Arizona Public Service Co. is restarting plans to install massive batteries on the electrical grid around Arizona after a fire and explosion brought that work to a halt more than a year ago.
The big bet on batteries came from APS as the company sought to get more of its power from solar panels. But the April 2019 fire at one of its first battery installations in the far West Valley injured several first responders and put plans on hold while the utility investigated and took other steps to ensure the batteries are safe.
Utility-scale batteries, which on the outside are similar in size and design to a modular trailer home, can store electricity generated during daylight hours from solar panels. That energy can feed into the power grid in the evening.
This will allow APS to use more renewable, solar energy and match the power supply with the demand. Doing that is difficult without batteries because people still use power after sunset, when solar panels stop producing electricity.
“We have made steady progress since setting our clean energy goal in January,” APS Vice President of Resource Management Brad Albert said in a prepared statement Monday.
“Moving ahead with our energy storage plans, our recent purchase of more clean wind generation, and our expanded voluntary energy conservation program all support meeting the needs of our growing customer base with reliable, affordable and increasingly cleaner resources.”
In addition to state clean-energy standards that were updated in November, APS has set a goal to get 65% of its energy from carbon-free sources by 2030 and to be 100% carbon-free by 2050. The company will end all coal-fired generation by 2031.
APS has plans for a Chicago-based company called Invenergy to install large batteries at six of its existing solar plants in Maricopa and Yuma counties, and is seeking bids for two others in Yavapai and Pinal counties.
The 600 megawatt-hours of battery storage that APS will have after all eight batteries are installed is enough to supply about 150,000 homes for an hour, or 75,000 homes for two hours, and so on.
Those eight battery installations are only a portion of the battery capacity APS announced it would build and that it eventually will need to meet its clean energy goals.Your stories live here.Fuel your hometown passion and plug into the stories that define it.Create Account
APS also announced Monday it is seeking requests for proposals for more renewable energy, and that the request is open to projects that address electricity demand as well as supply. Such projects could include technologies that help customers conserve power during peak demand, when the strain on the power grid is greatest.
What happened with battery explosion
Following the explosion at the McMicken Energy Storage facility near Grand Avenue and Deer Valley Road in Surprise, APS said officials wanted to ensure they understood what went wrong and how to prevent it.
This summer, APS issued a report of the incident, that stated one of the problems was that first responders didn’t have a plan for how to deal with the smoking battery before it exploded.
The McMicken battery was built by a company called AES, using lithium-ion batteries from LG Chem.
“The emergency response plan provided by AES to APS did not have instructions on how to respond to a potential explosion or how to enter the system after the fire suppression system had been discharged,” the report said.
Several other things went wrong and led to the explosion, according to the report, but the lack of a plan contributed to the injuries because firefighters opened a door on the facility about two hours after arriving on the scene. Two minutes later, the facility exploded. Eight firefighters and one police officer were taken to the hospital.
The follow-up report concluded that a faulty battery cell overheated and that damaged other modules nearby.
Lithium-ion batteries that fail in this manner enter something called “thermal runaway,” which is essentially a build-up of heat that can lead to a fire.
The building had a fire-suppression system, but it was only designed to extinguish small fires, like a burning trash can, that could lead to thermal runaway. It was not designed to stop batteries in the building that were already in thermal runaway, according to the report.
APS now requires its batteries to:
- Minimize or prevent heat transfer and thermal runaway.
- Use fire detection and suppression systems to aid in mitigating thermal runaway, including extensive heat and off-gassing.
- Allow for around-the-clock monitoring and remote reporting of smoke or gases.
- Use ventilation systems that disperse gases, rather than allow them to accumulate.
- Coordinate with emergency responders for training and coordination.
Reach reporter Ryan Randazzo at firstname.lastname@example.org or 602-444-4331. Follow him on Twitter @UtilityReporter.