Evolving technology: Residential energy storage systems
Industries use ESS as power storage from a large array of solar panels or wind-powered generators
Energy Storage Systems (ESS) are not new to the fire service. Those of us old enough to remember telephone exchange buildings know that most had a dedicated room for lead and acid battery storage designed to keep the telephone system operable even when there was a power failure.
Fast forward to today, and ESS is being used by many industries across the country. Primarily, these industries use the ESS for power storage from a large array of solar panels or wind-powered generators. However, instead of the old lead and acid batteries, modern technology has given us the smaller, more powerful lithium ion battery.
Electric fires pose a host of new obstacles
Lithium ion batteries power many devices, from our cell phone to alternative powered cars – most notably the Tesla models of vehicles. We’ve learned that poorly made or poorly shielded lithium batteries can catch fire from what is called “thermal runaway,” a chemical reaction inside the battery cell that causes an increase in temperature, eventually spreading from cell to cell and, in some cases, causing serious burns to people and devastating fires. This chemical reaction can also occur when an external fire sufficiently heats the battery to start the “thermal runaway” reaction.
Some of the more notable items that have caught fire are vape pipes, hover-boards and electric cars, primarily when they are involved in high speed crashes. Such fires burn at a high intensity because the lithium is an exothermal metal, and will react violently with a standard application of water. It is one reason why airlines have placed cabin restrictions on some items that are powered by lithium ion batteries.
For several years, Underwriters’ Laboratory (UL) has been doing research on the “thermal runaway” phenomenon. This has recently led to the development of a standard test: UL 9540a, the Standard Test Method for Evaluating Thermal Runaway Propagation in Battery Energy Storage Systems. The test helps to more clearly determine parameters, such as the number and type of batteries, their composition, size, capacity and spacing that can be safely used within an ESS.
For many years, the NFPA has also provided online tutorials on how to identify alternative fueled vehicles, how to handle extrications of their passengers and how to approach and fight fires within these vehicles. More recently, the NFPA has begun work on a new standard, NFPA 855: Installation of Stationary Energy Storage Systems, designed to cover the industrial use of ESS, but this new standard will probably take until mid-2019 to complete.
Standards needed for residential ESS
While both the UL and NFPA tests and standards address the industrial use of ESS, including clear hazard markings, systems isolation within a structure or in a separate on site building and extinguishment methods, there is a growing market for smaller ESS designed for residential use.
For example, in May 2018, California became the first state to pass legislation requiring all new home building construction to have solar panels to capture and subsequently store this energy for use within the residence. This code change can be met by either having solar panels for the exclusive use of one home, or a larger solar panel array set aside for an entirely new subdivision.
In either case, lithium batteries will have a predominate role in the energy conservation effort and require space either within the individual home or in a stand-alone storage building. It is the ESS in the individual home that causes me the most concern, and whether the safety of firefighters has been considered when developing the new residential building codes covering the legislative requirement.
How to make residential ESS with firefighter safety in mind
An internet search led me to at least one residential ESS manufacturer that indicated the energy storage system can easily be placed in the basement of any resident. That raises an alarm on at least two or more levels.
First, how will the ESS increase the fire load within the residence, especially the basement? We already know the difficulty in fighting a basement fire and the perils of structural collapse that has caused the needless deaths of dozens of firefighters in the past 10 years.
While our tactics for basement fires has changed, including a 360-degree assessment of any structural to determine the presence of a basement and whether there are any alternative “walk out” entrances for a transitional attack, the perils, injuries and deaths faced by firefighters associated with basement fires must remain paramount to fire officers.
Secondly, how will the residential ESS react to a fire caused by another source, such as a clothes dryer, when the temperatures reach the point where one or more of the ESS cells begins a “thermal runaway?”
In states where residential ESS are being required or even permitted, fire officials need to lobby for the best protection of these systems from both internal and external fires, for the safety of firefighters. In my opinion, it would be better for our fire service research, as demonstrated by the work being done by the UL, NFPA and others, to catch up and be codified within the residential and commercial building codes before these systems begin a wider use.
Third, on any residential or commercial structure where an ESS is present, the structure should be marked with an identification symbol to be clearly recognizable by responding fire personnel, such as a medallion similar to those once used for an all-electric home.
And, finally, that the fire officer in charge take into account the additional risks associated with an ESS before setting the strategy for the fire’s extinguishment.
No doubt with time a necessary level of fire safety will be standard with any ESS installation, but, for now, it is best for all of us to strongly weigh our decisions on the side of firefighter safety.