Solar Hydrogen Project Group Update 21 st July 2009

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

‘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

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

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

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

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 s resolution

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

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

Fe 2 O 3 (EPFL): 0.6V

Fe 2 O 3 (EPFL): 0.1V

Fe 2 O 3 : EPFL

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)

Photo-electrochemical Reactor Modeling: Week 3 Update Zachary Ulissi

Reactor Design: Original & Wedges

Reactor Design: Extra Post

Reactor Design: Small Wedge

Reactor Design: Extra Post

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

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

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

Insufficient Mixing!

Laminar Diffusion Completed