High Temperature Electrolysis Coupled to Nuclear Energy for Fuels Production and Load Following

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1 High Temperature Electrolysis Coupled to Nuclear Energy for Fuels Production and Load Following Bilge Yildiz, Mujid Kazimi, Charles Forsberg Massachusetts Institute of Technology Department of Nuclear Science and Engineering Tsinghua-Cambridge-MIT Low Carbon Energy University Alliance Video Conference January 13,

2 Electricity and hydrogen / syn-gas co-generation Nuclear Energy CO 2 -free Efficient and costcompetitive Size/location to address the industry needs Heat and electricity Electrolysis and Fuel cell processes: H 2 O (g) ½O 2(g) + H 2(g) Co-electrolysis: H 2 O (g) + CO 2(g) O 2(g) + Hydrogen, syn-gas and electricity cogeneration using non-co 2 resources; promising route to decrease CO 2 -emissions, and enable large-scale energy storage. Large incentive for a reversible hightemperature electrolysis-fuel cell (HTE-FC). GWs of gas turbines operate at few hundred hours per year to meet peak electricity demand (very expensive gas turbine). HTE-FC may be much more economic than HTE because of load following capability. H 2(g) + CO (g) Stoots et al., J. Fuel Cell Sci. Tech

3 Research approach in Laboratory for Electrochemical Interfaces ( lead by Prof. Bilge Yildiz, ) Isolate key parameters and unit processes using model systems in reaching to surface structure and chemistry in harsh environments. Surface electronic structure spatially resolved: Scanning Tunneling Microscopy/Spectroscopy (STM/STS) Surface chemical and electronic structure, laterally averaged; X-ray and Electron spectroscopies O 2, H 2, H 2 S O - e - Cathode Electrolyte GOAL: Understand the electronic and chemical behavior on oxide surfaces for energy applications: fuel cells, corrosion. Electronic structure, cationoxygen bonding, reaction and transport kinetics First principles-based and atomistic simulations 3

4 STM / STS set-up and experiment conditions XPS Gas doser; oxyge, hydrogen Surface cleaning conditions Measurement conditions (example for SOFC application) T = 500 o C P O2 = 10-5 mbar t = min T = o C P surface ~ 10-3 mbar. (Tested up to 20 mbar, 500 o C.) STM /nc AFM Omicron VT 25 4

5 Example: Effect of strain in oxygen conductivity in Y 2 O 3 stabilized ZrO 2 (Electrolyte for SOFC/SOEC) Oxygen plane 10 6 Cation (Zr,Y) K K 600 K 10 3 Vacancy 10 critical Increase up to a critical 2 strain 400 K strain (fastest strain); 10 1 Migration space, 10 O C bond weakening D O /D 0 O Tensile strain Oxygen Cation (O C) bonding plane Decrease at higher strains; Local relaxations, O C bond strengths. The maximum relative enhancement in oxygen diffusivity (D o /D o0 ): times at 4% strain at 400 K. Kushima A, Yildiz B: Oxygen ion diffusivity in strained yttria stabilized zirconia: where is the fastest strain? Journal of Materials Chemistry 2010, 20(23):

6 Example: In situ characterization of surface chemistry and electronic structure reactivity La0.7Sr0.7MnO3 (LSM) oxygen electrode for SOFC/SOEC 800x800nm 2 Tunneling at 2 V, 1 na A 200x200nm 2 B Tunneling Current (na) C RT, mbar 500 C, 10 3 mbar 500 C, mbar Bias Voltage (V) (A) Polycrystalline La 0.7 Sr 0.7 MnO 3 (LSM) thin film surface. (B) Step height-resolution (3.9±0.2 Å) on the epixatial (100) LSM surface, at 580 o C, 10-3 mbar. (C) PO 2 -dependence of the electron tunneling at 500 o C, on (B). Katsiev K, Yildiz B, Balasubramaniam K, Salvador PA: Electron tunneling characteristics on La0.7Sr0.3MnO3 thin-film surfaces at high temperature. Appl Phys Lett 2009, 95(9),

7 Example: Degradation of HTE materials Good adhesion Anode + Bond Layer 200μm SSZ Mn, from the IC coating Small amount of Cr Cr poisoning Cation / phase separation Sharma VI, Yildiz B: Degradation Mechanism in La0.8Sr0.2CoO3 as Contact Layer on the Solid Oxide Electrolysis Cell Anode, Journal of The Electrochemical Society, 157, B441-B448, 2010 Anode 4 3 Bond Layer Sr Poor adhesion 1 2 LSC Cr Co O = e - Anode SSZ 10 μm 20.0 µm 7

8 Potential project objective in this program To identify electrode compositions that are active and durable in reversible operation of solid oxide fuel cell (SOFC) / electrolysis cell (SOEC) Synthesize thin model films, Electrochemical performance characterization Correlation of electrochemical performance (activity AND durability) to surface chemistry and electronic structure. 8

9 University of Cambridge Atomistic Simulation Group Background Group Leader Dr Paul Bristowe Current Energy Related Projects Fast ion conduction in doped nanoscale zirconia STO YSZ interface Expertise: applied materials modeling using both classical MD and DFT Member: UK consortium on first principles calculations (UKCP) User/developer: CASTEP DFT code Energy related industrial collaborations: Pilkington Glass, Philips Electronics, Osram Semiconductors, Fiat, Bekaert Coatings Former MIT researcher & visiting professor Carbon capture in metal organic framework compounds Znbpetpa unit cell Doping mechanisms in oxide materials for solar cells, sensors and displays Department of Materials Science and Metallurgy 9