Plus Power ‘s Kapolei mega battery has been officially activated, marking a significant milestone in the transition to clean energy sources. This pioneering project highlights the ability to move key network functions from fossil fuel-powered plants to a more sustainable energy source.
In September 2022 , Hawaii’s last coal plant closed, removing 180 MW of fossil fuel baseload power from the Oahu grid, as part of the state’s commitment to stop relying on these fuels for electricity generation. However, this change raised the challenge of how to maintain a reliable grid during the transition to a renewable energy portfolio.
The answer is the gigantic Kapolei Battery, which has begun commercial operation on the industrial west side of Oahu. The energy storage system consists of 158 Tesla Megapacks that charge and discharge based on signals from Hawaiian Electric , the utility company.
With an instantaneous discharge capacity of 185 MW, the plant can react much faster than the previous coal plant, with a response time of 250 milliseconds. Instead of generating power, the battery absorbs power from the grid when there is enough renewable generation and supplies it in the evening hours when it is needed.
” It’s amazing to be a part of what Hawaii and Hawaiian Electric are doing to get to 100% renewable energy and play this enabling role in helping them get one step closer ,” Plus Power CEO Brandon Keefe told Canary Media. .
About Kapolei Mega Battery
The Kapolei battery construction process faced hurdles, as did the broader effort to replace the coal plant with a series of large-scale clean energy projects. The Kapolei battery was initially intended to begin operating before the coal plant was retired. However, the Covid pandemic caused delivery disruptions for the grid battery industry worldwide and Kapolei’s remote location in the middle of the Pacific Ocean further complicated matters.
Although Plus Power originally hoped to complete Kapolei by the end of 2022, completion was delayed another year, ultimately joining the grid ahead of several of the other large solar and battery projects scheduled to replace coal plant output with clean energy.
How do batteries replace coal plants?
Grid batteries operate fundamentally differently than coal plants, so Hawaiian Electric and Plus Power came up with a new framework to replace what needed to be replaced. The old coal-fired generator brought three essential values to Oahu, Keefe explained: power (most of the electricity), capacity (the instantaneous delivery of power on demand) and grid services (grid-stabilizing functions, unstable but crucial to keeping the lights on).
The battery directly replaces the latter two: it matches the maximum power output of the coal plant (or “rated capacity”, in industry terminology) and is programmed to supply the necessary grid services that keep the grid operating within of the appropriate parameters. The grid operates at a specific frequency, but events such as another power plant going offline or a sudden increase in solar production can cause the frequency to deviate from established limits.
The Kapolei project provides a first line of defense, called “synthetic inertia,” that responds to and corrects grid deviations in real time. If the situation worsens beyond a specific threshold, the battery’s rapid frequency response kicks in as a second line of defense.
With 565 megawatt-hours of storage, the battery can’t directly replace the coal plant’s power output, but it works with the island’s bustling solar sector to fill that role. “We are allowing the grid to add more clean renewable energy to the system to replace coal plant power“Keefe said.
Hawaiian Electric’s plan indicates that, in the first five years, it can mitigate the decline in renewable energy by approximately 69% through the use of the Kapolei battery, enabling excess clean electricity that would otherwise be lost, be directed to the network.
Likewise, the utility also requested “black start capability.” If a disaster, such as a cyclone or earthquake, completely knocks out the grid, Hawaiian Electric needs a power source to restart it. Kapolei batteries are programmed to maintain some reserve power for this purpose. Plus Power located the project near a substation connected to three other power plants so that the battery ” can be AAA to power those other plants ,” Keefe said.
Integrating all of these functions into a single facility (capacity, grid services, black start) leads Keefe to call Kapolei “ the most advanced battery energy storage facility on the planet .”
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