Lithium Ion Battery Safety Remains an Important but Rarely Discussed Concern

After attending the Solar Power International (SPI) conference in California in September, the growing impact of lithium ion (Li-ion) batteries in the renewable energy industry is clear. Nearly all battery vendors at the conference offer Li-ion technology, which is now an effective and economical tool for storing excess renewable generation. Despite its popularity and mostly clean track record, Li-ion technology comes with risks, most notably the potential for thermal runaway to cause dangerous fires. Safety remains an important issue in the industry, yet few vendors regularly discuss these risks and the steps being taken to mitigate them.

Cause for Concern?

Over the past several years, high profile incidents of Li-ion battery fires in consumer electronics have received significant media attention. Due to the inherent risks that come with the technology, large stationary energy storage systems take preventative measures, such as constant monitoring of temperature down to the battery cell level and sophisticated built in fire suppression systems. However, despite these efforts, fires at large-scale Li-ion battery plants are not unheard of. In the past year, three fires have been reported at utility-scale Li-ion stationary battery plants in South Korea, where the technology has recently been deployed on a large scale to provide grid stability services. While the exact causes of these fires are not known, they have occurred at various project sites, including a substation, solar plant, and wind farm. 

Despite the measures taken by battery vendors and project developers, fire safety remains a concern that is holding back the growth of the Li-ion stationary energy storage market. Commercial and residential buildings in densely populated urban areas with high energy charges could generate significant energy bill savings by deploying Li-ion battery energy storage. However, many local officials remain concerned about how to safely deploy Li-ion battery systems to reduce fire risks. Some cities, such as New York City, have entirely prohibited the installation of large Li-ion batteries inside of buildings until new fire safety codes are established. Other cities, such as San Francisco, allow indoor installation but have strict safety requirements, including placement of batteries in separate, dedicated rooms with automatic sprinklers, ventilation, and smoke detection. 

Standards Are Key

Improvements in Li-ion battery safety are constantly being made, including the use of chemistries that have limited thermal runaway risk, such as lithium iron phosphate. For the industry to truly scale and negate existing safety concerns, robust standards need to be established for the design, testing, installation, and operation of new projects. One of these new standards, presented in-depth at the SPI conference last month, is the Underwriters Laboratories (UL) standard 9540 A. This standard, titled Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems, outlines standardized testing procedures for Li-ion batteries at multiple levels, including individual cells, modules, racks, and entire installations, to evaluate and mitigate thermal runaway and fire propagation risks. The standard also includes installation parameters to limit the spreading of a possible fire, through spacing between battery racks, ventilation, and fire suppression. 

Although increasingly stringent standards may elevate costs for project installation and permitting, UL and other organizations will play a key role in the growth of the energy storage industry by establishing these and other standards to ensure the safe and effective use of battery technologies.