. The ESS monitors grid conditions 100 times per second and instantly delivers up to 3 MW of real power within 50 milliseconds, whenever the grid frequency drops below 59.8 Hz as shown in figure 1. This allows KEA to maintain their excellent history of grid stability while maximizing the islands’ abundantly available wind energy.
This energy storage system will be upgraded to lithium-ion batteries in 2017.