1. Department of Mechanical and Aerospace Engineering High Temperature H 2 Production and Energy Initiatives at UF Energy Park State of the Union on Florida Energy, University of Florida, Gainesville FL, 3/23/2016

2. Department of Mechanical and Aerospace Engineering Paths to Solar Fuel Production 2 Photons (hν) Electricity (e - ) Thermal Energy (U internal = f(T)) Synthetic Fuels via Process Energy Input Photobiological Photoelectrochemical Photocatalytic Photosynthesis Thermochemical Electrolysis H2H2 CO+H 2 CO H 2 O/ CO 2 + + CO 2 H2OH2O H2OH2O CO+H 2 Solar thermal processes inherently operate at high temperatures and utilize the entire solar spectrum, and as such provide a thermodynamically favorable path to solar fuels production. Fischer-Tropsch Methanation

3. Department of Mechanical and Aerospace Engineering Solar Thermal Electricity Production 3 Images: http://www.brightsourceenergy.com/

4. Department of Mechanical and Aerospace Engineering Thermochemical Fuel Production 4 Chemical Reactor/Receiver H 2 O/CO 2 H 2 /CO O2O2 FT Reactor Compression Cracking Liquid Fuels (diesel, kerosene, etc.) H 2 O purification/ CO 2 sequestration Q solar Heliostat Array Absorber Solar Concentration Image: http://www.brightsourceenergy.com/ High Temperature

5. Department of Mechanical and Aerospace Engineering Thermochemical Dissociation of H 2 O/CO 2 5 Q solar Chemical Reactor H 2 O/CO 2 H 2 /CO O2O2 Direct Dissociation H 2 O → H 2 + 0.5O 2 CO 2 → CO + 0.5O 2 Two-Step Redox Cycle 1) MO → MO 1- δ + δ/2O 2 2) MO 1- δ + δH 2 O → MO + δH 2 +Δ+Δ -Δ-Δ Two-Step Redox Cycle Lower temperatures (>1673 K) Inherent separation of product gases Direct Dissociation High temperatures (> 2500 K) Rapid quenching or separation of products

6. Department of Mechanical and Aerospace Engineering 2010 – First operable and cyclable solar reactor demonstrating complete redox cycle Average efficiencies reported ~ 0.6% Room for optimization in several areas Structural optimization Reactor optimization Material optimization Heat recuperation 6 porous ceria Solar Reactor Technology Chueh, W. C, Steinfeld, A. et al., Science 2010, 330 (6012), 1797-1801.

7. Department of Mechanical and Aerospace Engineering Solar Reactor 7 Reactor Front (water-cooled) Reactor D≈20cm H≈20cm CeO 2 structure Al 2 O 3 insulation Inconel Shell Quartz Window Inlet Purge Gas (Ar) Inlet Outlet Concentrated Solar Radiation 1500 ° C O2O2 O2O2 O2O2 900 ° C H 2 O / CO 2 CO H2H2 H2H2 Syngas (H 2 / CO) 1.Reduction: 2. Oxidation: Furler, P., Scheffe, J.R., Steinfeld, A., Energy & Fuels 2012, 26 (11), 7051–7059.

8. Department of Mechanical and Aerospace Engineering Solar Simulator – U. Florida 8

9. Department of Mechanical and Aerospace Engineering Reactor Prototype 9 Rear view Front view Schematic depiction : cross-sectional view and front view

10. Department of Mechanical and Aerospace Engineering 10 1.Reactive material 2.Reactor tubes 3.Centre tube ( gas outlet) 4.Gas inlet 5.Heated zone 6.Aperture 7.High temperature insulation layer 1 8.High temperature insulation layer 2 9.Microporous silica 1 2 3 6 5 4 7 8 9

11. Department of Mechanical and Aerospace Engineering Solar energy utilization probably greater because of isothermal operation and no separation work T H = T L < 1200 K Q heat = 0 E sep = 0 Solar Reforming CeO 2 CeO 2-δ CeO 2 δH2OδH2O TLTL TLTL δH2δH2 p CH 4 pH2OpH2O Q red + δCH 4 2δH 2 + δCO 11

12. Department of Mechanical and Aerospace Engineering Theoretical Efficiency 12 Peak at 1100 K because reduction reaction completed above this temperature No heat recuperation Further investigation of operating conditions necessary n i,CH 4 = 0.1

13. Department of Mechanical and Aerospace Engineering University of Florida Kent Warren Richard Carrillo Julie Reim Ben Greek Kelvin Randhir Prof. David Hahn Acknowledgements 13 Funding Sources ARPA-E UF: College of Engineering and MAE

14. Department of Mechanical and Aerospace Engineering