1. Solar Hydrogen Project Group Update 14 th July 2009

2. Progress To Do - efficiency trade off between PEC inputs / outputs (with SD - maybe Zachari?) - costs of prototype (with CC) and costing down exercise - review the model methodology (with Adam Hawkes) - economics of storage (mostly from literature at the moment)

3. Storage system PEC Production rate Compressor  Cost (ΔP,KW) Tank  Cost (P,Capacity) Installation  Cost (V, A, P?) Operation  Cost (P, turnover)

4. Storage system Tank  Cost (P,Capacity) Thermal Storage Capacity [kWh] 0 kWh 10 kWh 20-40 kWh Net Present Value [£] Initial model prediction: Limited benefit above40 kWh e Tank diameter0.83 m “Worst case” - Half annual demand <1500 kWh e - Hydrogen equivalent: 11.1 m 3 @ 20 MPa - Tank diameter: 2.7 m

5. Storage system PEC Production rate Tank  Cost (P,Capacity) Higher pressure  increased embrittlement

6. Storage system Operation  Cost (P, turnover) Operation  Cost (P, turnover) Compression energy

7. Storage system Compressor  Cost (ΔP,KW) Compressor  Cost (ΔP,KW) Literature figures: 6600 $ kW −1 >250kW<1000 $ kW −1 Usually based on large scale systems  Power dominant over pressure For small systems, maximum pressure assumed to be critical, but no reliable figures in literature. Any experts???? Model assumption: 10 £ MPa -1 Installation  Cost (V, A, P?) Installation  Cost (V, A, P?) Land cost factor300£ m -2 Installation cost650£ m -3

8. Optimum Storage Pressure

9. IrO 2 Deposition Tried electrodepositing Ir on WO 3 Heat treatment increases current remarkably Cannot conclude whether heat treatment affect WO 3 or Ir

11. Solar Hydrogen Project: SD Fe 2 O 3 work: –Steph/Monica: material produced by ultra- sonic spray pyrolysis –Comparative study of different types of Fe 2 O 3 : EPFL CVD (new samples received) EPFL USP (from Monica) Hydrogen Solar spray pyrolysis other?

12. Solar Hydrogen Project: SD The following slides were added post- meeting. Data for: –EPFL CVD (old sample): photocurrent-potential plots, showing large increase with chopping frequency. (Due to ?) –HS SP (poor performing): photocurrent-potential plot shows increase in photocurrent due to greater contribution from the transient photocurrent at short times. (NB: real current density has not been calculated.)

13. Fe 2 O 3 : HS (poor!)

14. Fe 2 O 3 : HS Photocurrent-potential

15. Fe 2 O 3 : EPFL CVD (better)

16. Fe 2 O 3 : EPFL Photocurrent-potential

17. FZ update Membrane Permeation and selectivity study Update on sartorius reactor fittings/ tubing

22. Modeling of Photocatalytic Reactors Zachary Ulissi Steve Dennison Geoff Kelsall

23. Top plate Spacer (fluid) Bottom Plate Membrane Electrolyte Inflow Electrolyte Flow (with H 2 or O 2 ) Light Source (monochromatic)

24. Mesh Cathode Electrolyte Inflow Electrolyte Flow (with H 2 or O 2 ) Photo-Anode Membrane Fluid Chamber

25. Mesh Cathode (Conductor) Membrane Photo-Anode Absorption, αe-e- h+h+ 2e 2H + H2H2 + Diffusion Kinetics Fluid Flow+ Diffusion Fluid Flow+ Diffusion H2OH2O + 2H + O2O2 Kinetics Absorption, Diffusion (2), Band Bending Electrolyte Flow (if laminar) (1) (2) (3) (4?)

27. log(Velocity / Centerline Velocity) Flow=3.5ml/min

28. log(Velocity / Centerline Velocity) Flow=3.5ml/min → 700ml/min Laminar → Turbulent at ≈200ml/min

29. log(Velocity / Centerline Velocity) Flow=300ml/min

30. Next Steps Determine whether inlet corners should be removed Couple diffusion in flow to constant flux on surfaces Identify approximate rates of diffusion of e/h and degree of band bending in photo- anode Approximate kinetics of surface reactions (most difficult portion)