Hawaii’s Solar Push Strains the Grid
http://www.technologyreview.com/news/534266/hawaiis-solar-push-strains-the-grid/[font face=Serif][font size=5]Hawaiis Solar Push Strains the Grid[/font]
[font size=4]Kauais utility takes a second stab at battery storage as solar heads toward 80 percent of peak power.[/font]
By Peter Fairley on January 20, 2015
[font size=3]The prospect of cheaper, petroleum-free power has lured the
Kauai Island Utility Cooperative (KIUC) to quintuple utility-scale solar capacity over the past year, building two 12-megawatt photovoltaic arrays. These facilities are the biggest and a significant contributor to the islands 78-megawatt peak power supply. When the second plant comes online this summer, peak solar output on Kauai will approach 80 percent of power generation on some days, according to Brad Rockwell, the utilitys power supply manager.
Now KIUC is taking a second try with batteries and hoping energy storage technology has progressed sufficiently to keep the same problems from recurring. The new system, installed beside the solar farm nearing completion on Kauais northeast shore, is one of the first commercial installations of grid-scale lithium-ion batteries manufactured by the French battery giant
SAFT.
The intermittent nature of renewable energy sources like solar power presents a range of challenges to utilities, depending on their grids size and design. Kauais difficulty is most acute when clouds drift over a solar plant. That can slash a plants power output by 70 to 80 percent in less than a minute. If the plant is providing a substantial share of the grids power, that rapid power loss can cause the frequency of the grids alternating current to drop well below 60 hertz, damaging customer equipment or even causing a blackout.
After Anahola comes online, Rockwell expects Kauai to see days when clear skies result in solar generation beyond what KIUCs grid can carry. Instead of throwing away the excess, McDowall says, KIUC could use the Anahola battery storage system to absorb it and then release that power after the sun goes down.[/font][/font]