Feasibility of a Microalgal Solar Cell

7/30/2019 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

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6.00

7.00

8.00

0 1 2 3 4 5 6

Power

(W)

Days

Direct Sunlight


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


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


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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Documents

Feasibility of a Microalgal Solar Cell