Hawaiian Electric is proposing to plug Oahu’s power grid into an enormous battery pack.

The plan, involving enough Tesla batteries to fill the rough equivalent of 244 shipping containers, would cost an estimated $200 million to $300 million and accommodate more renewable energy production across the island.

If the plan is realized, banks of liquid-cooled lithium­-ion batteries in 244 23-foot-long lockers could become the first and biggest stand-alone utility-scale energy battery system tied to the grid of Hawaii’s largest utility.

Hawaiian Electric proposes developing the project next year on 6 acres next to its Kahe power plant in Nanakuli.

The company also is proposing four smaller energy storage facilities on Oahu, Maui and Hawaii island.

All five storage systems are subject to a competitive bidding program where Hawaiian Electric was the initiator but is also a competitor and an initial decision maker.

Sharon Higa, a Hawaiian Electric spokeswoman, said company officials involved with selecting winning bids are prohibited from sharing information with colleagues involved in the company’s bids.

The state Public Utilities Commission also has independent observers and a technical adviser to oversee the process and proposals.

Hawaiian Electric in August solicited bids for renewable energy production and storage systems totaling about 900 megawatts on Oahu, Maui and Hawaii island — the largest and most ambitious push for renewable energy ever in Hawaii.

Most of this new capacity, about 600 megawatts, is slated for Oahu and can be developed with or without attached battery storage.

Higa said Hawaiian Electric believes it can produce stand-alone storage at a beneficial cost because the company can build battery facilities on land it owns next to substations that reduce infrastructure connection costs.

“We can save costs for customers,” Higa said. “It’s much more efficient.”

Hawaiian Electric plans to tentatively select winning bidders May 8. Ultimately, the PUC will determine which projects get approved in a process that includes public hearings.

Jeff Mikulina, executive director of the Blue Planet Foundation, said it’s exciting to see such a large-scale storage system plan that complements smaller storage systems connected with upcoming renewable power generation projects and rooftop solar where storage has become commonplace.

“We all know that storage is an integral part of achieving our 100% renewable energy future,” he said.

Storage is key because batteries will be needed to take energy produced during sunny and windy times during the day when electricity use is expected to lag future renewable generation. Storage also can play a role in distributing power when generation is slowed by a lack of sun or wind.

These factors become more crucial as the state shifts to more renewable energy with variable generation. Hawaiian Electric relies on renewable sources for about 25% of energy production now. State law mandates growing this to 40% by 2030, 70% by 2040 and 100% by 2045.

Hawaiian Electric intends to close the 180-megawatt coal-fired AES Hawaii power plant at Campbell Industrial Park by September 2022. This plant is the largest single producer of power on Oahu and can meet 16% of peak demand.

The AES plant is intended to be replaced by renewable energy projects including ones selected May 8.

The proposed Kahe battery facility with a 135-megawatt capacity could help accommodate much of this new renewable energy production and supply around 12% of Oahu’s typical peak power consumption, which runs from 5 to 9 p.m., using two-thirds of its total battery capacity.

Hawaiian Electric is also proposing a 65-megawatt battery system at Campbell Industrial Park, a 40-megawatt battery system on Maui and two systems on Hawaii island with a combined 18-megawatt capacity.

The company anticipates being able to bring its planned Kahe storage facility online in June 2022 if its bid is successful and development proceeds without unanticipated delays.

Under the competitive selection process, bidders including Hawaiian Electric are required to hold public meetings. Because of the coronavirus pandemic, virtual meetings will be held.

Information on each project along with instructions to participate in meetings via the internet, TV and phone are at bit.ly/2UtZSfB.

The Oahu storage project meeting is scheduled for 6 p.m. April 14 via WebEx online.

Because the Kahe project requires a special management area permit, a draft environmental assessment has been produced and is something on which the public can comment through the state Office of Environmental Quality Control.

A meeting for Maui is scheduled for 5:30 p.m. April 8 and will be held via Akaku Community TV Channel 54.

The Hawaii island meeting is scheduled for 5 p.m. April 15 via Na Leo TV Spectrum Channel 53 or the Na Leo TV mobile app.