169 - Engineering car parks for EV's with Ali Ashrafi and Pawel Woelke

Transcript

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Hello everybody, welcome to the Fire Science Show.

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In the Fire Science Show I really like to talk to fellow fire safety engineers about how do they solve their problems, and it's fun because the problems are usually the same in my country, in my location, and the same in the places where my guests come from.

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But the methods, tools that we use to solve those problems, solve those issues, are usually different, and I love to learn from fellow fire safety engineers because this gives me inspiration and breadth of knowledge that helps me solve my own issues, and that's the idea for inviting more fire safety engineers into the podcast and finding topics that unite us, topics that are challenging worldwide and that we all have to figure out together.

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One of such topics is fire safety of car parks.

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In relation to the electric vehicle hazards, a few months ago we had a phase two report from NFPA on modern vehicle hazards.

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We had a lot of research, some papers published over the last two, three years that shed new life into the problem of fire safety of electric vehicles.

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I had brilliant guests in the podcast, such as Professor Peter Sturm, who's burned electric vehicles in a tunnel, and I can probably say we have also participated in some experiments on electric vehicles, which will reach the daylight in some time I hope sooner than later.

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So I clearly see the knowledge base is growing and I also feel that the focus moves away from electric vehicles more towards scooters, which obviously seem to be more immediate hazard to tackle by the fire safety engineering community, or perhaps energy storage, which also is very, very interesting.

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Nowadays I think I see that electric vehicles and hazards related to them became some sort of a normal thing in the modern world of fire safety engineering, which is great.

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That's a sign that the field is maturing, that we have more solutions to work with, that we have gained enough experience to handle those topics.

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Just as another topic and yeah, this is what I want to extract from my guests I've invited two colleagues from Torrenton to Massetti.

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You've heard them previously in the podcast.

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One is Alia Shraffi, he's a principal, and the second one is Pavel Volker.

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He's a senior principal and applied science practice co-leader at Torrenton Tomasetti, and they've been on a podcast talked about energy storage, and today I'm going to pick their brains on how do they approach issues with car parks which are supposed to store battery-powered vehicles.

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So I guess that's enough for an introduction.

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Let's spin the intro and jump into the episode.

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Welcome to the Firesize Show.

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My name is Wojciech Wigrzynski and I will be your host.

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Hello everybody, I am joined today by Ali Ashrafi.

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Hey Ali, good to have you back in the podcast.

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Absolutely, love to be back.

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And once again, paweł Woli hey Ali, good to have you back in the podcast.

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Absolutely, love to be back.

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And once again, paweł Wolka, hello Paweł, hi Bartek, great to be here again.

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Welcome back to the podcast, guys.

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And the last time we were talking about energy storage facilities, and today I'm going to pull you further on the topic of electrifying our buildings.

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And then this time we'll be talking about electric vehicles, something that everyone in the fire science community loves.

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We, I guess, learned to live with them so far, but it's not that we have solved the challenges in the design and, of course, everyone tries to deal with them the best they can.

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So let's give people some ideas and solutions and let's talk it over.

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I'm really happy to do that.

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For a starting point, what's the situation in the US?

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How does it grow the EV market and, let's say, the knowledge of the designers and how to include them in their design?

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Looking back, I don't know 2016, 17, 19,.

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Do you see big differences how we approach those today?

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You know, if I were to start, I'm starting at the beginning of your question.

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I think that you know it's to a large degree driven by sales of EV vehicles in the US and that has stalled somewhat over the last number of years, two years or so.

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You know, I won't venture into the reasons behind it, but I think it's a temporary thing, temporary situation.

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So it will pick back up and then the electrification of transportation will proceed along the lines of EVs specifically and then for the longer range heavy haul vehicles it's probably going to be hydrogen drivencar parking in a variety of urban areas, especially urban areas, in parking garages that are basically multi-car park storage facilities.

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So that's one aspect that we see a lot of and the other one has to do with stationary energy storage type that basically supports grid, so it's not EV-related.

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Obviously these are, like I said, stationary energy storage systems, but there's a lot of those in and around large urban areas as well and they present similar challenges of course more energy, similar density, but more energy basically located in one place.

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And I would add that we have certainly a lot more consciousness of the issues and questions.

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There are a lot more people that are thinking about this issue.

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As you know, in the US, everywhere, codes are usually slow to catch up to evolving technology right, and the same is true in the US, and so I don't think the codes have changed as much as the questions and the nature of things that clients ask us and we look at in a design context.

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So if you're looking at prescriptive code requirements, there hasn't been as much change as when we look at it from an engineering perspective and try to come up with actual engineering-based solutions.

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Okay, and reading the emotions of the room some years ago, I felt the problem is very emotional, even up to the point of hysteria.

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You know we're going to have EVs in our car parks.

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How do we deal?

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At this point, I believe we're more talking about engineered solutions and real problems based on, finally, data, and this helps us craft solutions.

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Did you have the same feeling that the problem was very like medial emotional some years ago and now have changed into much more technical discourse, or is it still something you observe in US?

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I don't know that.

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I feel that the discussion was very emotional in the US, ever really Okay.

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I think it was one of those examples where there was no issue and then there was an issue, okay, and you know, I guess that may be a characteristic of the way US economy operates.

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There's a need for a solution, okay, and you know, I guess that may be a characteristic of the way US economy operates where there's a need for a solution, a solution gets developed and people are very pragmatic about it.

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So I don't really feel that the discussion was all that emotional.

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It is certainly practical right now and focused on solutions.

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I don't know that there is a sufficient awareness yet of the cost of these solutions or basically the types of the problems that we're dealing with, the nature of the problems, the nature of the hazard and then the cost of developing solutions.

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I think there's an appreciation that the solutions are passable and that's increasing, but I think that the appreciation of the cost associated with it is lacking a little bit behind.

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And to rephrase your question, I would say maybe a few years ago the questions were not as well understood and well defined, so people knew that there's some issue.

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They didn't know what the right questions are, and now we have better understanding of that.

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Certainly there's a lot more data out there so you can have a much more informed and detailed conversation.

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Yeah, for me in Poland at least, the discussion was very emotional.

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It was like EV fires were the headline topic of newspapers and I believed the fear for the big fires that come with EVs came here before the EVs even came vehicle sales.

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Already you already had a big fleet of vehicles that you could refer to.

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I mean, if you have a fire, having half a million electric vehicles in the US, that feels completely different than when we have a fire in Poland, or we see a fire and we have 50 of them or 100 or 1000, even.

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You know, I see that this perhaps was the driver.

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And to understand the infrastructure multi-car park storage facilities, how they are built in the US Are they typically separate structures?

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Are they built as a part of other developments, underground, overground, all of above?

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All of the above.

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Okay, it's very dependent on the specific developer, specific solution.

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Some of them exist and they're just going through conversion, where there's an increasing percentage of the vehicles that will be EVs or at least chargeable stations or spots, parking spots, so you've got all kinds.

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Basically, obviously, the ones that exist that are underground and not ventilated are the most challenging, but a lot of it, as to going into the solutions, or even the desire or the need for solution, goes back to who owns them.

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What is the sort of risk profile of that particular owner or risk appetite of that particular owner vis-a-vis code requirements, which don't necessarily impose on you any strict demands as to what you should do.

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So some owners will choose not to do anything because they don't have to.

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But, like I said, as far as the types that you're seeing, you've got everything that you've mentioned as far as coming up, and the new ones obviously create a bit of a more opportunity to address the issue up front, as Ali mentioned earlier, to apply a holistic sort of viewpoint to the solution and design them with the hazard in mind, as opposed to do sort of a mitigation after the fact.

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But the existing ones are calm online, so to speak sooner or later, simply because of the progressing fleet electrification.

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And, if you want to think of it, compared to Europe, we have a little more space in the US.

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And so there are a lot more places where you have room to have a dedicated parking facility in the suburbs or, you know, less populated areas.

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If you go in dense urban areas, of course you don't have that space, and then it becomes a mixed-use building that has a parking space and then you have a building above that.

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Yeah, and you've also mentioned the legislation has not followed the developments.

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Do you have any legislation related to having the spaces for electric vehicles?

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For example, in Poland we have new technical regulations for buildings that define how much electrical power has to be connected to a new development, how many charging points you shall have per X number of spots, and so on.

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So in that case, like requiring to design with EVs in mind already came here, but, as you said, the fire considerations are not yet part of that.

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So we've already our law already includes for EVs, just not for the risk management of the EV fires.

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Yeah, we have a similar situation, except that it's not at the federal level.

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So you have basically requirements that exist on a state by state level.

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So they obviously vary from state to state and also municipalities.

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So, again, there's probably a bit of a lighter touch in terms of mandating things for a number of specific EV-capable spots, so to speak, but they do exist.

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And part of that is and I'm sure we'll get more into that if you want to mandate a specific type of solution, for example, to some extent you want to know what you want to mandate and enough of those designs should be done where you converge to that.

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As opposed to if you want to be more performance-based and say, consider these things in design, you can, you have more room, but the US system is starting from a point of prescriptive.

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So you can do performance-based design but compared to the US, it's a lot more prescriptive design as a starting point.

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Okay, let's try with defining.

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We've used the word hazard a few times.

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Let's try defining hazards related to EV vehicles.

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I guess we can.

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Let's, for the purpose of this discussion, consider the internal combustion engine as the normal hazards.

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You know whatever that would mean, and let's try to distill what the new hazards would be like.

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What changes when you bring EVs into your mix of vehicles in your parking space?

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So perhaps you could try outlining the differences.

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Well, that's a hard one.

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I mean I think that it's worth saying at a high level that we have decades of safety research into the fire hazards of internal combustion engine vehicles.

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The ignition source, in terms of heat, and the fuel are separated quite a distance away.

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There's a lot of other safety features.

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We basically know what we're dealing with because we've been dealing with this for more than decades it's hundreds of years.

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At this point, obviously, evs are new and they create tremendous advantage from the point of view of simplicity of the vehicle built and construction.

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But to outline the hazards, with highlighting the points of departure, so to speak, from internal combustion engine, you obviously have a fire hazard in EV just as much as you do in an internal combustion engine.

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You also have an explosive hazard which technically could exist in an internal combustion engine vehicle, but it's basically taken care of as in it has been addressed through those safety features.

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And then you've got toxicity hazard in EV, which is also unique.

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So I would say explosive hazard and toxicity hazard are new to EVs.

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And going back to the fire, there's just sort of a binary description of fire.

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The fires are different, as we all know, so it may look if you look at the heat release rate.

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The internal combustion engine and EV look similar and you know, in both cases most of the fuel for the fire is actually given by the internals of the vehicle plastics and things like that as opposed to the actual powertrain fuel, be it gasoline or energy stored in batteries.

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But it's how that combustion chemistry actually progresses.

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That's where the differences are.

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So I would say there's a significant difference in the fire hazard between ICE and EV, and then there's explosion and toxicity in EV, which is unique to those types of vehicles.

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And let me add one thing here.

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So if you're dealing with situations where you have, let's say, one car and that's an easy problem to deal with and it's EVs want to make a big difference, big picture, in what the hazard is and how you're managing that, ultimately, a lot of times there's a car.

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They come and isolate the risk and they might let it burn.

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It's actually a better solution, but it's not a big game changer.

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I think the one place where you have more of these cars close to each other not on the risk side yet, but just on the hazard side the hazard which depends on how the fire propagates from one car to multiple cars does also depend on what we do in design and what the response to it is.

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So, for example, if you have a situation where there's a protocol and there's accidents and the fire department can come in and control that much more easily, or you've detected it faster, you can act on the hazard in a way that mitigates as much faster than if you don't have those situations.

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So that's a place where the hazard side is not given and then we're trying to just come up with a solution.

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The hazard also depends on what the response to it is.

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So I would like to come back to Pavel saying that the heat release rate would look the same.

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By that you mean, like the total energy release in the fire or the peak heat release rate would be ballpark similar at the peak right.

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So not the same.

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Just a slight caveat similar, yeah, and I would say the total energy.

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So the former, similar, the peak is going to look different.

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Peak is going to be higher in the case of ev and that peak is, as peaks tend to be relatively short-lived, but it has a tendency to be quite a bit higher than for internal combustion energy.

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That, the the energy, is a relevant question because, like, like I said, the bulk of the energy that is provided to the fire is internal elements, plastics and things like that.

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So the energy is going to look similar.

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Okay.

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So we just went through your literature review, which is in the review stage, you know.

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But also looking through the research, we also found some interesting artifacts of how those things are tested.

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So what we found in our research is that, looking over all the published data you can find on the internet, when people test those electric vehicles the focus is obviously towards battery, because that's the interesting part, right.

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So they go very heavy abused ignition sources like nailed through the battery as the ignition, or just two megawatt heptane fire underneath the car, which I don't think is a very realistic scenario.

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So the way how the tests are carried are very battery ignition oriented, whereas in the same, let's say, decade, the last 10, 15 years, when we saw tests of internal combustion engine vehicles, we've seen more attempts of ignition, like through the tire or through the interior.

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So I shared your opinion, pavel, that the numbers look similar or ballpark, they are near to each other.

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But I also see some artifacts of the way how we test and also the trends, like we're testing more and more electric vehicles because this gets you published, you know, this is the interesting part and less and less tests of internal combustion vehicles, and both types of vehicles get heavier, which means more plastics, exactly, yeah, so also, you know, comparing 2020 ev to a 2005 internal combustion vehicle, if you take battery away, if you take petrol tank away, there could be like 200 kilograms of plastic difference, which is significant.

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Yeah, so it's actually so.

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There are numerous studies that compare the size of the vehicle EV versus internal combustion engine.

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They both increase, have been increasing in size, just as you said.

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And then EV is about 20, on average about 20% heavier, which has to do with the weight of the batteries, but volume they have both been increasing.

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So that's one aspect that confirms what you said as well.

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That came up in some of our reviews, literature reviews.

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The other element that's interesting is there's a significant amount of noise, like you said, in the data right, because a lot of people test it with a specific objective and you get that objective.

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You don't necessarily get a full picture and the fact that there's still a limited amount of data that exists, especially of controlled tests, which I'll get to in a second, creates this uncertainty, significant uncertainty.

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The tests are not very well repeatable, because if you test the system like a car the entire system then you don't really have a fully controlled environment the entire system then you don't really have a fully controlled environment.

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You can control certain environments, but you really need to get into an element level or subsystem level to fully control the environment and have repeatability in the test, and that is currently lacking, because everybody's, like you said, very excited about testing the system and you know there's just too many parameters to control to make it a repeatable test, right, so it just doesn't really help.

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That said, you know, kind of separating the power train, separating the battery itself and then the fuel tank in the internal combustion engine.

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There are studies that go back to the 60s of both vehicles and buses that basically give you the idea of what the energy release is going to be in the fire of a bus or a vehicle, without consideration of the fuel itself, just burning the internals, burning the tires, burning the internals.

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So we have an estimate of those kinds of things, a variety of different vehicles, based on old tests, and those are fairly consistent, right, because you remove the most uncertain element, which in this case is a battery, and you have a picture basically of what it is.

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And based on those sort of comparisons, we obviously try to do, I'm going to say, a comparative analysis.

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Right, because it's not an additive analysis, it's not superposition.

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Obviously it doesn't work over here, but when you start quote unquote adding those elements, the fire of the internal elements of the vehicle, whatever the type of vehicle you're talking about and its energy release rate and again, in addition to I'm going to say in addition to use loosely here in quotation marks to what the energy is of the fire within the battery, fire off the battery, in comparison to internal combustion engine.

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And that's where my statement comes from in terms of saying that the majority of the energy is actually coming from the internals of the car, I would say significantly in comparison to the energy that's coming from a burning battery.

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I don't know if you've seen it, but NFPA, just a few months ago, released a second phase study where they're looking at, basically, hazards of modern vehicles and it parallels our conversation of modern vehicles and it parallels our conversation.

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So there are a lot of similar themes between vehicles, whether they're electric or not, and some of them are, as we talked about.

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The cars have just gotten larger, more plastic to burn.

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They're larger, so now they're like when they're parked next to each other they're actually closer to each other.

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So it impacts propagation, for example.

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Right, so big picture.

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When we look at all the variety in the data that you get because of just the changes in the size of the cars, the amount of fuel that you might have, how the ignition will start, whether it's EV or not in each of them, and you look at all of that, evs and combustion engine cars end up being in the same ballpark when you're looking at them as an individual car.

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So it's really when you're looking at a system and inside an enclosed area where you start to see the difference.

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That's a very interesting point.

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I'll just be specific.

00:22:18.928 --> 00:22:22.240
It's NFPA 13, which deals with design of the sprinkler system.

00:22:22.240 --> 00:22:29.643
Okay, that updated the rules and EVs are mentioned in the context of new cars in terms of their size.

00:22:29.643 --> 00:22:36.348
So it's an increasing size, increasing amount of plastics in the car that basically drives new requirements for sprinkler design.

00:22:36.348 --> 00:22:44.834
They're not driven and nfp admits that by ev consideration, ev or battery fire consideration specifically, and then that's not.

00:22:44.834 --> 00:22:46.143
Again they get nfp.

00:22:46.143 --> 00:22:48.410
The problem is difficult and they're trying as best they can.

00:22:48.871 --> 00:22:49.923
It's just a difficult problem.

00:22:49.923 --> 00:22:52.333
Good, good, good, uh, and I like.

00:22:52.333 --> 00:23:01.730
Well, of course, in Europe we have a kind of different vehicular trends than you guys have in the US and I know that there are those very large pickup trucks.

00:23:01.730 --> 00:23:05.827
I've heard about electrical Humvee that must be like a massive fire source.

00:23:05.827 --> 00:23:12.567
Is this also affecting your procedures, this different fleet that you have in the US?

00:23:13.089 --> 00:23:13.530
Absolutely.

00:23:13.530 --> 00:23:20.279
I mean you look at a facility, whatever the facility, parking facility might be, and you have to evaluate the type of cars that are coming.

00:23:20.279 --> 00:23:40.644
And you know we obviously, when we run analyses like this, dtap analyses like this, like these, we don't focus on a vehicle but we usually look at the range, we look at the traffic data within this location and then basically determine the offending vehicle as a source and the offending vehicle has to do with the whole thing.

00:23:40.644 --> 00:23:51.363
So basically, the body that it has, the amount of energy that it stores and then in its internal plastics that add, to add the fuel to the fire, basically I had to ask about a huge american vehicle.

00:23:51.383 --> 00:24:02.329
Sorry guys, but it's interesting, like for me as a european, I would love to burn a humvee, like I just wonder if I just wonder if 20 megawatt food is sufficient enough to handle the beast.

00:24:02.329 --> 00:24:07.307
Okay, the, the heat release rates, let's say, are similar, but there are nuances as well.

00:24:07.307 --> 00:24:13.182
So since the beginning of the ev considerations, we were worried about the jet flames from the EVs.

00:24:13.182 --> 00:24:16.991
This, from my perspective, have different kinetics in two ways.

00:24:16.991 --> 00:24:25.365
In one way, you shoot fire for a larger distance, but also the fire has higher velocity, which impacts the conductive heat transfer.

00:24:25.365 --> 00:24:35.423
And from the smoke control perspective, that's also completely different entrainment than the buoyant smoke pools that we are used to as smoke control engineers.

00:24:35.423 --> 00:24:41.422
So are those details, or those are important things for your considerations?

00:24:42.784 --> 00:24:47.253
It's the latter the important elements or important details for the consideration.

00:24:47.253 --> 00:24:49.061
Jetting is one element.

00:24:49.061 --> 00:25:12.449
I'll just talk a little bit about this in a second, because we're looking at it from two different viewpoints, I think as far as jetting, but also, you know, the peak release rate tends to be higher and it can cause very local, very intense for more short-lived but very intense impingement on structural elements and that can cause, in some cases, concrete spalling, for example, exposing but very local right.

00:25:12.509 --> 00:25:14.133
It's like almost a point exposure.

00:25:14.641 --> 00:25:18.191
Right, I mean in the world of fire, whatever point means in the world of fire.

00:25:19.580 --> 00:25:41.556
It's not a point point, but yes, it's local, but that can propagate because there's several different things that can happen inside a concrete mix, both from the point of view of the vapor pressure that goes inside, but also thermal expansion and the shear stresses it can cause at the layer that is basically that has a high gradient, thermal gradient inside of it and where the cage sits, reinforcing cage.

00:25:41.556 --> 00:25:56.570
So there's a lot of different details and if you neglect them completely you might basically miss the picture, because if they fall, even what we could consider again, quote unquote point can propagate across the large surface area of a slab and that can cause a significant damage structural.

00:25:56.570 --> 00:25:57.701
So that's one aspect.

00:25:57.701 --> 00:25:59.003
So that is an important detail.

00:25:59.003 --> 00:26:07.561
Jetting, obviously, is very important as well, because if it is somewhat high pressure, I'm not going to call it high, high pressure because it tends not to be excessive.

00:26:07.561 --> 00:26:13.865
We're not talking about supersonic pipe flow, you know, like we know in the natural gas world, but it is high pressure.

00:26:13.865 --> 00:26:33.846
It can be high pressure jetting and it's directional and that can contribute to fire spread, fire propagation, because you don't necessarily have to propagate battery to battery, right If the battery starts the fire and then you have a directional flame that impinges on the tires of the adjacent vehicles, it will go, and it doesn't really matter that the battery of the adjacent vehicle will go.

00:26:33.907 --> 00:26:36.593
Later it will start with plastics in the car.

00:26:36.593 --> 00:26:38.222
The fire doesn't care.

00:26:38.222 --> 00:26:47.214
The nice quote-unquote, very quote-unquote, nice or the easier thing about it is when it spreads like this, you're avoiding explosion.

00:26:47.214 --> 00:26:49.180
The fuel that's released is burning.

00:26:49.180 --> 00:26:50.320
You already have a fire.

00:26:50.320 --> 00:26:51.001
It will burn.

00:26:51.001 --> 00:26:54.423
It's unlikely that it will accumulate before ignition.

00:26:54.423 --> 00:26:59.307
That of course assumes that you've got a certain layout or an open layout of the parking garage.

00:26:59.307 --> 00:27:11.256
If you've created pockets, individual pockets, so to speak, that can allow gas accumulation, even though in the adjacent pocket, so to speak, or the area you could burn, then you may have both, or the area you could burn, then you may have both.

00:27:11.256 --> 00:27:13.218
So a lot of it depends on the details.

00:27:13.218 --> 00:27:24.369
But under the assumption that you have an open space and several vehicles parked next to each other, the fire spread basically fuels the fire, but the explosion issue is somewhat secondary at that point.

00:27:24.980 --> 00:27:29.769
And Roy says we're going to go back to that, I'm sure that fire versus the explosion side, absolutely.

00:27:29.769 --> 00:27:35.009
But one more thing to add and you deal with car parks all the time, right?

00:27:35.009 --> 00:27:39.728
So I've heard this from you multiple times and it's true they're just a challenging place to design.

00:27:39.728 --> 00:27:47.799
Once you get past a small fire, right, if you have a fire that engage multiple cars at some point, it becomes a very hard thing to deal with, right?

00:27:47.799 --> 00:27:52.381
So really a lot of the question is making sure that if you have a hazard thing to deal with, right.

00:27:52.381 --> 00:28:07.288
So really a lot of the question is making sure that if you have a hazard, it's a hazard that doesn't spread fast and large enough to a point where you can't control it but going back to my reality and this kind of hysteria that happened in the media is also not that a battery will immediately trigger another battery and another and another.

00:28:07.690 --> 00:28:18.811
There, like, there were two videos, that uh viral videos, one showing a I think it was a in china, where that actually happened like boss to boss to us, and so I was crazy.

00:28:18.811 --> 00:28:26.799
But there was also a fire of seven, eight electric vehicles I believe that was australia where they propagated.

00:28:26.799 --> 00:28:31.326
They've burned, but there was no thermal runaway in any of the secondary vehicles.

00:28:31.326 --> 00:28:37.415
They went through a significant fire yet there was no thermal runaway of the battery.

00:28:37.415 --> 00:28:44.794
So it's not that you subject battery to a jet flame and then immediately you'll have another jet flame from another.

00:28:44.794 --> 00:28:46.962
It's not that dramatic.

00:28:46.962 --> 00:29:00.222
The cascade Also, you know, whenever I talk with fire scientists and at this point we also have experience of our own actually setting those batteries on fire just with an external heat source is not that easy.

00:29:00.222 --> 00:29:01.606
It's a very interesting point.

00:29:01.646 --> 00:29:12.549
It goes back to the point you made earlier as far as testing and what people focus on, and that also goes back to the difficulty of the problem and the novelty of the problem and constantly changing chemistry.

00:29:13.080 --> 00:29:23.195
If you take a module not even a pack, but a module, multiple cells and you test it under nominally the same condition in the lab environment multiple times, you're not going to get the same result.

00:29:23.195 --> 00:29:31.152
Sometimes some batteries will be easier to trigger than others and sometimes the same battery will be relatively easily triggered in one test.

00:29:31.152 --> 00:29:37.650
The same battery will be relatively easily triggered in one test and then you basically try to replicate that test, but with nominally the same battery or the same type of battery.

00:29:37.650 --> 00:29:43.990
Obviously you're not going to use the same one, but basically nominally the same battery in the same environment and you will trigger it.

00:29:43.990 --> 00:29:46.409
So there's significant uncertainty related to this.

00:29:46.409 --> 00:30:06.962
We just don't understand enough about the mechanism of initiation of thermal runaway within the individual cell, sweeping conclusions and and that's a pretty important piece from the point of view of fundamental research as far as the understanding well, I think we we have a perfect grasp of what happens when you nail them, you know.

00:30:07.042 --> 00:30:19.951
But let's say, the natural causes of thermal runaway and the initiating chain of events that initiates a natural fire like one that you could expect in your car park while charging or whatever.

00:30:19.951 --> 00:30:24.290
This is still something we need more to research.

00:30:24.290 --> 00:30:41.263
And also, you know, going back to these artifacts of testing, it's very difficult to distinguish the natural growth and development of these events versus the trigger, because if I have two megawatts of heptane and I accelerate this, I don't even know how much I've accelerated, you know.

00:30:41.263 --> 00:30:47.931
And then, taking the number from this experiment to my design, am I conservative or am I just wrong?

00:30:47.931 --> 00:30:49.286
I don't know that right.

00:30:49.900 --> 00:30:57.036
Yeah, and I think that's one of the key issues right, and that goes back to that uncertainty of nominally the same event and you can have multiple different consequences.

00:30:57.036 --> 00:31:01.548
It's really difficult to say, and I think again the evolving nature of the technology itself.

00:31:01.548 --> 00:31:06.636
Separators change what happens at the interface between the electrode and the electrolyte.

00:31:06.636 --> 00:31:24.790
That changes because the chemistry changes, the amount of oxygen you have, the phosphates you've got, a different amount of oxygen than in other chemistry Solid states, how they evolve, use of supercapacitors in addition to the solid state battery there's a constant evolution of these things and they cause changes in the way those batteries react.

00:31:24.790 --> 00:31:27.669
But I mean, at the end of the day it's an electrochemical cell.

00:31:27.669 --> 00:31:31.611
We're dealing with an unstable or conditionally stable system.

00:31:31.611 --> 00:31:38.787
The energy does not want to sit there, so it will get out under the right conditions.

00:31:38.807 --> 00:31:40.210
What those conditions are is at this point not very well understood.

00:31:40.210 --> 00:31:44.105
We're trying to pack as much of that energy to as little space as we can.

00:31:44.105 --> 00:31:45.809
You know that's the optimization front.

00:31:46.751 --> 00:31:48.042
What about the tools of engineering?

00:31:48.042 --> 00:31:55.647
We now talked about the evolution of the systems, and everyone can see that evolution is so fast-paced.

00:31:55.647 --> 00:31:56.847
It's ridiculous, right?

00:31:56.847 --> 00:32:01.164
We don't even know what's happening in the R&D labs of those big manufacturers.

00:32:01.164 --> 00:32:02.008
We have no clue.

00:32:02.008 --> 00:32:05.263
What are the next generation separators, electrolyzers?

00:32:05.263 --> 00:32:05.924
We'll not know.

00:32:05.924 --> 00:32:10.852
It's very difficult to obtain that knowledge, but yet I need to design my car park today.

00:32:10.852 --> 00:32:13.663
You know that's going to stand there for 50 years.

00:32:13.663 --> 00:32:16.569
What do I do in the in this uncertain reality?

00:32:16.951 --> 00:32:21.087
we operate in the risk world right, and risk assessment has two elements to it.

00:32:21.087 --> 00:32:24.403
There's the likelihood or probability of occurrence and then there's its consequence.

00:32:24.403 --> 00:32:36.000
Once the event does happen and you know, usually in the perfect world you've got visibility into both elements and you can have also actions that affect both elements.

00:32:36.000 --> 00:32:48.330
So in the first instance, if you're affecting likelihood or probability of occurrence of an event in this case let's just say thermal runaway then you would basically take certain actions that would reduce the probability of occurrence.

00:32:48.330 --> 00:32:51.108
We do not have that ability at present.

00:32:51.339 --> 00:32:55.146
Does the car park manufacturers or sorry, car manufacturers battery manufacturers?

00:32:55.167 --> 00:32:55.809
They do absolutely.

00:32:55.809 --> 00:33:19.299
But you know, specifically to your question and that's the world we operate in you come at a problem from the viewpoint of a car park manufacturer or an owner and if you own a car park or are building a car park, you don't get to necessarily choose which vehicle you're allowing to park and you're not going to make a call to a car manufacturer and ask about the details of their battery and the safety system or their battery management system, for example.

00:33:19.299 --> 00:33:22.189
And if you were to do this, you're not going to get any answers right.

00:33:22.189 --> 00:33:36.411
So you operate in a bit of a dark space as far as the probability of occurrence and you also have even less influence on limiting that or reducing the probability by certain active measures, as in, you know, basically prevention.

00:33:36.759 --> 00:33:43.990
So in what we do, for the most part and there are some exceptions to it and I can't really get into the details, but some of it is government-sponsored research.

00:33:43.990 --> 00:33:54.768
So, with the exception of those, if you're talking about a commercial world, we are assuming that the event will happen in a vehicle and you focus on the other side of the risk, which is consequence.

00:33:54.768 --> 00:33:56.352
We know the consequence is high.

00:33:56.352 --> 00:33:57.643
So how high is it?

00:33:57.643 --> 00:34:00.451
What does it really mean and how do you mitigate the consequence?

00:34:00.451 --> 00:34:11.661
So you basically are saying we understand that as an owner of a facility like this, you've got limited at best, at worst zero influence on the probability of occurrence, and reducing that.

00:34:11.661 --> 00:34:19.449
All of your influence sits in understanding and managing the consequences of the event, and that's where we, a majority of our focus, really is.

00:34:20.101 --> 00:34:22.849
And that's not uncommon in the engineering world.

00:34:22.849 --> 00:34:32.791
So we have different levels of uncertainty on the input side, but we always work in the context of what we know is limited and what we know will change.

00:34:32.791 --> 00:34:36.880
Like you design a building and that building is going to be there for the next 50 years, right?

00:34:36.880 --> 00:34:39.690
So there's also things that you haven't considered.

00:34:39.690 --> 00:34:52.389
As Pavel said, we can look at it and take a range for that uncertainty but say what are the things we could do on the consequence side to make the design better compared to baseline, where we were not going to do those things right.

00:34:52.389 --> 00:35:01.135
And so you can certainly show that you're making an improvement, understanding that none of what we do is targeting zero risk.

00:35:01.135 --> 00:35:01.938
That doesn't exist.

00:35:01.938 --> 00:35:02.179
Right.

00:35:02.179 --> 00:35:16.588
For everything else that we do for designing buildings for earthquakes and wind and flooding and all that it comes with a specific chance that things could happen that are more than that, and the same is true for any fire-related scenario.

00:35:16.940 --> 00:35:28.248
But I think there's an interesting point here that's worth highlighting, I think, because I think we're getting pretty good in general not us necessarily, but a community, if you will, research community and engineering community.

00:35:28.248 --> 00:35:35.293
We're getting better at quantifying and understanding the consequences and developing solutions, and that knowledge will accelerate.

00:35:35.293 --> 00:35:38.585
Dissemination of that knowledge will accelerate over the next three to five years, I think.

00:35:38.585 --> 00:35:49.670
So that creates a bit of an opportunity because as practical solutions are being implemented, that knowledge again dissemination will accelerate further because people will basically use it as a precedent.

00:35:49.670 --> 00:35:50.902
So that's one aspect.

00:35:50.902 --> 00:35:53.067
And then there's a question of cost right.

00:35:53.067 --> 00:35:56.103
Those solutions will remain costly as they disseminate.

00:35:56.103 --> 00:36:02.369
They will remain costly, which will force the issue of more and more fundamental understanding on the probability of occurrence.

00:36:02.369 --> 00:36:07.326
Would it be cheaper to prevent it from happening in the first place than mitigating the consequence?

00:36:07.326 --> 00:36:11.581
And I think that will over the next again, three to five years, maybe a little bit longer.

00:36:11.581 --> 00:36:16.545
We will see that change a little bit and the shiftID onset and whatever happens later.

00:36:16.545 --> 00:36:16.764
I'm done.

00:36:34.161 --> 00:36:40.688
Access to firefighters in X time which we believe is sufficient to deploy, like what would be your goal in design.

00:36:41.260 --> 00:36:48.762
But do you mean in the context of just looking at the consequence or trying to also think about the probability of occurrence?

00:36:48.762 --> 00:36:50.166
No, just consequence.

00:36:50.527 --> 00:36:51.210
Just consequence.

00:36:51.489 --> 00:37:01.202
Yeah, I think you know, and Ali alluded to this earlier on right, like if you have a single vehicle catching fire, single EV catching fire and you've got, for whatever reason, I guarantee that it's not going to spread.

00:37:01.202 --> 00:37:04.257
For example, it's a single vehicle in a large space, you let it burn.

00:37:04.257 --> 00:37:10.364
It's not going to bring the building down or a car park down Highly unlikely unless something else was done Not quite right.

00:37:10.364 --> 00:37:13.945
So limiting the spread is the name of the game when it comes to fire.

00:37:13.945 --> 00:37:22.932
From that point of view, even if two vehicles were to burn, that's okay and there's no number, I guess that you could throw an absolute and say that would be okay.

00:37:22.932 --> 00:37:25.494
It all depends on the circumstances where those cars are.

00:37:25.494 --> 00:37:38.702
But you could manage individual vehicle or individual vehicles on fire, evs and obviously once the fire starts spreading, it doesn't discriminate, it doesn't care if it's internal combustion engine or ev next to it, as long as you limit the spread.

00:37:38.702 --> 00:37:41.840
That's probably the single most important thing from the point of view of fire.

00:37:41.940 --> 00:37:50.331
I'll emphasize that um just to highlight that distinction yeah, and the tools, things that come to my mind obviously, sprinklers, that would be your game.

00:37:50.331 --> 00:37:53.922
Uh, in here not not that popular though I think.

00:37:53.922 --> 00:38:03.588
The ev hazard, even though, if you may agree that it's not that much difference than combustion engine hazard, but, uh, it makes a change.

00:38:03.588 --> 00:38:12.547
Like people would like to install them because of this new hazard, even though we may agree that from the heat release rate or total energy release, it's all.

00:38:12.547 --> 00:38:15.411
Park similar separation distances, but that's very difficult.

00:38:15.411 --> 00:38:17.751
We want to pack as many as we can to car parks.

00:38:18.655 --> 00:38:23.289
I like playing with the heights of the ceiling because I feel there's a huge value in.

00:38:23.289 --> 00:38:25.114
Yeah, very important, very important.

00:38:25.114 --> 00:38:31.027
And we saw that we just burned the car during the summer school and the ceiling was at three meters.

00:38:31.027 --> 00:38:35.527
You could see like, once the fire hit the ceiling, you could see how it went quickly.

00:38:35.527 --> 00:38:42.284
You know, I strongly believe it is a huge variable Walls, opening factors, whatever else comes to your mind.

00:38:42.284 --> 00:38:52.021
How do you realistically affect or decrease the probability that fire will spread between vehicles or and, in consequence, you're going to limit the consequences of the?

00:38:52.061 --> 00:38:52.302
fire.

00:38:52.302 --> 00:38:55.153
Well, you mentioned separation, and separation.

00:38:55.153 --> 00:39:12.655
Distance is powerful, right, but, like in absence of a distance between the vehicles, you can bring in a separation, a physical separation that's not necessarily there in place from the beginning but is retractable or dropped or put on an offending vehicle or serious vehicles and isolated.

00:39:12.655 --> 00:39:18.362
The challenge with these, especially the more permanent barriers or rigid barriers, is that you may exacerbate the issue of explosion.

00:39:18.362 --> 00:39:31.724
You may exacerbate the issue of explosion Because those elements that separate the fire, especially the rigid ones, will likely allow accumulation of the flammable gases if it is released from a battery without being ignited.

00:39:31.724 --> 00:39:35.501
So that's a very, very important consideration that's often lost in the discussion.

00:39:35.501 --> 00:39:46.643
And the other thing and that goes, I guess, around moving into the explosion aspect, once you start releasing the gases and you ignite a flammable gas cloud that is accumulated in a particular space.

00:39:47.836 --> 00:39:49.181
And I'm going to add one more thing.

00:39:49.181 --> 00:39:54.181
There are other aspects which are not engineering, but broader design.

00:39:54.181 --> 00:39:58.222
So how are you designing your space in terms of the layout of cars?

00:39:58.222 --> 00:40:03.324
How are you designing it in the sense of providing access to fire service?

00:40:03.324 --> 00:40:07.967
How are you doing it with respect to how people can get out of that area safely?

00:40:07.967 --> 00:40:11.815
And those things are really important too in terms of what the consequences are.

00:40:11.934 --> 00:40:29.271
So if you think about these early in the design so the EVs are not an afterthought, but you know you're going to have a certain number and you can start looking at how am I laying them out and how close are they to openings and how easy is it for the fire department to come in?

00:40:29.271 --> 00:40:37.148
And can I protect people to be able to evacuate if needed in a way that gives them time and they're exposed to less risk?

00:40:37.148 --> 00:40:40.364
And all those things really do drive the consequences.

00:40:40.364 --> 00:40:47.460
They drive the strategies on how to fight the event, both the explosion and the fire side of it.

00:40:47.460 --> 00:41:12.525
So when you're looking at eViz, it's best to look at it as something that can inform all of the design and have that conversation early on and have that holistic design, and then you can converge to a solution, that's a much better solution and it's a much cheaper solution as opposed to coming to it at the end and most of your design is set and now your options are much more limited.

00:41:12.875 --> 00:41:13.960
And what about the explosion hazard?

00:41:13.960 --> 00:41:20.382
There's a lot of details that don't really matter all that much from the fire point of view, but they do matter from the point of view of explosion.

00:41:20.382 --> 00:41:23.969
So confinement and congestion are two key elements, right?

00:41:23.969 --> 00:41:35.181
So confinement speaks to inability of burning gases or hot gases to expand, and when you prevent that expansion from happening, you've got pressure rise basically.

00:41:35.181 --> 00:41:35.983
So that's one element.

00:41:35.983 --> 00:41:38.402
And then anything that changes the flame speed.

00:41:38.755 --> 00:41:45.443
If you throw a lot of congestion into it, the flame speed, hence the flame itself, the flame front tends to change its shape.

00:41:45.443 --> 00:41:49.706
You've got a bigger surface of heat transfer and you start accelerating the flame front.

00:41:49.706 --> 00:41:56.469
And you can in the case of hydrogen, that's a known fact you can basically turn deflagration into detonation.

00:41:56.469 --> 00:41:59.364
Ev of gas is 35%, roughly hydrogen.

00:41:59.364 --> 00:42:00.777
It's a mix, obviously.

00:42:00.777 --> 00:42:05.023
So you're dealing with a much more complicated gas mix from the combustion chemistry point of view.

00:42:05.023 --> 00:42:10.559
But you know there's no research right now that says you will not change that.

00:42:10.559 --> 00:42:17.623
You will not transition from deflagration into detonation and, given the high hydrogen content and its characteristic, that's something to look at.

00:42:17.623 --> 00:42:29.429
And even if you don't change, if you don't basically end up with a detonation, congestion or any element that will accelerate the flame front will lead to significant increase of overpressure.

00:42:29.958 --> 00:42:30.911
It's just that trade-off.

00:42:30.911 --> 00:42:33.822
Right, sometimes all your objectives are in line.

00:42:33.822 --> 00:42:38.123
You can mitigate everything with the same tools.

00:42:38.123 --> 00:42:52.608
Between fire and explosion there's that trade-off where sometimes you do something that makes fire better and explosion worse, or vice versa, which means when you're trying to come up with the right solution, it's the right solution in the context of a specific building.

00:42:52.608 --> 00:42:54.862
It's not the right solution everywhere.

00:42:54.862 --> 00:43:00.208
It's the right solution for that building in that particular condition, with those sets of TVs in those places.

00:43:01.177 --> 00:43:06.199
Do you have any experiences with using ventilation or smoke control for mitigating the explosion hazard?

00:43:06.199 --> 00:43:07.141
Absolutely.

00:43:07.744 --> 00:43:15.036
That's one of the best ways in the sort of department of once the thermal runway happens, can you prevent the explosion from occurring?

00:43:15.036 --> 00:43:16.300
The answer is yes.

00:43:16.300 --> 00:43:21.559
If you ventilate the hell out of the place, then you will basically prevent gas accumulation.

00:43:21.798 --> 00:43:22.521
How do you detect?

00:43:22.521 --> 00:43:25.628
Because you assume you would like to have it automated, right?

00:43:27.059 --> 00:43:32.226
Yeah, so there's a number of different and it's obviously a nascent technology in a nascent area and it's evolving.

00:43:32.226 --> 00:43:39.313
But there's a number of different sensors that allow you to get somewhat of an advanced notice of a gas detection.

00:43:39.313 --> 00:43:43.043
Some are focused on hydrogen, specifically hydrogen gas detectors.

00:43:43.043 --> 00:43:49.090
Some are focused on the actual lithium-ion gas mixture release.

00:43:49.090 --> 00:43:53.282
A lot of them are based on particle permillion, basically the gas particles that are in the air.

00:43:53.282 --> 00:43:57.699
Some of them are focused on temperature, some of them are focused on pressure.

00:43:57.699 --> 00:44:07.806
There's a whole suite of different sensors that allow you to do this and I'm going to say allow with again another one of those quotation air quotes, so to speak.

00:44:07.847 --> 00:44:25.219
We're not aware of a single silver bullet over here, but it is a critical element, as you've pointed to, wojtek, in terms of you know, when you kind of trigger, obviously one answer would be to say, okay, in a highly critical space you might just run your active ventilation system all the time, but then it becomes incredibly costly.

00:44:25.559 --> 00:44:43.643
But you know, I only mentioned that to highlight that active ventilation system and we're not talking about insignificant rate of error changes, right, it's a significant amount depending on the details that you would have to exchange per hour to make a problem go away, but it is doable, it is possible to basically make the problem go away.

00:44:43.643 --> 00:44:49.681
So and I specifically mentioned that in the context of, let's just say, you have a relatively small room within the building.

00:44:49.681 --> 00:44:58.137
You're not talking about any e-parking, but you're talking about scooters and bikes, e-bikes and e-scooters in a relatively, again, small room that is fully enclosed.

00:44:58.137 --> 00:45:00.440
So a potentially bad scenario.

00:45:00.440 --> 00:45:20.411
You can design a ventilation system that will exhaust all of the gases from this thing before any explosions can occur, and this is not, again, an expensive solution, but not a practical solution in terms of even running that system all the time, so that you don't basically get any gas, flammable gas, accumulation in there.

00:45:20.896 --> 00:45:25.144
I'm going to ask you a horribly difficult question, but if you would have an answer, that would be amazing.

00:45:25.144 --> 00:45:28.802
Any idea what would be the flammability range for those mixtures?

00:45:28.802 --> 00:45:29.925
A ballpark assumption?

00:45:31.596 --> 00:45:33.222
That's a difficult question, I know.

00:45:33.222 --> 00:45:40.961
Yeah, I think that we're operating under the flammability range that is not dissimilar from hydrogen.

00:45:40.961 --> 00:45:41.724
Okay, that's massive.

00:45:42.755 --> 00:45:43.277
That's massive.

00:45:43.277 --> 00:45:47.740
Obviously I like this discussion because we're Polish, so you can resonate with that.

00:45:47.740 --> 00:45:53.992
In Poland we had these propane-fueled tanks and we tried to kick them out of car parks.

00:45:53.992 --> 00:45:54.677
It didn't happen.

00:45:54.677 --> 00:45:57.485
So we had to figure out how to allow them safely in car parks.

00:45:57.485 --> 00:46:03.059
So we've developed systems to detect propane gas to activate ventilation in those spaces.

00:46:03.059 --> 00:46:08.750
Propane is also heavier than air, so it spreads on the floor, not underneath the ceiling.

00:46:08.750 --> 00:46:24.708
So I kind of find a lot of similarity between those hazards that we've already learned to deal with, at least in Poland, in terms of LPG-fueled cars, and potential explosion challenges brought by the world of electric vehicles.

00:46:24.708 --> 00:46:33.309
Do you know how common it is that the thermal runaway gases do not ignite and form this hazardous cloud?

00:46:33.309 --> 00:46:34.601

169 - Engineering car parks for EV's with Ali Ashrafi and Pawel Woelke

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