Plus Power has begun operating its Kapolei Energy Storage facility in Hawaii. The KES battery project, located on 8 acres of industrial land on the southwest side of Oahu near Honolulu, uses 158 Tesla Megapack 2 XL lithium-iron phosphate batteries. It offers the grid 185 MW of total power capacity and 565 MWh of electricity, acting as an electrical “shock absorber” often served by combustion-powered peaker plants — responding in the blink of an eye (250 milliseconds), rather than the several minutes it takes combustion plants to come online.

The Kapolei Energy Storage facility on Oahu.

“This is a landmark milestone in the transition to clean energy,” said Brandon Keefe, Plus Power’s Executive Chairman. “It’s the first time a battery has been used by a major utility to balance the grid: providing fast frequency response, synthetic inertia, and black start. This project is a postcard from the future — batteries will soon be providing these services, at scale, on the mainland.”

Customer-sited solar power has become so abundant that Hawaiian Electric must regularly ‘curtail’ or turn off large volumes of existing utility-scale solar and wind to keep the electric system in balance.

Hawaiian Electric’s modeling found that in its first five years in operation, the KES battery plant will allow the utility to reduce curtailment of renewable energy by 69% and integrate 10% more new utility-scale renewables than previous models had allowed, while providing for the continued rapid growth of individually-owned renewables such as rooftop solar.

“KES is an important part of a portfolio of resources that work together to provide reliability and energy security on Oahu’s isolated island grid,” said Jim Alberts, senior vice president and chief operations officer of Hawaiian Electric. “Energy storage technology that responds quickly to constantly changing conditions is an essential tool for us to use to manage the grid and operate it as efficiently as possible.”

According to Hawaiian Electric, the project will save customers money. The Hawaiian Electric filing for KES estimated it will reduce electric bills by an average of $0.28 per month over a 20-year contract life.

The KES plant interconnects near three of Hawaiian Electric’s critical power generation facilities, enabling KES to support the reboot of those power plants in the event of an island-wide emergency, otherwise known as ‘black start’ capability.

“No one has used batteries to provide such a diverse range of grid-forming services at this scale before in the world,” Keefe said.

The KES batteries will help replace the grid capacity formerly provided by an AES coal power plant less than a mile away. That plant once produced up to one-fifth of the electricity on Oahu, home to nearly 1 million of Hawaii’s 1.5 million people and Army, Navy, Air Force, and Marine Corps bases that require reliable power. The coal plant closed in September 2022.

News item from Plus Power