Battery fires with Roeland Bisschop

Wojciech Wgrzyski: 0:00

Hello, everyone, welcome to episode five of the Fire Science Show. Today another episode, another important issue that troubles many fire safety engineers and myself included. We're gonna talk battery fires and electric vehicle fires, the knowledge on this type of fires in in neverending demands for fire safety engineering, so I hope you'll truly enjoy this one, it's gonna be a bit different, it's gonna be a two piece episode. In part one I'm welcoming with me, Roeland Bisschop was a project manager at RISE in Sweden, who will share his firsthand experience in burning some of electric vehicles and what they've learned while doing that. And I'm very happy to learn from him, because it's some really important data points for my own research. And in the next episode, the next week, I'm going to take the mic and tell you a little bit of our research on what are the consequences of electric vehicle fires in modern car parks. And if there are any solutions that we can already implement, despite the fact that the knowledge is limited, the data is limited. And yeah, we kind of have to work with what we have. That's the only solution. So yeah, I hope you will enjoy this interview and the next episode that will follow in the next week. So without further ado, let's spin the intro and jump into the episode. Welcome to the Fire Science Show. My name is Wojciech Wgrzyski, and I will be your host. Hello, everybody. Today I'm here with Roeland Bishop from RISE in Sweden, with whom I'll discuss the topic of electric vehicle fires and car battery fires. Hey, Roeland, thanks for joining me.

Roeland Bisschop: 2:04

Hello. Thank you. Thank you for having me.

Wojciech Wgrzyski: 2:07

Can you introduce yourself a bit? How did you land up doing the battery fires?

Roeland Bisschop: 2:12

It's a long story? But yeah, my name is Roeland. I'm originally from the Netherlands and eventually moved to Sweden for some studies as a mechanical engineer, met my girlfriend here and ended up staying here. But yeah, I'm not I'm not like an fire engineer or electro/chemical or electrical engineer. I'm just a mechanical engineer who kind of ended up in the whole battery research area because that was kind of growing so fast. At RISE. When I started working there, the need for doing tests and gaining knowledge in that area was growing so fast, so I had to grow along with it. So to say.

Wojciech Wgrzyski: 2:51

That's not an uncommon story, like both stories. I brought you here because I I've read your paper written with Hong Kong Polytechnic University. I think it was first authored by Peiyi Sun. It's a review on on battery fires in electric vehicles. And, and I must say this, this paper was so useful to me, because I'm trying to research the consequences of fires in car parks. And I would really love to learn how these fires of electric vehicles, battery fires and electric vehicles, how do they differ from from the fires that we meet every day in designing the car parks, the ones that we've been studying and learning from for decades. So um, the first thing is, when I see the videos of electric vehicle fires, if you like go YouTube go electric vehicle fire, you'll find a lot of them and, every now and then there's a new one. And they seem very similar to each other in the way that there's usually this huge cloud of smoke coming from from nowhere, this this huge jet of flames coming from out of nowhere and very, like rapid development into this jet fire type of fire. So is this something that touching the subject scientifically you also observe?

Roeland Bisschop: 4:20

Yeah, I would say there are many different ways in which batteries or battery packs can fail and what the outcome outcome may be. But if you just look at like the lithium ion battery cells themselves, when we do test we see first, when we start abusing them, we overcharge them or we heat them up or whatever. They will released like a cloud of smoke, they'll pop like they build up pressure, they pop they release small cloud of smoke. And that already is like flammable. cloud of smoke. It's not a very large amount. Nothing major is happening yet then. But if we then keep pushing the battery keep abusing and then we get into this thermal runaway stage and the battery releases lots of gas very rapidly, which may or may not ignite, sometimes it does, sometimes it doesn't.

Wojciech Wgrzyski: 5:14

So it's like a cascading fire of the of the smaller cells within the whole battery pack?

Roeland Bisschop: 5:20

Yeah, so this process will happen to each cell in the in the battery pack, and how it will cascade through the battery pack. It can vary a lot, like you have different cell sizes and chemistries and materials in between the cells if you have cooling or not how the failure was initiated, that can affect how the firewall or the thermal runaway will propagate through a battery pack. There are many, many variables.

Wojciech Wgrzyski: 5:49

Obviously, it is a whole emerging field of science, it's not something you can answer with a single with single answer.

Roeland Bisschop: 5:58

It's kind of annoying, cuz usually when we get questions like this from from a customer, they say, "Okay, if my battery goes into thermal runaway, what will happen?" And I say, yeah, depends.

Wojciech Wgrzyski: 6:12

I think it's the, in the media in the in the internet, you are probably biased towards the outcomes that are most visually impressive. What I mean, there was this famous viral video of a fire in Shanghai, I think that where there was a electric vehicle, and it's very rapidly developed into a large fire. Actually, you know, that that video was the reason why I've, why I've picked up this this subject in my studies, because I was not like, I was not scared that electric vehicles will burn and fail or that it was like, the media gives this impression that now we're unsafe, because there's electric vehicles around. Yeah. But my point was that if it happened once it means it may happen. And I would really love to know, what are the consequences of these, of these fires to the carparks in their users, if such an event could happen? And from your perspective, because you've studied that, such an outcome like like this, this fire on the video, is that something like typical for this fire? So or it was just one extreme type of behavior that can happen?

Roeland Bisschop: 7:39

So here comes the fun answer. It depends. But the thing is, what you see in that video, I agree that's that's quite the extreme kind of scenario where one battery cell fails, then it propagates almost throughout the entire battery pack in the span of a minute. That can happen. I have seen it happened in the tests that we've done. But I would say more my experience with doing tests is that it can take quite a long time from like the very first very, very first cell that fails, it can take a very long time until anything happens after that. So sometimes we do a test, we start the thermal runaway one one, so we wait 10 minutes, nothing happens, wait 15 minutes, nothing happens. 20 minutes, still nothing happens. And then maybe eventually, we get some more action, then all all everything kind of happens all at once. happens sometimes it's like that sometimes it's it's not like that.

Wojciech Wgrzyski: 8:37

Like you said not nothing happens. But do you see like indications of some failure going on in the battery? And I'm not not I don't mean the battery management system system, which probably does see some, like from an outsider perspective, imagine you're standing next to such a vehicle, would you be able to tell that it's ongoing failure,

Roeland Bisschop: 8:56

you may you may be able to see the very initial failure, you may see that there's like a puff of smoke that is being released. But after that, I don't think you can see it.

Wojciech Wgrzyski: 9:06

I'm asking these questions because in our studies, we focused on the very initial face of the fire and we were curious about what would happen in the car park if the fire developed very quickly. Like in that video in a way it shows the development of of a fire almost instantaneously. And we design our car parks based on some certain design fires currently. And we wondered, okay, if I designed my car parks for last 20 years in this way, if now there's an electric vehicle or some sort of battery powered device inside that goes to a such a rapid fire development. Will my occupants be able to escape? And will my systems be able to detect and response to that threat in a timescale that would matter you know, because if there's such a growth of fire and it takes five minutes for my systems to respond, then it means my systems were not really that useful in the fire. So I'm really interested in this in this very early phase of the fire, where it can actually quickly cascade into into something large. Although I found it reassuring, that you said it was on, it was rather an extreme not not a typical fire that you would see every time you

Roeland Bisschop: 10:28

No, no, we don't see it every time. But it can happen. Absolutely. But that when it comes to designing your systems to be able to handle such an extreme case, I don't know if that's even possible to be honest with you,

Wojciech Wgrzyski: 10:43

we found that it's like, almost impossible, like they make almost no difference. And the only variable was was the height, which I'll discuss in here more thoroughly, because it is kind of interesting to see that it's such a threat, we're kind of helpless as as fire engineers. The other thing that they found reassuring in your paper was that heat release rate, if you can say or peak heat release rate of the vehicle fire when you consider electric vehicles versus internal combustion engine vehicles. You didn't find any, like, significant differences between these vehicles like they were. I mean, it was still in the level of few megawatts, not, not that one would be 100MW and the other would be 1MW... Yeah, exactly. Could you comment on? How did you get to this findings? And what did you observe?

Roeland Bisschop: 11:33

So there have been some Institute's that did full scale fire test on electric vehicles in comparison to internal combustion engine vehicles. And at RISE, we did these tests. Also, we compare, we did tests on three vehicles. So one internal combustion engine vehicle, and then the exact same vehicle, but then the electric version of that. And then we had an EV family car, it is like you say, we don't see any significant difference in the peak heat release rate, or even a total heat release, for that matter, actually, but we found that it's not so much the power train. So if it's electrical, or if it's gasoline, diesel, whatever that makes the big difference. It's more, how does the fire start? Which really has an impact on how rapid does the fire grow? And how high will the peak heat release rate get? That is actually the main significant thing rather than the vehicle itself. That being said, there are some some things still to, to study when it comes to these really worst case, kind of thermal propagation scenarios that start within the battery pack. I don't think anyone has tested that yet on on a full scale, of course,

Wojciech Wgrzyski: 12:46

I think we all realize in the fire safety side of the problem that it's something we need to find a solution because I mean, this is the direction of where we are heading. Now. We cannot like escape this issue that is too hard or too complex or non interesting, we cannot deal with that. Now we need to we need to find solutions and experiments, like you mentioned, these are pioneering studies that reveal that the behavior of these devices. And I find it fascinating because if you study how the batteries are built, at least the ones with cells that are built from like small elements put into packages, which are merged into larger packages. So it's really interesting how the scales will play around. Absolutely, yes, it is also something that you study in RISE, when touching the subject.

Roeland Bisschop: 13:42

Yeah, I mean, the skills, they have a huge, huge impact, like what batteries, the battery cells themselves that you use in your battery pack, they have a very large impact on how the fire will develop. Those, for example, in the vehicles that we tested, we had a battery pack that had pouch cells, so kind of like this aluminum bags that contain the cell that you usually also have in smartphones. And in those cases, we saw for that specific battery pack that when we when we had a fire in the battery pack did become involved in the fire, almost the entire like all the cells in the battery pack were contributing to the fire at the same point. So in that case, we had actually very, very high peak heat release rate compared to the other electric vehicle that we tested which had other cells which are prismatic cells, so they are like metal cans. And those take a bit longer to heat up and they can tolerate pressure a bit more. And in that case, we saw much like longer. Yeah, it burned longer in the battery pack, you can say and we could much more clearly see like, Here one, so is ventilating guys here goes to next. So here's a next cell with the pouch of everything went at once. So so that's the That's just the form factor of the cells, then you also have to think about the chemistry and how much energy is stored in each individual cell with which can also impact the results.

Wojciech Wgrzyski: 15:11

This is this is great, you seagwayed me to the next thing I wanted to ask you, because you have also compared the heat release rate in the function of the range of the vehicle. So I was astounded that the behavior of this gasoline versus battery vehicles is very similar in terms of the energy released burn the fuel mass in the vehicle, I guess for the internal combustion vehicles, it's it's directly like linearly correlated with the amount of flammable liquids you have in the in the vehicle. Yeah, what what makes the batteries more dangerous when they charged?

Roeland Bisschop: 15:50

Actually, I would almost put it the other way around, I would say the full fuel tank is more dangerous than the fully charged battery pack. Because what we've seen in our tests, like vehicles, they usually use plastic for fuel tanks. And as soon as they rupture, you have like a huge pool fire, which can easily spread through multiple vehicles at once. Whereas when we did these tests with the battery packs, the ones we test, at least they're like, solid aluminum enclosures that that actually contain whatever is going on inside of the battery pack quite well. But when it comes to the like that the size of the battery pack in how that correlates to the amount of energy that is released during the fire, we actually saw that the electric total heat release from a battery pack scales quite linearly with the amount of electrical energy that is stored in the battery and

Wojciech Wgrzyski: 16:49

The maximum the maximum that it can take, not at the at the current moment, right?

Roeland Bisschop: 16:57

Usually, we express the the the energy of the battery pack in terms of the nominal. Okay, so that's kind of like the midpoint. So usually, when we calculate that we we, yeah, we look at what is the nominal voltage and the capacity of the battery pack, and we relate that

Wojciech Wgrzyski: 17:15

so it almost linearly correlated with the nominal?

Roeland Bisschop: 17:17

Yeah, yeah, exactly. But this is not the case for heat release rate. Heat release rate, it's quite hard to relate that to the size of the battery, because it's, it's very dependent on the specific battery and the specific battery cells and the charge level, like it's much more sensitive to that

Wojciech Wgrzyski: 17:37

if you take the research on vehicle fires from the past, when you really think a good look into these experiments, you usually find that an open window may have had a bigger impact on the fire than the type of a vehicle or whatever other like physical condition the vehicle was in,

Roeland Bisschop: 17:57

that's what I meant with conditions for the vehicle like to burn itself can

Wojciech Wgrzyski: 18:03

When you exclude the the power train is the same vehicle it has a couch, it has upholstered interior, it will have a lot of cables, it will have a lot of plastics that are not related to the fact that is in particular electric vehicle. I mean, you also mentioned that you actually had the two copies of a vehicle, one of which was electric, one of which was a conventional internal combustion engine vehicle. And and you burn them both and did the observations match like they

Roeland Bisschop: 18:33

No, I remember that when we did the test. The when we did the internal combustion engine vehicle, we had simulated like a pool fire underneath underneath the vehicle, okay. And within, I think it was five minutes, the plastic fuel tank ruptured, and then we get a very, very fast fire growth. When we did the test with the electric vehicle, we had a burner directly underneath the battery pack. And there I believe it took about 15-20 minutes before the battery pack actually started to contribute to the fire.

Wojciech Wgrzyski: 19:07

You know, these things are fascinating because we as fire scientists, we sometimes don't appreciate enough the consequences of our choices during the research, which are usually honest choices because we need to make choices like you said, where to place your ignition source or how to simulate some some events. And we as scientists do this to capture the truth in the best way we can. And my second hat is an engineer and I do a lot of CFD simulations for car park, I help smoke control engineers design smoke control systems for car park, and in this world, they don't really care that much. If your window was open or closed for them, it's a car fire and they just want the value of heat release rate they can place in the simulation. And solve the issue of designing this specific car park. And in a way, it's a system that works. Because if we have a design fire for vehicle, if we base our solutions in the building on that particular design fire, I mean, it's it's a method that can be replicated among many offices, it allows us to compare the systems. So, yeah, but then, as a scientist, if you think if you could define a single design fire curve for car parks, like, are we in the place where we could do that now for electric vehicles.

Roeland Bisschop: 20:37

And now, I think we need to do more tests there. The developments with electric vehicles and battery packs, they're going so fast. And we haven't done so many tests yet, honestly. So we are we have some nice data now that we have from our tests, and also from tests done in France and Canada, which, which is very helpful. But maybe they're not even representative of next year's electric vehicles anymore. So that we, we have some catching up to do, you can say, well

Wojciech Wgrzyski: 21:13

now now that you mentioned that it's true that the current technology is rapidly advancing. And you can see that, from a consumer perspective, looking at the range of the vehicles, how it grows, like every year, the vehicles can travel further, and they are lighter, which means there must have been some improvements in the battery technology, because it's unlikely they have much lighter upholstery.

Roeland Bisschop: 21:36

Now exactly like when I started working at RISE, who were maybe testing like battery cells, the individual cells, maybe they were just the cylindrical ones were two and a half and Amp-hours and prismatic ones larger ones were 50 ampere hours. But now I'm looking at cells that are close to 200, amp power hours, but much, much larger and much more stuff happening when they do actually catch fire. So just based on that, they can see that, yeah, we have some some way to go still.

Wojciech Wgrzyski: 22:07

And from your perspective, as a researcher, is the fire behavior of these batteries a factor in designing the cells or it's just a byproduct of the design that has to be solved and not really being the driver of the of the design,

Roeland Bisschop: 22:22

no fire safety, it's not off the battery. So it's it's I wouldn't say that's a driver of the design, of course, it's important. It's more about having as much energy as little weight as possible. That being said, from my from my perspective, it's not so much that the individual battery cells shouldn't be allowed to fail. I think my perspective more that if you design a battery pack or electric vehicle, or energy storage system, whatever, you need to design it in such a way that you can tolerate that a battery cell will fail. But still keep everything under control. So it doesn't spread throughout the remainder of the pack. So you should Yeah, design that you should allow for this type of failure to happen. Basically,

Wojciech Wgrzyski: 23:10

while this is this is really powerful, because I think you have in that sense, you have captured the Spirit of Fire Safety engineering, like we are not here to prevent Elon Musk from building electric vehicles, we are here to help them build them in a way that the risks are tolerable and, and we can manage them. That's the point. Because if we enter if we enter the design, and we know how to manage the risk, we can do that. And the product is safety. Yeah, we're exactly we are selling the safety to the people. So that's that's really

Roeland Bisschop: 23:48

great. And then you don't have to worry about this video that you were thinking about earlier.

Wojciech Wgrzyski: 23:54

Yeah. But these videos are powerful, because it drops you a narrative on the whole subject. Yeah. And sometimes these things are positive, because it lets you grab the attention there an issue is emerging, and you can solve for that issue. But on the other hand, they might do a lot of damage to the whole field because suddenly every incident is associated with this type of a fire. Yeah, there's also this third aspect, the issue of probability of failure or battery and cascading the fire. That's a whole different topic and to understand how often this this type of events can occur, if we if we are the viral videos, there was also a recent video of like, series of small buses like having the fire jump into from vehicle to vehicle but also like me viewing this video from fire science engineering perspective. I mean, that was a fire of the whole of the of the vehicle, not just the battery. It was like the interior was burning. It was a fire And the interesting part was it was propagating quite quickly. Is this vehicle to vehicle propagation, something that you were already studying or it's something for the future?

Roeland Bisschop: 25:13

So so in the tests that we did, we sort of looked at it but not not in great detail. We, we had some play thermometers on either side of the vehicle, this kind of estimate how much heat the surrounding vehicles could be exposed to, but vehicle to vehicle propagation, and we have not touched on that yet. But hopefully, we can do that in the future. But yeah, as you can imagine, like burning vehicles is not, it's not so cheap to do. Getting one vehicle getting one vehicle is a challenge to getting six vehicles next to each other.

Wojciech Wgrzyski: 25:50

That's another thing you've mentioned, you measured the blade thermometers around vaguely, I think that's a great starting point. And because I know there was a very good PhD by Mohd Tohir, one of the best PhDs I've read and he was calculating this effective thermal dose if you can, if you can call it like that, that is needed to ignite the certain parts of the vehicle and associate probabilities of fire spreading from vehicle to vehicle based on these values. And I think even that they've implemented in B-Risk with with Mike Spearpoint at some point, I mean, in the past there was research on on spreading the fire from vehicle to vehicle and now you have the new boundary condition because your initial fire is completely different than fire off of the of the interior of the vehicle. So that's something to look for probably

Roeland Bisschop: 26:45

and this thing with electric vehicles is some some cases when you have the battery pack fire you also have quite long jet flames that are rejected from the battery pack which also brings into some something new into into play,

Wojciech Wgrzyski: 27:01

when you say electric vehicle fire this jet fire is the first thing that comes to my mind because of the media attention that this this element gets. Now after this talk, I may look at this seeking different cues and and different development of the fire but I will be honest with you coming to this talk, the jet fire behavior was the one that I had in my mind associated with the with the electric vehicle fire. So so that's definitely something to to look on. And that definitely changes the physics of the of the whole fire in the car part. I mean, even from this perspective of of smoke entrainment, if we design traditional vehicle car parks, we can see the fire source of the vehicle as thermal buoyant plume of smoke now and we calculate the entrainment into this this plume that is driven by buoyancy. And in the jet flame you have this quite significant amount of kinetic energy inside the jet because it's it's it's like propagating outside, which is completely different momentum. That just the buoyant plume of smoke

Roeland Bisschop: 28:20

that's actually sometimes problematic for when we do fire tests. Because we have the larger calorimeter hood sucks up all the gas and then we know the heat release rate. But in some cases, when we do fire tests on battery packs the jet flames though, extend for several meters. And then we miss all of this

Wojciech Wgrzyski: 28:47

that's something I've discussed with Matt Bonner when he was on the show that we had this issue like we've missed the interesting part of the of the fire by 20 centimeters, you know, if the thermocouple was like 20 centimeters to the left, it would be perfect, but it was not. And then then we figured out it's it's probably more valuable to stick 20 cameras into the experiment then then stick 100 thermocouples because at the end you may have more information from just observing the fire than from instrumentation.

Roeland Bisschop: 29:21

Yeah, yeah, observation is underrated. I think sometimes

Wojciech Wgrzyski: 29:24

Yeah, that's that's one of the themes of the podcast. You touched a very important subject in here because yeah, in if you want to exhaust the smoke from the carpark it's very similar to exhausting smoke in the experiment from the hood. So do you like I said this this thing about the physics of the plumes based on my knowledge of the of the of the smoke was but do you really observe this this different behavior of the smoke clouds produced from battery fires like that?

Roeland Bisschop: 29:59

That's, that that is a challenging question to give a good answer to. But let's say the cloud itself that is released at a very early stage, it's flammable gas. And even during the thermal runaway stage, if the gas is not ignited from the battery, it's also flammable gas. So in our case, we're, we're usually not so concerned about the the smoke that is being produced by the battery's burning, we're more concerned about the smoke is produced when when it's not burning. That's something we're worried about in our in our testing house. But when it comes to how the smoke moves around, yeah, we have seen that the smoke is quite heavy.

Wojciech Wgrzyski: 30:50

Yes, some people call it heavy. Yeah, that doesn't want to it doesn't want to move upwards, which means it does not have buoyancy. in it.

Roeland Bisschop: 30:59

We also noticed that that in the smoke itself, we have lots of metal particles, like where you find Oh, metal metallic particles. And even some, some of the, like the electrolyte contents that are inside of the battery. So they they can they have like quite a high boiling point. So if I get all the smoke on me, I can have some sticky residue on my clothes.

Wojciech Wgrzyski: 31:31

You probably don't to do that? I would strongly recommend?

Roeland Bisschop: 31:36

No, no, it's, it's not, it's not good for the health, I can say.

Wojciech Wgrzyski: 31:41

I also know that you have researched the contents of this of this smoke or the product of these of these fires. Could you give a general overview of what's produced in these fires, because I guess it's, it's not carbon dioxide and water, like we would like from

Roeland Bisschop: 32:02

So products depending on whether you have an ignition of the battery gas, or after the ignition of the battery gas. So before you have ignition of the battery gas, the the gas that is being produced, it's a lot of hydrogen, and co2. And more we see after ignition or the gas has lots of CO and even even HF that is being produced then. So people usually are worried about HF because it's not only when you inhale it that it's bad, but it can penetrate the skin and so on. So So when there's burning, we get much HF, when there's no burning, we don't detect that usually. But when it comes to electric vehicles versus internal combustion vehicles, when either of them burns, they produce very large amounts of toxic gases that are really, really bad for you. So it's it's like, yeah, electric vehicles compared to an internal combustion vehicle, they produce more hydrogen fluoride. But that is the main The only difference. Regardless, they're both very, very bad for you.

Wojciech Wgrzyski: 33:14

Yeah, because obviously in a normal fire, if we can call it the normal fire, in an internal combustion engine vehicle fire, there will be a lot of carbon monoxide produced and there will be some very, like hydrogen cyanide or something produced if you have polyurethane, for example, using upholstered furniture of the car. So so in the interior, so so so yeah, I've also I've read that this HF is the one thing that differentiates between this these two behaviors. Now, I'm wondering, it would be interesting to quantify maybe such studies exists already and I just don't I'm not aware of them, but it could be interesting to quantify the amount of this HF in the mix related to the to the soot content or or the general visibility or obscuration characteristic of the of the cloud of gas, because in like everyday fire engineering, there is this assumption, not not sure where the origins of that are. But my good guess would be great britain, that if you have met your visibility conditions in the carpark the concentrations of the toxic products are probably not meeting their tenability criteria yet. And this means that it simplifies your analysis because if your goal is to maintain a certain level of visibility in your carpark, like, let's say 10 meters, it means that if you succeeded in 10 meters, it must obviously mean that you have succeeded in your in your toxicity as well because it's its almost impossible for the toxic pollutants to be in that concentration that would be immediately dangerous when there's not enough soot to drop the visibility below 10 meters. So that that's a concept that simplifies this this lot. I'm wondering if, if adding the HF to that makes it can like make the tipping point somewhere that now may be necessary to really solve for that and measure that? Because you could possibly have the visibility meyt, but still the concentrations of these products exceeded?

Roeland Bisschop: 35:38

Yeah. Actually, we did actually do some simulations based on the tests we did we simulated like, electric car fire in, in a car park. I don't I don't have the results of them in top of my head. But yeah, I could I could share the link to the report if

Wojciech Wgrzyski: 35:57

Thats great. Yeah, if you, if you can, after after the talk, send it to me and I will put it in the show notes. So I will definitely read it up. And and I hope some of the listeners will as well. It's it's really, it's really intriguing because this emissions are like if we want to understand the problem completely we need we need to understand how do these fires ignite, how they propagate? What's the consequence? And in the end, what products Yeah, so that's a big question to be answered here.

Roeland Bisschop: 36:28

And then you want to have done it for many different vehicles and many different types of fire initiations.

Wojciech Wgrzyski: 36:34

Oh, yeah. Welcome. Welcome to the world of fires, the world of complexity. I, on my list of questions, I also had this question about extinguishing these fires. Because another thing that you learn from the media is that firefighters have big troubles putting them out and impossible. Yeah, you've seen this videos where the fires when they've they've put it down and it reignited put down reignited, that's, that's kind of it is. It's something that he also observed while studying them that it's like, Okay, what do you do with the burnt electric vehicle after your experiment? What do you how do you manage that?

Roeland Bisschop: 37:16

Well, our motto is actually, if it burns, let it burn,

Wojciech Wgrzyski: 37:21

like to the fuel the end, okay?

Roeland Bisschop: 37:23

Yeah, like if we have a battery pack that catches fire, during a test or whatever we don't, we don't interfere, we just let it burn until it's burnt out. If for some reason, you don't have that option, you you want to suppress it in some way. And then, yeah, there are different ways of suppressing the fire. But from my point of view, the most important thing is, is that you're able to cool the battery cells that are inside of the battery pack as much as possible, because you want to stop this cascading effect that one battery cell fails, then the next one, the next one, next on next one. So when one battery cell has failed, you need to remove heat from the surrounding area, if you can, best way of doing that is to somehow inject the battery pack with water or, or another type of cooling media.

Wojciech Wgrzyski: 38:18

You mean is inside the pack? Yeah, no, inside, nobody spray, sprinkle it on top of the pack,

Roeland Bisschop: 38:25

no. Okay, so you can spring good on top of the pack. And that's better than doing nothing, of course. But imagine you have this thick steel aluminum enclosure. inside of this aluminum enclosure, we have battery modules, which is another enclosure and inside of the battery modules, you then have the battery cells. So just spraying water on the outside of the battery pack. It it requires lots of lots of water to eventually cool sufficiently off so that it reached the battery cells inside of the pack. So it's not the very efficient way to do it like that. Ideally, you have I mean, from my point of view, ideally, there should be some type of connection on the battery pack to which the fire brigade can connect their fire hose For example, when needed, connected they just flush the battery pack as long as they need to select

Wojciech Wgrzyski: 39:19

like a safety valve that you could connect to and just Yeah, that would obviously the challenge is it would have to be standardized, because then you would end up with American plug European plug... And that will probably be not not great. When you were talking about that I had this crazy image in my head that I mean water is very efficient at cutting things so and there are these high pressure nozzles that you put against the wall and it literally drills a hole through the wall to penetrate the interior. But then again I realized it may not be the smartest thing to to damage the the cells inside

Roeland Bisschop: 40:00

Exactly you may cause more damage than

Wojciech Wgrzyski: 40:03

that's like they want I also saw some recommendations that you can flood the car like drop it in the in the tank water. Is that the strategy or? Or is just PR

Roeland Bisschop: 40:14

yeah no I wouldn't say that's PR I think that's a viable strategy. There are some things of course you need to consider that you you may have a burning vehicle and how are you going to handle a burning vehicle with a crane and lift it into a place like doing that procedures and you will have to be careful of course, but it will be more efficient than spraying water on the outside of a car battery pack and some of the benefits of taking the car and putting it in a container filling the container with water any any like byproducts from the fire, water runoff, etc. It's all contained in that container. So you can take the Yeah, the fire water and destroy Yeah. And

Wojciech Wgrzyski: 41:00

that that's a that's a very very, very good point you mentioned because in fact, the fire science has a history of developing very, very efficient extinguishing methods like we used to use halons and then we figured out they destroyed the atmosphere. There were certain types of foams that were used that we figure out they were very harmful for the environment they were very efficient for the fire but unfortunately they were very efficient that damaging the life in the water as well. Talking about halons is Is there any experience with using other medium than water on extinguishing this these types of fires?

Roeland Bisschop: 41:40

there is some some experience, not for me personally, most of the tests that we've done have been with water or heater with water and some type of foam added if I do know that tests many tests have also been done with using for example inert gas or novec for example. And they they may be successful in like knocking out the flame and preventing combustion of the battery gas but they do not usually stop thermal runaway they don't stop the thermal runaway process and they usually don't actually provide cooling to the to the battery cellor the cells that around it and

Wojciech Wgrzyski: 42:24

so is like two issues to solve one to remove the flaming which they can succeed that but they cannot prevent the creation of the new fuel and

Roeland Bisschop: 42:35

yeah, well in one way Yes. You want to remove the flaming in its Yeah, in another way. No, you don't want to remove the flaming either. Because Yeah, when when we see batteries that are burning, we're not worried. It's fine. If we see a battery that is not burning and it's releasing a lot of gas. Okay, then we start to get worried.

Wojciech Wgrzyski: 42:58

Okay, yeah that's a tricky one. That's a tricky one as a fire engineers I don't think we can tell our clients that as long as it burns its okay. I don't think this is the strategy they could accept.

Roeland Bisschop: 43:14

Yeah, ideally you keep you keep the fire burning, but you cool the battery cells around the burning fire so that they don't get involved. But

Wojciech Wgrzyski: 43:23

I think the strategy that you mentioned isolating the the item on fire in the in case of a car park isolating the vehicle and fire from the other parts of the of the car park this actually could be a valid strategy to provide safety because you know, copper is also designed the ones that have installations in them like sprinklers smoke control and everything. They are designed to handle a single vehicle fire. And usually it's you would not expect it from a single vehicle I would not expect the damage to the car park that would be dangerous for the for the entire car park. You know, the images that we saw were the damage, the buildings were destroyed, like the airport in Norway. These were huge fires involving multiple vehicles, or like Liverpool in England or we had the such firing in Warsaw as well. The funny part about the Warsaw fire is that there went a rumor that it was caused by an electric vehicle. It was not. As far as I know, it was never confirmed. And it was just something that started running around the internet, you know, when the fire happened and more so. And the next day everyone was saying that electric vehicles destroyed car parks. And the severity of the fire is because there was an electric vehicle inside and all these crazy things that are very difficult to debunk from like perspective of time, because they are so powerful images that they come to the mind of the person. And it's difficult to say that it was just fire dynamics, not not necessarily affected by the vehicle was fueled by this type of fuel. Right? I had. I know, we're running short on time. But I had this one one more question to be asked. One thing that really differentiates the way how we use electric vehicles from internal combustion vehicles in car parks is that we charge them in our car parks and charging is a process. If you leave vehicle and it's idle, it's it's shut down. I think it's a different state than when you plug it in and, you know, charge it for many hours. In your studies, did you see like differences in in I don't know, occurrence of the fires or severity of the fires when charging was involved versus idle vehicles

Roeland Bisschop: 45:50

Usually when we have seen fires that occured with vehicles that were being charged, or while while they were being charged was that the fire was not related to the battery pack, rather improper electrical installation of the charging stations so that the fire started in the charging station and from there on spread to the battery pack. That being said, during charger Yes, during chargers, you're you're putting energy into the battery pack. And while you're doing so the individual battery cells, they heat up a little bit because of their internal resistance. So in that sense, if one of the cells in the battery pack may fail the surrounding cells could be at somewhat of an elevated temperature, and then that sense increased the risk that you get the cascading failure. And when it comes to charging, in theory, you can if you if you don't have any safety systems like what happened with many hoverboards, for example, they did not have any any battery management system or any built in system that prevented them from being overcharged. So many people that bought hoverboards, they put them on the charger, they leave them there, and it's just a matter of time until they catch fire. But this this cannot happen with electric vehicles they have such like advanced battery management systems and protection systems that as soon as it detects one of the battery cells in the battery pack is is going beyond any limit, they just interrupt charging.

Wojciech Wgrzyski: 47:25

Let's say you have like two safety points, one should be in the charger and one should be in the battery management system of the vehicle. Yeah.

Roeland Bisschop: 47:31

So yeah, that's the best, the safest way of charging is to have both the safety built in in the charging system. And in the battery management system. There are some like charging types where charges where you put just a socket in the wall, and then you connect that to your vehicle, then you only have the safety in the in the battery management system. You don't have any safety in the charger itself.

Wojciech Wgrzyski: 47:55

My neighbor does that.

Roeland Bisschop: 47:59

Time to move I think

Wojciech Wgrzyski: 48:00

I'm a bit concerned now. Maybe Maybe, maybe I'll just build a wall between us. And then it actually is in Poland. I mean, everywhere we are we as engineers have to deal with this problem. Because as we as we spoken in the green room, it's difficult to ban this and banning is not a solution.

Roeland Bisschop: 48:19

It's not the solution.

Wojciech Wgrzyski: 48:21

Yeah. So so in Poland, the the the solutions are, for example, putting walls between parking slots where where electric vehicles are allowed to burn to provide a physical barrier between the vehicles. So if one vehicle ignites it, they cannot like ignite the secondary vehicle through this jet fire even if it occurs because there's a physical barrier and it's very unlikely that the secondary vehicles will burn from the heat emitted from the smoke itself, you know, yeah. So in a way that that that provides some sort of safety against cascading fire that one recognizes another another another now, and I think in a way sprinkler systems would work would provide the same role, because obviously sprinklers will not have any impact on the on the battery itself. But they will cool the gases around they will limit the probability of fire jumping to another vehicle. So again, isolating is seems like like if I had to propose something to an architect tomorrow, isolating vehicles after this talk sounds like a very good idea. I have some other ideas but that's for another episode.

Roeland Bisschop: 49:37

And it's not only positive for electric vehicles of course I mean for for all even internal combustion engine vehicles. This This can be an issue. I mean, apart from internal combustion vehicle can also catch fire. And

Wojciech Wgrzyski: 49:53

Uhm, well Roeland, thank you. Thank you so much for doing this. I learned a lot about about this fires And there's so many things going through my head, how to put that into the knowledge into practice. And then I need to read up on the emission paper. And I'm looking forward to that. So what's the next step for you? Are you still working on on battery fires?

Roeland Bisschop: 50:18

Yeah, yeah, I'm working quite intense on battery fires, we're building a new lab here in Sweden, called the Swedish electromobility lab. And that is a lab that is built to do as some batteries. And we're building it in such a way that we can have an explosion, anything can happen, and the building will still be be standing there. So that's pretty exciting.

Wojciech Wgrzyski: 50:42

That's as good. It will involve like large scale fire experiments and stuff like that.

Roeland Bisschop: 50:49

Yeah, yeah. And all sorts of, you know, abusive tests on batteries. And we're going for kind of environmentally friendly solutions, our lab will have like, a smoke cleaning system, which which I know many people that like to do tests just out in the outdoors when it comes to batteries. So hopefully, we can do a good thing for the environment with our lab two.

Wojciech Wgrzyski: 51:13

That's a good that's, that sounds really exciting. And I hope that there will be a lot of new developments from RISE and and your team in this regard. Because so far, you have provided priceless points of view on on topic that we barely know anything on. So yeah, everything is needed. Thank you so much. And yeah, thank you so much for thinking they invite and

Roeland Bisschop: 51:38

No worries.

Wojciech Wgrzyski: 51:39

See around. Thank so much.

Roeland Bisschop: 51:41

Thank you for having me. Bye, bye.

Wojciech Wgrzyski: 51:44

Yep, that's it for the interview. I hope you enjoyed that. I certainly did. I've learned so much from Roeland and it's gonna be very useful to my science and engineering. I was quite surprised at the bigger challenges with what when the battery does not ignite, when it just releases toxic gases and flammable gases. But when you think about it kind of makes sense with fire we can do when it's a poisonous cloud, it probably poses a completely different set of challenges. And in the next week, I'm going to take you into a journey through my own research and the research of my group, which is on the rapidly growing fires, we've taken some artificial design fires that grow to a large heat release rate very quickly dropped them into computer model of a car park and compared how they behave and what consequences of this fire we can observe versus something we could call, let's say, traditional design fires for car parks. The results are quite interesting. And we've definitely identified height of the car park as one of the main variables. We've run 480 CFD simulations. So there's a lot of findings inside of that. So I hope I'll be able to tell you the biggest findings from that and give you some of my own thoughts on how can we make car parks safe, including electric vehicles in them with the knowledge we have today, with the best practices as of today, because I think it's very important, we don't have time to wait for all the research to end. And as Roeland said today, the developments in battery technologies are probably quicker than the ability of the fire community to understand them. So yeah, we have to work with what we have. And that that's the next episodes gonna be about. So thank you for being in here today. I'm welcoming you to the next episode next Wednesday. If you enjoyed the show, if you like the show, please let me know somewhere and or share the episodes with your friends with your colleagues. And I highly appreciate making this podcast available to anyone who doesn't know about it yet but could actually benefit from from what we're doing in here. Thank you for listening. And yeah, stay safe. See you next Wednesday. This was the fire science show. Thank you for listening and see you soon.