Plus Power, an independent developer with offices in San Francisco and Houston, on Wednesday celebrated the groundbreaking of the long-awaited Kapolei Energy Storage facility.

The battery storage project was approved by the state Public Utilities Commission, with numerous conditions, in May of this year.

With 185 megawatts of power and 565 megawatt­-hours of battery energy storage, the lithium-ion project would be the largest stand-alone battery storage system in the state upon its projected completion next year.

Hawaiian Electric has touted the Kapolei Energy Storage project as key to providing backup electricity for Oahu when AES Hawaii, Oahu’s 180-megawatt coal plant, retires as required by state law in September 2022 and when energy reserves will be tight.

The Kapolei Energy Storage facility is expected to provide load shifting and fast-frequency response services to Hawaiian Electric, and enhance grid reliability, according to a news release, plus accelerate the “integration of readily available renewable energy.”

The PUC had many concerns with the battery project earlier this year, mainly that the battery would have to be charged primarily by fossil fuel-based sources due to years-long delays in getting a number of large-scale solar-plus-storage projects online. This, they said should have been a “last resort.”

Commissioners were also concerned with the high costs of the project and potential impacts on ratepayers.

Hawaiian Electric objected to six out of the nine conditions attached to the approval of the Kapolei project, and after some back-and-forth, the PUC agreed in May to modify some of those conditions.

One of those conditions included establishing minimum thresholds of renewable energy to charge the battery project and a “prudence review” of fossil fuel costs if they are not met. The PUC agreed to remove specific thresholds and timelines, and to instead automatically conduct a “prudence review” on an annual basis for the first 10 years of the project.

“Plus Power is proud to deliver a cost-effective and unique infrastructure project that is key to Hawaii’s reliability, renewable energy, and climate goals, and that will facilitate additional clean, customer-sited energy resources,” said Head of Origination & Commercial Transactions Bob Rudd in the news release. “We’re excited to work with Hawaiian Electric and our other stakeholders to realize this project and deliver its economic and environmental benefits to Oahu residents.”

The Kapolei project is on roughly eight acres of industrial land at the Kapolei Harborside project, where it will interconnect to a critical Hawaiian Electric substation.

It had the support of state Sen. Glenn Wakai, the Land Use Research Foundation of Hawaii and the landowner, the James Campbell Co. Plus Power also said the project received unanimous support from the local neighborhood board.

It is expected to generate local construction jobs and attract additional high-tech growth to West Oahu.

“We’re committed to building a sustainable energy future for Hawaii,” said Scott Seu, Hawaiian Electric president and CEO, in the news release. “This project is an important step to further reduce the state’s dependence on imported fossil fuels and increase the use of renewable energy. A simple, cost-effective alternative to the coal plant, KES will displace 277 million gallons of oil over 20 years, reduce greenhouse gas emissions, and lower our customers’ exposure to changing oil costs. It’ll also be a critical resource that will add reliability and resilience to Oahu’s energy system.”