BATTERIESA Huge Battery Has Replaced Hawaii’s Last Coal Plant

By Julian Spector

Published 15 January 2024

Plus Power’s Kapolei battery is officially online. The pioneering project is a leading example of how to shift crucial grid functions from fossil-fueled plants to clean energy.

Hawai’i shut down its last coal plant on September 1, 2022, eliminating 180 megawatts of fossil-fueled baseload power from the grid on O’ahu — a crucial step in the state’s first-in-the-nation commitment to cease burning fossil fuels for electricity by 2045.

But the move posed a question that’s becoming increasingly urgent as clean energy surges across the United States: How do you maintain a reliable grid while switching from familiar fossil plants to a portfolio of small and large renewables that run off the vagaries of the weather?

Now Hawai’i has an answer: It’s a gigantic battery, unlike the gigantic batteries that have been built before.

The Kapolei Energy Storage system actually began commercial operations before Christmas on the industrial west side of O’ahu, according to Plus Power, the Houston-based firm that developed and owns the project. (The company just had the good sense to wait to announce it until journalists and readers had fully returned from winter holidays.)

Now, Kapolei’s 158 Tesla Megapacks are charging and discharging based on signals from utility Hawaiian Electric. The plant’s 185 megawatts of instantaneous discharge capacity match what the old coal plant could inject into the grid, though the batteries react far more quickly, with a 250-millisecond response time. Instead of generating power, they absorb it from the grid, ideally when it’s flush with renewable generation, and deliver that cheap, clean power back in the evening hours when it’s desperately needed.

“It feels incredible to be part of what Hawai’i and Hawaiian Electric are doing to get to 100 percent renewable energy and to play this enabling role to help them get one step closer,” Plus Power executive chair Brandon Keefe told Canary Media.

The construction process had its setbacks, as did the broader effort to replace the coal plant with a roster of large-scale clean energy projects. The Kapolei battery was initially intended to come online before the coal plant retired. COVID disrupted deliveries for the grid battery industry across the board, and Kapolei’s remote location in the middle of the Pacific Ocean didn’t make things easier. By summer 2021, Plus Power was hoping to complete Kapolei by the end of 2022, but it ended up taking another year. Even then, it has joined the grid before several of the other large solar and battery projects slated to replace the coal plant’s production with clean power.