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[TEXT] Green Revolution with Lisa Van Pay, PhD (Scientist)
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[TEXT] Solar Power
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LISA VAN PAY: So here’s the sun,
right?
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It’s about 93 million
miles
[TEXT: (149 million kilometers)]
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away from the earth.
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It’s big, and it’s got a lot of
energy.
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Light is how energy moves
through space.
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But the snag is when light hits
the earth, the energy is all
spread out,
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so we have to figure out how
to collect it and concentrate
it,
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so we can use it. To get lots of
power,
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we use solar farms. On some
farms, thousands of mirrors
focus sunlight to
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heat pipes filled with fluid.
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On others, rotating mirrors
aim the sun’s rays at a
liquid-filled tank
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at the top of a tower.
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Both convert heat energy to
electricity using a generator.
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And then there are huge
farms of solar cells collecting
the sun’s
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energy and turning it directly
into electricity.
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But solar cells can work on a
smaller scale,
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too, powering everything from
streetlights to houses to
stores, even airports.
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But what about flexible
cells that go where you go? Then
you could charge
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your cellphone while you’re on
your way to meet a friend.
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Researchers at Arizona State
University are looking to the
solar experts —
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plants — to see if we can make
solar cells that work better
with your life.
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[TEXT] Brad Brennan, ASU Graduate Student
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LISA VAN PAY: Brad, can you tell me a
little bit about what kind of
research you’re
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doing in your lab?
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BRAD BRENNAN: Our group likes to
focus on the first steps of
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photosynthesis, where plants
take light and start converting
it into energy.
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LISA VAN PAY: In a plant, chlorophyll
molecules absorb light
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from the sun and use that energy
to move around electrons.
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Solar cells based on
photosynthesis can be smaller,
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cheaper, and more flexible than
the ones we have now.
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[TEXT] How does it work?
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LISA VAN PAY: Most of the solar cells we
use now are made from layers of
silicon
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engineered to make them positive
or negative.
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When the layers are sandwiched
together, the space in between
acts kind of like a magnet.
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Light energy can excite
electrons, making them jump into
the in-between space,
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and its magnetic properties push
them to the other side.
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Once the electrons build up, the
negative charge makes them push
each other through the circuit,
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creating an electrical current
we can use.
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Brad is making colored dyes
that help the solar cell absorb
even more
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light energy, like chlorophyll
does in plants.
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BRAD BRENNAN: We make more and more
complex molecules for us to,
eventually, try and
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get a very good mimic of what
the plant does.
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[TEXT] So what … happens next?
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LISA VAN PAY: So what are we looking at
here?
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BRAD BRENNAN: We’re looking at different
pieces of a dye-sensitized solar
cell
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showing kind of the different
parts to form our solar cell.
[TEXT: Completed cell, thin film, dye & film]
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We have a very, very thin film
on that.
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We cover that film with one
of the dyes that we make that
absorbs light very well,
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and if we’ve clipped two wires to
those pieces of glass and put
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it in the sunlight, we’d be
getting electricity out of that.
[TEXT: Dye-sensitized solar cell, thin film, dye]
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It’s basically a stepwise
process in research. You just
never know
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what’s going to work and what
doesn’t work.
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LISA VAN PAY: In this case, you might need
to collaborate with some other
people that
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could give you ideas on how to
do that?
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BRAD BRENNAN: A lot of people have
different specialties. And they
might be
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10,000 miles away on the other
side of the earth at a different
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university, but they know how to
solve your problem.
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[TEXT] Far away? Close enough.
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LISA VAN PAY: Collaboration is an
important part of solving
problems. Remember that
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thin film Brad was talking
about? That’s another thing
that researchers are
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working to improve.
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So, Brittany, can you tell me
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[TEXT: Brittany Lynn, Undergrad
Researcher, Univ of AZ]
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a little bit about the work that
you’re
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doing in the lab right now?
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BRITTANY LYNN: The goal of the lab
right now is to make organic
solar cells more efficient.
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And the work that I was doing to
help this along was to take
certain layers
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on a solar cell and try to make
it so they were bumpy.
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And what being bumpy
does is it helps the interface
between two
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surfaces have more surface area.
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LISA VAN PAY: So there’s more surface
area, but the two surfaces still
have to be
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close enough together for the
electrons to jump.
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BRITTANY LYNN: Yes, so they are
limited in the distance they can
move by the
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material that we’re using.
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So we have to make really thin
solar cells.
[TEXT: “Bumpy” Solar Cell, thicker film]
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But when it’s really thin, you
can see through it more easily.
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And so if you can see
through it, that means the light’s
not
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getting absorbed by the
material.
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So what we want to do is be able
to have it thicker, so more is
absorbed
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from the sunlight and you get
more power.
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I wanted to do some
work over the summer that would
give me some
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experience in a chemistry lab,
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so I could actually touch some
of the machines like we were
learning about in class.
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And also to work with solar
cells because that’s a big field
in optics and science.
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LISA VAN PAY: Every day, the earth
receives a huge amount of energy
from the sun,
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and every day we’re getting
better at harnessing that
energy.
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New ideas are shared every
summer as students from all over
the world
[TEXT: U.S. Department of Energy Solar Decathlon]
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participate in the Solar
Decathlon,
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a competition to see who can
make the best solar-powered
house.
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Soon, photovoltaic shingles
for your house and light,
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flexible cells that can charge
your stuff on the move will be
everywhere.
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And someday, we might even have
solar power beamed down from
satellites.
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The National Science
Foundation supports researchers
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who look at stuff we already
know a lot about,
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like plants and solar cells, and
think about them in new ways.
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New ideas that could lead to a
brighter tomorrow.