TECHNOLOGY

Home energy storage is a fire hazard; FDNY is on the case

The scenario hasn't yet come to pass, thankfully. But Lt. Paul Rogers knows the day may come that a large lithium-ion battery, set up in a New York City building, catches on fire.

If that happened today, would the average New York City Fire Department crew know what to do? Rogers, a 23-year veteran of the FDNY, guessed not. "They'd probably hand this off right now to the hazmat unit" -- his unit, he said.

Why? Because lithium-ion batteries don't often catch fire, but when they do, it's no garden-variety blaze.

"There's not a lot of information on what happens when these things go on fire," he said, referring to stationary lithium-ion systems. "I don't want to scare the public. We'll be able to manage that type of thing. But it's a concern until we can get data to prove otherwise.

"We don't want to stop any kind of technology from coming into the city," he said. "We just want to know what we're up against."

Rogers' caution mirrors that of some of his colleagues in the firefighting world.

They accept that large, lithium-ion batteries are being attached to the grid to make it cleaner and more efficient. But they've also noticed the occasional fires that have occurred on planes, in cars and on the grid (ClimateWire, Feb. 27).

As these batteries enter homes and buildings, Rogers and others say they still have questions about them.

Should they douse the battery with water or another agent? Is the battery giving off toxic or flammable gas? How quickly is it radiating heat? Will firefighters' suits hold up against that?

Their questions point to the lack of universally accepted safety standards for lithium-ion batteries of this size, type and function. They also show how the conservatism of the fire service is bumping up against the urgency of companies that want to capitalize on the energy storage market.

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"Some of the questions on safety, there's really no data to back it up," said Matthew Paiss, a fire captain for the San Jose Fire Department who helps design codes at the National Fire Protection Association, or NFPA. "We have to be very conservative in making sure we're not allowing something into the building environment that could pose a risk for the occupants or first responders."

A rare occurrence

Fire safety standards already exist for the lithium-ion batteries in phones, laptops and electric cars. Fires are so rare that experts struggle to quantify them.

Some in the research community ballpark the failure rate at 1 in 5 million to 10 million, said Chris Orendorff, principal investigator for the Battery Abuse Testing Laboratory at Sandia National Laboratories. Even that includes cells that fail "gracefully": They stop working but pose no safety risk.

Nevertheless, the Department of Energy has flagged fire safety as a key issue lithium-ion batteries must overcome to become widely used on the grid.

"The prospects of employing Li-ion cells in applications depend on substantially reducing the flammability, which requires materials developments (including new lithium salts) to improve the thermal properties," DOE said in a report last year.

As it turns out, it's not as simple as borrowing the safety standards used for phones, laptops and cars. Lithium-ion battery cells act differently depending on how they're used.

So scaling them up for a home or building reintroduces the question of whether lithium-ion's fiery tendencies come back into play.

For now, localities are left to answer that question for themselves.

In New York, the utility Consolidated Edison Inc. has connected three stationary lithium-ion systems to its grid.

Con Ed worked with the FDNY and the city's Buildings Department to set up a testing and permit process, spokesman Allan Drury said. Lead-acid batteries also have to go through the process.

"We are technology agnostic. We value battery projects based on their performance in helping reduce peak load and on their durability. If a project is unsafe, it will not be approved by the city," he said in an email.

Systems roll out ahead of standards

But firefighters said more battery systems are coming and they need to know more before the wave hits.

Their aim is a system where fire codes, product standards and firefighting practices all work together.

For example, if someone wants to install a lithium-ion system in Manhattan, the FDNY could look at its fire code and ask whether the battery meets the product standard listed there. Later, if the battery catches fire, a crew can know its specs and draw up a game plan before they even get there.

Paiss, who works for the San Jose Fire Department but consults widely with other fire departments in the Bay Area, said many homes are slated to buy home storage systems, such as Tesla Motors' Powerwall.

He wishes he knew more about how these systems behaved when they catch fire. His biggest question is whether they should be required to have internal fire suppression systems.

"I am concerned about the large number of systems that could be showing up in residences before we know whether or not the system should have any fire protection or if the standards are adequate," he said.

Lithium-ion chemistry has always been known to have a temper. Most cells work without a hitch, but if one malfunctions, heat can build up there. That can potentially infect neighboring cells. Overheat enough cells and the entire battery can burst into flame.

To reduce the risk of that scenario, manufacturers try to build the cells to fail gracefully: to seal themselves off, posing no danger.

Smart software and electronics can do most of that work, said Jason Zhang, a chief scientist on battery technology at Pacific Northwest National Laboratory.

But they can't do everything. A physical blow from the outside can damage cells and lead to fire. And a fire from the outside can boil the chemicals in the battery and push it to the breaking point.

"In general, I think lithium-ion batteries are very safe for microgrid, for building applications," Zhang said. "But we need to take some precautions, especially when we have a large amount of power put in a single location."

He said manufacturers could use safer versions of the lithium-ion chemistry, or build vents that let leaked gas go outside.

Setting fires to prevent fires

Last month, Ken Willette visited a Tesla Motors facility in Nevada. There, he and others said, Tesla lit one of its stationary battery systems on fire.

Willette, a former fire chief in Massachusetts who now works for the NFPA, said he was there to see the package: not a cell, not a pack, but an entire battery system as it would look in someone's home or business.

The fire looked contained, Willette said. The next step: The NFPA wants to comb through the data from the test and see what lessons can be learned for the fire service.

The step after that: buying a full-scale battery system so firefighters can study it to their satisfaction.

Paiss of the SJFD wasn't at the Tesla demo, but he noted "it was a demonstration, not a scientific experiment” that a third-party lab ran under controlled laboratory conditions.

He said manufacturers like Tesla are conducting their own safety tests but are wary of sharing their "secret sauce" with independent testers. That's why fire professionals haven't been able to get full systems to do their own tests, he said.

"Manufacturers pay certification labs to test their equipment but are often reluctant to share the failure data produced out of fear of this data being used by competitors or to support more stringent regulatory actions," he said.

Willette said he's not aware of any full-scale independent test that's currently taking place. He said one option is to use government funding to buy a system, then turn it over to a research institution for testing.

Con Ed and NYSERDA, New York State's energy research office, are also offering funding for lab tests.

Not all think lithium-ion will get a passing grade in New York. Some think competing technologies, like lead-acid and "flow" batteries, will gain the upper hand in the city.

"That argument, that batteries need to be really small, I don't think is as important in this application as the batteries need to be really safe and really cheap. There's a different need. You have to rebalance the things that you need," said Joshua Gallaway, a research scientist at the City University of New York's Energy Institute.

Gallaway said he owns less than 1 percent of Urban Electric Power, a company marketing a zinc-manganese dioxide battery.

"I don't think there's anyone in the industry that thinks the deal is sealed for lithium-ion," he said. "I think it's an open question as to what's going to happen."

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