This California city is trading an old gas plant for a giant grid battery

MENIFEE, California — For a decade, twin smokestacks loomed against the bright blue skies of Menifee, in Southern California’s Inland Empire. But the old gas combustion plant came down, and on the flat industrial site it left behind an army of batteries is now being assembled.

When it comes online this summer, developer Calpine’s Nova power bank will store more electricity than all but one battery plant currently operating in the U.S. The billion-dollar project, with 680 megawatts and 2,720 megawatt-hours, will help California shift its nation-leading solar generation into the critical evening and nighttime hours, bolstering the grid against the heat waves that have pushed it to the brink multiple times in recent years.

The facility embodies the clean energy transition in multiple ways. The power plant itself will shift from an 800-megawatt combined cycle plant, installed by GE in 2008 as a model of efficiency, only to languish when its 12-hour startup time made it a poor fit for the era of cheap gas and weather-dependent renewable production. The town of Menifee gets to move on from the power plant exhaust that used to join the smog flowing from Los Angeles, dulling the rays that inspired the name for nearby Sun City, which sprang up in the 1950s as home for heliotropic retirees. And the grid gets a bunch more clean capacity that can, ideally, displace fossil fuels.

“A lot of us remember what was here just a year ago with the two big smokestacks,” Menifee Mayor Bill Zimmerman said. ​“It would take all day just to get that thing up to speed and running, and they would have to anticipate whether or not they would need it. This is going to be ten times better and ten times more efficient, without all that extra work.”

Moreover, Nova represents Calpine’s grand arrival in the energy storage market, after years operating one of the biggest independent gas power plant fleets in the country alongside Vistra and NRG. Houston-based Calpine previously dabbled in battery technology with two California projects, but Nova’s pricetag and power capacity catapult Calpine into the upper echelons of storage developers and owners.

Federal analysts predict 2024 will be the biggest-ever year for grid battery installations across the U.S., and they highlighted Calpine’s project as one of the single largest projects. The 620 megawatts the company plans to energize this year represent more than 4% of the industry’s total expected new additions.

Many of these new grid batteries will be built in California, which needs all the dispatchable power it can get to meet demand when its massive solar fleet stops producing, and to keep pace with the electrification of vehicles and buildings. The Menifee Power Bank, and the other gigawatts worth of storage expected to come online in the state this year, will deliver much-needed reinforcement.

Massive scale, built fast

The scale of the Nova project is difficult to grasp, even if you visit in person. A hefty yellow crane looms overhead, Star Spangled Banner flapping below it, indicating something grand being constructed. But the flat ground obscures the full heft of the project: 1,096 total battery containers, holding 26,304 battery modules, or a total of 3 million cells, all manufactured by Chinese battery powerhouse BYD, according to Robert Stuart, an electrical project manager with Calpine.

That’s enough electricity to supply 680,000 homes for four hours before it runs out, Calpine explained. The project is not literally wired to back up any specific homes, but it gives California that much extra firepower.

What’s remarkable is just how quickly the project came together. Construction began last August, and is expected to hit 510 megawatts of fully operational capacity over the course of this summer, even as installation continues on other parts of the plant. Erecting a conventional gas plant of comparable scale would have taken three or four years of construction labor, due to the complexity of the systems and the many different trades required for it, Stuart told Canary Media.

Developers of gas plants or batteries have to do legwork prior to the installation to secure land, permits and connection to the grid. At Nova, Calpine moved quickly because the grid was already built to receive lots of power from the site. Calpine only started working with the city to secure permits in 2021, said Emily Precht, strategic origination manager at Calpine.

“Given the fact that this plant was retiring and there was all of this existing infrastructure on this site, batteries really helped with grid reliability in the face of all of these intermittent renewables,” she said. ​“They are instantaneous ramping, you can start and stop them whenever you need to, and it just made a whole lot of sense.”

That speed and flexibility makes batteries a crucial solution as utilities across the nation grapple with a spike in expected electricity demand unlike anything seen in the last few decades. Some utilities, particularly in the Southeast, are planning to build a raft of new fossil gas plants to deal with this predicted surge. If time is of the essence, the Menifee project demonstrates that grid batteries have the clear advantage.

Battery installations move expeditiously due to their modular nature. The enormous battery — and others like it — is really a series of much smaller, identical blocks containing inverters and battery enclosures that all eventually connect to the project’s substation and from there to the broader grid. To build an enormous battery storage plant is to wire up the same design over and over again until it’s done. That’s why Calpine can energize swaths of the project as they become ready — something that’s not possible for a gas turbine.

“When Phase One will be completed, operators will take it over, while we’re still working on Two, Three, and Four,” Stuart said. ​“We’ll be actively building these and then turning them over right away as they’re ready.”

Calpine transitions to batteries at pivotal time

California is in the thrall of its battery buildout now, but all of this construction has its roots in the state’s much earlier decision to mandate battery storage for its utility companies.

That 2013 policy kicked off a decade-long project to will an energy storage market into existence through methodical policies and regulations, and the knock-on effects of building the nation’s foremost solar fleet.

Those energy storage policies succeeded in jumpstarting the modern grid battery market: California leads the nation with more than 7 gigawatts of batteries installed as of last year (though Texas is poised to overtake California in battery installations this year, on the back of no particular policy effort but a general openness to building energy projects).

But for all of that effort, California hasn’t excelled at actually closing gas plants. The state had years to prepare for a 2020 deadline to shutter ​“once through cooling” plants that use ocean water, only to flip at the last minute and ask those targeted plants to keep burning gas to avoid a grid calamity. Today, despite its nation-leading renewables buildout, gas is still the leading source of electricity generation in the state.

Operating gas plants has only grown more lucrative lately, as the state’s shortage of on-demand power has sent capacity prices to staggering heights. Calpine, which operates roughly 26 gigawatts of power plants in competitive markets of the East Coast, Texas and California, still makes most of its money burning gas.

But California’s interlocking climate regulations effectively rule out new gas construction. The state’s energy roadmap instead calls for massive expansion of battery capacity to shift the ample amounts of solar generation into the evening peaks. These trends, along with the falling price of batteries and maturing business model for storage, nudged Calpine to get into the battery business, too.

It started with a battery project in Santa Ana, a historic town in Orange County. That system grew to 80 megawatts over a few phases of development. Another battery project in the Bay Area plays the role of ​“black start,” providing the energy necessary to restart power plants after a major grid outage. Now, portions of the Menifee project will provide capacity for utilities Southern California Edison, San Diego Gas & Electric and the community choice aggregator Peninsula Clean Energy.

Menifee is Calpine’s first battery project that’s at a scale even close to comparable to its legacy gas projects. The sheer size of this project means it will control more battery capacity than all but a handful of other California operators once online.

“There was a need in California for making the grid cleaner and adding more dispatchable resources, and we felt that it was an opportune time to start developing this site,” Precht said. ​“All the pieces came together.”

Calpine is developing a portfolio of 2,000 megawatts of California battery capacity, including Menifee, she noted.

Getting on the learning curve

Strategic hesitance has also created opportunities for Calpine to learn from others’ mistakes.

Another top gas power producer, Vistra, embraced the battery revolution before Calpine and built the nation’s largest grid battery at an old gas plant site in Moss Landing, south of the Bay Area. Vistra expanded that facility over multiple phases to hold 750 megawatts and 3,000 megawatt-hours as of last June. But Moss Landing’s reputation for bolstering the grid suffered due to multiple fires that not only halted operations but temporarily locked down the surrounding region.

Two of those separate Moss Landing fires weren’t actually caused by faulty lithium-ion batteries. Faulty sprinkler systems set them off, meaning the pipes intended to suppress fires actually caused them.

Calpine took a different approach to fire safety. The company rebuilt the fire hydrant system to expand its capacity, but elected to not connect the water system to the battery containers, Stuart explained. No water means no accidental fires from trigger happy sprinklers. But if a battery fire ever happens, alarms will sound and responders can hook up a hydrant to the enclosure in question and flood it entirely, or isolate the fire and let it burn itself out safely.

In other words, the Nova project benefits from the many iterations in large-scale battery development that came before. The engineering firm Mortenson handled the actual construction on behalf of Calpine, and applied techniques it has honed building big batteries elsewhere in the West.

“It’s only getting faster, and you know, this isn’t Mortenson’s first project,” said Stuart, with Calpine. ​“They do have good communication within their company, they talk to each other to make sure that all their battery projects are going at the same rhythm and lessons learned aren’t lost on one project.”