Nanotechnology for Energy and Environment

BIOE298 DP

A major technological challenge for human race in 21st century is the transition from fossil-fuel-based energy economy to renewable (sustainable) energy one.

• Collective energy demand of the planet is predicted to be doubled by the mid of 21st century and to be tripled by the end of this century.• There is a urgent need to develop CO2- neutral energy sources.• The sustainable energy alternatives should be cost effective.

Sustainable Energy: Need a Major Breakthrough

Quantum size effects (atomic level of matter) result in unique mechanical, electronic, photonic, and magnetic properties of nanoscale materials • Chemical reactivity of nanoscale materials greatly different from more macroscopic form, e.g., gold

• Vastly increased surface area per unit mass, e.g., upwards of 1000 m2 per gram

• New chemical formation , e.g., fullerenes, nanotubes of carbon, titanium oxide, zinc oxide, other layered compounds

The Importance of Nanoscale Properties

• The melting point of gold particles decreases dramatically as the particle size gets below 5 nm

• For nanoparticles embedded in a matrix, melting point may be lower or higher, depending on the strength of the interaction between the particle and matrix.

Benefits already observed from the design of nanotechnology based products for renewable energy are:•An increased efficiency of lighting and heating•Increased electrical storage capacity.•A decrease in the amount of pollution from the use of energy

Portfolio of solar/thermal/electrochemical energy conversion, storage, and conservation technologies, and their interactions

Workshop on Nanotechnologies for Thermal and Solar Energy Conversion and Storage, August 10,11, 2008, Jacksonville, FL

Opportunities of Nanoparticles for Energy and Environment

More efficient devices for…• LED-based lighting• Thermoelectric refrigeration• Thermoelectric and thermo-photovoltaic conversion of

waste heat• Photovoltaic conversion of solar energy and production

of hydrogenOther benefits• Compact• Robust• Low environmental impactChallenges• Efficiency breakthroughs needed!• Availability and price of raw materials• Manufacturing costs

Electricity generation accounts for about 37% of primary energy consumption in the U.S.• Lighting accounts for 22% of the nation’s electric power usage.• The DoE SSL Goal: a solid-state lamp that is more efficient, longer lasting and cost competitive compared to conventional technologies, targeting a system efficiency of 50% and the color quality of sunlight.• Implications of Success: 33% reduction in energy consumed for lighting by 2025, eliminating need for 41 1000MW power plants, and saving consumers $128 B+.

Low cost solution:Blue (In,Ga)N LED with partially absorbing yellow phosphorLimitations: poor color rendering, low efficiency due to Stokes shift

Warm light solution:Board-level integration of (In,Ga)N/yellow phosphor and (Al,Ga,In)P red LEDsLimitations: “green gap”, high cost of assembly

III-V LEDs cover the visible spectrum,but not with one materials system

Compound Semiconductor, June 2008, pg. 17

• Generate electricity directly from sunlight• 2 Main types:– Single-crystal silicon (traditional)• Widespread• Expensive to manufacture– Dye-sensitized (“nano”)• Newer, less proven• Inexpensive to manufacture• Flexible

Photovoltaic Solar Cells

Silicon-basedsolar cell

Dye-sensitized solar cell

• Problem: Fast energy loss by hot carriers– Hot carriers are produced when solar photons with energy significantly higher than the band gap of the semiconductor is absorbed. Excess energy leads to lattice vibrations and thus affects the efficiency.

• Solution 1: Use of Si nanocrystals with different band gap values to capture the full solar spectrum• Solution 2: Use of quantum confined nanocrystals to generate multi-exciton generation

Organic dye sensitized solar cells

• Charge-carrier recombination problem can be

addressed by using nanoparticle /nanostructures.

• Carrier collection efficiency can be improved by

using one dimensional nanostructures such as

nanowires and nanotubes.

• Nanotechnology may provide routes for cost

reduction by using thin films.

Hydrogen from solar water splitting

• Photoreduction of CO2 with water to form hydrocarbon

(methane, methanol etc.)

– This approach is very interesting as using CO2 as a raw

material to produce hydrocarbon fuels just by using sun

light.

– Negative CO2 foot print

– Not only interesting from the environment point of view,

but also from the view of sustainable transportation using

the existing Infra structure for fuel distribution

• TiO2 nanoparticles are used in solar water splitting• Increasing the efficiency of the process is a main challenge• Oxynitride of TiO2 (TiO2-xNx) is a better alternative• Nanosized TiO2-xNx can absorb in the visible region

Solar Photocatalysis

• Despite the huge advantages, their commercialization is hampered by:– High cost– Durability issues– Operability issues• Solutions for some these bottlenecks will be from nanotechnology• e.g.: Replacing Pt catalysts with some cheapermaterial in low temperature fuel cells

Fuel Cells

What is the problem? Hydrogen fuel cell development has some practical issues associated with cost benefit and infrastructure development for safety and economics (e.g., fuel manufacturing, transportation, and storage).

Although hydrogen has a high energy density by weight, it has a low energy density by volume as compared to hydrocarbon-based fuel cells. Thus, hydrogen storage is one of the bottlenecks for hydrogen fuel cell development since high-pressure compressed gas tanks are large and heavy. In addition, compressing hydrogen to high pressures require energy as well, defeating some of the cost benefits with fuel cells. Liquid hydrogen storage, which does not have a great energy density by volume as compared to hydrocarbon, also requires cryogenic storage – a bulky and expensive option.

a) Hydrogen production and storage by renewable resource, (b) hydrogen storage in metal doped carbon nanotubes , (c) storage in mesoporous zeolite: by controlling the ratio of different alkali metal ions (yellow and green balls), it is possible to tailor the pressure and temperature at which hydrogen is released from the material, (d) hydrogen storage in metal–organic framework (MOF)-74 resembles a series of tightly packed straws comprised mostly of carbon atoms (white balls) with columns of zinc ions (blue balls) running down the walls. Heavy hydrogen molecules (green balls) adsorbed in MOF-74 pack into the tubes more densely than they would in solid form.

Hydrogen storage in tanks presently used in hydrogen-powered vehicles

Hydrgen gas (red) adsorbed in an array of carbon nanotubes (grey). The hydrogen inside the nanotubes and in the interstitial channels is at a much higher density than that of the bulk gas

The growth of large-area graphane-like film by RF plasma beam deposition in high vacuum conditions. Reactive neutral beams of methyl radicals and atomic hydrogen effused from the discharged zone and impinged on the Cu/Ti-coated SiO2/Si samples placed remotely. A substrate heating temperature of 650 °C was applied

http://www.intechopen.com/books/hydrogen-storage/hydrogen-storage-for-energy-application

a) STM images of graphane. The bright protrusions in the image are identified as atomic hydrogen clusters; (b) after annealing at 300 °C for 20 min; (c) after annealing at 400 °C for 20 min; (d) graphene recovered from graphene after annealing to 600 °C for 20 min. Scale bar 3 nm

Nanotech Materials for Truly Sustainable Construction

60% of global industrial waste is from the construction and demolition of buildings

60% of electrical use in developed nations is by buildings

40% of total energy consumed is by buildings

Old or new? (Damascus 900-1750AD)

• Arms race? The first crusaders encountered better steel

Wootz steel, developed in India & Sri Lanka ~300 BC greater strength & flexibility due to carbon nanotubes technique lost ~1750AD

The Revolution in building science

A quick overview

Steel Concrete Glass Gypsum Drywall Fabrics & Carpet Energy/HVAC

Filtration Electronics / Sensors Tools Coatings & Paints Lighting Insulation

Put on your running shoes…

Steel Nanocomposite steel is available & stronger

(per ASTM) Withstands temperatures as low as -140F Increased plasticity Free of corrosion-causing carbide paths Results:

reduced amount of steel Simplified placement of structural

concrete 20 to 40% savings

Concrete Production of concrete accounts for 8%

of total CO2 emissions worldwide Translucent concrete?

Glass Can block UV & glare Self-cleaning glass coated (titanium dioxide coating

breaks down organic matter

Switchable Glass

Switch!!

Gypsum Drywall

Nano-drywall is lighter, stronger and water resistant

Fabrics and Carpet

Nano-treatments are used on commercial fabrics Color-fast, stain proof and dirt proof Naturally hydrophobic, no mold or mildew

Energy / HVAC

Solar cells infused with nano-technology are thin, flexible and come in rolls so they can be applied as roofing material

Tools Doped Nanophostate Lithium Ion batteries Cordless tools are more powerful than corded!

Coatings and Paints

Nano particles enhance physical and aesthetic qualities

Hard, durable finish

Excellent water resistance

Scrub-ability

Stain blocking and other properties

• LEDs (point source) & OLEDs (sheet)

40% of commercial energy goes to lighting LED is most efficient, sustainable solution 10X more efficient than incandescent 50,000 - 100,000 hours (vs 10,000)

Lighting

"No other lighting technology offers so much potential to save energy and enhance the quality of buildings"

U.S. Dept. of Energy

46% average annual growth from 2001-2004 HB LED market $4.2 billion in 2006 Growing to $9.9 billion in 2011

Big technology push

Solid-state lighting

*Examples: Osram, Philips, OptiLED Holdings (Hong Kong)

Solid-state lighting

Insulation

Aerogel, a translucent thermal-acoustic insulator

Looks like frozen smoke Best insulating solid in the world Weighs only 90 grams per liter Extremely flexible- blankets, beads, sheets

The new “plastic”**Not really—it’s amorphous silica

(sand)

How to use these innovations?

• Steel• Concrete• Glass• Gypsum Drywall• Fabrics & Carpet• Energy/HVAC

• Filtration• Electronics / Sensors• Tools• Coatings & Paints• Lighting • Insulation

Sound Transmission: Acoustic Performance

•Truck Noise •10 db attenuation 40 - 400 HZ sound transmission •loss 2-3/4” FRP

(.wav)

Sound pressure level vs. time

Fiberglass insulation

Nanogel® (.wav)

About aerogels Well-known, insulating nano-substance that is translucent

and 97% air NanogelTM* panels – developed for skylights –

Lightweight Hydrophobic Highly translucent Thin Superb thermal / acoustic insulator Manufactured as large, rigid panels

Heat, Light, & Noise

Noise 50% Sound

Reduction

Thermal Performance R-20 The insulating value of

a 6” stud wall

TestingPermanence ofperformance Non-combustible/

no smoke Mold/mildew resistance Condensation resistance UV Stable

More about Aerogels Nanomaterial known since 1931 Used extensively in aerospace NanogelTM is a proprietary form of “aerogel”

- skylights- exterior glazing- pipeline insulation- apparel- medical devices

Nanogel used across North America & nine European countries

Not an experiment! Cabot is 125 years old, a $2.9 billion public

company- 21 countries- 36 manufacturing sites- 8 R&D facilities

More about Aerogels

Examples – Skylights

• Application : a 25mm thick multi-wall polycarbonate sheets façade filled with nano-material

• (Total surface of 1450m2) on the whole perimeter of the building (surface of 3360m2).

• The façade had to meet a thermal insulation value < 2.7 W/m.K

• The nano-material allows to achieve a value of 0.89 W/m.K

Applications

• Shaders were not an option : very costly, heavy structure, not in line with the architect’s concept of a smooth building surface

Shaders

Options

Versus Double-pane Glass• Glass, profiles : €300/m² €435,000• Shaders €130/m² €188,500 Total cost €430/m² €623,500

Versus PC without nanomaterial• Polycarbonate sheets : €100/m² €145,000• Shaders €130/m² €188,500 Total cost €230/m² €333,500

Nano-material Solution + Polycarbonate• Polycarbonate sheets : €100/m² €145,000• Nano-material cost : €67/m² € 97,000 Total cost €167/m² €242,000

Energy savings €3000/year on lighting €2000/year on heating

Savings €263/m² €381,350Immediate payback

+ €5,000/year on energy

Savings €63/m² €91,500Immediate payback

+ €5,000/year on energy

Nano-Materials (aerogels) applied to the Building Industry

Cost comparison

Nanotech Materials for Truly Sustainable Construction

Results

Natural daylight evenly dispersed inside the buildingNo glare, no shadow, no “light tunnel” issues

High comfort level for the players and spectators

Natural daylight evenly dispersed inside the buildingNo glare, no shadow, no “light tunnel” issues

High comfort level for the players and spectators

Results

A new way of thinking Photocatalytic cement with TiO2 Self cleaning Removes pollutants in area around building (CO2, NO2,

etc.)

What is Nanogel?

Aerogel resists the transfer of heat, making it a great insulator.

- Unsurpassed thermal insulation- R-value of 8 per inch / U-value of .64W/m²K per 25 mm’- Increased natural light transmission- 75% per 3/8 inch / 80% per cm- Superior light diffusion – elimination of glare- Improved acoustic performance- Reduced solar heat gain/loss- Decreased energy consumption – heat, air conditioning, lighting, ventilation, carbon emissions- Unmatched moisture resistance – 100% hydrophobic- Exceptional color stability and insulation performance

Nanogel Performance

100 µm10 µm1 µm100 nm10 nm1 nm0.1 nm

Conventional Filtration

Microfiltration

UltrafiltrationReverseOsmosis

H2O(0.2 nm)

Hemoglobin(7 nm)

Virus(10-100 nm)

Microbial Cells(~1 µm)

Protozoa(>2 µm)

PM 2.5

Aerosols

Nanoscale contaminants in water and air (little is known)

Size Spectrum of Environmental Particles

Pollens(10-100 µm)

Adenovirus 75 nm

Bacteriophage 80 nm

Influenza 100 nm

E. Coli 1000 nm

Fullerenes, nanotubes

After Wiesner

WWW.EPA.GOV/NCER Go to Publications/Proceedings

OZONE AND NANOTECHNOLOGY

Ozone Layer Depletions

In the 70s it was discovered at the University of California

Actually, it is not a hole but a decrease of the ozone layer’s thickness

In the equatorial regions where the ozone layer always has been thinner, this decrease is more obvious.

The ozone hole grows and decreases every year with the stations, disappearing slowly as the south hemisphere reaches the maximum of his summer. Climatic Factorstemperature Rainfalls

The Problem

Why is The Ozone Hole Continue to GROW UP Since Montreal Protocol (1987) Small groups of the Chemical Industry, knowing that refrigerants will be banned, started to produce more. So, from 1990 to 1995 it was produced more since refrigeration with CFC’s started.

CFC’s substances take a long time (10-15 years) to reach the ozone layer’s level

CFC’s (Freons) were invented in the 30s. The most commons are CFCl3 (freon 11), CF2Cl2 (freon 12), C2F3Cl3 (freon113) y C2F4Cl4 (freon 114).

DESTRUCTION PROCESSRelease chlorine of certain stable compounds, which is attacked by the intense UV radiation, can strip of an atom to the ozone molecule giving rise to ClO and normal oxygen. Each molecule of CFC destroys thousand and thousand of ozone molecules.

As they are not very reactives, CFC’s spread slowly (it takes years) towards the stratosphere without undergo changes; there they decompose because of the UV radiation of λ=175-220nm

Despite the fact that the growth-rate of ozone depletion potential (ODP) in the atmosphere is starting to drop, without Molecular Nanotechnology(MNT) the impact of ozone-depleting substances(ODS) on stratospheric ozone will continue.

ODS refrigerants can be replaced with MNT → The growth-rate of ODP in the ODS reservoir will become zero.

Drexler proposed using sodium-containing balloontype nanobots

The nanobots, powered by nano-solar cells, collect CFC’s and separate out the chlorine in the stratosphere. Combining this with sodium makes sodium chloride. When the sodium is gone, the balloon collapses and falls. Finally, a grain of salt and a biodegradable speck fall to Earth. The stratospheric CFC is quickly removed.

There can be used also nanobots containing otherbmetals (Ca, Mg) to remove stratospheric CFC.

Among ODS, halogens other than chlorine (Br) could be neutralized using this tecnique.

Metal Nanoparticle Solution to Ozone Depletion

Nanostructure Size Example Material or Application

Clusters, nanocrystals, quantum dots

Radius: 1-10 nm

Insulators, semiconductors, metals, magnetic materials

Other nanoparticles Radius: 1-100 nm

Ceramic oxides, Buckyballs

Nanowires Diameter: 1-100 nm

Metals, semiconductors, oxides, sulfides, nitrides

Nanotubes Diameter: 1-100 nm

Carbon, including fullerenes, layered chalcogenides

Jortner and C.N.R.Rao, Pure Appl Chem 74(9), 1491-1506, 2002

What are the materials of nanotech?

How can these properties be used to protect the environment?

Nanomaterials have unique properties

Characterizing Nanomaterials

Applications of Nanotechnology

Applications of Nanotechnology

VDI

The Challenge

Use nanotechnology research to:

…Help clean up past environmental damage

…Correct present environmental problems

…Prevent future environmental impacts

…Help sustain the planet for future generations

• “Because of nanotechnology, we will see more • change in our civilization in the next thirty years • than we did during all of the 20th century”

- M. Roco, National Science Foundation

The future of is here now

Resources

Material Connexion, Beylerian & Dent (Wiley, 2005) Material Architecture, Fernandez (Oxford, 2006) EU Nanoforum Report (December 2006;

nannoforum.org) Transmaterial, Brownell, (Princeton, 2006) Material World 2, MateriO (Birkhauser, 2006) Extreme Textiles, McQuaid (Princeton, 2005) The Dance of Molecules, Sargent (Penguin, 2006) The Nanomaterials Handbook, Gogotsi (CRC, 2006)