Pumped Thermal Energy: the Overlooked Storage Solution with Alexis Dole (SynchroStor)

Hello, and welcome to transmission. Today, Q is joined by Alexis, CTO at Synchro Store, a company developing pumped thermal energy storage technology using low cost materials like recycled glass. In this episode, they discuss how thermal energy storage works, how it targets longer duration wind dominated markets, and why diversifying beyond lithium ion batteries could be crucial for energy independence. As always, if you're enjoying transmission, please feel free to like, comment, and subscribe wherever you get your podcasts. Now, let's jump in.

Hello, Alexis, and welcome to the podcast.

Hey, Quentin. Thanks thanks for having me. It's great to be here.

So we're doing this podcast because we we met on LinkedIn. Right? I someone posted something, maybe even me, and that was controversial to you, I think. And then we ended up talking about it and saying you should get on the on the podcast. So so let's start there. What what was that?

Yeah.

I think you you made a comment on on one of the podcasts about how, I guess, the the the UK government is spending money pretty widely on many different things, which probably don't all make sense. And I think you made a tiny comment about a a company using some weird glass, and I thought, oh, that that must be us. We we must be the the weird glass people. So I thought, I'll I'll poke queue just in case.

No. It wasn't. It wasn't you guys at all. I actually wasn't poking at anyone. It was more just a just a comment on on UK research innovation in general.

I my belief, as I said in that thread is I just think that startups especially, it can be very attractive to go and get money from the government rather than money from customers. And I think a startup's number one job is to learn as fast as possible, way faster than the competition. And the best way to learn is to to spend time focusing on the customer rather than the government. But I get it that some technologies need need a bit bit more help.

But yeah, that's where that came from. So let's Yep. Let's get straight into it then. SynchroStore.

You're the CTO at SynchroStore.

Most people, I would hope, if they're listening to this podcast, are very familiar with lithium ion and pumped hydro. But thermal energy storage, we don't talk about much. So can you just walk us through what thermal energy storage is? And then let's talk about SynchroStore and what your company does that's special.

Yeah. So I guess pumped thermal energy storage is a is a way of of storing energy, and I think we can use use it to store electricity to electricity as form of heat. So we we use a different types of media to store, energy as heat, and we use heat pump as that's the pump thermals. We use heat pumps to to create that heat and cold energy. We store that in different types of material, and we use a heat engine, to be very, very simple, to to extract that energy and generate electricity.

And the benefit of pump thermal is that with a heat pump, you can have a a higher coefficient performance in the charge mode. So that gives you a coefficient performance of one point five, one point six, two. And then that gives you a round trip efficiency around fifty to seventy percent, is is quite typical for for these types of panthermal energy storage. And I guess the big benefit against battery energy storage is the the really low cost of energy.

So the the the material we use for for storing energy is really, really low cost. It could even waste material. You can pay to to to to use that material. So the the differentiator against, battery energy storage is we we have relatively high cost of power.

Our power modules are quite expensive, but we get much cheaper, longer duration. So it tends to be a curve where, yeah, same as pumped hydro above eight to ten hours, pumped hydro or pumped thermal energy will be cheaper than battery energy storage. And that's because battery energy storage tend to have a a relatively high energy cost relative to to this other technologies.

So, yes, that's that's pumped hydro in in general. There's many different forms of of pumped hydro. There's many different ways and and flavors.

The you might have heard of compressed energy storage. So that's that's kind of one one type of Carnot batteries, they they called. So you you store compressed air, but also some heat. You also have liquid energy storage, so you store some liquid some of the energy has formed as a as a liquid nitrogen, but you also store some some heat that you can bring back in the in the circuit. And thermal energy, so it just focuses on heat storage. So it's no storage of compressed air or compressed gases.

And there's different benefits of of doing that, pros and cons of of of using different architectures.

And so I imagine a lot of our listeners will be thinking and and me as well. Well, the first thing that came to my mind is we often come across companies and technologies that claim to be cheaper than lithium ion. And, you know, when we first started doing this podcast, I remember we had Marek on, friend of the podcast, who was the the face of Florence at the time. And we were talking about long duration being longer than four hours. And there were a number of technologies that claimed they were cheaper than lithium ion for longer than four hours. And that's crept up to eight hours, and then you just mentioned eight to ten.

And it feels like with the cost curves becoming so aggressive on you know, it just it just keeps on getting cheaper lithium ion cells, and they're already produced at scale. The question is, is lithium ion really more expensive than other technologies right now at eight to ten hours? And then if you even if you fast forward that to, you know, when you're on a technology s curve and costs keep on coming down, you know, where is that limit? Is it ten hours?

Is it fifteen? Is it twenty? And I know that a lot of our listeners who are in the lithium ion world would say, well, lithium ion may may be cheaper may be more expensive than pumped hydro even, for example. It's a ridiculous example because there's so much duration there, but these long duration systems right now.

But you can see, if you skate to where the puck is going, then surely everything is gonna be lithium ion. Would be like a fundamentalist lithium ion person response to this. And so when you talk about SyncraStor's technology being cheaper than lithium ion, what do you mean by that?

And I think I think we we need to consider different markets. So the from from my point of view, the the battery energy storage and lithium batteries are perfect match for a solar dominated market like California and Texas and part of Australia, and that's because the the amount of the the duration of storage required by by this market is gonna be in in the range of ten hours, and then you'll be able to cover twenty four hours of generation through most of the year using battery storage and and solar. But in wind dominating markets, like Northern Europe and and UK and Scotland in particular, there is no solar production pretty much in winter. There's four months of absolutely no solar production. So you then have this this market dominated by by wind production.

And the prime of wind generation is that they have these these cycles of long duration no. Long generation, about two to three days, these weather events coming in regularly. So two to three days of of wind and two to three days of almost no wind. And that's where we we're gonna need longer duration than what is currently being deployed in the market. And from from our perspective and the the analysis we've done, we we we think we're gonna need around twenty four to to to between twenty four and forty eight hours of of storage are gonna be competitive in the market. I'm gonna be able to to absorb this excess electricity from wind generation and provide it back to the grid for for this for this duration.

So battery energy storage are gonna be cheaper at up to ten hours and and probably even even longer. But if we consider duration of twenty four, forty eight hours, then the benefit of this really low cost of energy becomes quite powerful. We actually use some of your some of your data from some some of the curve you you've compared yourself with, pumped hydro.

And, I mean, we're still a long way from having a a fully developed, product, and we get a lot of assumptions, but we we probably half half the CapEx cost of battery energy storage at twenty four hours. So the the the curves are kind of crossing around ten ten hours, but at at twenty four hours, we almost have the price of of battery energy storage.

But not not yet at scale?

No. Of course. Not at yeah.

I'm aware this probably feels like walking to the lion's den. Right? Because my job to figure out because we we have lots of folks that we talk to either on and off the podcast working on different technologies, and there's a range of qualities out there these technologies, some that make sense and some that don't. Right?

And I I mean this with the greatest respect. But it is difficult when when one claims that a technology is cheaper than lithium ion, but not yet at scale, there is there is a gap there. And I know you that's a time in market thing. It's just gonna take some time.

But it's not necessarily like for like when one is in market and and operating at scale. One of the things you mentioned there on solar output. So solar output you you you mentioned that Scottish solar output is is is there is no solar output in the winter. Right?

But I thought we should probably check this out. I thought it was somewhere around twenty, twenty five percent across the winter, which still is much less than in the in the in the summer, but it's not zero.

It's not zero, but the the demand in winter is also gonna be much higher as we as we electrified as we electrify heating. So if you consider, okay, fast forward ten ten years from now and we've electrified heating, then the demand in winter is probably gonna be almost double what the the summer demand. So, therefore, the the solar production, to go to match this demand is just not gonna be, not gonna be there. And wind, on the opposite, is much higher capacity factor in winter.

There's a lot more production in winter, so much better match than than solar. So I doubt that significant amount of solar would be able would be deployed in in Northern Europe or or the US because wind is just gonna be more competitive. That but that that's my view. Yeah.

Yeah. I reckon you'll be surprised. I reckon you'll be surprised. So let's talk about your product then, PTES, the pump to thermal storage.

So what does this thing look like? You know, we're we're thinking about a a grid scale asset here. I guess that's where where you guys are headed. What does a, you know, a fifty hundred megawatt, one of these things look like?

Yeah. And that that's actually one of the place we we want to differentiate ourselves from other technologies. So most pump thermal and liquid air and compressed air need to be very large scale, and that's because they use off the shelf turbo machineries, and they tend to be more efficient and cost competitive if you go in the in the hundred megawatt, two hundred megawatt. We are developing, actually, the the core technology of synchro storage is not pump thermal use storage. It's actually we're developing our own reciprocating compressor expander.

And I guess it's analogous to the difference between a a gas turbine and and a reciprocating gas engine. So we we're developing the gas engine of the the equivalent to to gas engine. So we tend to be a smaller scale. The the first demonstration we we're deploying will be make megawatt power module, and we expect in the in the short term to do about two megawatts per forty foot container of of compressor expander system.

And we would basically stack containers and and and power modules to increase the the power level. And we actually believe that in Europe, particularly, there there's a a large number of smaller scale sites. Of course, in in in US, Australia, there's this huge storage site with hundreds of megawatt of of power. But we think there's actually a a market for colocation of of storage with with smaller smaller grid connected assets such as solar farms or wind farms, small wind farms, and also industrial users, which would require smaller level smaller level of energy storage. And, of course, this, again, comes with an impact in in the capital cost, but we think we can provide additional revenues if we if we manage to collocate with distributed connected distribution grid connected assets. So we we we're not targeting the very large scale systems. We think all the technologies are gonna be more suited, but we're targeting distributed connected asset.

Okay. And so we we said two megawatts is roughly a shipping container. And then where where is it stored? So where's the energy actually stored?

The benefit is that the the power module and the energy storage are completely decoupled. So in in our case, we expect you to store our energy. We actually we're actually moving our material. That's one of the the the aspect we we decide to do.

So we're moving our storage material from ambient pressure, silos. So one is insulated at high temperature, and one is at ambient, temperature. And those would look like farm sheds, very large farm shed farm sheds. And if you want to increase the energy storage, you basically make a larger shed.

And connected to this is your is your power module, which apps uses the the storage material and and transfer it from the hot storage to the the ambient storage.

So, yeah, it will be a power module and and some and some sheds.

Who's a customer? Who do you guys serve?

We we still we still developing the technology and looking for for partners, but we we aiming for solar farm developers.

And actually, we we've been talking to a number of of developers, and the interest is by collocating long duration storage with with a solar farm in the UK. You can actually expand the install capacity or the the capacity of the the the solar farm for a given grid connection. So we we've calculated by we could increase the the solar farm capacity by a factor of three for a given grid connection. So what we expect is that there's gonna be a big market of because because of the grid constraint and and the an an availability of grid is to use existing grid connected solar farm and expand them by a factor three and collocating energy storage. And not not all solar farms are gonna be available, but quite large numbers could be could be expanded relatively easily.

And long duration storage would would enable this. So increasing dramatically the revenue of the the solar farm.

For a solar farm, so what duration battery then are you guys thinking about putting on solar farms?

So based on on the model, and, course, we we we need to to keep learning and then the the market is evolving, but we we see an optimum at twenty four hours at the moment of of collocation of storage and about the same ratio of, like, the the power level of the grid capacity in terms of in in in for the for the storage. So if we have fifteen megawatts grid capacity, we we have about fifteen megawatt of storage and about fifteen megawatt, five zero megawatt of solar farm connected to this.

Right. Okay. Cool. So then let's talk about the technology itself then. So you the where does the energy go? It's been stored in you you said there's a few different materials that you can use.

Which is the best? What what's the performance of that material look like?

Yeah. So we we actually using glass as our as our storage, and we actually glass glass beads. And there's a a few reason for in terms of performance of of the system.

But the reason we chose glass is we we expect we are to use quite a large amount of waste product from the the recycling industry. About twenty percent of glass can't be recycled, and it's just used as as aggregate. So we we expect this could be a good a good starting point, a good starting material for for the technology. But we can we could use we could use other types of of ceramics, for example, which which could be made relatively cheaply. But the glass is our is our starting material and the the one we use for for testing at the moment.

So we can put this into perspective. What's the because the to think about heat pumps in cars and on houses and that whole compression cycle is very efficient in transferring energy. Right? So what's the round trip efficiency of a thermal energy storage system with a heat pump on it?

So I think there's number of of, yeah, existing system on the market, and we we we've got some simulation model and some some ideas, but we haven't tested. But we we expect around sixty percent is is possible. So round trip efficiency. So the the COP of charging is in around one point nine on the on the hot hot hot hot cell, and the the discharge power, which is very, very similar to what you have on on gas turbine is about thirty percent.

That's kind of the the maximum. And you get a number of losses around around the system that you have to really optimize to to, you know, to to improve the round trip efficiency. And your compressor expander is is the one of the main loss in in panthermal. And because we're using reciprocating machine, we actually have fairly efficient compressors.

So one of the businesses that we've come across and actually I really respect is Tepio. Did you come across Tepio? They do thermal energy storage for domestic, but they have rather than a compression cycle, I'm pretty sure it's direct.

It's like a they call it a zero emissions boiler Mhmm.

Which is a it's quite a rudimentary way of of a heating element, I believe, and then a thermal mass. So if you have the option of using a heating element or you have a heat pump like you guys have got. What's the difference there? Why did you choose to go down the the heat pump route? I guess the benefit of Tepio is they're already they're smaller systems for domestic, so they they look and feel like a boiler and you would stick them in a house like a boiler. But for grid scale stuff, it's a different kind of scaling problem.

Yeah. So so we basically, we're in charging, you will have a cup of one. And so basically, your round trip efficiency, maximum round trip efficiency will be thirty percent if you use thermal energy storage as a electric direct electric heating as your as your starting point. So thirty percent will be, really start impacting your your, the value of your system.

And because you actually need, you need a a heat engine to to discharge your power, you actually need the infrastructure, for your to generate the electricity. And in in our case, actually, that's that's a big differentiator for our technology that we can use the same powertrain in both direction. So we our technology can can be reversed, so the the same powertrain can be used as the heat pump and the heat engine. So we we don't have an additional CapEx, basically, to go from from charge to discharge.

And that's that's actually quite a big differentiator of our our technology. So we we expect for a one to one per kilowatt, our compressors will be more expensive. But because we only need a single pouch for you to do charge and discharge, we we think we it will really help our value proposition against other other types of pump thermal storage.

Okay. Cool. Do wanna tell us a bit more about the the company then? So who's involved in this, and how long has the company been going?

Who had the grand idea to do it in the first place? And yeah. Wait. What projects have you got on at the moment?

So as as I mentioned, well, the the technology evolves from a actually, an idea used for hydraulic. So, actually, I've been working in developing, reciprocating our radio piston machine for about fifteen years for the for the for the hydraulic market. So the the company was called Artemis Intelligent Power, and we we actually developed a wind turbine transmission, a seven megawatt wind turbine transmission, fully hydrostatic. And we had two demonstrators in the field and worked very well.

And then the company was actually bought by Danfoss Power Solutions at a later stage through something completely different. So we actually applied the same technology to the mobile market, so excavators and things like this. And and our technology is much more efficient and controllable than existing hydraulic machines. So we we we can save thirty percent energy on on excavators.

And, basically, we we are applying the same concept. And actually, a large part of the team working on this hybrid machine as I move move to to Synchro stores. So we have got quite a of experience of developing this radial piston machine. So instead of pumping oil, we're now pumping gas, which provides its own, fun challenges.

So working at very high temperatures, and with gas, it's completely different. But, but we've got this experience of bringing technology from, yeah, low tier all the way to to tier nine with with with Danfoss. And I think that's one of the strengths of of SyncroStor. The the company, the idea, just started about seven years ago by by professor Win Rampen.

He's actually professor at Edinburgh University, and, actually, he he saw this opportunity to apply the technology to, energy storage.

And about three years ago, we we received this big contract from the, from DESNES, from the the UK government to develop this megawatt scale demonstrator here in our facility in Scotland.

So we've finalized the first phase of the of the of the program, and we now have a, actually, a demonstration of our compressor. Our heat pump is now fully operational. So we have a a test rig at two hundred kilowatts working in the lab and, yeah, compressing happily, making heat. So that's actually quite, quite positive.

And what we actually decided is to focus a lot of the team on applying this technology, this compressor technology, to the industrial heat market. So that's actually two different streams, the the technology applicable for. So energy storage part, with with plant thermal. But we we we are basically a very efficient high temperature heat pump applicable to industrial applications.

So we actually, yeah, spending a lot of resources. And as you say, really trying to heat the market as quickly as possible to in the industrial heat market. So that's that's keeps us busy, I don't know.

Alright. And so Aldez so you had a contract with Aldez. Was and you you you've got your demonstrated project, hundred kilowatts, which I assume is in did you say in Edinburgh?

It's in one megawatt. Yes. So the One megawatt. Pump thermal was actually was is designed for one megawatt.

The first test rig, the first iteration is a two hundred kilowatt test rig. And, yeah, we it's it's all based in Edinburgh. So we have a preclude facility. So we the office, the workshop, and the test lab all in one one place in in Edinburgh.

Alright. Well, we should put some photos and links in the show notes. If you wanna check this thing out, go and have a look.

And let's move on to where the company's headed then. So we've got a couple of hundred kilowatts test rig, and now you we're I assume you're out of the prototyping phase and into the commercialization phase. So what what does that look like for the next five or ten years?

I think we still well, we call we we we say we're about TRL six, so that means that we have a a fully operational demonstrator at scale in a, like, a representative environment. So, yeah, the next stage is for us to continue maturing the technology. So, actually, we're working on our product development program to to bring this technology to TRL seven and eight and in parallel work with with customers. So we're actually, yeah, looking for for for customers.

So if anybody is interested in high temperature heat pumps, we they can get in contact. Particularly interested in drying application is is what we're gonna focus on at at at the start here. And so the the aim for us is to, yeah, t reach TRL seven eight. We will just start pilot production in the next two to three years to start ramping up the the the sales in two to three years.

But capacity to to start demonstration project and first of a kind in yeah. As soon as next year.

Alright. Well, wishing you the best of luck. Let's move on to oh, is there anything that you wanna plug before we move on into your contrarian view?

Yes. I suppose I I I've plugged already quite a bit. But, yeah, we we love having people coming around and and seeing what we do. So we we're not a PowerPoint making company.

So we we've got this this test rig now working, and we're starting to to broadcast a bit more. Hence, my my visit here to the to the podcast. So, yeah, it'd be interesting to to get people to, yeah, get in contact and and learn about what we do. Yeah.

Contrarian view, I guess, maybe linked to what we what we said earlier is, like, the cost of of battery is gonna keep going down, but there's also a small risk that the the price doesn't, when we see that the the the the production is dominated by a single country and the whole value chain is is dominated by by China. There's a small risk that the margin made by the the the Chinese, suppliers will will increase and slow down the the reduction price of battery energy storage in in the near future. But I agree. I we we can't stop physics, and things are gonna get cheaper as you move forward.

What I expect is that we we can track it and be competitive at this longer duration with with our system.

So is your contrarian view that over time, the cost to produce batteries, lithium ion battery cells will decrease because, I mean, it has to. Right? I mean, the the amount of overproduction the amount the the overbuild of production facilities of lithium ion cells in China is breathtaking.

Mhmm.

So these batch cells have gotta go somewhere, but I think are you saying your contrarian view is that the Chinese manufacturers or or the government could could bring up the drawbridge and then increase the margins to the export market?

I think that that's a possibility. And I and I think that's why I think governments like the UK need to diversify. We need to have different options. We can't just rely on one single technology. I think that that that's quite dangerous, particularly if you if you don't control the the the production of that of that technology. So I think adding a number of options on the on the table, I think, is quite, will be quite useful for for for the UK government.

I guess in the spirit of our our introduction on LinkedIn, in that same spirit, I mean, there is a possibility, of course, that that happens. Personally, I think it's pretty unlikely, but there's a possibility. But then there is a case, as you say, for governments and economies that are ex China to diversify their supply of energy storage. But I'm not sure about the the leap from that assumption or thesis.

The leap from that to other technologies that don't demonstrate better performance. Now, of course. It would be like saying, like, South Korea is gonna be the the biggest supplier of LCD TVs. Right? And so we're worried that they're gonna increase margin on LCD TVs. So what we need to do in the UK is start producing, I don't know, black and white TVs. Yeah?

No. I I I totally understand that. But we I guess, if if nobody invests in in r and d and new technologies and new ideas and also technology which plays to the strengths of our of our economy, so we we the the reason, I think, China has moved to making electric cars and batteries is that we we were too competitive in Europe to make engines, petrol engine and diesel engines, and it just leapfrogged us and went to a a completely different technology because it couldn't compete. And and maybe this is actually one of the strengths of of European countries and and the US is to to manufacture this this reciprocating machines. And, actually, what we what we're offering here is is looks very much like an engine. So, actually, one an ideal partner for us will be an engine manufacturer wanting to diversify and look at an alternative for their their production capacity.

And that because I think I think as a society, we also have to be to be mindful that we we need to preserve some some jobs in in in in in our countries, and we can't just export all of it to to to other other countries. But I I guess that's as you say, sometimes, it's like a a good discussion by at the pub, so we can we can continue that.

We could have we should do this over a beer. Yes. Yeah. I I'm not sure. I'm not sure.

And I and I think that's that's that's the the problem. Like, we we're not sure what's what the future will will bring. So we we need to be we need to diversify. We need to have other other options on the on the table.

Yeah. Yeah. Okay.

Well, I hope that you can probably tell that I'm I I I've sort of made my mind up that lithium ion's gonna take over. And this might be me take this is you could you could be listening to this and say, this is Q talking his own book, which, you know, is a is a fair fair point.

But I've sort of made my mind upon that, but I'm open to change it. And I hope I hope I'm wrong, and I hope that the Synchro Store technology really takes off, and you get from technology readiness level six to to grid scale. And yeah, I mean, more energy storage jobs in the UK would always be a good thing.

We we we we have the beer together in a few years to discuss it.

Yeah. Yeah. Yeah. Yeah. I but my argument is, well, yeah, let's build some lithium ion plants, you know?

Yeah. Yeah. But that's a very tricky thing to do as well.

I think it's it's probably too late to compete with with with the Chinese manufacturers there. I would think that's difficult.

Yeah. Absolutely. Yeah. Well, thank you very much for joining us on the podcast. If you listen to this and you wanna find out more about SynchroStore and their technology, then head to the link in the show notes and find Lexus on LinkedIn and follow them and and keep up with their progress.

Thanks, Quentin.

Thanks for joining us.

Great. Great to be here and love your podcast too. Keep keep it on.