Feasibility of a Microalgal Solar Cell
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Transcript of Feasibility of a Microalgal Solar Cell
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Feasibility of a Microalgal
Gratzel Cell
Tamara Michelle P. Dominado
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Objectives
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General Objectives
This study aims to extract natural dyes from
three algal species, Tetraselmis spp.,
Nannochloropsis spp.andChaetoceros
calcitrans, and develop a working solar cell
using the extracts as sensitizers.
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Specific Objectives
The power output of the solar cells deposited with the algal
extracts were measured and compared at different light
intensities:
Under direct sunlight (on a sunny day, about 1-2pm)
Under artificial light with the use of 35W and 50W halogen
lamps
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Significance of the Study
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Significance of the Study
Develop solar cells using practical methods that can operate
efficiently
Sensitizers to be used will be different
More environmentally-friendly and cost-efficient
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Scopeand
Limitations
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Scope and Limitations
Algae were taken from UPV-NIMBB
Oct 2011 Mar 2012
Extraction was done using acetone and centrifuge
TLC and UV-Vis (Spectronic21) for pigment identification
Cells exposed to Direct sunlight, 35W and 50W halogen lamps
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What is a Gratzel Cell?
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What is a Gratzel Cell?
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How does it work?
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How does it work?
Works like plant leaves
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How does it work?
Subsystem Gratzel Solar Cell Photosynthesis
Electron Acceptor Nanoparticle TiO2 Carbon Dioxide
Electron Donor Electrolyte Water
Photon Absorber Dye Chlorophyll
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How does it work?
Anode Reaction:
Dye + energy Dye*
Dye* + TiO2 e-(TiO2) + Dye
+
Cathode Reaction:
e-(TiO2) + CE e-(CE) + TiO2
Dye+ + 3/2 I- Dye + I3
-
e-(CE) + I3- 3/2 I
- + CE
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Why a Gratzel Cell?
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Why a Gratzel Cell?
Does not require direct exposure to sunlight
Able to operate at a high temperature
Easier and less expensive to make
Made with readily available non-toxic materials
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What is a Sensitizer?
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Sensitizer
Part of the solar cell which initiates the process of
converting sunlight to energy
Can be synthetic (Ruthenium) or natural (Chlorophyll,
Anthocyanin)
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Sensitizer
So far, the highest attained efficiency of solar cells produced
in the lab using synthetic dyes has reached only up to 10%
(Sokolsky and Cirak, 2010)
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Ideal Properties
High broadband absorption and black in the UVA, visible
and IR
Electrons transfer must be rapid and energetically favorable
Stable and capable of multiple redox cycles without
decomposition
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Where will they come from?
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Algae
Plant-like photosynthetic organisms capable of utilizing solar
energy
Samples belong to groups Chlorophyta and Diatoms
Nannochloropsis spp
Chaetoceros calcitrans
Tetraselmis spp
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Chlorophyll
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Chlorophyll
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Carotenoid
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Methodology
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Culture ofPhotosynthetic
Organisms
Stock cultures will be obtained and culture insterilized containers with medium enriched bynutrients and are aerated
Extraction ofPhotosynthetic
Pigments
Cultures will be
crushed andblended and will
then be centrifuged
UV-Vis and TLCAnalysis
Wiltshire et. al. (2000)
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Preparation ofConductive Slides
A glass slide will be coated with Antimony-dopedSnCl4at 400C
Deposition ofTiO2 Film
TiO2 will be deposited on the conductive glass
slide at 450C for 30minutes using a hot plate
Carbon Coatingof Slide
A conductive slide will be coated withlight carbon film using a pencil lead
Gratzel and Smestad (1998)
Ahmad Mohamed Ali and Nayan(2010)
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Gratzel and Smestad (1998)
Ahmad Mohamed Ali and Nayan(2010)
Determination of Solar Output
The cell will be exposed to the light source for at least 2min beforemeasuring the current using a multimeter
Solar Cell Assembly
Binders will be used to hold the anode and cathode together and theelectrolyte solution will then be added
Staining
Slides will be submerged in extracts and live samples and will be left in adark room to allow reaction
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Species
Power (W)
Direct Sunlight 50W 35W
Tetraselmis spp. 4.418 A 0.020 A 0.009 A
Nannochloropsis spp. 4.757 A 0.032 A 0.006 A
Chaetoceros calcitrans 4.047 A 0.021 A 0.010 A
Carica papaya (std) 18.057 B 0.560 B 0.047 B
Power Readings
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Efficiency
Species Efficiency (%)
50W 35W
Tetraselmis spp. 0.039 0.026
Nannochloropsis spp. 0.064 0.017
Chaetoceros calcitrans 0.042 0.030
Carica papaya (std) 1.120 0.134
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UV-Vis Analysis
Species Observed Absorbance
Spectra (nm)
Possible Corresponding Pigment
Tetraselmis spp 430, 660 Chlorophyll a and b
Nannochloropsis spp. 416 Xanthophylls (Violaxanthin)
Chaetoceros calcitrans 431, 658-663 Chlorophyll a, b, and c
Carica papaya 429, 598, 661 Chlorophyll a, b, and c
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TLC AnalysisSpecies Possible Pigment
Chaetoceros calcitrans Chlorophyll a, b and c, Xanthophyll,
-carotene, Lutein, Violaxanthin
Tetraselmis spp Chlorophyll a, b, Xanthophyll,
-carotene, Lutein
Nannochloropsis spp Chlorophyll a, b and c, Xanthophyll, Violaxanthin,
Lutein, Neoxanthin, Fucoxanthin
Carica papaya Chlorophyll a, b and c,
-carotene, Xanthophyll, Violaxanthin, Neoxanthin
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Degradation
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
0 1 2 3 4 5 6
Power
(W)
Days
Direct Sunlight
Chaetoceros calcitrans
Tetraselmis spp
Nannochloropsis spp
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Degradation
0.0000.005
0.010
0.015
0.020
0.025
0.030
0.035
0 1 2 3 4 5 6
PowerW)
Days
50W
Chaetoceros calcitrans
Tetraselmis spp
Nannochloropsis spp
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Degradation
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0 1 2 3 4 5 6
Power
W)
Days
35W
Chaetoceros calcitrans
Tetraselmis spp
Nannochloropsis ssp.
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Self-Made Slides
Species Power (W)
Direct Sunlight
Tetraselmis spp. 0.003
Nannochloropsis spp. 0.008
Chaetoceros calcitrans 0.016
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Conclusion
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Algae
IT WORKS!
Although it did not come to par with previous studies that
used terrestrial plant extracts, this study has proven that it is
feasible to use algal pigments as dye for solar cells. Further
studies must be conducted to enhance the performance and
efficiency of the cells.
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Recommendations
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Recommendations
Degradation of the dye over time
Use of new conductive slides instead of reusing overused
ones to ensure even conductivity along the surface
Attachment of the dye to the anatase
Consider area of cell to power output of the slide
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Recommendations
Other types of solvent to be used for pigment extraction
Further identification of pigments present in the extracts by
HPLC
Use Scanning Electron Microscope (SEM) to further
characterize the photosynthetic pigments
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Recommendations
Use more accurate instruments (UV-Vis)
Concentration of the pigment and how it affects power
output and efficiency
Measuring different parameters like pH, temperature and
salinity that may affect the efficiency of the algal solar cells
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:DThank you!
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UV-Vis Analysis
0.05
0.100.150.200.250.300.350.40
350 450 550 650 750Absorbance
Wavelength (nm)
Nanno
0.00
0.200.400.600.801.001.201.40
350 450 550 650 750A
bsorbance
Wavelength (nm)
Tetra
0.000.050.100.150.200.250.30
350 450 550 650 750Absorbance
Wavelength (nm)
Chaeto
-0.01
0.01
0.02
0.03
0.04
0.05
350 450 550 650 750
Absorbance
Wavelength (nm)
Papaya
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