 Okay, so thank you for that introduction. It's a real pleasure to be here and be able to give you an update on our GCEP project on South Oxide flow batteries for grid energy storage a couple years back We gave a talk as well on the cell material advancements. We've been working on Today's talk we're going to focus more on the system concepts That will hopefully enable the technology to move it forward Before moving into that I just want to acknowledge our team members PhD student Chris Wendell and Professor Bob Key at the School of Minds Professor Scott Barnett and doctors Gareth Hughes and Zan Gao at Northwestern are really working at advancing the cell technology So in today's talk, I'm going to briefly give you an overview of what exactly is this technology And followed by with I guess I would say our view of some of the motivation and the technology requirements That are needed for energy storage to move forward I'll then move into some descriptions of reversible South Oxide Cells as flow batteries here We'll look at a little bit at theory of operation and performance considerations as well as some performance estimates of really these large scale Mega watt size gigawatt hours capacity systems that we would envision for bulk storage Brief I'll give a brief update of some of the Exciting developments in the cell Development area where we were really trying to push towards a 600 c operation cell using LSGM technology We have some very interesting and encouraging results related to cycling to show of these cells And that's very important when we're going to operate forward and backward modes with this technology We don't want degradation there Lastly, we'll touch on some of the economic projections for these kind of large-scale bulk energy storage systems I'll then briefly touch a little bit on what we've learned in future directions So in principle a solid oxide flow battery really leverages Similarities to fuel cells where we're going to operate reversibly here Reversibly is not in the thermodynamic sense. It's in the sense of reversing the current For these systems to operate in a power producing mode and in electrolysis or charging mode And we're going to tank the reactants and capture Those in gaseous storage and that's particularly useful for us because it gives us really the flow battery advantage We get the decouple power capacity From storage and so the power will scale at the size of the cell stack and The energies will scale with the size of the storage tanks. We also get the high efficiency advantage of solid oxide cell technology Which enables us to have really high round-trip efficiencies as we move between modes We don't experience high polarization and electrolysis mode and The novel relatively novel HCO chemistry that is experienced directly within the cell allows us to produce high energy dense fuels So shown here is a real simple schematic of a solid oxide cell and oxygen conducting one With some fuel storage here. We're showing methane and syngas and We're going to feed it with air and we're going to take the oxygen from air reduce it get those anions moving and electrochemically oxidized those gaseous reactants into H2O and CO2 We will capture that tail gas in a tank and Essentially produce our power now in reverse mode. We can then accept Apply voltage drive occurrence essentially put our power in to the device and then move into the opposite mode where we'll remove those previous products of reaction out of storage back to our cell will strip out the oxygen Liberate some of that oxygen and in the meantime directly within the cell. We will produce methane and syngas In general that'll give us favorable scaling this device, but also Something additionally unique is it gives us really low-cost working fluids compared to advanced and other types of flow batteries In terms of motivation certainly the variability of renewable energy resources is well known and motivates Developing grid energy solutions. I like to at least see some picture of what that means here Some minute-by-minute data shown from Hawaiian electric power on a wind farm We can see really a 10x change within 30 minutes of the power requirements And it's not just wind variability if we look at developing Activities and concentrating solar power and of course PV penetration. You've got power fall-off In the evening hours as well that will need to be addressed to get high capacity factors So currently there is no battery technology that really serves most of our energy storage Worldwide is predominantly palm Tidro and that's but this problem still exists and Those who are facing this primarily off and island nations for example are Already trying to develop solutions and I will call them poor solutions Taking high-grade electrical energy and storing it in low-grade hot water for example a so-called thermal battery That's being done by Hawaiian electric power to manage these this variability It's also be done electricity arbitrage models in Minnesota for example I would call them the dubious honor of having the largest thermal battery perhaps in the country at one gigawatt hour High-grade electrical energy low-grade hot water. It's essentially thermodynamics sin But on the other hand, you know good economics doesn't necessarily always mean good thermodynamics In general though to in order to enable that technology. We've got to reach some certain targets We've been keeping our eye on these as we look at this technology Certainly capital costs and round-trip efficiency But perhaps most importantly some levelized cost of electricity storage around a dime For kilowatt hour cycle we need cycle capability and depending on the application. You'll need various modes various duration of storage If we now turn to looking at the technology itself Just operationally we can take a look at a voltage current plot which is a representation of the cells performance characteristic and shown here we can see That in power producing mode or fuel cell mode the voltage will decrease as you increase the current density or produce More power in response to over potentials and irreversibilities within the cell the slope of this curve represents the overall resistance in fuel cell mode the higher the voltage the higher the efficiency electrolysis mode we can see a relatively smooth transition shown here in this cartoon But that's actually what we see experimentally as well There isn't a large over potential that gives us good electrolysis Efficiencies low applied voltage needed there, but here you want low voltage equals high efficiency in electrolysis mode So if we look at the round-trip stack efficiency Which is not shown here. Okay Is basically the voltage of the fuel cell divided by the voltage of the electrolysis device? That's the ratio so you want high fuel cell voltage low electrolysis voltage that will give you a high round-trip efficiency At the system level We not only need to be mindful of the stack But we're moving these reactants back and forth between the tank and the stack And so there's an auxiliary power component that enters into this ratio So in the end how we can improve system efficiency. We can improve the cell by reducing over potential and at the system level we got to be mindful of the balance of plant and thermal management and When we look at thermal management one of the unique attributes here is by doing Methanation locally within the cell in a lot in an electrolysis mode We're able to attain low electrolysis voltages get towards a thermal neutral operation as well So when we look at a fuel cell it requires heat rejection where air cooled We're operating at relatively high temperatures, but an electrolysis. This is of course an endothermic process It requires a heat source as and we can see that when we reduce H2O. That's that's certainly the case We're going to leverage HCO chemistry here and because of the nickel in in the fuel electrode We can also do heterogeneous chemical reactions and reduce CO2 as well through H2 and Provide us with some CO which can then be combined with hydrogen to methanate which is highly exothermic And that's very nice for us because we have a exothermic local source where we have an endothermic process We've got good matching of sources and sinks there and ultimately low temperature is what we would want in relatively high pressure to achieve that methanation One of the considerations we're faced with as well is if we're going to design one of these systems What do we charge the tanks with what is the composition we want and what are the considerations therein? So in these systems, we have to be concerned about carbon deposition This is a deleterious effect on on solid oxide cells And it degrades their performance rapidly should that happen So shown here is in the right is essentially a compositional space using a so-called Gibbs diagram or ternary diagram where the shaded area above the red indicates the thermodynamically favorable region for carbon deposition to occur and the the open what the white zone really is Is unfavorable for that and that's where we want to operate? So in doing so you can see the red dot up here is where we might start on a hydrogen carbon ratio Oxygen ratio for fuel saw mode as we oxidized the fuel will move towards this fully oxidized region shown in the light blue And we don't really want to be fully oxidized in this system We want to be not fully oxidized and not fully reduced This is our operating window if you will to move back and forth If we look at the bottom graph we can see basically on the left hand side an equilibrium gas Constitution on a molar basis It's a wet basis shown here versus oxygen content and we can basically move back and forth between shown here exists between four and forty percent Oxygen conversion which will allow us to Have fairly high storage capacity We can produce methane in 60-40 ratio with hydrogen here on a dry basis and at this end of the cell Basically as you produce in fuel cell mode You'll see us reducing the ch4 producing h2o these of course will be tanked for electrolysis mode so one of the proposed Applications we've been looking at it's really bulk storage To in order to get there we need very large tanks and very large tanks can be realized with pressurized underground gaseous storage of our reactants using salt caverns for example natural gas reservoirs saline aquifers And so we're this concept is actually being very seriously considered particularly in Europe in Germany and We're looking in collaboration with the Danish technical University at Designing the so-called surface system which will convert and store our reactants Using survey data on natural gas reservoirs in Denmark for example We can estimate 500 gigawatt hours of storage would be available for one plant that has a 250 megawatt capacity And the punchline here is we'll get to this later But in the end that these storage costs can reach three to four cents per kilowatt hour with storage durations of months Which is particularly important Germany and particularly very interested in month-long duration storage because of the low PV Insulation and during the winter in particular Because we produce methane we find it really interesting that technology is also suitable to support the so-called power-to-gas platforms that are very of increasing interest Particularly by Europe and getting off of Russian natural gas and using renewable Green electricity if you will to make SNG this technology is perfectly applicable to that in the end though, we need this top surface system and That involves systems integration and thermal management strategies in moving essentially Between the caverns and the stack and so just very briefly We we have to pressurize and preheat the reactants to get over to the stack We can recover some of that energy from fuel cell exothermic operation to reduce our balance of plant parasitics From the cavern will take our CH4 preheated and expand it because it's operating at say 160 bar in the stack is at 20 bar We'll recuperate some power and we'll introduce steam and use the tail gas if you will of that process to meet the process Heating needs before dumping it into the co2 cavern We'll get DC power out and when we go to electrolysis mode. We basically reverse and store in the co2 cavern Store in the CH4 caverns Importantly in order to make this viable. We want to use the same equipment Okay, so that means they have to be sized and operated in design such that that can be done We also have to carefully manage water and these systems We're going to knock it out and generate it because we can't really easily store it in these caverns and extract it When we look at performance trades Clearly a key issue is what pressure and temperature should this stack be operated out One of the things we like about this project is we got cell material development We got systems aspects going on and the two get to talk to each other We can say from a systems view. I don't really need very low temperature Or I need a different pressure for you guys to focus on perhaps depending on the application So here we show a plot of round-trip efficiency for the stack and the system We'll just focus on that versus stack pressure and we see an optima is Here and that optima basically is the interplay between The auxiliary power Depending on what the stack pressure is so if the stack pressure is relatively low We can get net power out of our system in fuel cell mode and that can offset our electrolysis pumping requirements in the end that interplay gives us an optima of around 20 bar Which we like because that matches a lot of the high-pressure turbine spools that are available That might be integrated with the system similar trades are our presence when we look at temperature and reactant utilization and and those optima are shown here If we just quickly move into Now looking at some of the cell technology advancements that have been ongoing with this project We're really focused on these next generation material sets leveraging Really LSGM technology to push towards 600 C and with high cycle durability Briefly here's an SEM image of the microstructure of one of the cells and you can see the thick LSGM electrolyte layer the dense layer that's that's right here Overall the some of these layers is quite thin But you can see here. There is on the air electrode. We have our gas diffusion support. It's LSF We have a nickel infiltrated LSGM fuel electrode that allows us to get high current densities for high triple phase boundary Area if you will this is on an SLT support What gives it strength and one of the the unique pieces of this is is the nanoparticle nickel infiltration in the fuel electrode If we look at the performance characteristics, we can get high performance high performance here demonstrates at a power density of 1.6 watts per square centimeter at 650 C as far as we know that's that's one of the records It works in both modes very well at the area specific resistance is point one eight. We've been targeting point two Ohms square centimeter for the system and we've demonstrated that at this at really button cell level We have to do better on the 600 C Polarization curve if you will that's getting slightly higher and we still need better performance there But most interestingly I think one of the tests that we've been running is on cycle durability We need to cycle these things forward and backward and no one has really tested this kind of technology in this mode So we've looked here at really one in 12 hour cycles You can see a 30 minute operation on one mode 30 minute operation on the other Switching back and forth between these modes For different cycle times. So here is one hour show, but we've also done 12 hour cycles And is well so six hours in one mode six hours in the other mode at different operating current densities And what you'll notice here is on this light blue curve if you're just operating electrolysis mode You get fairly rapid degradation But as we change into cyclic mode We get reduced degradation as exhibited by the change in total resistance over time And we've tested this for a thousand hours And as you can see is once you get below a certain threshold operating current density the degradation Mechanisms are turned off essentially or interrupted and we find that that actually happens around point eight amps per square centimeter Which is at least twice as high or about twice as high as we think is economically needed To develop the technology. So we're really encouraged by these results in particular in the remaining minutes I'd like to give you a little snapshot of the economics when we first presented a couple years back There are a lot of questions on that. We had no data. I can report some data on this at this time and That's unfortunate this okay. I'm in IBM PC and these equations aren't showing up But what I would say is briefly there's a simple calculation that basically takes the It takes the investment costs and divides by the energy storage and around trip efficiency in the number of cycles And you get essentially a simple storage cost metric In cents per kilowatt hour the challenge with this method is it assumes a hundred percent capacity factor in doing so In order to they'll perform this we need to cost out the plant So we've done some bottom-up plant costing using some of these Parameter values here briefly highlighted here 250 megawatt rating we've shown we can get higher round trip efficiency, but we just put in 70 percent here Mature life projections for solid oxide cell technology again We're using costs from solid oxide fuel cells. They're very applicable here, but perhaps not exactly applicable depending on on the cell material sets The storage there's a fair amount of good data here We've been leveraging existing natural gas reservoir data from Lillatora facility in Denmark 120 million cubic meter natural gas reservoir facility We make use of 70 million cubic meters of that we need a 50 million cubic meter cushion gas To support the activity and we've priced out that cost Based on the existing costs that we know for that that and we've extrapolated for co2 caverns there That's relatively unproven storage co2. We've essentially taken the ch4 costs and more or less double them for the risk In the end we get a capital cost at this scale of around less than 1,100 hours per kilowatt If you look at the total expense breakdown up here, it's not Just capital costs. We got operating maintenance costs here and and staff and so forth to operate But in the end we're about 30 percent on on the stack in less than 15 percent in the storage If this simple costing method then allows us to get us around three cents per kilowatt hour on storage costs with this method Which if you look compares favorably against compressed air Hydrogen and and pumped hydro in these other bulk storage categories We think that's perhaps a little too simple and more we could leverage instead The resources of this storage facility using electricity spot market prices and essentially using supply and demand characteristics of the grid market and Do essentially market arbitrage to buy and sell power essentially buy power cheap charge your system and sell it When the price of electricity is high so the cautionary note here is In making these calculations, of course, we knew what the prices were its historic prices and We could optimize the sell-by strategy, which then means This is really a maximum annual income estimate, okay? So if we look at 2008 electricity spot market prices our colleagues in DTU really perform this study They use the Danish market because that's what they were interested at the time with our system and We don't get a capacity factor of hundred percent in this scenario. We get 61 percent When you look at the life cycle cost that raises it from almost three cents to almost eight cents But you do get revenue from this and you can drop that by four percent to a net overall storage cost of just under four cents at 3.7 cents per kilowatt hour There is lots of considerations that in the future increasing renewable energy penetration will mean higher electricity price volatility And you could essentially do more arbitrage under those scenarios with those scenarios then there has been because Denmark in particular is interested in a hundred percent renewables integration by 2035 They are very seriously looking at then the price impact on their markets and they have done scenario forecasting We've used those forecasts with the 2008 buy-sell our Strategy and we show that under that and shown here in the red curve is the buy-sell strategy And the price spot market prices that might be expected in the future with high penetration You could actually make money with electricity Electricity storage again, this is maximum and of course there's lots of uncertainties here But it does suggest that if you won't even if you weren't perfect you might end up as zero cost on storage Okay, so to wrap up here The we see that there are a lot of markets That we could enter within this technology not only this so-called power gas platform We can do bulk storage and more recently within the project confines. We're turning now our attention to distributed scale storage that will compete with advanced flow batteries and sodium sulfur batteries In in the kilowatt hour to low megawatt hour ranges There's a lot of work that certainly needs to be done yet We need really need to push the envelope on the operating temperature further with the LSGM technology of results shown here for small-scale cells Okay, cell scale up is always a challenge and that needs to be done Long-term stability and durability testing we have to operate in slick look modes with the actual reacting gases We envision and of course if you're going to run this thing up and down you need to know something about the dynamics of the capability of the system So with that I'd say we've learned a fair amount. We believe we can get fairly high round-trip efficiencies We can even get above 80 percent if you can integrate thermally with nuclear CSP for example And Regardless of how we we estimate the economics we think they're much they're very attractive and can meter exceed the DOE targets With that I'd like to thank some of my collaborators and open it up for questions Yeah, I have a question about if you guys have any problems with select, sorry here With selectivity when you're running an electrolysis mode Converting the CO2 to methane. Do you have any issues with making C2s or you know products that you don't want? No, actually the the electrodes are catalytically active enough that they reach equilibrium rapidly with Without even pulling out oxygen or you pull out oxygen obviously will drive the equilibrium forward but We make methane and CO and H2 is exactly as you might predict thermodynamically Can you hear me yeah nice work. Can you care about the Comment about the the coaking problem and whether you see it More in the in the electrolysis mode than in the fuel cell mode That's a good question because as you move from electrolysis mode you're moving towards the coaking boundary Certainly one of the questions we have is you know the thermodynamics analysis You know is nice and it provides you know insight and guidance on how to select conditions But you really are dealing with local phenomena when you're flowing these Reacting gases through the passages of the cell and if you don't have a good distribution you have you could have locally rich zones so to speak which could could Produce carbon deposition which would degrade performance So what's not so well known is what we would call the safety margin? That would be required to to push you away from that thermodynamic boundary So what hydrogen and carbon ratio and what operating conditions would give you sufficient safety margin to not coke up? So that that will be revealed more in the cell testing As a part of this project. We built a pressurized rig at Northwestern And they're going to be operating under Syn gas conditions at pressure and temperature and that'll give us some better insight Nevertheless, they're still fairly well-mixed conditions under lab lab environment So how important it is to lower the operating temperature of these Devices and what do you think is the main barrier in that direction of research or how do how you think you can achieve that goal? Okay, so Lowering the the operating temperature really makes More sense so at the large bulk scale. We don't think we need that lower temperature at this point But when we look at when we start turning towards distributed scale systems, you know Tens of kilowatts to hundreds of kilowatts or a megawatt We think we'll have we basically in order to keep the cost low We want to strip out a lot of that BOP equipment that we can so we think we can get relatively simple and elegant designs, however We'd like to avoid pressurization in those situations as well And so shown here for example is a round-trip efficiency versus stack temperature We do have an expander included, but you can see that as we lower the stack temperature We can get close to seventy eight percent round-trip efficiency at six hundred C for one of these small-scale systems And we really think we need you know depending on whether or not you have the expander You're going to be closer to seventy percent efficiency if you don't but you really need the six hundred C The barriers are really of polarization resistances that are incurred the Resistances go up as you reduce temperature because the ionic connectivity of the cell goes down One of the strategies could be to reduce The air electrode polarization resistance We think there might be able to do that by doing more Nanoparticle infiltration on that electrode just like has been been doing on the fuel electrode with nickel except it might be done with Samaria for example Good question. You mentioned in your cost analyzers said your stack probably should last for at least five years So could you explore a little bit and say why you believe it will be as long as five years? Yeah, we don't know how long it will be right now What we see is after a thousand hours and these small-scale cell tests virtually no degradation The challenge is of course we have to operate on the carbonaceous fuel feedstocks We envision and that hasn't been done over hours the cycling doesn't seem at this point Okay, it seems like it does have promise other solid oxide cell technology has been demonstrated Well past 20,000 hours all the developers of that traditional Focus in technology development Are focused on increasing endurance? It's going to take certainly several years. I'm sure to achieve that But that's economically what the target has been Some cells like see old Siemens tubular cells they lasted 70,000 hours But we think 40,000 is where you're gonna have to start to enter the marketplace. That's real consistent with fuel cell technology