Hawaii home to ‘world’s most advanced grid-scale battery’

Aerial shot of the The Kapolei Energy Storage facility on Oahu in Hawaii (battery)
The Kapolei Energy Storage facility on Oahu, Hawaii (Image: Plus Power)

Plus Power has begun operating its Kapolei Energy Storage facility on Oahu, Hawaii, calling it the “most advanced grid-scale battery energy storage system in the world”.

Plus Power executive chairman Brandon Keefe said, “This is a landmark milestone in the transition to clean energy. 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.”

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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, each roughly the size of a shipping container.

It offers the grid 185MW of total power capacity and 565MWh 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.

“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,” Hawaiian Electric senior vice president and chief operations officer Jim Alberts said.

“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.”

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.

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.

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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 a 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.

By June 2024, Plus Power says it will be operating a total of seven large-scale battery energy storage plants across Arizona and Texas, for a total of 1325MW/3500MWh.

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