Transcript Solar Hydrogen Update - Imperial College London

Solar Hydrogen Update
24th November 2009
Updates
-Carver’s reactor
- Reactor fitting
- Mirrors
- Improvements on model
- Reactor models discussion
- Mechanistic studies
- Kinetic data
- Feasibility of annular configuration
Carver’s Reactor
Reactor setup
Issues
H2 O2
• Extra pumps
• Extra inventory
Reactor
Pump
Feed
Tank
Pump
Carver’s Reactor
Reactor setup
Issues
• Limited feed tank opening
H2 O2
Reactor
Pump
Feed
Tank
Carver’s Reactor
Reactor setup
H2
Reactor
Pump
Feed
Tank
O2
Issues
• Rate of gases separate
from liquid
• Might need a hydrocyclone
for gas-liquid separation
Mirror
From Optical Mechanics Inc. Quotation is yet to receive
Mirror
Reaction Kinetics
Semiconductor + hν
2H+ + 2eH2O + 2h+
H2O
k1
k2
k3
Semiconductor (e-, h+)
H2
2H+
H2
+
+
½ O2
½ O2
How fast is the hydrogen generation ?
• This rate might overcome the low efficiency performance
• Mechanistic study get help from chemistry ?
• Study on the reaction rate can be obtained from the current reactor
• This would improve the reactor model
Annular Configuration
Spoken to Prof. James R Taylor (Imperial College
Physics Dept.)
• Energy loss ~10 db/km
• Could Si or quartz as fibre material
• It is feasible and worth investigating in future
Annular Configuration
Lens in focusing the
light
Fibre optic coated with
photo-anode at the
outer surface
Hollow fibre
membrane
Cathode
Focusing task
• Setting up carver’s reactor for preliminary testing
• Should we get new burette?
• Improve on the current reactor model
• Run the plasma deposition unit for photo-anode
characterisation
Light Intensity - Spectra:
PBR1 – Low intensity LED array
PBR2 – High intensity LED array
Culture reactor – Cool white fluorescent lights
Sartorius reactor – Cool white fluorescent lights
Light Intensity – Spectral matches:
CC-124 absorption to fluorescent emission
CC-124 absorption to LED emission
Pumps – Watson Marlow:
Peristaltic 300 series - £1222.00
Flow up to 2l/min
Microprocessor or manual control
Brushless DC motor
2 year warranty
5.6kg, 233x230x132mm
Peristaltic 500 series - £603.00
Flow up to 4.5l/min
Fixed speed pump
AC motor gearbox
2 year warranty
11kg, 360x170x140mm
Pumps – KNF Neuberger:
Liquid Diaphragm Pump, NF30 series - £114.06*
General:
• Oscillating displacement pump
• DC motor
• Mounted in any position
• Oil/maintenance free
• Weight ≈ 500g
Gas Diaphragm Pump, modified NMP830 - £182.73*
Flow:
• Around 0.3l/min for liquid pump
• Around 2l/min for gas pump
• Flow rate adjusted by changing
input voltage – 4 lead DCB
(brushless) motor for optimum
control
Modification:
• NMP830 gas-tight
• Aluminium head
• EPDM diaphragm and valves
• G1/8 threaded port (Swagelok
connection)
• Designed for He pumping
Pumps – KNF Neuberger:
Modified Liquid Diaphragm Pump, NMP015 series
Solar simulator (Fessehaye) reactor:
• NMP015 may be modified to be
gas-tight (expensive)
• Stainless steel/aluminium head
• EPDM diaphragm and valves
• “Low algal death rates”
MSc/PhD Students:
Stephanie Hoarau (SEF):
• Develop MIMS system
• Develop filtration system
Annalisa (University of Milan)
FZ
• Design – flat panel bioreactor
• Update on instrumentation and data
analysis
Flat Panel design:
•
•
•
•
gravitational flow
Cleaning
Probes
Support
Assembling the system:
NI USB-6229 BNC
•16-Bit, 250 kS/s M Series, Integrated BNC, External Power
•16 differential BNC analog inputs (16-bit, 250 kS/s)
•4 BNC analog ouputs (16-bit, 833 kS/s), 48 digital I/O (32 clocked, 8 BNC), and 32-bit counters
•NI Signal Streaming for sustained high-speed data streams over USB; OEM version available
•Compatible with LabVIEW, ANSI C/C++, C#, Visual Basic .NET and Visual Basic 6.0
•NI-DAQmx driver software and NI LabVIEW SignalExpress LE interactive data-logging software
Fe2O3: spray pyrolysis
• Effect of Sn doping on:
– Electrochemical properties
– Morphological properties
Undoped Fe2O3: 10 layers
Current-voltage characteristics of Undoped Fe2O3 films under light and
dark conditions
3
2.5
Current Density (A.m-2)
2
1.5
Dark
Light
1
0.5
Cycles: 1
Scan Rate: 0.01 V.s-1
Step Potential: 0.01 V
0
-0.4
-0.2
0
-0.5
0.2
0.4
0.6
0.8
Layers: 10
C.A. Pressure: 50 psi
Applied Potential (V)
Undoped Fe2O3: 20 layers
Current-voltage characteristics of Undoped Fe2O3 films under light and
dark conditions
2.5
2
Current Density (A.m-2)
1.5
Dark
Light
1
0.5
0
-0.4
-0.2
0
-0.5
0.2
Applied Potential (V)
0.4
0.6
Cycles: 1
-1
Scan Rate: 0.01 V.s
Step Potential: 0.01 V
0.8
Layers: 20
C.A. Pressure: 50 psi
Doped Fe2O3: 10 layers
Current-voltage characteristics of Sn doped Fe2O3 films under light and
dark conditions
0.9
0.8
0.7
0.6
Current Density (A.m-2)
0.5
Dark
Light
0.4
0.3
0.2
Cycles: 1
Scan Rate: 0.01 V.s-1
Step Potential: 0.01 V
0.1
0
-0.4
-0.2
0
0.2
-0.1
-0.2
Applied Potential (V)
0.4
0.6
0.8
Layers: 10
C.A. Pressure: 50 psi
Doped Fe2O3: 20 layers
Current-voltage characteristics of Sn doped Fe2O3 films under light and
dark conditions
0.5
0.4
0.3
Current Density (A.m-2)
0.2
-0.4
Dark
Light
0.1
0
-0.2
0
0.2
0.4
0.6
0.8
-0.1
-0.2
Cycles: 2
-1
Scan Rate: 0.01 V.s
Step Potential: 0.01 V
-0.3
Layers: 20
C.A. Pressure: 50 psi
Applied Potential (V)
Doped Fe2O3: 15 layers
Current-voltage characteristics of Sn doped Fe2O3 films under light and dark
conditions
0.5
0.4
Current Density (A.m-2)
0.3
Light
Dark
0.2
0.1
0
-0.4
-0.2
0
-0.1
0.2
0.4
Applied Potential (V)
0.6
0.8
Cycles: 1
-1
Scan Rate: 0.01 V.s
1Step Potential: 0.01 V
Layers: 15
C.A. Pressure: 50 psi
Undoped Fe2O3: 15 layers
Doped Fe2O3: 20 layers
On-going work
• Effect of Sn-doping
– Lower/higher doping concentrations
• Film thickness measurements
• Quantum efficiency measurements
– Effective H2 yields
CO2 Reduction Mechanism
• CO2 + e-  CO2– CO2- + H+ + e-  HCOO– CO2- + H2O + e-  HCOO- + OH– CO2- + H+ + e-  CO + OH– CO2- + H2O + e-  CO + 2OH-
Low CO2 concentration in aqueous systems
Feed CO2 in gas phase through gas
diffusion electrodes along with steam
PEC Reactor Development