The Golden State has more energy storage installed than any other part of the US, but recent fire events led to California’s energy policy and planning agency saying such incidents have to stop.
California has more energy storage capacity than any other US state [1] – with 7.3GW installed – but concerns are rising among the state’s governmental agencies about battery storage fire risk.
In September last year, there were a high-profile energy storage fire at the 139MW / 560MWh Valley Center Energy Storage Facility in San Diego County, which is owned by renewable energy company Terra-Gen. The fire broke out at the facility – which produces enough electricity to power up to 140,000 homes for four hours on a single charge – although Terra-Gen had safety protocols in place, a large fire broke out causing serious concern. [2]
Storage fire causes injuries to first responders
In another incident in September 2022, a Tesla Megapack caught fire at a battery storage facility operated by Pacific Gas & Electric in the Northern California town of Moss Landing. No injuries were reported, but California Highway Patrol closed a section of Highway 1 and redirected traffic away from the site for a number of hours. Meanwhile, in 2019, an explosion at an energy storage facility in the city of Surprise in the state of Arizona – which neighbors California – resulted in injuries to nine first responders.
Given that the Terra-Gen incident was the latest in a number of high-profile fire events at energy storage facilities, the Californian authorities made clear their desire to put a stop to such incidents. In the aftermath of the Terra-Gen incident, David Hochschild, chair of the California Energy Commission issued the following warning: “The stakes are high. We have to have effective storage. Generally, I’m very pleased with the performance of the storage fleet in California, but we cannot have fires on a regular basis.”
Storage fires jeopardize the sector’s reputation
In an effort to further guard against energy storage fire risk, new legislation requiring battery storage facilities to put in place safety and communication protocols was signed into law by state governor Gavin Newsom last October. Senate Bill 38 (SB 38) makes it obligatory for battery storage facilities in the state to put in place emergency response and emergency plans – in addition to existing requirements for their maintenance and operation – to meet standards set by the regulatory California Public Utilities Commission (CPUC). [3]
With the lives of first responders, billions of dollars of energy storage investment, and the storage industry’s reputation in jeopardy in California and elsewhere, developers and owners must take steps to protect energy storage assets against fire risk. In addition to the potential danger to life, battery storage fire incidents can cost developers, owners or operators up to $2 million as a result of the catastrophic loss of an asset and loss of revenue from up to 18 months’ worth of downtime.
Energy Storage Risk Mitigation
Fire Risk
NFPA 855 is a dynamic standard that governs the installation of stationary energy storage systems, reflecting the latest safety considerations and technological advancements. As technology and best practices evolve, NFPA 855 will undergo periodic updates to address emerging risks and incorporate new solutions. Continuous analysis and review are essential to ensure compliance with the latest requirements and to maintain optimal safety standards. Organizations must stay vigilant and adapt to these changes to effectively manage the risks associated with energy storage systems.
It is also important to consider the inclusion of a battery management system, which monitors, controls, and optimizes performance of individual or multiple battery modules, and can also control the disconnection of the modules from the system in the event of abnormal conditions.
It is recommended that energy storage units are grouped into small segments limited to certain amounts of kilowatt hours and spaced from other segments and walls to prevent horizontal propagation. Depending on the energy storage type and capacity, as well as whether sprinklers are present, systems should be spaced between 0.9 meters and 4 meters apart [4].
Consideration should also be given to the fact that only 11% of fires and explosions are linked to battery module failures, according to EPRI [Electric Power Research Institute], with 43% stemming from failures in electrical equipment such as PCS [power conversion systems], and 46% attributable to control equipment malfunctions.
Explosion Risk
The NFPA says that, if there are enough batteries in a confined space to create an explosive atmosphere, explosion prevention systems or deflagration venting should be installed per NFPA 69, Standard on Explosion Prevention Systems, and NFPA 68, Standard on Explosion Protection by Deflagration Venting.