Author(s): Jesse Roman. Published on May 1, 2018.

Rapid Advance

An update from the evolving world of energy storage systems, including the development of NFPA 855, Installation of Stationary Energy Storage Systems


Last September, on a sweeping plain of asphalt 30 miles north of San Diego, the company AES Energy Storage turned on the power to what was at the time the world’s largest lithium ion battery array.

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Housed in rows of windowless industrial white boxes, the energy storage system (ESS), as such arrays are called in industry speak, don’t look like much to a layperson. To local utilities, though, it has been something of a savior. In late 2015, an enormous methane leak erupted at the nearby Aliso Canyon natural gas storage facility, cutting off a critical supply line and dealing a blow to the region’s energy production capabilities. The closure caused utilities to warn of possible blackouts—the outcome when electricity demand outpaces a utility’s capacity to supply it. None of the usual fixes made sense. Building a gas- or coal-burning power plant to replace the lost energy generation would take years; solar and wind are weather dependent and can’t be fired up at a moment’s notice when energy demand spikes.

Instead, the utilities opted for a newer strategy: they would increase capacity to handle the electricity load by keeping a reserve of excess energy in large rechargeable batteries, ready to be deployed at a moment’s notice. Including the AES battery, utilities in Southern California have installed at least 100 megawatts of ESS capacity in recent years, enough to power tens of thousands of homes for hours when the need arises.

“To go from something that we thought of as kind of future technology, to all of a sudden having it come to the rescue so quickly—yeah, I think that’s a huge success story,” John Zahurancik, president of AES Energy Storage, told a newspaper shortly after the project was completed, a task that took just six months.

Despite the successes, the proliferation of thousands of large energized boxes across the country—including many in buildings where people live and work—does not come without risk. Identifying those risks and how to deal with them has been a significant focus for NFPA and other safety and research organizations over the last several years.

A centerpiece of these efforts has been the push to create NFPA 855, Installation of Stationary Energy Storage Systems. The developing standard includes guidance for a wide range of battery and chemistry types on thorny issues such as installation, ventilation, maintenance, operation, decommissioning, and fire prevention. The draft also includes an appendix of best practices for firefighters as well as an overview of system hazards. The first edition of NFPA 855 could be published as soon as early 2019.

This guidance is badly needed for those tasked with regulating and responding to emergencies involving ESS, said Howard Hopper, a fire protection engineer and program manager at UL who has been involved with NFPA, the International Code Council, and the International Association of Fire Chiefs in addressing ESS standards.

“As we see more of these large-scale ESS installations, there is concern from authorities having jurisdiction (AHJs) that there is a lack of protection in the legacy fire code requirements,” he told NFPA Journal. “They are asking us how they can adequately protect these systems if the codes they are enforcing don’t really have anything that addresses the hazards. When they hear in the news about fires involving lithium ion batteries, they think, ‘well, what about this large installation in my jurisdiction?’”

ESS topics and education occupy a prominent place at the 2018 NFPA Conference & Expo in June in Las Vegas, including the launch of an updated NFPA training course on ESS designed for the fire service. There is also a separate education session track devoted to professionals and responders who interact with the systems.

Energy proliferation

ESS installations are becoming commonplace across the globe as utilities, businesses, and even many consumers unleash the technology’s potential to help control energy costs and increase efficiency. As a result, deployed worldwide energy storage capacity has skyrocketed in recent years and shows no signs of slowing. According to a recent report from Bloomberg New Energy Finance, energy storage capacity is expected to double six times in the next dozen years, going from less than 5 gigawatt hours deployed in 2016 to an expected 300 gigawatt hours in 2030. The ESS market in the U.S. projects a 12–fold increase in ESS deployments by 2022, according to GTM Research.

While the biggest batteries grab the headlines—the record for world’s largest lithium ion battery has been eclipsed four times in the past year—the vast majority of deployed ESS blend silently into the background, hidden inside nondescript boxes outside of office parks or subdivisions. Increasingly, they are tucked inside apartment buildings, in parking garages, on rooftops, in strip malls, and on worksites. Others, like AES’s battery in San Diego, sit humming in obscurity in industrial parks, ready to provide power when other sources fail or are stressed.

It all amounts to “a lot of new technology installed in a lot of places where batteries haven’t traditionally been,” said Hopper, who is a member of the 855 technical committee.

On the product side, UL’s battery research program has ensured that almost all commercially available ESS meet minimum safety requirements, but “you also have to look at the risks and exposures out in the real world” where they are installed, Hopper said. “If you have a large lithium ion ESS on a wind farm out in a rural area, you have a lot different protection scenarios and exposures than if you put the same battery in an urban area or on the fourth floor of an occupied building.”

Understanding the many risk variables involved for a specific installation—ESS type, size, quantity, application, location, etc.—then trying to limit those risks, is NFPA 855’s main objective. But it hasn’t been easy.

The relative newness of ESS, coupled with the growing number of locations and applications where the systems are used, means there is limited fire testing data for the committee to consult. As a result, critical safety guidance such as battery spacing, maximum allowable sizes and quantities of batteries inside a room, and even what type of suppression systems will adequately extinguish an ESS fire remain best guesses.

“Because of those uncertainties we had to come up with fairly conservative requirements,” Hopper said. “But also because of all of these unknowns, the code says that if you do large-scale testing and show that it is safe to increase sizes and quantities, or decrease spacing, then code officials can relax those requirements.”

Even as ESS research continues, the reality is that nothing seems to stay the same for long in the world of ESS. Labs across the world are investing heavily in making batteries more efficient at a fraction of the cost, and the free market keeps inventing new ways to use them. New battery chemistries and applications continue to emerge, bringing with them more unknowns.

In some countries, for instance, it is becoming common for owners of electric vehicles (EVs) to use their car batteries to power their homes when the vehicles are not in use. In other cases, older degraded EV batteries, no longer fit for the road, are being recycled for household use, providing backup power and a form of peak shaving—the cost-saving practice of switching to battery power when utility-provided electricity prices spike, and recharging the batteries during off hours when prices are lower. Some believe that, as household consumer ESS grows along with solar generation, neighborhoods could soon form their own self-sustaining standalone electric grids apart from traditional centralized utilities. Experts question how such a development could impact regulation and fire protection.

Even more futuristic is the proposal from Uber to launch a fleet of flying electric aircraft, which would be charged by large ESS on city rooftops. Beta testing of the program is expected to start in Dallas, Los Angeles, and Dubai in 2020. Some people even envision a future where wireless electric chargers are built into public roadways to seamlessly charge electric vehicles as they drive.

“This is something we’ve talked a lot about in our code meetings: how will the codes address technology and uses we haven’t even seen yet?” Hopper said. “It is a real issue.”

Traditionally, if a new technology is omitted in a code or standard, it’s simply not regulated and therefore AHJs have little or nothing to go on. The NFPA 855 committee, however, has taken a different approach, proposing stringent limits on new technologies in the standard unless large-scale fire testing results confirm that it is safe.

As might be expected with any new technology, the first draft of NFPA 855 received significant attention when posted for public input last year. The technical committee received more than 500 public inputs from interested parties, many from utilities who generally aren’t keen on regulation. Other commenters worried that restrictions on the size and spacing of indoor ESS would result in making installations cost prohibitive and hold back ESS adoption for businesses.

The first draft of NFPA 855 is scheduled for publication in early May, and second draft comments are due to the committee July 12.

Responder concerns

While AHJs eagerly await more ESS guidance, the fire service is asking its own questions, according to Ron Butler, a former Detroit firefighter and the president of Energy Storage Safety Products International, a safety consultancy for the ESS industry.

“Firefighters know a lot about a lot things, but ESS is not something we are experts in,” Butler said recently during an ESS training he led at NFPA headquarters for a group of Boston Fire Department officers. “From a fire service perspective we need to make sure that our ducks are in order on this.”

Listening in on Butler’s class, the reasons for unease were readily apparent: ESS is complex, changing rapidly, and still has many fire protection unknowns. When one Boston fire officer asked Butler how his firefighters should put out an ESS fire, the answer was “lots and lots of water”—that is, unless you are dealing with a less-common sodium sulfur battery, which “reacts violently with water.”

Another officer wanted to know which fire suppression systems are required for spaces that house ESS. “At the moment, there really is no solid guidance,” Butler replied. “We are still writing the standard, so it varies from state to state and can depend on the fire marshal.”

The full range of gases released by a burning battery and the toxicity of the fumes also remain unclear. In some batteries, those gases are also flammable at certain concentrations, and if an ignition source is present an explosion is possible. In other types of systems, like flow batteries, which use circulating liquids called electrolytes to store energy, fire isn’t as much a concern as the toxicity of spilled electrolyte, which requires a different type of response.

Another difficulty for firefighters is the tendency of lithium ion batteries to reignite like trick birthday candles long after they are extinguished. That being the case, how would a firefighter know when it is safe to turn a fire scene back over the building owner? That also hasn’t been fully worked out.

A related topic (and one that NFPA also has a training course on) concerns electric vehicles—a significant area of concern for firefighters. In Mountain View, California, in March, the local fire department responded to a crash involving a Tesla Model X, where the car’s battery was split open and on fire, and individual battery cells were strewn across the freeway. The scene was simultaneously a fire, HAZMAT incident, and an electrocution hazard. "Because the battery was exposed, we were unsure whether it was safe for us to move the vehicle," Mountain View Fire Department officer Art Montiel told a local television station. The crash shut down three lanes of the freeway for six hours.

Because of the uncertainties and relative newness of the technology, many departments are still without standard operating procedures, preplans, and training programs for ESS emergencies. Standardizing the installation of ESS and the safety elements that must be present—a main objective of NFPA 855—will bring more consistency to the process and help firefighters develop procedures and preplans.

Even as the development of NFPA 855 continues, the task facing the fire service when it comes to ESS remains enormous. Presently, there are nine distinct ESS types included in the NFPA 855 draft standard, and many of those have various subcategories with different properties and unique hazards. In a few more years, there could be many more. Firefighters maintain that something has to give.

“It isn’t a reasonable expectation for firefighters to know every battery chemistry for every battery that’s in every building,” Butler told the class of Boston fire officers. “The fire service has a universe of responsibilities, and it can’t just be on our shoulders to make sure ESS is safe—it needs to be a collective effort.”

The partners essential for success include building owners, maintenance workers, facilities managers and others, Butler said, all of whom should also be trained, just like the fire service, on the chemistries, hazards, and particulars of the batteries installed in their facilities. “They all need to help us out,” he said. “We need to work together.”

JESSE ROMAN is associate editor for NFPA Journal. Top Photograph: San Diego Gas & Electric