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Hawaii building huge new battery, bidding farewell to coal

Plus Power’s Kapolei battery aims to keep Oahu’s grid steady as the island’s fossil fuel plants shut down.
By Julian Spector

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HONOLULU, Hawaii — When coal plants on the mainland U.S. began to shut down in droves, natural-gas plants were ready to take their place, ramping up as needed to keep the lights on. In Hawaii, that’s not an option — both because of the state’s commitment to having a carbon-free grid by 2045 and because delivering natural gas to the islands is prohibitively expensive.

When Hawaii’s last remaining coal plant ceases operations on the island of Oahu in September 2022, the state will turn instead to a giant battery to ensure the grid keeps functioning smoothly. The Kapolei Energy Storage facility (KES) will rank among the largest stand-alone batteries in the world, at 185 megawatts/​565 megawatt-hours. It is contracted with utility Hawaiian Electric to keep the grid running for the next 20 years, a crucial interval leading up to the 2045 deadline.

Here, today, on Oahu, Plus Power and Hawaiian Electric are sending a postcard from the future,” said Plus Power’s lead developer Bob Rudd at a ground blessing ceremony last week. I’m certain that someday we’ll all look back, when there are dozens of projects just like KES on the mainland and all across the world, and we’ll think, We were there. Hawaii showed the world how to do it first.’ ”

Soon, 158 Tesla Megapacks will arrive on the 7-acre patch of dusty, previously disturbed land in the James Campbell Industrial Park, a cluster of heavy industry on the west side of Oahu.

Large batteries are becoming an increasingly common source of power for evening hours in the desert Southwest on the mainland. But KES will shoulder duties that batteries have never had to perform at this scale in order to keep the grid running reliably for Oahu’s 1 million residents and the U.S. military’s Indo-Pacific Command facility.

KES still needs to get built, and then to operate as advertised. But as other states and the U.S. Congress contemplate 100 percent clean energy goals, KES will become an early test case for whether high-tech clean alternatives can take over from fossil fuel plants and keep the grid running.

Ultimate pacemaker for the grid”

Large batteries of recent vintage typically serve a bulk capacity role: Their primary job is to deliver a bunch of electrons in the hours when the grid needs it. KES will do that, but it will also carry out several rarely performed but highly valuable tasks.

First, the battery will be able to jump-start the grid if some calamity knocks it out — grid wonks call this black-start capability.” Islandwide blackouts hit Oahu in 2006 and 2008 after an earthquake and a lightning storm, respectively. Tsunamis and cyclones threaten to wreak similar havoc in the future.

Second, Plus Power specifically designed the battery to prevent the grid from shutting down in the first place. KES will reserve 50 megawatts of capacity to push out in a fraction of a second if grid frequency falls out of safe range, an event that can precede a cascading grid failure. Texas infamously came within 4 minutes and 37 seconds of a frequency-related collapse in its February winter storm, which could have knocked out power to many in the state for weeks.

If the problem continues, the full battery will respond with what is called grid-forming services.” The state’s last remaining coal plant, owned by AES and located just down the road from the KES site, maintains grid frequency with the physical inertia of its spinning metal turbine. KES will replicate that effect with digital controls and a field of Tesla batteries, becoming what Plus Power’s policy leader Polly Shaw called the ultimate pacemaker for the grid.”

On a daily basis, KES will act as a communal battery for the island as a whole, using the bulk of its capacity to absorb excess midday solar power and feed it back to the grid to serve evening demand. That creates space for more rooftop solar and larger solar fields as Oahu pushes toward 100 percent renewable power.

Claiming a first is always risky in the fast-moving storage industry. Plus Power’s leaders acknowledge that KES’ functionality is not entirely unique; some small-scale batteries in remote or off-grid settings perform similar roles. But KES will have considerably greater impact, as it adds up to roughly 17 percent of the 1,100-megawatt peak demand on Oahu.

As far as I understand, this would be the first project that provides a combination of load-shifting, fast frequency response, virtual inertia and black-start [capabilities] at 100-plus-megawatt scale,” said Rudd, who previously led large-scale storage sales for Tesla.

Plus Power employees and Hawaii energy leaders ceremonially turn the dirt at the site of the future Kapolei battery plant. (Photo credit: Julian Spector)

Land is scarce in Hawaii

Like many ribbon-cuttings, Plus Power’s ceremony last week included thanks to teammates and local dignitaries. Then Kahu Kordell Kekoa, a Hawaiian spiritual leader, blessed the field with 25-year-old rainwater and called attention to the past and the future of the land that is both sacred and scarce.

Today, we’re going to turn the dirt. But the turning of the dirt is not just for this place; it’s for what will come out of this place,” Kekoa said. Our children will never know what this looked like. In fact, they won’t even know what a coal station looked like. And what a blessing that is.”

Hawaii’s land scarcity makes development quite challenging, even for clean energy. Last year, Hawaiian Electric contracted for several solar-plus-storage projects intended to fill the gap when the coal plant shuts down, with the first expected to become operational in mid-2022. But some of these projects have seen their completion dates slip to late 2022 or into 2023 due to a thicket of permitting and technical challenges, leaving a potential shortfall in electricity supply.

KES pushed back its timeline as well. When the project was first announced in 2020, Plus Power was targeting an online date of June 2022, pending regulatory approval. The Hawaii Public Utilities Commission approved the project’s contract in May of this year, and the start of operations is now expected by the end of December 2022. Plus Power attributed that delay to the global supply crunch that has hit the energy storage industry at large this year.

The developer did, however, avoid protracted struggles for permission to build on its chosen location.

Real estate juggernaut the Campbell Company owns the KES site and its surroundings, including the site of the AES coal plant. The neighbors aren’t likely to complain about the battery when the facilities at the site are a coal plant, a garbage incinerator and an oil refinery. KES won unanimous support from the local neighborhood council.

We are encountering a lot of public concern about renewable energy projects, and for the most part, it’s grounded in the desire to be part of the process, part of the decision-making. It’s not anti-renewable energy,” said Hawaii Chief Energy Officer Scott Glenn at the ground blessing. By locating the project here, in Campbell Industrial [Park], we don’t have to have those kinds of hard conversations.”

That choice of location was possible because recent advances in battery technology allow developers to cram considerable power into a smaller footprint. Solar power plants need much more acreage, which sends developers out to more remote locations, including agricultural lands. Plus Power wanted to be near the people using electricity.

We can place large power plants in small spaces, and that means we can get closer to the right locations,” said Plus Power General Manager Brandon Keefe.

The cluster of existing power plants in Kapolei means the transmission network is well built out there. KES has enough high-voltage transmission hookups that even if not one but two nearby lines were knocked out, the battery could still deliver power to the broader grid.

Plus Power employees and Hawaii energy leaders ceremonially turn the dirt at the site of the future Kapolei battery plant. (Photo credit: Julian Spector)

What’s charging up that battery?

Oahu has so much solar production from its many rooftop systems and larger-scale plants that midday supply often exceeds demand. When that happens, Hawaiian Electric has to curtail production at the plants it controls, unless there’s somewhere to store it.

Hawaiian Electric’s modeling suggests KES will store enough to reduce the curtailment of renewables by 69 percent and enable the grid to use 10 percent more renewable energy in its first five years, Shaw noted. All told, the project should save Hawaiian Electric customers more than it costs over the 20-year contract.

What KES cannot do is generate electricity — it only stores it. Given the delays holding up construction of Oahu’s other clean energy projects, Hawaiian Electric may need to burn more oil and diesel in the near term after the coal plant shuts down — generating carbon emissions and higher bills for customers.

Without the battery energy storage, the ability to retire the AES coal plant didn’t seem possible,” said Dean Nishina, who leads Hawaii’s Division of Consumer Advocacy at the state’s Dept. of Commerce and Consumer Affairs. But, he noted, bill savings stemming from the project are a possibility but…not a guarantee,” because it ultimately comes down to which power plants Hawaiian Electric uses to charge the system.

Governor David Ige (D) launched a task force, chaired by Chief Energy Officer Scott Glenn, specifically to speed up the rollout of the remaining clean energy projects. Meanwhile, the state’s Public Utilities Commission has fast-tracked programs to draw more power from home batteries and community-scale solar projects.

How much of that is ready for the AES coal plant retirement remains to be seen. But the long-term trajectory of renewables in Hawaii is clear, and the Kapolei battery will soon be there to help usher in that future.


Next up: Read our three-part newsletter series on Hawaii and clean energy:
• Hawaii vs. fossil fuels
• The battery knocking coal out of Hawaii
• How people can play a role in Hawaii’s shift to clean energy

(Lead photo: A giant new battery in Hawaii will help the state make this coal pile a thing of the past. Photo credit: Lucas Assenmacher)

Julian Spector is a senior reporter at Canary Media. He reports on batteries, long-duration energy storage, low-carbon hydrogen and clean energy breakthroughs around the world.