Thermal runaway in Li ion batteries: a problem we'll need to contend with if we are going to keep using them (and at scale). Oh, and while you struggle to pay your Xcel bill, others get a discount.
Thermal runaway in lithium ion (Li-ion) batteries.
The LA Times story linked first below was shared by a reader and I wanted to put it up and discuss a bit. It deals with fires at some of California's electric grid battery storage facilities and the concern it causes to those living near to them.
If we are to make renewables and battery storage of renewable energy an effective means of supply for our grid, we are stuck right now with liquid Li-ion batteries because the best alternatives that we know of are either years away or they cannot provide a rapid burst of energy to meet quickly-changing loads on our power supply. That is, things like the iron-air battery proposed to go near Pueblo doesn't supply current quickly enough and the solid state Li-ion batteries (which are not as fire prone as liquid) are years away.
So, if we're going to use chemical batteries as storage for renewable energy, right now the only option we have that can scale well is liquid Li-ion batteries, which, though they're improving, by their chemistry have the potential to burst into flames suddenly.
Heard about this in local news when we talk about transitioning Colorado? Yeah, me neither.
Battery storage will be integral to any plan to remove any and all fossil fuel generation in this state. Period. End of story.
Right now, the options we have for this are few and far between.
There is talk about hydrostorage batteries. Feasible and safe, but whose canyon gets put underwater? Guessing it won't be anywhere near Boulder or the Front Range.
We have the iron/air battery going in at Pueblo, but that technology is unproven at scale and will also not work well to meet rapidly-changing conditions on the grid (e.g.if the wind shifts which it's been known to do). Think of it more like banked coals. Warm and will remain so a while, but slow to respond if you wanted hot water suddenly.
If the Democrats running this state continue on the path they're on, if they listen closely to the extreme voices of some environmentalists, we will give up any and all fossil fuel generation before an apples to apples replacement, not only in terms of cost but also in terms of safety of generation.
It wouldn't be the first time this state followed California's more foolhardy decisions, but try to act surprised if it happens (if out of politeness if no other reason).
https://www.latimes.com/business/story/2023-10-12/battery-storage-is-a-key-piece-of-californias-clean-energy-transition-but-theres-a-problem-with-fires
In the previous post I discussed some trouble that California is having at some of its battery farms from "thermal runaway" in their lithium ion (Li ion) grid storage batteries.
If you're at all like me, after hearing about the problem, you'll ask yourself what causes thermal runaways in Li-ion batteries in the first place.
Well, I did ask, and I did look. Before I get into the details, let me warn you that I am a physicist and not a chemist. Expect more of the details of the dynamics (how things change with time) than about specifics over chemistry here. I do not know and cannot give the details on how it is that a defect starts in a battery or the chemical reactions that scoot it along.
This will also be a layperson's intro. I included a link below that is a bit of a stretch for a layperson, but if you can handle some technical detail, it's a good starting point. What I write here will be a step down from that.
Thermal runaway, like any other chain reaction, is the result of a positive feedback loop. But, like all loops, you need a seed to get things going. Some event that starts things off.
For a Li ion battery this could be a number of things. A fault in the manufacturing process, a mechanical failure in the material, some damage from an external source, trying to charge too much or too quickly (or the same but with discharging), the idea being that some event kicks off a specific kind of chemical reaction inside the battery that produces more energy than it takes to start the reaction.**
The excess energy from such a reaction causes the surrounding material to start to react. Which causes that material to start to react, and off we go.
You see, the reaction that I'm talking about here depends not only on the chemicals being present, but it's speed depends on the temperature, so you have a positive feedback loop where the more the reaction happens, the more it can happen, and the faster it will happen.
Mathematically, what you're looking at is an example of a situation where the rate is proportional to the quantity present at any one time.
To do a full treatment, I'd have to go into some calculus, but we don't need that for a rough understanding (that is, I'll give you the same thing you'd do in calculus, watching a reaction progress at equal time intervals, I'll just do it in the slowed down version).
I wrote out some quick, made-up numbers in a table to give you a sense of what this looks like. I also attached a graph of what this looks like where my numbers are in blue and a comparison with a reaction which progresses at a steady rate looks like in orange. I attached that as a screenshot.
In my example, we start off with 10 units of reaction. The rate the reaction proceeds at is always the amount present times 0.5. To advance to the next time step, we use the rate plus the current quantity. This becomes our next seed value. So, as in the table, we start with 10, the rate is 5 and so at the next time step (1 second later) we have 15 units which becomes our next value to calculate our rate and so on.
To make a comparison with a steady rate increase, you would simply add 5 to the value each time. This is the orange line and it's made by 10 + 5 = 15 at the beginning, 15 + 5 = 20 for the next time step, and so on. You add 5 each time.
See the difference between a chain reaction (blue line) and the linear increase (orange)? This is why batteries run away.
A seed event, say something breaks in the battery and a short circuit causes enough heat to break down the materials of the battery, starts off a reaction which introduces enough heat to start the material around the short to break down. This breakdown creates more, exponential growth of the heat happens, and up the blue line you go.
The reference I linked to below goes into a bit more detail on what engineers are currently doing to try and fix the problem. They are getting better (from what I read here and in other places), but my intuition tells me that the solution will be mainly one of being able to wall off the fire rather than eliminating its cause (for Li ion batteries at least). This is alluded to a bit in the interview I used as a reference and I think it sound reasoning about the problem.
I say that because the fault is in the exothermic reaction which is a property of the materials you make the battery from. Perhaps some different chemistry could eliminate the problem, but then you run the risk of having a different voltage in the cells.
We'll see where things go. It's hard to predict the pace of changes and I wonder which will come first: a rival technology without this fire risk, or a substantial improvement.
**If you have had any chemistry, this will likely ring a bell in your head. The proper term for this kind of reaction is exothermic--heat generating. Hand warmers (the kind you shake and put in your shoes or gloves) are a ready example of such a reaction. The chemical reaction releases heat as it progresses.
https://www.batterypoweronline.com/news/thermal-runaway-understanding-the-fundamentals-to-ensure-safer-batteries/
One last niblet on electrical energy: special rates from Xcel for their preferred (big) customers?
It used to be mines and other heavy industry that was the big draw on the power grid (I'm thinking of what used to be called CF and I steel, now Evraz, and their electric blast furnaces--those must've been a HUGE load), but apparently data centers coming to Colorado are the new big player on the stage.
Sign of the times, I suppose. Our state has long been moving toward a "knowledge economy" (look at the demographics and the education levels of those moving here, along with the businesses that are moving here too).
As I've written before, I have no problem with economic change that is what I term "organic" (happening due to market forces and not mandates). In that sense, data centers coming in and soaking up electricity is fine.
As long, that is, that they pay the same as any other big draw.
I get the sense that this has the potential to not be the case from the Sun article linked below. Xcel has long offered different electric rates to big customers and the data center profiled is no different. Xcel is going to offer them a discount (right now confidential) on their electric service if the PUC okays it.
To see some of the arguments against the deal Xcel is proposing, take a look at the lengthy quote from the article (attached as a screenshot).
I don't disagree. I'm okay with a discount that's in line with what Xcel has done before. But I'm not going to shoulder yet more utilities cost to help a data center that doesn't share its profits with me.
They (or Xcel, I don't care which), can pay their own way.
https://coloradosun.com/2023/10/11/aurora-data-center-to-become-one-of-xcels-biggest-customers-rivaling-mines-and-steel-mills/