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Battery Facility Is Source of Pride

The battery storage project AES Corp. is building for San Diego Gas & Electric Co. in Escondido would normally take years to permit, contract, design and build. But thanks to accelerated work by both companies, and a state fast-tracking process, this one has taken just a few months, potentially pointing the way to rapid development of other projects.

The nation’s largest battery storage facility consists mainly of two dozen white, shipping container-size buildings lined up next to an Escondido electrical substation. It looks like a trailer park devoid of cars and residents.

But to the people who worked like mad to get the thing up and running by the state-imposed deadline of Jan. 31, it stands as an example of San

Diego Gas & Electric Co. overcoming challenges when circumstances demand fast action.

Such a project would normally take years to contract, permit and build. This one took months.

SDG&E had little choice. A catastrophic leak at a natural gas storage facility sister company Southern

California Gas Co. operates in northern Los Angeles County prompted the California Public Utilities Commission in May to fast-track energy storage projects that could help ensure the region has enough power to keep households in the region warm this winter.

Fortunately, SDG&E was already considering where to build future battery arrays following closure of the San Onofre Nuclear Generating Station. The Escondido project aligns with the CPUC’s call for greater investment in energy storage and an industry trend toward facilities that can accommodate more solar and wind power, which don’t always generate electricity when it’s needed most.

Powerful Resource

The result is a compact but potent array of Samsung lithium-ion batteries that, when combined with a facility one-fourth the size that SDG&E is opening in El Cajon, will be capable of powering 25,000 homes for up to four hours. It will be monitored by SDG&E and the project’s contractor, Arlington, Va.-based AES Corp., but operated remotely by the agency that controls the state power grid, the California Independent System Operator (CAISO).

At 30 megawatts and 120 megawatt-hours, the Escondido installation southwest of Interstate 15 and state Route 78 rivals what has been the largest single U.S. battery storage project, a 20-MW, 80-MWh facility Southern California Edison ordered from Tesla Motors. That project, big enough to power every home in Solana Beach for an entire Super Bowl broadcast, was also expedited because of the leak SoCalGas workers discovered in October 2015 at the Aliso Canyon storage site.

SDG&E has built or contracted a total of about 100 MW of energy storage in the San Diego area. The CPUC has permitted an additional 166 MW statewide. The commission has ordered SDG&E to procure 165 megawatts of energy storage by 2020; the installations are supposed to be operational by 2024.

Valuable Lessons

The Escondido project is especially significant to SDG&E because of what the company learned during the construction process, which involved as many as 65 unionized concrete-pourers, carpenters, electricians and others occasionally working at the same time almost side-by-side since the start of construction Oct. 18.

“We know where we could have done better,” said the utility’s manager of advanced technology integration, Josh Gerber. He wouldn’t go into details but added next time the company will try to limit the number of tasks performed simultaneously, like design and execution. “The first time you do anything hard, you learn a lot.”

At its most elemental, the project is a series of 380,000 batteries the size of a car stereo. Twenty at a time were assembled into suitcaselike containers weighing about 100 pounds. Each of the site’s 24 storage buildings contains about 800 of those containers.

Improved Efficiency

The batteries, built in China and South Korea, were chosen because of their reliability and Samsung’s large manufacturing capacity. They operate at between 85 percent and 90 percent efficiency — a significant improvement over the 70 percent attributed to another leading mode of energy storage, pumped-storage hydroelectricity — and can be fully discharged in four hours, the same duration required for recharge.

AES has guaranteed the system’s performance for 10 years, though SDG&E expects the project to last well beyond that amount of time. Because the project is scalable, it can be expanded and underperforming batteries replaced. The company said it expects to recycle the batteries eventually.

The 24 air-conditioned battery storage buildings are divided into three modules, each with its own circuit and switch allowing the independent grid operator, CAISO, to quickly deploy 10 megawatts at a time. They are connected by underground wiring to an unmanned control building on site.

Under a provision approved by the CPUC, the price of the project has not been disclosed, and won’t be for three years. SDG&E ratepayers will ultimately pay for the battery facility in the form of higher rates charged for electricity.

Besides evening out the delivery of solar and wind power, battery storage is considered a way to reduce the need for so-called “peaker” power plants, which don’t store energy but get switched on for short periods to generate power during times of peak demand.

SDG&E spokesman Hanan Eisenman said both types of energy infrastructure — batteries and peakers — are still needed as a way of balancing supply and demand.

“We don’t see it as an either-or option,” he said, adding that the utility has ordered five 100-MW peakers for the Carlsbad area.

Quick turnaround

A senior energy storage analyst at GTM Research, Daniel Finn-Foley, said by email the Escondido project’s quick deployment is particularly noteworthy: Its approval and construction processes together lasted about the same time it takes just to secure an environmental permit for a peaker plant.

The process was fast even by energy storage standards, he noted, making it something of a test case for an industry more accustomed to seeing battery storage used for short-term power rather than as an energy resource.

“The construction, interconnection and testing process before these systems can come online is complicated and time-consuming, so the industry will be watching closely to see if the project can meet (SDG&E’s) promised milestones,” Finn-Foley wrote.

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