On a windswept patch of the Mojave Desert, the Tehachapi Energy Storage Project achieved many firsts for Southern California Edison. It was launched as a two-year project to demonstrate the performance of lithium-ion batteries used to store power from hundreds of wind turbines under real-world conditions.

It turned into a seven-year run of technological achievements that are helping SCE to realize a clean energy future and be responsible stewards of the environment.

"Tehachapi was instrumental in paving the way for where we are today in terms of how much we're installing and integrating batteries into the grid," said Josh Mauzey, SCE Grid Technology Innovation senior manager whose team oversaw the project. "This project has really helped us think through and better understand the full life cycle of a utility-scale battery energy storage project."

Located in a valley 100 miles northeast of Los Angeles within the Tehachapi Wind Resource Area, the project could supply 32 megawatt-hours of electrical energy and eight megawatts of power for four continuous hours when it began in 2014. That could power between 1,600 and 2,400 homes.

Today, SCE has nearly 1,400 megawatts of emissions-free energy storage currently online, with an additional 2,800 megawatts planned by 2026. These batteries allow for the reliable storage of clean energy from wind and solar generation, which can later be dispatched onto the grid when customers need and use it most.

The Tehachapi project transformed the lithium-ion battery storage industry by propelling the development of commercial products. As the first to participate in the California Independent System Operator market, and one of the first to be connected to the CAISO system, it contributed to the integration of renewable and storage-based resources on California's grid.

Now, as it goes through the final stages of decommissioning, the Tehachapi project is once again achieving firsts — this time in how a utility-scale lithium-ion battery energy storage system (BESS) reaches the end of its useful life.

"When materials reach the end of their useful life, we follow all federal, state and local laws and regulations to determine how they'll be reused, recycled, resold or disposed of," said Juan Castaneda, SCE Grid Technology Innovation's principal manager. "We seek opportunities to implement a circular economy by reselling or donating material and assets. Where these options don't exist, we evaluate the material for recycling or disposal."

The project team developed a decommissioning plan that includes a mix of auction, disposal and repurposing equipment.

"Decommissioning a battery energy storage project is a first for SCE, and the technicalities were complex," said Md Arifujjaman, SCE lead senior engineer for the project. "We learned that end-of-life recycling of batteries could represent a significant cost for a large-scale BESS."

As one of the largest lithium-ion batteries for storing electricity in North America, the facility contained 604,832 lithium-ion battery cells supplied by LG Chem — the same cells installed in battery packs for General Motors' Chevrolet Volts. The batteries were housed in 10,872 modules of 56 cells each, stacked in 604 racks. All of the battery cells will be recycled while the inverter, which converts direct current (DC) output into alternating current (AC) output for everyday use, will be repurposed.

The project was initially funded in part by the US Department of Energy as part of the American Recovery and Reinvestment Act of 2009. It officially ceased operations and its connection to the grid in May 2021. But the facility's physical dismantlement is expected to be completed by the end of 2022.

"The work we accomplished on this project is moving us toward a 21st-century power network that can adapt to all our energy needs," said Castaneda. "It's a key component to the bigger picture of modernizing our grid and integrating more clean energy."