Lecture (10,11,12)
Energy Applications and Cleantech
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We have…
• An increasing number of
environmental concerns
at the global level
and
• A decreasing amount of depletable
resources like coal, petroleum and natural
gas,
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• Wind, solar and hybrid power are viable
alternatives to fossil fuels.
• Not only are they readily available, but they are
renewable as well.
• If we can create the technology to make them
cost efficient and sufficient to meet our needs we
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can become independent of foreign oil.
Following is a graph that shows the % of our total energy
provided by renewable energy.
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http://www.fi.edu/guide/hughes/renewables.html
Sustainable versus Renewable
• Sustainable refers to a system that replenishes
itself so that it can be used by future generations.
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Sustainable versus Renewable
• Renewable implies something can be done more
than once, or a resource that can be used
repeatedly. For instance, crop-derived fuels (bio
diesel) are renewable.
Something that is
renewable is not
necessarily sustainable.
Not all crops can be
grown sustainably, yet
they can be renewable.
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Clean Energy
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Solar cells
A photovoltaic cell converts solar energy into electricity.
Silicon Solar Cells:
fragile
expensive
15-25% efficiency
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(10% efficiency = 100 W/m
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Nanosolar
Popular Science innovation of the year 2007!
CIGS (Copper Indium Gallium Selenide)
nanoparticle ink coated onto aluminum alloy foil
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http://www.youtube.com/watch?v=-XIL9BgPZX0&feature=related
Panels can be made for about a tenth of what
current panels cost and at a rate of several
10
hundred feet per minute (16.4% efficiency )
Quantum Dots Boost Efficiency
Utilizes semiconductor
quantum dots to modify the
internal structure of the
semiconductor material
Improved efficiencies
Reported cell efficiency 40-42%
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Multi-Junction Photovoltaics
with Quantom Dots
Reported cell efficiency 40-42%
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http://upload.wikimedia.org/wikipedia/commons/a/a4/PVeff(rev110707)d.png
Generation I – bulk Si solar cells
• single
• polycrystalline
Generation II – thin films
• Amorphous Si
• Polycrystalline CdTe and CuInSe2
• Dye Cells
• Organic PV cells
Source: http://www.science.doe.gov/bes/reports/files/SEU_rpt.pdf
High Efficiency + Low Cost / Watt
Generation III – emerging
technologies
• Triple junction cells for CPV
• Other novel concepts for high
efficiency solar cells
• Nanomaterials ? 14
Fuel Cells
Terminator 3: Rise of the Machines
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Nano Fuel Cells
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Their maximum output is 86 kilowatts, or about 107 HP.
Because hydrogen fuel cell stacks produce power without
combustion, they can be up to twice as efficient as internal
combustion engines. They also produce zero carbon
dioxide and other pollutants.
Fuel Cells
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Hydrogen Fuel Cell
Polymer Membrane Electrolyte
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Fuel Cell Efficiencies are not
limited by thermodynamics
Polymer Membrane:
Cell: 50–70%
System: 30–50%
Solid Oxide:
Cell: 60–65%
System: 55–60%
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Solid Oxide Fuel Cell
1
2
O
2
s  
H
2
g  
O 2 g

2e   O
2
s 
H 2O g   2e 
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Thin Film Solid Oxide
Fuel Cells
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DFC300: Large scale fuel cells suitable for mediumsized hotels, grocery stores, and similar commercial
operations.
300 kW
47% electrical efficiency
24 hours a day, 7 days a week
FuelCell Energy, Inc. 22
www.fuelcellenergy.com
Fuel Cells
Efficient: generates more
electricity using less fuel with
unparalleled electrical power
generation efficiency of 47%
Ultra-clean: emits low CO2 and
virtually zero pollutants into the
atmosphere
Quiet: operates virtually
unnoticed, making them suitable
for almost any location
Reliable: achieves availability
rating exceeding 96%,
significantly higher than other
alternative energy technologies
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Economical: produces up to six
times more electrical power
than other forms of distributed
generation with the same fuel
input and can operate at up to
80% efficiency when used in
Combined Heat and Power
(CHP) applications
Simple: real-time monitoring of
fuel cell system from FuelCell
Energy's state-of-the-art Global
Technical Assistance Center
(GTAC)
Versatile: operates on a variety
of fuels for use in a wide range
of applications
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DF3000: suitable for hospitals, universities, large
commercial complexes, and utility grid support
applications
2.8 MW
47% electrical efficiency
Combined Heat and Power
FuelCell Energy, Inc.
www.fuelcellenergy.com
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Definitions of Cleantech
• What is "cleantech"?
• The term "cleantech" refers to technologies that:
– - Use energy, water and other raw materials more
efficiently and productively,
– - Deliver equal or superior performance,
– - Improve customer profitability, through cost
reduction and / or increased revenues, and
– - Create less waste or toxicity
• ... as compared to incumbent technologies
• http://cleantechvc.blogspot.com/
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Companies in Cleantech
• Energy
– Solar, fuel cell, batteries
• Environmental Remediation
– Air, water, soil
• Water purification
• Sensor technology
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Clean Energy
•
•
•
•
•
•
•
Solar energy
Fuel cells
Batteries
Motors
Wind production
Hydrogen production
LED and CNT lighting
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Solar cells
It is a photovoltaic cell that converts solar energy into electricity. A photovoltaic cell
consists of semiconductor layers.
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Nanosolar
Popular Science innovation of the year 2007!
http://www.popsci.com/popsci/flat/bown/2007/index.html
The company produces its PowerSheet solar cells with printing-press-style
machines that set down a layer of solar-absorbing nano-ink onto metal sheets as
thin as aluminum foil, so the panels can be made for about a tenth of what current
panels cost and at a rate of several hundred feet per minute.
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Nanosolar
A thin-film solar cell consists most fundamentally of an absorber layer (the
semiconductor) sandwiched in between a top and a bottom electrode layer.
The thin films of a solar cell are deposited directly onto a highly conductive metal foil
(as opposed to glass or stainless steel), then the bottom electrode gets much
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simpler because the substrate can do the job of carrying the current.
Conductive Substrate
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Nanosolar
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Nanoparticle Ink
A homogeneous mix of nanoparticles in the ink in just the right
overall amounts ensures that the atomic ratios of the four
elements are correct wherever the ink is printed, even across
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large areas of deposition.
Nanosolar
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Semiconductor Printing
Printing is much simpler and more robust than vacuum deposition techniques such as
sputtering or evaporation which have conventionally been used to fabricate thin-film
solar cells.
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Nanosolar
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Fuel Cell Technology
A hydrogen fuel cell would bring in hydrogen and oxygen, create electricity to power
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your vehicle, home, etc, and release water and heat.
A fuel cell will is made up of two electrodes (anode and cathode)
surrounding an electrolyte. Hydrogen, or a fuel like methanol containing
hydrogen, is fed into the anode, where the hydrogen atoms, encouraged
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by a catalyst, split into protons and electrons.
The protons pass through a selective electrolyte membrane, while the
electrons are sent off to another path, creating a usable electric current.
The protons and electrons rejoin at the cathode, where the hydrogen
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reacts with oxygen from the air to form water.
Nano Fuel Cells
Nanotechnolgoy will help make fuel cells smaller and more efficient so that
they can eventually be used to power everyday portable devices.
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Nano Fuel Cells
Some of the initial
commercial portable fuel
cells improve conventional
methanol polymer electrolyte
membrane (PEM) fuel-cell
technology with
nanostructured catalytic
layers and MEMS-based
micro reformers.
http://www.smalltimes.com/display_article/312009/109/ARTCL/none/none/1/Nano
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-enables-practical,-portable-fuel-cells/
Thin Film SOFC
Ultra-thin solid oxide fuel cell (SOFC) structures containing electrolyte
membranes 50-150nm thick were fabricated with the help of sputtering,
lithography, and etching. They were made of 50nm YSZ electrolyte and
80nm porous Pt as cathode and anode. The peak power densities were
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200 and 400 mW/cm2 at 350°C and 400°C, respectively.
Solid Oxide Fuel Cell
1
2
O
2
s  
H
2
g  
O 2 g

2e   O
2
s 
H 2O g   2e 
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Electrolyte Material Properties
The role of the electrolyte in a SOFC is two fold:
It must form a barrier to prevent fuel and oxidant
gases mixing.
Transport oxygen ions across the membrane from the
cathode to the anode (with minimal electronic
conductivity).
In a working fuel cell the electrolyte must therefore posses various properties:
● Stability in both reducing and oxidizing environments.
● Sufficiently high ionic conductivity at the cell operating temperature
● Good thermal stability.
● In addition, the material must be able to be formed into a thin, dense film gas tight
to hydrogen.
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Grain boundaries act as high diffusivity pathways, allowing more
oxygen ions to move through the electrolyte, therefore increasing the
overall efficiency of the cell.
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Nanofiltration/Water Purification
Nanoporous membranes are suitable for a mechanical filtration with extremely small
pores smaller than 10 nm. Nanofiltration is mainly used for the removal of ions or the
separation of different fluids
The liquid to be filtered passes over the
membrane at high velocity. Depending on
the membrane pore size, different sizes of
molecules are able to pass through the
membrane.
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The water treatment plant at Méry-sur-Oise provides the Parisian suburbs (4 million
inhabitants) with high quality water thanks to a membrane process developed by
researchers at Veolia Water.
This process, first used in the medical world, has been adapted by researchers at
Veolia Water to allow for its use with large volumes of water and for the large
scale production of drinking water at prices suited to market demand.
Nanofiltration has been used since 2002 in Coliban, Australia, to treat up to 126
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million liters of water a day
Photocatalytic Air Purifier
8200V electronic filter absorbs the
miniature dust and decomposed
particles.
Producing a high ion density. therefore
provides you the most healthy air.
Nanophotocatalytic filter disinfection,
enabling better performance in
removing germs and eliminating
stinking air.
UV lamp effectively destroys the DNA and
RNA of all sort of germs. It also
activates the photocatalytic device.
The TiO2 filter conducts the first
disinfection process and slows down
the air flow for better particle
absorption
Pre-filter provides the first cleaning
process to remove larger particles,
dust mites, hairs or fibers.
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