US: Plus Power brings most advanced battery storage system online in Hawaii

Plus Power has brought online what it says is the most advanced battery system, Kapolei Energy Storage. The facility in the US state of Hawaii has a total power output of 185 MW and a capacity of 565 MWh. In addition to its conventional use for short-term energy storage, the system provides several support services to the power grid. The project aims to help the state switch from fossil fuel-based electricity to renewable sources.

US company Plus Power announced that it had brought its Kapolei Energy Storage (KES) battery storage project online in Hawaii. It is located on the island of Oahu, near an industrial zone, on a site just over 30,000 square metres in area. The battery system consists of 158 Tesla Megapack 2 XL lithium iron phosphate batteries. The facility can therefore provide a total output of 185 MW, with a maximum energy storage capacity of 565 MWh.

"This is a milestone in the transition to clean energy. This is the first time a battery has been used by an operator to balance the grid: it provides fast frequency response, synthetic inertia and black start. This project is a glimpse of the future – batteries will soon provide these services at scale on the mainland too," said Brandon Keefe, executive chairman of Plus Power.

The Kapolei Energy Storage project combines the following energy and support services:

• 135 MW / 540 MWh of installed power capacity and available storage capacity,
• 50 MW / 25 MWh of additional “fast frequency response”, which helps maintain grid frequency,
• “Virtual inertia” to replace the power-smoothing effect of spinning synchronous generators connected to the grid,
• “Black start”, which enables the grid to be restored in the event of a blackout.

Its location near three critical Hawaiian Electric power plants even allows it to provide black-start service to all three plants in the event of a complete loss of electricity supply.

“This is the first time a standalone battery site has provided support services on this scale. This is a critical service for grids with a high penetration of renewables, delivered by Megapack inverters,” said Mike Snyder, director of Tesla Megapack.

Integrating renewables into the grid

Hawaiian Electric’s model shows that during the first five years of operation, the storage facility will enable the company to reduce renewable energy curtailment by 69%. At the same time, the batteries will enable 10% more new renewable energy sources to be connected than previous models allowed. The grid operator estimates that the project will reduce each customer’s electricity bills by an average of 0.28 dollars (roughly 6.4 Kč) per month for 20 years.

“KES is an important part of the portfolio of resources working together to ensure reliability and energy security on Oahu’s island grid. Energy storage technology that responds quickly to constantly changing conditions is an essential tool for us to manage the grid and operate it as efficiently as possible,” said Jim Alberts, senior vice president and chief operating officer of Hawaiian Electric.