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  • 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 Solid Oxide Flow Batteries for

  • Grid-Energy Storage.

  • A couple years back, we, we gave a talk as well on the cell material

  • advancements we've been working on.

  • In 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 Wendel, Professor Bob Kee at the School of Mines.

  • Professor Scott Barnett and, and Doctors Gareth Hughes and, and

  • Zhan 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 in to some descriptions of reversible solid

  • oxide cells as flow batteries.

  • Here we'll look at, little bit at the theory of operation and

  • performance considerations.

  • As well as some performance estimates of really these large scale, megawatt size,

  • gigawatt hours, capacity systems that we would envision for, for bulk storage.

  • Brief, I'll give a brief update of some of the exciting developments in the South

  • development area where we're, we're really trying to push towards the 600 in sea

  • operation salutes and all this GM technology.

  • And we have some very interesting and encouraging results related to,

  • to cycling to show of these cells.

  • And that's very important how we're going to operate forward and

  • backward modes with this technology.

  • We don't want degradation there.

  • Lastly we'll, 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,

  • in featured reactions.

  • 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 the system to operate in a power

  • producing mode, and in an electrolysis or charging mode.

  • And we're, we're going to tank the reactants and, and

  • capture those in, in gaseous storage, and that's particular 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 with 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 in electrolysis mode.

  • And the novel, relatively novel HCO chemistry that is experienced directly

  • within the cell, allows us to, to produce high energy dense fuels.

  • So shown here is a, is a, a real simple schematic of,

  • of a solid oxide cell and oxygen conducting one with some fuel storage.

  • Here we are showing methane and syngas and we are going to feed it with air, and

  • we're going to take the oxygen from there, reduce it, get those anions.

  • Moving and electrochemically oxidized those gaseous reactants into H2O and CO2.

  • We will capture that gas in a tank and essentially produce our power.

  • Now, in reverse mode, we can then accept ply voltage,

  • driver currents, and essentially put our power into the, 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.

  • We'll strip out the oxygen.

  • Liberate some of that oxygen.

  • And in the meantime, directly within the cell, we will produce methane and, and

  • syngas.

  • In general, that'll give us favorable scaling this device, but

  • also something additionally unique is that 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 is well-known and motivates developing grid-energy solutions.

  • I like to at least see some picture of what that means?

  • Here are some minute by minute data shown from Hawaiian Electro Power

  • on a wind farm.

  • We can see really a ten exchanged within 30 minutes of, of power requirements.

  • And it's not just wind variability if we look at developing activities and

  • concentrating solar power and of course, PV penetration,

  • they've got power fall-off in, in the evening hours as well that would,

  • 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 pumped hydro.

  • In, that's, but this problem still exists, and those who are facing this,

  • primarily, often island nations for example, are,

  • are already trying to develop solutions, and I'll call them poor solutions.

  • Taking high grade electrical energy, and storing it in low-grade hot water for

  • example, so called thermal battery.

  • That's being done by Hawaiian Electro Power to, to manage this,

  • this variability.

  • It's also being done in an Electricity Arbitrage Models in Minnesota,

  • for example.

  • I've called them the, the dubious honor of having the largest thermal battery in

  • perhaps in the country at one-gigawatt hours.

  • High-grade electrical energy,

  • low-grade hot water is essentially thermodynamic syn.

  • But in, on the other hand you know,

  • good economics doesn't necessarily always mean good thermodynamics.

  • In general,

  • though, 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 cost and round-trip efficiency but perhaps most importantly

  • some levelized cost of electricity storage around a dime per 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, or produce more

  • power in response to, to overpotentials and irreversibilities within the cell.

  • The slope of this curve represent the overall resistance.

  • In fuel cell mode, the higher the voltage the higher the efficiency.

  • And in electrolysis mode we can see a rel, 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 electricity in electrolysis mode.

  • So, if we look at the round-trip stack efficiency, which is not shown here, okay.

  • It's 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 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 and electrolysis mode, we are able to obtain low

  • electrolysis voltages, get towards a thermal neutral operation, as well.

  • So, when we look at a fuel cell, it requires heat rejection.

  • We're air cooled we're operating it at relatively high temperatures.

  • But in electrolysis this is of course and endothermic process.

  • It requires a heat source.

  • As, and we can see that when we reduce H2O that's certainly the case.

  • We're going to leverage HCO chemistry here and because of the nickel in, 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, okay?

  • 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, 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 used in a so called Gibs diagram or ternary diagram.

  • Where the shaded area above the rad indicates the thermodynamically

  • favorable region for carbon deposition to occur.

  • And the, the open, 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, for fuel cell mode.

  • As we oxidize the fuel, we'll 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