1. Solar Hydrogen Project Group Update 21 st July 2009

2. CC-124 growth kinetics model Bojan Tamburic Error caused by O 2 bubble evolution Data outliers ‘brushed’ Fit Logistic (Sigmoid) curve of the form:

3. ‘Guess’ initial r and t 0 range Minimise the total least squared error of r and t 0 Fix r and t 0 values Use linear optimisation to recover K

4. So K is the maximum attainable OD t 0 and r tell us something about the growth rate – but not easy to visualise Biologists typically use doubling time – not really appropriate for logistic curve Gradient at t 0 – maximum growth rate Regression coefficient = 0.98

5. Plan: 1.Fit logistic curves to existing growth kinetics data 2.Obtain new data to investigate the effects of light intensity, agitation and CO 2 sparging on growth kinetics, but: Sartorius reactor under modification Algae appear to be contaminated Need about 2 months of data collection to obtain ‘good’ results

6. Solar Hydrogen Project: SD Fe 2 O 3 work: –First stage of comparative study of different types of Fe 2 O 3 : Old EPFL CVD –Voltammetry –Impedance –Transient photocurrent measurements

7. Solar Hydrogen Project: SD Photocurrent transients: –Measured with 0.1M NaOH, solution = water or 80:20 water/MeOH –Set potential to 0.6 V,  V = -0.1V –Chopped at ~3 Hz, recorded photocurrent transients at 10 -5 s resolution

8. Fe 2 O 3 (EPFL): NaOH-H 2 O

9. Fe 2 O 3 (EPFL): NaOH-H 2 O/MeOH

10. Fe 2 O 3 (EPFL): 0.6V

11. Fe 2 O 3 (EPFL): 0.1V

12. Fe 2 O 3 : EPFL

13. Conclusions Preliminary (and not concluded yet) –In the absence of MeOH see cathodic “dark” current, even at 0.6 V. –As applied potential is increased, the photocurrent becomes increasingly transient –As applied potential is increased the cathodic “dark” current increases (relative to the photocurrent)

14. Photo-electrochemical Reactor Modeling: Week 3 Update Zachary Ulissi

15. Reactor Design: Original & Wedges

16. Reactor Design: Extra Post

17. Reactor Design: Small Wedge

18. Reactor Design: Extra Post

19. Mass Transfer In the Laminar Regime (300 ml/min liquid flow) Goal: 2 A/m 2

20. Mass Transfer Limit for Laminar Flow Goal: 2 A/m 2

21. Mass Transfer Limit for Laminar Flow Goal: 2 A/m 2

22. Insufficient Mixing!

23. Laminar Diffusion Completed