Utility Arizona Public Service reaffirmed its commitment to grid batteries after a fire at one such facility injured four first responders.
The April 19 explosion at the McMicken facility prompted Arizona's largest utility to power down its remaining energy storage plants, and raised questions about the future of this rapidly growing grid technology. APS committed in February to a considerable escalation of energy storage installations, to capture more solar power during the day and make it available at night.
The investigation to determine the cause of the fire is still underway, but APS is not giving up on those plans for battery expansion, President Jeff Guldner told Arizona regulators last week.
"As you know, we have moved forward and made an announcement as to work that we intend to pursue on battery storage," Guldner said. "This hasn’t changed our determination to move forward on that.”
In February APS announced plans to deploy 850 megawatts of battery storage by 2025, the single largest storage procurement from a utility to date.
Indeed, the investigation will provide valuable information to ensure safe practices as that expansion proceeds, locally and nationally. “This is important because battery technology is such an important future component to the operation of the grid," Guldner noted.
The full remarks, made at the April 23 meeting of the Arizona Corporation Commission, are visible on a public video recording (starting around 2:46:00).
The ACC similarly signaled that it sees batteries playing a larger role in the future of the state’s grid.
During the hearing, Commissioner Boyd Dunn made that point explicitly.
"I agree with your comment that batteries are our future," he said. "Wherever you go, that’s going to be the talk."
"Clean Peak" requirement would further boost storage
Energy storage also featured in a draft overhaul of the state’s energy rules that commission staff published on April 25. The proposed changes would increase the renewable electricity requirement from 15 percent by 2025 to 40 percent by 2035, while instituting a requirement that a portion of peak-hour electricity come from clean sources.
The Clean Peak aims to address the creeping cost of serving peak power in the hot, air-conditioning-dependent state. As solar power boomed, utilities including APS described a need to build expensive natural-gas-fired peaker plants to meet demand in the evening and nighttime, after the solar plants stop producing.
Traditional renewable energy requirements, known as renewable portfolio standards, fail to address the time of day when that energy reaches the grid, creating a dynamic where states may accelerate solar power but still need more gas plants to cover the evening ramp.
Requiring a certain amount of peak power to come from clean sources would push utilities to make clean energy dispatchable on demand. Lithium-ion batteries are the current market leader to perform that service. The ACC staff's draft plan calls for 15 percent of peak power to come from clean sources by 2035.
The interest in batteries for peak power derives from Arizona's especially robust solar resource. The grid already receives a flood of cheap power during the sunny hours. The economics for shifting that power with batteries became apparent in February 2018, when First Solar beat out gas plants with a solar-plus-storage bid in a competitive solicitation for peak capacity.
"What’s happening here in Arizona is because of the nature of our system," Guldner said. "We’re at the leading edge on some of these technologies."
APS has installed three utility-scale batteries and awarded several more large-scale contracts, putting it ahead of most utilities in the country. The operational experience from the initial projects informed the rapid acceleration proposed earlier this year.