By Brian O’Connor, P.E.
From the August 2019 Issue
Energy Storage System (ESS) technology stores energy in various forms for use as electrical energy at a later time. The term ESS can refer to several different types of technology such as flywheel energy storage, pumped hydro energy storage, or battery energy storage. This article focuses on lithium-ion battery ESS, since it is the most common type and technology being installed these days.
The popularity of ESS is clearly on the rise around the world. Global ESS deployment is projected to grow 13 times in size over the next six years (2018-2024) with the United States and China leading the charge, according to research from Wood Mackenzie Power & Renewable. Given this growth trend, it is likely that facility managers will be responsible for overseeing an installation in a building that they manage in the near future. To help navigate potential challenges and obstacles related to ESS installations, the National Fire Protection Association (NFPA) has developed NFPA 855, Standard on the Installation of Stationary Energy Storage Systems—which will be released this fall.
The beauty of lithium-ion ESS is that it offers excellent energy density and is becoming increasingly affordable. The technology packs a lot of energy in a small envelope, which means there is an increased likelihood of fire and life safety hazards such as stranded energy, the release of toxic gases, and greater fire potential.
ESS is attractive to business owners and consumers alike for a variety of reasons. Peak shaving (the practice of charging an ESS when the price of energy is low and using the energy when the price of electricity is high) is a great way to save money and improve efficiencies. Facility managers who oversee buildings that rely on solar panels or wind turbines for power may also want to supplement their green energy resources with ESS so that they can generate electricity when the wind is not blowing and the sun not shining. No doubt, alternative energy systems offer significant environmental and economic benefits but they can also pose potential harm to people and property.
This article will not replace the need for building professionals to read the actual standard, NFPA 855. Instead, it will hopefully serve as a reminder of the considerations that need to be weighed when looking to install ESS technology.
One of the greatest concerns related to ESS, from a practicality standpoint, is whether or not there is enough room available to store the desired energy capacity. NFPA 855 requires most installations to have a three-foot separation between groups of 50kWh ESS and between those 50kWh groups and the walls. NFPA 855 also has a maximum stored energy threshold that is specific to each technology. For example, for lithium-ion ESS it is 600 kWh.
The requirements of NFPA 855 also vary based on where the ESS in located. NFPA 855 breaks down the location of ESS into two main groups—indoor and outdoor. The standard further classifies indoor installations as being in a building dedicated to ESS or existing in a facility that has other uses. If the installation is in a mixed-use facility, NFPA 855 requires a 2-hour fire-rated separation from other areas of the building. Additionally, the document identifies outdoor installations as either remote or non-remote, which means that they are at either a minimum of 100 feet away from exposures, or not.
Not surprisingly, ESS will be required to be protected with a NFPA 13 sprinkler system using a minimum density of 0.3 gpm/ft2 over the area of the room or 2500ft2, whichever is smaller. First of its kind ESS sprinkler research, based on some testing from UL, was released by the Fire Protection Research Foundation, an NFPA affiliate, in June 2019 to help inform facility managers and others.
Certain ESS can go into thermal runaway and generate toxic and flammable gas that can create an explosion hazard. Given the potential for adverse events, explosion control, ventilation, and smoke and fire detection will be required for certain installations. There are also additional requirements for impact protection to help protect against mechanical damage and for signage to assist first responders in identifying hazards.
Preparing for emergencies is a critical component of ESS installation planning. An emergency operation strategy and associated training are required to be developed prior to putting an ESS into service. The facility management staff has to be trained annually. Authorities are also required to coordinate with the local fire department so that first responders are aware of the ESS hazards in specific locations, and are prepared to respond accordingly. The NFPA updated its free online, self-paced training for first responders earlier this year. The module is an excellent resource for educating local fire personnel on ESS terms, hazards, and response tactics. NFPA 855 also includes an annex on firefighting operation considerations that is a helpful resource for first responders.
While energy storage systems provide countless benefits and applications, these do not come without risk. NFPA 855 is here to help mitigate those risks and ensure that all installations are done in way that takes into consideration fire and life safety.
O’Connor is a licensed fire protection engineer, and serves as an NFPA staff liaison for several Fire Protection Systems and Building Fire Protection Technical Committees. Visit NFPA for more on this topic.
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