How to Protect Battery Energy Storage (BESS)?

8/16/2023

What is the recommended practice to protect Battery Energy Storage Systems (BESS)?

NFPA 855 states that if the BESS is not a walk-in unit, then fire suppression is not required.

How do you define a "walk-in unit"?

If any suppression is not required in side the unit, is there any requirement for systems protecting the outside?

Thanks in advance.

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6 Comments

Pete H

8/16/2023 06:45:49 am

From NFPA 855 (2023):

3.3.9.4 Energy Storage System Walk-In unit. A structure containing energy storage systems that includes doors that provide walk-in access for personnel to maintain, test, and service the equipment and is typically used in outdoor and mobile energy storage system applications.

So I'd go with that definition, if it's got a door and any area someone can step inside, even if it's only a step, for maintenance, it needs protection.

Then I'd go through Annex B and figure out what types of batteries/chemicals are actually in your unit.

Take with a grain of salt, I have never touched one of these.

chad putney

8/16/2023 08:16:00 am

IMO--- Aspirating smoke detection (not vesda specifically) is best to catch it and then inerting agent like nitrogen. Siemens has a good product line for both.

I am not a fan of water mist. Thermal runaway needs to be prevented, you are not suppressing or extinguishing it once it is in runaway.

Chad

8/16/2023 08:21:11 am

.....If we are specifically talking about Li-Ion

Kris K.

8/16/2023 08:22:39 am

First off make sure you're looking at the 2023 version of NFPA 855 - the 2019 version was a terribly written code.

I agreed with Pete H., however NFPA 855 §A.9.5.2.3.2 states enclosures do not include ESS cabinets where personnel can partially enter in the outer enclosure to perform service or maintenance. Furthermore, it states enclosures include ESS within an outer enclosure similar to an ISO shipping container. So I'd say you have some wiggle room on what is considered "walk-in" - a step inside may still be considered a cabinet.

The requirements for fire control and suppression are outlined in §9.6.2 and are required for ESS in indoor ESS and outdoor ESS; however, there are numerous exemptions based on location of ESS, type of ESS, available water supply etc. I recommend reading through Chapter 9 of the 2023 edition and figuring out exactly which sections/requirements apply to your specific ESS. The chapter is set up like a flow chart so it's very intuitive. You may have options for no sprinkler system or an alternative suppression system.

A fixed water supply is likely required in accordance with §9.6.3, but again there are exceptions and alternatives which may apply to you. Apply Chapter 9 to your ESS and it should be straight forward to work through.

Dan Wilder

8/16/2023 08:24:40 am

Pete got the first half.

Anything fire sprinkler related within or outside the unit will fall under 4.9.2 which is one of two options...

4.9.2.1 - Under 50kWh = .3 GPM / 2500 FT²
4.9.2.2 - Greater than 50kWh = FPE report based on testing (UL9540A) per 9.1.5 to identify density/area or sprinkler type/minimum discharge/max area (Special application).

In either case watch for Phantom Flow NFPA 13 - 22' 28.2.4.2.5 and previous versions to 2016, only change is where to add the additional water, because these rooms are sometimes small.

FERC 2222 link

9/22/2023 07:42:43 am

Offering insights and strategies for safeguarding battery energy storage (BESS) systems, ensuring their longevity and efficient operation while minimizing risks.

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