Fruit Pulp & Juice Plant, RTS Juice Plant, Fruit Juice Plant, Fruit Pulp Plant
Juice from Juice Workshop Presentation (Slightly condensed) Updated April 2015.
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Transcript of Juice from Juice Workshop Presentation (Slightly condensed) Updated April 2015.
Overview of JfJ Project• Goal: develop dye-sensitized solar cell (DSSC) kit that
1. Supports state science curricula and standards (3rd – 12th grade)
2. Gets students involved in solar-energy technology3. Reinforces inquiry-based learning and invites further
discussion/investigation from students• Integration of three scientific fields under one DSSC unit
Physics
ChemistryBiology
DSSC
Chemical potential
Electron transfer
Light absorption
DSSCs vs. Traditional Photovoltaics
Solar window prototype by Solaronix - EPFL
Sony Hana Akari (“flower light”) lamps: lampshades are
screenprinted DSSCs
Caltech Holliston parking structure
Today’s Workshop
anthocyanin
TiO2 surface on FTO glass
hν
e-
“Sandwich” dye-sensitized solar cell
photosensitizerphoto = light
DSSC Components• TiO2 nanoparticle paste• Natural dyes used as photosensitizers
– Chlorophyll (spinach leaves)– Anthocyanin (berries, fruits)– Betalin (beets)
• Conductive glass electrodes (FTO)• Redox electrolyte (I-/I3
-)• Light source (projector or sun)
John Muir HS Chemistry student (PUSD) TiO2 electrode soaking in crushed berries
Assembling the Electrodes
TiO2 layer
TiO2 layer dyed with blackberry juice
Assembled sandwich
Completed cell with electrolyte in between the layers
Graphite counter electrode
This ball has potential energy and can do
work by knocking over some dominos at the
bottom of the hill
Conceptual DSSC Explanation
The ball is like an electron – we can get the electrons to “roll down a hill” to make electricity!
Atomic Energy LevelsEn
ergy
1s
2s
2p
First, consider General Chemistry’s atomic-orbital energy levels. Electrons populate these energy levels, and can be excited to higher energy levels. We use similar energy diagrams for electrons in molecules and solids, too!
Electron TransferEn
ergy
TiO2
I-/I3-
But for our new energy diagram, there is no spatial x-axis dependence, so let’s rearrange the locations to see our analogy better.
In this scheme, we positioned the energy levels to spatially correspond to our materials’ locations.
Dye
Electron Transfer
TiO2
Dye
I-/I3-
Load
We also added a load that the electrons pass through, as in the picture.
Although we’ve spatially rearranged the energy levels , they still sit at the same energies!
Ener
gy
Electron Transfer
TiO2
Dye
I-/I3-
Load
Light excites the electron in the dye from the dye’s valence band to its conduction band
Ener
gy
Electron Transfer
TiO2
Dye
I-/I3-
Load
The electron then ‘rolls down the hill,’ passing through the load ‘knocking over dominos,’ then returns to the ground state in the dye
Ener
gy
Electron Transfer
TiO2
Dye
I-/I3-
Load
The electron then ‘rolls down the hill,’ passing through the load ‘knocking over dominos,’ then returns to the ground state in the dye
Ener
gy
Electron Transfer
TiO2
Dye
I-/I3-
Load
The electron then ‘rolls down the hill,’ passing through the load ‘knocking over dominos,’ then returns to the ground state in the dye
Ener
gy
Electron Transfer
Energy
TiO2
Dye
I-/I3-
Load
The sun does all the work for us! It throws the electrons to the ‘top of the hill,’ while we simply make use of the electrons’ energy as it rolls down! This is our SOLAR ENERGY.
Electron Transfer
Energy
TiO2
Dye
I-/I3-
Load
Our load can be a light bulb or other electronic device. Today it is a multimeter.
Chemical Reactions Resulting in Electron Transfer for Current Flow
Image credit: http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch19/oxred_2.php
Reduction I3
- + 2e- 3I-
wOxidation
3I- I3- +2e-
-2 e- +
-
LEO the lion goes GEROIL RIG
Using Multimeters DC = Direct Current Variable Units of Measurement Context
Current ‘I’
Amps (A) = Coulomb/sec
Electron travel rate
Voltage‘V’
Volts (V) = Joules/Coulomb ‘Push’ [or energy] per electron packet
Resistance‘R’
Ohms (Ω)= Volts/Amps Opposing force [like friction in mechanics]
Power‘P’
Watts (W) = Joules/ sec = Volts*Amps
Energy transfer rate
P = I*VJoule’s Law
V = IROhm’s Law
Why this System?
• Materials cheap, abundant, non-toxic• Right energy level alignment of dyes, FTO, TiO2,
I-/I3-, graphite
• Detectable I and V
• Other dyes [other fruits or synthetic dyes] can be used, other metal oxides besides TiO2 can be used; however, energy level alignment and electron transfer rates must be satisfied
Sub-Module: BiologyPlants Solar Cells
Light Absorber Molecules Materials
Fuel Produced Chemical Electrical
Fuel Storage Yes No
• Chlorophyll and colored markers contain various pigments (chemical compounds) that have different affinities for solid vs. liquid phase• Separate via thin layer
chromatography (TLC)• Characterize by Rf value
• Effect of color of light on absorption
TLC plate
Sub-Module: Chemistry• Output voltage due to reduction/oxidation (redox) reactions
– Different metals have different reduction potentials– Create activity series using Zn, Cu, Sn, and Mg
E (V)
-0.5
0.0
0.5
1.0
Galvanic cell DSSC
Sub-Module: Physics• Nature of light
– White light can be made from individual colors (additive)
– Prisms disperse white light into its components
– Dark colors absorb some light and transmit/reflect others (subtractive)
• Converting light to electricity: solar cells– Conversion efficiency– Output dependence on intensity and color
http://www.astro.virginia.edu/~rsl4v/PSC/light.html
Commercial DSSC Kits• Juice from Juice kits distributed by
Arbor Scientific• Includes all materials for the
integrated labs we have developed– DSSC Fabrication………………..$110– Electrochemistry (Chem) &
Chromatography (Bio).……….$50– Light & Solar Cells (Phys) ……$70– DSSC Refill.………………………...$39 – Chem Refill.……………………..…$19
• Enough materials for a 30 person class
• Materials can be reused for several years
“I need help!”• “I don’t have enough $$ for the kit!”
– Kids in Need Foundation, DonorsChoose.org, local power company grants– Donations from parents, PTA, bake sales– Even aluminum cans!
• “I don’t remember how to do it!”– YouTube videos and lesson plans online
http://thesolararmy.org/jfromj
– We can do a demo at your school!– Email questions – [email protected]
• “I don’t have time in my curriculum!”– All the labs fulfill state standards!– Incorporate as much as you can – some renewable energy education is
better than none
Conclusions and goals• Integrate basic science with
push towards clean energy• Get students and teachers
directed toward research in solar energy conversion
• Feedback and continued project development– Improvements to curriculum
Thanks – and have fun!
Physics
ChemistryBiology
DSSC
Chemical potential
Electron transfer
Light absorption
Questions: [email protected]