EPRI Current Excerpt—Battery Energy Storage Systems: Lessons in Safety, Risk, and Deployment
With the causes and impacts of the Eaton & Palisades Wildfires in Los Angeles and Moss Landing fire bringing into sharp focus both the resilience opportunities that Distributed Energy Resources afford as well as safety concerns surrounding battery deployment in communities, VX News shares this excerpt from a recent episode of the EPRI Current Podcast featuring host, Samantha Gillman, EPRI Energy Storage Technical Executive, Stephanie Shaw, EPRI Energy Storage Principal Team Lead, Lakshmi Srinivasan, and Senior Research Engineer in the Research Environment and Sustainability Group of Southern Company, Kieran Claffey, who elaborate on the evolving safety protocols, research and resources—including EPRI’s Battery Electric Storage System Failure Incident Database and Analysis on Failure Root Cause—informing operational best practices for deployment of battery and energy storage technologies.
“This high visibility brings a growing awareness of battery storage in the public sphere. We’re seeing this with an increased interest, both from the media and also during BESS permitting processes, where public interest and comments are playing an increasing role in how projects are evaluated.”
Samantha Gillman: Stephanie, can you quickly give us an overview of the current landscape of battery energy storage in the U.S.?
Stephanie Shaw: Battery energy storage deployment continues to grow rapidly — this is happening both in the U.S., but also globally. In the past three years, around 40 gigawatts has been added, which is amazing. Now, 90% of what’s been installed is lithium-ion battery based, although there are a variety of other technologies. We have our traditional pumped hydrological storage, and a bunch of new technologies that are in development as well.
This high visibility brings a growing awareness of battery storage in the public sphere. We’re seeing this with an increased interest, both from the media and also during BESS permitting processes, where public interest and comments are playing an increasing role in how projects are evaluated.
Samantha Gillman Speaking of media attention, we’ve seen a lot of stories lately about the safety of battery energy storage. Lakshmi, let me ask the blunt question: is it safe?
Lakshmi Srinivasan: Energy storage has been operated safely and will continue to be. We have batteries in our laptops and cell phones, and we’re comfortable with them. Like any technology, grid-scale battery storage carries some risk, and there’s still risk reduction to be done.
Our work at EPRI has pushed some of that research forward. We've done a lot of work on root cause analysis for battery failures, for improving designs, for doing risk assessments, and some of our research has shown that the failure rate of batteries at the grid-scale level has dropped significantly, 97% in the last few years, and that's down to improvements in the design and codes and standards and operational learnings.
We're continuing to reduce the frequency and the risk of these failures, while also learning to improve the design and how to respond to these incidents so the impact is minimized.
Samantha Gillman: Interesting! Over to you, Kieran. Working for a company that deploys energy storage systems, how has Southern Company been utilizing this research that Lakshmi is referring to and working alongside EPRI?
Kieran Claffey: I think some of the work EPRI is doing is at the cutting edge —the tip of the spear for this technology. It is helping us explain the need for it [energy storage], and to basically to mitigate the fears that are out there.
Lakshmi made the point about operating safely. When I get asked, “Are they safe?” I make the comparison to cars. Driving a car at 120 miles per hour down the road isn’t safe, but it depends on what you do with it. What EPRI is helping us do is to not drive that car at 120 mph--they’re helping us drive it at a good 60 mph, right at the speed limit.
Samantha Gilman: Great analogy. I like that. And speaking of these news stories, we’ve seen quite a bit particularly around the Moss Landing facility in California. Stephanie, what can you tell our listeners about how this may impact the industry going forward?
Stephanie Shaw: Any failure of a piece of infrastructure like this is going to get a lot of scrutiny to try to understand what the process was, what happened. A root cause analysis will occur, and then the insights from that analysis will be brought across the industry to help inform designs of battery storage systems.
It may inform response strategies for any emergencies that may occur, no matter how low the likelihood of that happening is, and they’re used as the basis for future research to make all of these strategies both safer and more robust moving forward.
Samantha Gilman: Speaking of a particular incident, it’s my understanding that EPRI keeps a record of all of these sorts of incidents that happen. Can you tell us a bit about that resource that EPRI is collecting and maintaining?
Stephanie Shaw: EPRI created a Stationary Storage Failure Incident Database. Lakshmi actually maintains that, so you probably want to go to her for a longer answer.
Samantha Gilman: Ah, excellent, Lakshmi, tell us about this database.
Lakshmi Srinivasan: This database was begun in 2021, and it’s entirely public. A search for “Storage Wiki” or “EPRI Failure Database,” will lead you to it.
We gather information from news and public media sources on battery failure incidents, and capture not just that it happened, but a lot of other information around that incident to help understand, and then improve, future designs and responses as Stephanie said.
So we capture things like, what was the design, what was the chemistry of the technology involved, what was the description of the event? What was the civic impact? What was the environmental impact? We're gathering all this, and then we use that to not only inform the industry about these events, but also understand what are insights that we can take from the aggregate view of looking at all these incidents in context for the deployment in the industry, and also for the incidents themselves.
We recently published a paper last year on looking at root causes for these events, and we're working on new research to understand if we can provide more statistical assessment of the impacts of failure.
These are all intended to understand why and how these events happen and how we can prevent them in the future. Gathering the information is a first step to understanding how to prevent failures.
Samantha Gilman: Taking it one step farther. What are some of the recommendations that people can do today to improve safety?
Lakshmi Srinivasan: Safety is a multi-layered approach, right? There are a lot of things you can do, starting at the cell level all the way up to the system, through all phases of a project.
One of the key insights that we pulled out from our recent research is the importance of the commissioning phase of a project—that's really where all the different parts of a battery, all the different manufacturing entities come together to build a product on the site and install it. That’s a phase where bringing more quality control, rigor, testing and awareness of safety during that process can really eliminate failures, as we've seen.
A lot of the failures we record in our database happened within the commissioning or first couple years of a project. So, making sure that the connections, the integration, the testing is all done with quality and rigor, is really a key place to focus for especially new projects going into the ground.
Kieran Claffey: Can I make a point there? During COVID, I read the entire EPRI event database because it was there, and I could learn from it.
What I did learn from it was a lot of these incidents were occurring during commissioning. So, it's great that you've connected the dots for us on that, and has actually helped us with our commissioning process. We implemented a thing called a Pre-Startup Safety Review. And basically what that is, is anything that's been given credit in a hazard mitigation analysis or a failure modes and effects analysis gets physically tested and has witness testing on site.
That's an extra commissioning test that we do at Southern Company based off of the knowledge that we gained from looking at all the events that were occurring.
It seems now, looking back in hindsight, like a simple thing, but I think that's definitely helping us. And I'm telling other utilities that that's our recommended practice. That's what we have been doing for our fossil fuel plants. So, we're taking a utility process, and we're making it relevant to lithium-ion BESS.
Samantha Gilman: To continue that conversation, what else can be done to avoid or eliminate fire risk?
Stephanie Shaw: The work that we're doing in collaboration with the electric power companies has provided a long list of leading practices that we've all learned over the years. That includes everything from ways to specify or request certain safety features in the request for proposal for a project; specific operational strategies, what kinds of limits do you use on certain metrics that might be measured when the system is operating; or the types of sensing to detect if anything abnormal might be happening and alerting and checking functions as the system is being operated.
So, there's a whole host of details like that can be incorporated, along with a lot of specifics on design features, such as the amount of spacing between various sections of capacity that the storage system creates. Or the way that you would design a mitigation technique if abnormal operations begin. What are things that could be done to make any potential rare event, even less impactful, like making sure that the ventilation is handled properly.
And then, of course, there's a lot of training going around, not just between the developer and the owner to make sure that the system moves forward and operates the way it should, or that it was commissioned that way, but between other stakeholders, like the permitting authorities as well as the first responders that might respond in the event of an incident, because there are some different strategies that you use when you have stored energy in a battery versus stored energy in a fossil fuel, and those strategies are actually pretty well developed at this point and tested, but it's important to get that information out to responders so that they feel comfortable at the point of evaluating the design of a facility.
Samantha Gilman: A lot of what you all have talked about so far is sharing these best practices and sharing what Southern Company has learned with other electric utilities out there. Kieran, I’m hoping you can speak a little bit to the LDES—also known as Long Duration Energy Storage—National Consortium Safety Working Group. That’s quite a title for a working group, but can you tell us about the activity with that group?
Kieran Claffey: We’re looking at emerging energy storage technologies beyond lithium-ion, more so in the 10-hour-plus duration. Lithium-ion, we think, will have a shorter duration, up to about maybe six hours.
But these technologies that are emerging—the vendors that are doing this fantastic research, which we need—are focusing on their box and making it operational. Safety is kind of like, “Yeah, we’ll get to that.”
But I’m like, “No, no, no. You have to do it. You have to do it all in unison. You have to do it all together and think about these things.” The Achilles heel in lithium-ion batteries is thermal runaway. But for another type of chemistry, it may be hydrogen evolution and explosion risk. The UL9540A test doesn’t test the worst-case for that particular chemistry, and yet the industry wants you to have that UL test, even though that test was set up for lithium-ion batteries.
We need to develop a new set of testing for these emerging technologies. Well, first of all, we need to figure out what those technologies will be and try to get them into the code as early as possible. The codes were lagging with lithium-ion batteries, and we don’t want to make that mistake with these longer-duration energy storage technologies.
You can say it's a mistake, and everyone’s vision is 20/20 after the fact, but we’re learning very fast and want to get it right with these technologies.
Lakshmi Srinivasan: I’ll add that EPRI is looking at these other emerging technologies, and we’re considering not just performance, commercial viability, and technical maturity, but also safety and other aspects. One of the things we’re doing specifically is learning from frameworks that we have for understanding hazards and risks for lithium-ion, that we’ve developed over the last few years, and applying them to these new technologies and adapting them. We’re taking a lot of that learning forward.
We’re not starting where we started with lithium-ion as the initial technology. We’re a couple of steps ahead of these new technologies and learning what questions we need to ask of them.
Stephanie Shaw: Just to continue in this vein, it’s really important that as these technologies evolve, they're not just scaling, they're changing, and they’re being tested. We're doing demonstrations, and we're giving that feedback back. That feedback includes the performance, safety, and potential environmental considerations, and then that goes into the design process, so it's an iterative process. We're not waiting until those technologies come to market to do these assessments. We’re doing them now to help make sure that what comes out on the market is viable moving forward.
Samantha Gilman: We’re at just about time, but I want to allow each of you to leave any final thoughts with our listeners — maybe something you weren’t able to mention during our conversation, particularly about the benefits of energy storage and why we are continuing down this path. Lakshmi, let me turn to you first. What final thoughts do you have for our listeners?
Lakshmi Srinivasan: I think safety is one of those aspects of a technology that really invites — and requires — collaboration and cooperation, not competitiveness. It’s an important space for bringing in the whole set of stakeholders within an industry and sharing information and learning from each other. That is a key aspect of safety.
And the other side of it is that every technology carries risk, but it also has benefits. So, to your question about benefits, I think there’s a need to better communicate and understand what benefits storage can bring to communities. For the neighborhoods and places that are being chosen to site these technologies — what are the tangible benefits they get from hosting that technology? I think that needs to be better understood and communicated, so that the risks are balanced appropriately with the benefits to society and to those communities.
Samantha Gilman: Stephanie, what about you?
Stephanie Shaw: One thing I want people to understand is that even as the potential risks from these storage devices have been dropping rapidly, EPRI, the electric power companies, people in this space — we’re doing more and more to try to prepare for a potential failure, even though that risk is dropping.
That’s because we’re taking a precautionary approach. We’re trying to look at all of the potential leading practices that can continue to make everybody involved safe and still provide those benefits of storage.
Samantha Gilman: And Kieran, any final thoughts for our listeners?
Kieran Claffey: From the utility perspective, we’re deploying a lot of solar because it’s the cheapest generation for the model load. But solar is not reliable on its own. We need batteries to make it reliable, but we’re deploying it because it makes economic sense. That’s the first thing. The first benefit for society is going to be cheaper electricity for you.
We also have net-zero goals for 2050, and energy storage helps us with that. Lithium-ion batteries, we need not be afraid of deploying on a mass scale. It’s like driving a car. We just need to drive the car at an appropriate speed, and it will be safe. And it is safe — if we do that. It’s an amazing tool for society, and we should deploy a lot more.
