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158 Tesla Megapacks will be installed for a 565 MWh project in Oahu, Hawaii to enable the shutdown of coal-fired power plants in 2023.
Hawaii is preparing for the permanent closure of its 180 MW coal-fired power plant on Oahu, and both public energy storage and distributed storage resources will play a key role in helping Hawaii maintain the reliability of its power grid. The coal-fired plant, owned by AES, currently provides 15% of the island’s electricity demand, but is scheduled to be decommissioned soon. Hawaiian Electric aims to replace it with renewable and storage resources.
To do this, the Kapolei Energy Storage project, developed by Plus Power, is being built on the island of Oahu. It will have a capacity of 185 MW/565 MWh and will be one of the largest autonomous batteries in the world. It will be powered by 158 Tesla Megapacks. Kapolei Energy Storage was scheduled to launch in the summer of 2022 but has been pushed back to March 10, 2023, due to supply chain issues.
The battery will be able to jump-start the grid if some calamity knocks it out, which grid wonks call “black-start capability.” 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. If the problem continues, the full battery will respond with what is called “grid-forming services.” KES will replicate and maintain the grid frequency with the physical inertia of its spinning metal turbine, as the coal power plant did, but 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 towards 100 percent renewable power.
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. The project should save Hawaiian Electric customers more than it costs over the 20-year contract.