Managing the Battery Fire Risk in Wind Energy Storage

Windmill fire

The Battery Fire Problem

The intention of this article is not to demonize lithium ion, advanced lead acid, or any other battery technology. The truth is that these batteries power the world, and will in a much greater way in the future. However, risk managers, underwriters, and others involved in growing the burgeoning wind energy sector should be aware of their primary downside; fire/explosion risk. This must be done so that proper precautions can be put in place to minimize the fire/explosion risk thereby minimizing losses and improving safety.

Current generation batteries used in wind energy storage are generally lightweight, powerful, and environmentally safer than prior generation alternatives. However, they store large amounts of energy and the fire and explosion risk associated with them can be high. Storing large amounts of energy can be inherently risky. Anytime energy is stored in a confined space it naturally tries to escape, sometimes violently. Considerable effort should be made to manage the safety aspect of these batteries, with special attention paid to safety and fire/explosion issues.

Battery risk and safety management remains a young yet important field. The fire issues present challenges to a wide range of industries that manufacture, ship, store, and manipulate these powerful tools; most certainly the wind energy sector. These issues present challenges relative to risk management. They beg many important questions. How do we in the wind energy industry quantify the threat? How do we protect against the potential dangers? What are the safety considerations? What are the underwriting and potential financial loss issues?

Battery Fire Behavior

Many batteries are capable of producing a fire or explosion. However, the battery chemistry that has recently received the lion’s share of attention relative to the fire issue is Lithium ion (Li ion). Lithium ion batteries provide high energy density and can be recharged time after time. These batteries contain no highly volatile free lithium metal, but do contain lithium ions and extremely flammable electrolytes. Li ion batteries have shown a tendency to overheat, which is usually the pathway to fire.

Overheating may be caused by electrical shorting, rapid discharge, overcharging, manufacturers defect, poor design, or mechanical damage, among many other causes. Overheating results in a process called thermal runaway, which is a reaction within the battery causing internal temperature and pressure to rise at a quicker rate then can be dissipated.

Once one battery cell goes into thermal runaway, it produces enough heat to cause adjacent battery cells to also go into thermal runaway. This action may produce a fire that repeatedly flares up as each battery cell in turn ruptures. The result is the release of flammable electrolyte from the battery. An enormous issue is that these fires can’t be treated like “normal” fires and require specific training, planning, storage, and extinguishing interventions.

The amount of data relative to the fire behavior of large format batteries is limited. However we can predict that when a battery goes into thermal runaway, the propagation creates identifiable markers; the battery behaves in a certain way. The fire may be a progressive burn-off or one that is explosive in nature. The good news is that both of these types of thermal events, as well as their negative byproducts (jetted shrapnel, molten metal, burning electrolytes, and other matter), can be kept under control with proper management, storage, and suppression systems.

 Wind Sector Battery Fire Incidents

There has been many high-profile fire/explosion instances that highlight battery fire concerns. The most visible and recent issue was the fire(s) aboard the Boeing 787 Dreamliner. At the time this article was written, the fire cause was yet to be determined. However, the clear consensus seems to be that the fire originated in the lithium ion battery or its battery management system (BMS). While the fallout from the incident is yet to be decided, it can be inferred that some damage has been done to the company, to the airline industry, and to the companies involved in the development of the airliners’ battery power systems. To be sure, Boeing is certainly not the only organization to experience these fire issues.

The wind energy sector, of course, is most concerned with incidents involving energy storage on wind farms, etc. To this end, there have been some high-visibility incidents involving battery generated fires. Wind farm fires involving turbines are well documented. Though similar protection methodologies need to be developed for this aspect of the problem, this is a discussion best saved for another day and another article. Fires directly involving the battery energy storage capacity receive less attention, but may be far more threatening to the industry in the long run.

Research and Testing

Since the rapid exploitation of current generation high-power batteries into commercial and industrial applications, little data exists regarding wind energy storage and fire response guidelines. The NFPA presents the most comprehensive collection of data relative to these issues; at least as far as Li ion is concerned. The Fire Protection Research Foundation of the NFPA published the Lithium-Ion Batteries Hazard and Use Assessment. This document provides suppressant research data, limited fire test data, and other information relative to fire and safety issues in small-capacity lithium ion batteries. The document serves as a fine place to start when developing a sound understanding of the fire/explosion risk issues associated with lithium batteries.

Ongoing research will eventually present firm protocols relative to the safe storage, fire management, and fire suppression issues of batteries in wind energy storage configurations. While movement is slow in this area, those concerned can rest assured that there are organizations willing to expend time and resources towards developing effective solutions. For example, the United States military (particularly the Army and Navy), have invested considerable resources towards tackling the fire/explosion safety issues and preparing their employees for the worst case scenario.

Managing the Risks 

The good news is that battery fire risks can be managed effectively. Proper planning, risk assessment, energy storage design criteria, and response protocols can go a long way in managing the fire risks of lithium batteries. The following areas should be addressed when developing strategies for managing battery fire risks.

Training

Since batteries in wind energy storage configurations present critical challenges to organizations that possess them, it is recommended that training be included in any risk management strategy. A robust training program that includes emergency response and standard operating procedures is a must for companies that employ battery, and other, energy storage technologies. Training brings awareness of the unique hazards that these batteries bring to bear. Training might address issues like battery awareness or include more detailed situational training such as battery fire behavior, emergency response procedures, and fire extinguisher use (battery focus). This type of training lends itself well to the preservation of life and property.

Standards and Standard Operating Procedures

For the most part, standards that guide the design, development, installation, maintenance, and operation of wind energy storage are difficult to find. Of course, there are some standards that affect the industry, but those that might sync practices that would increase safety and ultimately lead to mitigation of destructive fire events simply don’t exist. Effective standards might include developments such as fire suppression systems designed specifically to contain and control the unique fire hazards presented by stored energy configurations. This would limit the use of methodologies that were designed for other purposes, but used for wind energy storage because nothing better existed.

The lack of effective standard operating procedures (SOP’s) relative to wind energy storage also casts a negative cloud on the industry. Good SOP’s would include processes that guide daily handling, maintenance, storage, and other functions involving batteries. Proper SOP’s will address every facet of the battery life cycle and help provide a safer and operationally efficient environment. These procedures represent the best starting point for developing effective risk management processes.

Though the NFPA and other standard writing organizations have yet to complete standards and guidelines by which to manage the wind energy storage battery fire issue, there are strategies that may help manage the risks. Identifying consultants that specialize in developing battery fire management and suppression strategies is great step towards developing proper interventions. These companies are different from generic fire suppression consultants and distributors as they are well versed in the unique hazards presented by battery energy storage and understand risk management practices that address the energy storage battery fire issues. Until proper standards and SOP’s are developed, OEM’s, integrators, insurance underwriters, investors, operators, and risk management professionals must take the lead and begin to identify areas in which they might influence positive change.

Emergency Response Procedures

In most instances, battery fires shouldn’t necessarily be treated like common fires. The burn characteristics and toxic by-product release components are simply different. An organization might determine their level of risk through proper assessment, and create emergency response procedures based on sound response and battery handling data. Close attention should be paid to MSDS sheets and other suggestions from manufacturers, integrators, and distributors. These documents prescribe possible methodologies for proper storage, handling, and emergency response. A caveat is that MSDS recommendations vary widely and at times are quite different, ultimately adding to some confusion. However, some of the suggestions are quite good and can be used to help develop a strong emergency response process.

Effective Fire Suppression Systems

As noted earlier in the article, most wind energy storage systems employ fire suppression protection that is not designed for the unique suppression requirements presented by batteries. In general, the systems that are integrated into energy storage were designed for common hazards and have limited extinguishing and containment effectiveness. Li ion batteries, for example, create unique challenges for fire suppression. Li ion batteries ignite and burn differently than the common combustibles and a result, require different suppression approaches. The thermal runaway process that enables battery fires often produces enough heat to propagate to adjacent battery cells triggering additional thermal runaway events. This produces a fire that spreads quickly, eventually engulfing the entire battery system. As a result, these fires can’t be treated like “normal” fires and require specific training, planning, storage, and extinguishing interventions.

Current fire suppression might not cool batteries sufficiently, thus preventing interruption of the thermal runaway process. The fires often go unchecked frequently resulting in total loss of the energy storage system and potentially threatening human life and safety.

Where does risk management go from here?

It is clear that the battery fire risk in wind energy storage is clearly a concern. What is less clear is the path that needs to be taken to properly limit the fire/explosion risks and effectively shrink the downside. Proper planning, storage, and training can result in the development of robust battery management processes. Leaders in the wind energy industry would be wise not to wait on standards and SOP’s and decide instead to be proactive and develop guidelines of their own. At least until the wider standards industry has time to catch up. Paying attention to the fire and explosion issues can go a long way in protecting valuable lives and property from these risks.

About the author

Ron Butler is CEO of ESSPI (Energy Storage Safety Products International). ESSPI provides specialized fire and safety management solutions to companies that manufacture, store, transport, and employ lithium and lithium ion power technologies.

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