Matt Simon: Long-Duration Energy Storage

When we think about the transition to renewable energy sources, many of us imagine rooftop solar panels and wind turbine-dotted hills. But it’s not just about capturing energy, it’s also about keeping it. This week on Sea Change Radio we speak with Matt Simon, a Grist senior staff writer, to discuss long-duration energy storage. The transition to renewables for utilities is still very much evolving — efficiency, intermittency, and storage are among the issues scientists have yet to perfect. Simon shares some ideas for how we can build upon existing technologies to store solar and wind power, with longer capacity than lithium-ion batteries, ranging from reservoirs and caverns to our existing fleet of electric vehicles.

Narrator | 00:02 – This is Sea Change Radio covering the shift to sustainability. I’m Alex Wise.

Matt Simon (MS) | 00:23 – We’re actually in this really fascinating time where we are better understanding that the Earth is a resource not for extracting the fossil fuels out of it. That’s stupid and done. We need to stop doing that now. We’re turning more to the energy that is naturally produced by the earth, but also the energy that we can pump underground, for instance, and store down there as a battery. It’s a fascinating frontier.

Narrator | 00:48 – When we think about the transition to renewable energy sources, many of us imagine rooftop solar panels and wind turbine-dotted hills. But it’s not just about capturing energy, it’s also about keeping it. This week on Sea Change Radio we speak with Matt Simon, a Grist senior staff writer, to discuss long-duration energy storage. The transition to renewables for utilities is still very much evolving — efficiency, intermittency, and storage are among the issues scientists have yet to perfect. Simon shares some ideas for how we can build upon existing technologies to store solar and wind power, with longer capacity than lithium-ion batteries, ranging from reservoirs and caverns to our existing fleet of electric vehicles.

Alex Wise (AW) | 01:50 – I’m joined now on Sea Change Radio by Matt Simon. Matt is a senior staff writer at Grist. Matt, welcome to Sea Change Radio.

Matt Simon (MS) | 01:58 – And thank you for having me. 

Alex Wise (AW) | 02:00 – It’s good to have you back. You have left wired after a dozen or so years there, and congratulations on joining Grist covering climate. How’s the transition been so far for you?

Matt Simon (MS) | 02:13 – Thanks. Yeah, it’s been fantastic. It’s, um, it’s amazing to be here with a truly phenomenally talented group of people that are laser focused on climate stuff. So I’m, I’m here covering climate solutions, which I feel like, um, is the most optimistic way, um, for my mental health to be approaching climate coverage this day and age. Um, so I’m feeling surprisingly good. 

Alex Wise (AW) | 02:37 – I wanted to discuss a piece you’ve written for Grist recently, which delves into long duration energy storage. We often think of just energy storage as battery storage, and that’s a very short-lived type of energy. If you can define long duration energy storage, how the people who run electric grids look at this piece of the puzzle, that would be terrific.

MS | 03:03 – Sure. So the core of the issue here is that as we are deploying more renewables like wind and solar, we need ways to store that energy. So when the wind isn’t blowing or the sun isn’t shining, we need electricity to flow to people’s homes. Um, so the idea here that a lot of people have probably heard about by now is that you have these giant banks of lithium ion batteries on the grid. We have, uh, some of these in California already. They have these also in Texas, wherever you’re seeing the proliferation of renewables, you’re seeing these battery banks pop up. Um, so the idea here is that you, uh, have the sun go down. You’re not generating any solar energy. You draw from those battery banks to give people electricity. Uh, the issue is that even a very large lithium ion battery bank will discharge in about four hours, and that is not nearly long enough to hit you through the nights. 

AW | 03:58 – So it’s like a stop gap measure for renewables during like a heat wave or something, let’s say. 

MS | 04:03 – Exactly. So it’s, this is, this is short duration energy storage. What we’re now thinking about on a, a bigger scale is long duration energy storage, and these are techniques that store energy for half a day or longer. So one technique that is already in existence, and in fact there’s, there’s over 40 of these in the United States that probably not many people have, have heard about. Um, this is, um, using the, using gravity and water to, to store electricity in this, I guess more specifically, you’re storing energy that you then turn into electricity. So what happens is when there’s a bunch of renewables on the grid, uh, if it’s windy or sunny, you pump water up into a reservoir, and then when that energy disappears, those energy sources disappear during the day. Um, when it’s not windy or at night when it’s not sunny, you let that water flow back down downhill that spins turbines generates electricity. So you’re essentially using the landscape itself as a enormous battery, and you can store a lot of water in these reservoirs and, you know, tap into this energy for half a day or longer. So if, um, you know, it’s a cloudy week, um, for instance, and you’re not generating much solar energy, you’re still generating some, but not nearly as much as if it were a sunny day, um, you can fall back on these long duration energy storage techniques. Um, so it’s, it’s just thinking on two timescales. We’re still going to need a bunch of batteries on the grid to be sure. Um, but this is going to be backup for that backup essentially. 

AW | 05:40 – And, and explain the difference between this reservoir source that you’re describing from traditional hydroelectric power.

MS | 05:51 – It’s essentially the same thing. It’s just working two ways. So hydropower, yes, you have a reservoir and you are letting that water loose, uh, by way of gravity turning the turbines to produce electricity. This just reverses that essentially. So it, it sends that water, you pump it uphill once again when you have a lot of renewables on the grid, um, and let it flow back downhill, back and forth and back and forth. It’s, it’s a, an additional layer to traditional hydropower as we think of it. 

AW | 06:21 – And it’s, it’s a lot less dependent upon a water source like a, a river or a waterfall, et cetera. And so, like this company, was it Toronto based company, hydro store shoots water up in from caverns, and maybe you can explain it, but they basically create these reservoirs wherever they need to be. 

MS | 06:42 – Yeah. What they’re doing is a little bit different from that, that more traditional hydro storage that, that we were talking about. They’re using underground caverns for sort of the same purpose. So what they do is that when, again, there’s renewable energy on the grid, they pump air underground, um, this forces the water in that cavern up to the surface where it pools, and then when you need that energy, that electricity, you let that water flow back underground forces that air back up to a facility where it spins turbines and produces electricity. Slightly different, but it’s actually probably more versatile in the United States because you can cite that more places than, you know, with the hydro stuff. You have to have a reservoir above and a reservoir below. You’re a little bit more restricted in where you can put those but what this this company is doing is probably going to be able to be deployed, uh, much wider in the United States. 

AW | 07:38 – Yes, that’s what I was trying to understand is, is can an existing facility utilize their technology? Can you always access caverns if you just go deep enough and then create these reservoirs right at the source? So, uh, close enough to the power plant to use it as a long duration energy storage system? 

MS | 08:00 – So these are purpose built facilities for this company. So it’s like you have to build this from scratch, but what you can do is tap into caverns that are either naturally occurring in the ground, um, or have been previously dug out by these, um, these hydrocarbon industries. So the extraction of oil and gas leaves caverns, and they can actually then utilize these now instead for renewable energy, which I think is a, a neat little, a little turn. Um, so yeah, the idea is that you can either use what’s in the ground naturally, what has been dug, or you can also dig your own caves and, uh, you’re again turning the landscape itself into a battery by storing energy in these, these really interesting ways. 

AW | 08:46 – Ho