The Kapolei Energy Storage facility on Oʻahu is officially online.
After several delays, the utility-scale battery farm kicked off commercial operations shortly before the holidays. It has a storage capacity of 565 megawatt-hours of electricity, making it the largest storage project in the state.
The project's developer, San Fransisco-based Plus Power, believes it is the first time a battery has been used by a major utility to balance the grid.
"There really hasn't yet been a standalone storage battery project that has proven it at scale," said Bob Rudd, the chief commercial officer at Plus Power.
Its capacity will help Hawaiian Electric deal with the problem of clean energy curtailment, also called over-generation, Rudd said.
When Oʻahu produces too much power with no way to store it, some of it has to be "curtailed." Variable renewable energy like rooftop solar is more likely to get curtailed, as traditional firm power stations are harder to ramp up and down.
"Unfortunately, with many thermal units, there is a minimum operating limit below which you can't really curtail it unless you turn it all the way off," Rudd said.
That means more renewable energy is likely to be wasted than fossil-fuel energy.
But now, when Oʻahu has an oversupply of power, KES can store that energy until it's useful to the grid.
"You'll have that solar energy that otherwise would have been destroyed in the present moment," Rudd said.
Hawaiian Electric’s modeling found that in its first five years in operation, the KES battery plant could cut curtailment of renewable energy by 69%.
