Utility Arizona Public Service has contracted for a new grid-scale battery — not to demonstrate the technology, but because it’s a lot cheaper than the conventional alternative.
The company will purchase two 1-megawatt/4-megawatt-hour storage systems from AES for the small town of Punkin Center. This 600-person hamlet, 90 miles northeast of downtown Phoenix (and known for a bar with a prominent jack-o’-lantern sign) is bumping up against the limits of its distribution grid.
The traditional approach, which APS considered, would be to upgrade the 20 miles of 21-kilovolt cables that service the town. That requires construction through hilly and mountainous terrain, with considerable expense and local disruption.
The utility decided that batteries would be cheaper.
By tucking the AES storage systems on APS-owned land in Punkin Center, the company can deliver locally stored power on the 20 to 30 days a year when local and system peaks are expected to strain the wires.
The primary application is to make local load disappear, according to Erik Ellis, transmission and distribution manager for technology assessment and integration. He wouldn’t disclose the cost of the system, but said it was less than half of the upfront expense of the traditional wires approach.
“It means we’re evolving toward a more sustainable and effective grid where we’re no longer forced to make investments in these large, significant steps,” Ellis said. “We can take much smaller incremental steps to manage the need as it arises and not have to over-invest in some cases, as utilities have traditionally had to do in the past.”
The storage provides a targeted solution to the distribution challenge, but it also does much more.
The system will also serve as a new source of capacity. It also can use its inverters to perform voltage regulation and power factor regulation. And it can be used for energy arbitrage to soak up negatively priced energy and dispatch it when costs are higher.
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