An Investigation of the Current and Future Impact of Nanotechnology

Final ReportRET 2010 Summer Program

Prepared byAllan Fluharty

Science Teacher, Chicago Public Schools

____________________ ____________________Allan Fluharty Dr. Thomas L. TheisRET Fellow RET Mentor

University of Illinois at ChicagoResearch Experience Experiences for Teachers

NSF RET Grant – EEC 0743068August 7, 2010

ContentsAcknowledgements 3

Abstract 4

Introduction 5

What is nanotechnology?........................................................................................................................5

How does nanotechnology work?...........................................................................................................6

Why is nanotechnology important?........................................................................................................7

Impact of Nanotechnology using Life Cycle Assessment.......................................................................12

Example of Appling LCA to Nanotechnology:.....................................................................................15

How Will Nanotechnology Develop?.....................................................................................................17

Demand for Nanotechnology................................................................................................................18

Embodied Energy...................................................................................................................................23

Methods and Other Considerations 25

Production Volume Calculations............................................................................................................25

Nano-Cerium Oxide............................................................................................................................26

Nano-Titanium Oxide.........................................................................................................................28

Nano-Zero Valent Iron.......................................................................................................................31

Quantum Dots...................................................................................................................................35

Nano-Silver........................................................................................................................................39

Carbon Nanoparticles........................................................................................................................43

Steel and Aluminum...........................................................................................................................46

Embodied Energy Calculations..............................................................................................................47

Results53

Conclusions 56

References 57

2

Acknowledgements

Research MentorDr. Thomas L. Theis, DirectorThe Institute for Environmental Science and PolicyUniversity of Illinois at Chicago

Financial support by NSF RET Grant – EEC 0743068 (Andreas Linninger, PI) is gratefully acknowledged.

3

Abstract

Nanotechnology allows scientists and engineers the ability to see and manipulate matter at a size

scale of atoms and molecules. This capability has the potential to dramatically improve many

aspects of our lives, potentially providing solutions to social, economic and environmental

problems. There has been intense research and development of nanotechnology since the late

1990’s and an increasing number of products and applications that utilize nanotechnology are or

are in the process of being commercialized. Although nanotechnology is expected to generate

major economic impacts estimated in the billions of dollars, little is known about the potential

environmental, health and safety risks associated with exposure to nanoparticles by the public or

workers employed in this industry. Due to their ever larger use, it is important to estimate

consumption trends of nanomaterials in order to determine and predict their associated

economic, health, social, and environmental impacts. This research, conducted as part of a

Research Experience for Teachers Fellowship at the University of Illinois at Chicago, provides

an approximation of the present and future production volumes and embodied energy of several

important types of nanoparticles.

4

Introduction

What is nanotechnology?

Nanotechnology is the design, characterization, production, and application of structures,

devices, and systems by controlled manipulation of size and shape at the nanometer scale

(atomic, molecular, and macromolecular scale) that produces structures, devices, and systems

with at least one novel/superior characteristic or property (source: www.nanowerk.com).

Nanotechnology operates at the first level of organization of atoms and molecules for both living

and anthropogenic systems. This is where the properties and functions of all systems are defined.

Such fundamental control provides a broad and revolutionary technology to industry,

biomedicine, environmental engineering, safety and securing, food, water resources, energy

conversion, and many other areas. There is no globally recognized definition of nanotechnology.

However, any definition would include three elements:

A size range between single atoms and molecules to about 100 molecular diameters or

about 100nm.

The ability to measure properties and control the transformation of material at the

nanoscale.

An ability to exploit nanoscale properties, the key motivation that will drive the

movement of nanotechnology into the marketplace.

According to the National Science Foundation and NNI, nanotechnology is the ability to

understand, control, and manipulate matter at the level of individual atoms and molecules, in the

size range from about 0.1 to 100 nm, in order to create materials, devices, and systems with

5

fundamentally new properties and functions. An understanding of how material behaves and how

to control material at the nanoscale promises to provide new products and generate more

efficient manufacturing methods.

How does nanotechnology work?

When matter is as small as 1 to 100 nanometers, many physical and chemical features change

compared to bulk material. One key feature the huge surface area of nanoparticle—one gram of

nanoparticles has the surface area of 1275 football fields (Figure 1). This dramatic increase also

significantly increases properties that depend on the surface area. A second useful feature of

nanotechnology that it lets product designers take advantage of quanta effects and do things like

change the color of a material by changing the particle size. Medieval glass artisans used this

property of gold nanoparticles to create the different colors in stained glass windows (Figure 3).

Figure 1: The surface area increases the particle size decrease given the same volume of particles, which provides more opportunity for reactions to occur that take place at the surface.

6

Figure 2: Ancient stained-glass makers knew that by putting varying, tiny amounts of gold and silver in the glass, they could produce the red and yellow found in stained-glass windows (graphic: New York Times, 2/15/2005).

Why is nanotechnology important?

The projected social and economic benefit of nanotechnology has driven large global

investments by nations and companies. Since the United States launched the first national

nanotechnology initiative in 2000, more than 60 nations have launched similar initiatives. In

7

2006, global public investment in nanotechnology was estimated to be $6.4 billion, with an

additional $6.0 billion provided by the private sector. Over 1,000 products in the market now

incorporate nanotechnology (PEN 2010). These products generally offer incremental

improvements over existing products. However, proponents maintain that nanotechnology

research and development currently underway could offer revolutionary applications with

significant implications for the US economy, national and homeland security, and societal well-

being. These investments, coupled with nanotechnology’s potential implications, have raised

interest and concerns about the US competitive position (Sargent 2008).

Nanotechnology applies to dimensions under 100 nm in size. However, nanotechnology is not

just about the size of very small things. It also concerns the science of manipulating matter at the

atomic or molecular scale. Using the tools of nanotechnology, scientists and engineer now have

the ability to design and build molecular compounds. Science and technology can now control

matter at a scale that was once based on abstract theory. Prior to the 1990’s, scientists knew

atoms existed but no one had seen one—they were just too small. It is now possible to see and

manipulate individual atoms (Figure 3).

Figure 3: World’s Smallest Logo—35 xenon atoms. In April 1990, researchers used a proximal probe to bringing a splash of publicity to IBM. The result is shown here in an STM picture of 35 precisely placed xenon atoms. The

8

precision here is complete, like the precision of molecular assembly: each atom sits in a dimple on the surface of a nickel crystal; it can rest either in one dimple or in another, but never in between (Courtesy of IBM Research Division).

And because science and engineering are the primary drivers of global technological

development, the promise of nanotechnology is tremendous. Table 1 shows the potential

applications of nanotechnology projected over the next 15 years.

Table 1: Commercial applications of nanotechnology over the next 15 years.

Current Cosmetics : nano-titanium dioxide and zinc oxide are used in some sunscreens to absorb and reflect

UV rays and yet are transparent to visible light Composites : carbon nanotubes are used in polymers to control or enhance conductivity, with

applications such as antistatic packaging Clay composites: nano-sized flakes of clay find used to improve car bumpers Coatings : optoelectonic devices, catalytically active and chemically functionalized surfaces, the self-

cleaning window, scratch-resistant hard coatings, breathable, waterproof and stain resistant fabricsShort-term (next 5 years) Thinner paint coatings that are fouling resistant, paints that change color in response to change in

temperature or chemical environment, or paints that reduce heat loss Remediation : nanoparticles react with pollutants in soil and groundwater and transform them into

harmless compounds Fuel Cells : nano-engineered membranes to enable higher-efficiency, small-scale fuel cells Displays : improved flat-panel displays using nanocrystalline zinc selenide, zinc sulphide, cadmium

sulphide and lead telluride Batteries : nanocrystalline nickel and metal hydrides require less frequent recharging Fuel Additives : nanoparticulate cerium oxide improves fuel economy of diesel fuel Catalysts : high surface area of nanoparticles enhance catalytic activityLonger-term (next 5-15 years) Carbon nanotubes have exceptional mechanical properties, particularly high tensile strength and light

weight Lubricants : Nanospheres could be used as lubricants by acting as nanosized ‘ball bearings’. Magnetic Materials : improved motors, analytical instruments, microsensors, and data storage Medical Implants : Nanocrystalline materials are wear resistant, bio-corrosion resistant and bio-

compatible. Machinable Ceramics : Ceramics are hard, brittle and difficult to machine. However, with a reduction

in grain size to the nanoscale, ceramic ductility can be increased. Military Battle Suits : energy-absorbing materials that will withstand blast waves; incorporation of

sensors to detect or respond to chemical and biological weapons

9

Revenue involving nanotechnologies is predicted to reach $2.5 trillion by 2015. Two trillion of

which will be directly attributable to nano-enabled products and about $3 billion associated with

nanomaterials (Lux Research 2009). While these numbers can be debated (see Berger 2007), it

is undeniable that between 2006 and 2009 the number of nano-enabled consumer products nearly

tripled. During the same period the public’s awareness of nanotechnology remained stagnant,

with about 70% of the population having heard little to nothing about nanotechnology (Figure 4).

The risk is that the public may react to the rapid proliferation of nanotechnology the way many

have reacted to genetically modified crops. A consumer backlash against nanoproducts would be

understandable if product developers and government regulators do not align the introduction of

nanotechnology with public needs or values.

0%

10%

20%

30%

40%

50%

60%

Heard nothing at all Heard just a little Heard some Heard a lot Not sure

Survey of ~1000 adults asked, "How much have you heard about nanotechnology before today?"

2006 (1,014 adults) 2009 (1,001 adults)

Figure 4: Results of a survey of adults asked, “How much have you heard about nanotechnology before today?” (Hart Research Associates, Project on Emerging Nanotechnologies Survey, September 2009).

In the long-term, nanotechnology will likely be increasingly discussed within the context of the

convergence, integration, and synergy of nanotechnology, biotechnology, information

10

technology, and cognitive technology (EPA 2007). Convergence involves the development of

novel products with enhanced capabilities that incorporate bottom-up assembly of miniature

components with accompanying biological, computational and cognitive capabilities. For

example, the convergence of nanotechnology and biotechnology, already rapidly progressing,

will result in the production of novel nanoscale materials. The convergence of nanotechnology

and biotechnology with information technology and cognitive science is expected to rapidly

accelerate in the coming decades. The increased understanding of biological systems will

provide valuable information towards the development of efficient and versatile biomimetic

tools, systems, and architecture.

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

1940 1960 1980 2000 2020

0.1 nm

1 nm

10 nm

0.1 μm

1 μm

0.1 mm

1 mm

1 cm

10 μm

0.1 m

NAN

OM

ICRO

MAC

RO

Reaching nano-world

Size of Structure

Figure 5:In 2000, a convergence had been reached between fundamental theories of science (bottom up) at the nano-scale and our ability to measure, manipulate, and understand nano-scale structures (top-down). In the years beyond, one may expect divergent trends as a function of particular system architectures. Several possible trends are guided molecular and macromolecular assembling, robotics, biomemetrics, and evolutionary approaches (Roco, M. 2007).

11

This “nanotechnology-convergence” is happening because many sciences—such as chemistry,

biology, physics, and materials science—and their associated engineering disciplines use the

same tools and principles to create new knowledge in their particular fields (Figure 5).

Eventually as time goes on, one may expect a divergence of the sciences as nanotechnology

becomes more mature and new sciences and technologies are developed. Possible new fields

include guided molecular and macromolecular assembling, robotics, biomimetrics, and

evolutionary approaches (Roco 2007).

Impact of Nanotechnology using Life Cycle Assessment

The mass production of nanomaterials has led to the emergence of a large number of consumer

goods (nanoproducts) containing these materials. However, not much is currently known of the

environmental impacts and health risks associated with these materials. To address this,

researchers have begun implementing more comprehensive assessment tools such as Life Cycle

Assessment (LCA). An LCA can establish the comparative impact of products or processes in

terms of specified impact categories using well-defined and documented methodology (Figure

6). Typical impact categories include global warming/climate change, stratospheric ozone

depletion, human toxicity, ecotoxicity, photo-oxidant formation, acidification, eutrophication,

land use, and resource depletion. The potential advantage of LCA-based evaluations for

nanoproducts is that they can address both the health and environmental consequences associated

with the inclusion of nanocomponents. The ultimate goal is to ensure that the potential benefits

of nanocomponents are realized in a manner that is safe for both consumers and the environment

without resulting in unintended consequences. A flow diagram of the LCA process is shown in

Figure 6.

12

Figure 6: Life Cycle Assessment (LCA) is a tool used to assess the environmental impacts of a product, process or service from design to disposal i.e. across its entire lifecycle, a so called cradle to grave approach. The impacts on the environment may be beneficial or adverse. These impacts are sometimes referred to as the "environmental footprint" of a product or service (http://www.rsc.org).

For any material, there are four main aspects of its life-cycle that must be considered with its use:

material selection, manufacturing, use, and disposal or recycle. Using this as an outline, an

overview of each aspect and how it can impact the life-cycle of nanoproducts is given below.

Material: The material that a designer used to create a nanoparticle depends on the desired

composition and the geometry. The geometry can be a variety of shapes that are dependent on

the method of synthesis. The composition of nanoparticles can be organic (dendrimers,

polymers, etc.), inorganic (metals, metal oxides, metal hydroxides, etc.), carbon (single walled

nanotubes, multiwall nanotubes, buckyballs, graphenes), or a combination of these. More

complex systems are possible if surface fictionalization is used to control surface charge and

interactions. The physical properties will control the transport and possible interaction of these

materials in the environment. For example, if silver nanoparticles, which are useful for their

13

antibacterial properties, were to collect in the environment their antibacterial properties cold

contribute to ecotoxicity1 and disruption of the food chain.

Manufacture: There are a variety of ways to synthesize nanoparticles and to create material that

contain nano-ingredients. These techniques can be classified based on the type of approach (top-

down or bottom-up) and nature of the chemistry involved (wet or dry). Top-down manufacture

uses bulk materials to create nanoparticles or nanocomponents. Examples include lithography to

create computer chips, etching to create precision engineered surfaces, and attrition (grinding).

With bottom-up approaches, nanoparticles or nanocomponents are built up from the atomic or

molecular level. Wet processes involve the use of solvents or liquid reagents as done during the

production of some nanostructures using chemical precipitation. Dry synthesis methods include

thermolysis, laser ablation, vapor deposition, pyrolysis (flame spray and laser), and plasma arc

discharge. The manufacture of nanomaterials can generate waste streams that must be treated

prior to release. In addition, the manufacturing process used to make nanomaterials has not been

optimized: energy to produce bulk quantities for many newer nanoparticles uses significant

levels of electricity, generated from fossil fuels, when compared to traditional materials such as

steel. Many nanotechnology manufacturing processes include highly toxic solvents and require

intensive safety practices. An example is the etchings used during semiconductor manufacturing.

Use: Nanomaterials can be used in a mixture with other materials (naturally dispersed) or in a

composite for a range of applications, including environmental, medical, consumer products, and

“other” specialty applications, such as in construction materials, electronics, etc. When naturally

1 Ecotoxicology has been defined as "the branch of toxicology concerned with the study of toxic effects, caused by natural or synthetic pollutants, to the constituents of ecosystems, animal (including human), vegetable and microbial, in an integral context” (Truhaut 1977).

14

dispersed, a nanocomponent maintains its nanoscale properties and therefore exhibits greater

mobility and reactivity upon release. A common example of this type of application is the

remediation of groundwater using dispersed zero valent iron nanoparticles (zNPI). The potential

ecotoxicity of these materials is not yet fully understood. When used in composites,

nanomaterials are held in place and will not impact human and ecotoxicity in the use phase

unless a breakdown of the composite matrix occurs. However, a breakdown will most likely

occur after disposal, resulting in the release of nanomaterials.

Disposal: Direct disposal involves landfill, incineration, or removal during wastewater treatment.

A recent study has estimated that up to 95% of key nanoparticles (silver, titanium dioxide,

carbon nanotubes) used in cosmetics, paints, coatings, and cleaners are most likely to end up in

water treatment plants as a result of either release of runoff during initial application or abrasion

and liquid entrapment during use (Meyer, et al. 2009). Other nanomaterials used in composites,

such as carbon nanotubes used in plastics, sporting equipment, and electronics will remain intact

until their disposal either in landfills or incinerators. The potential for nanomaterials to be

accumulated in the environment after disposal is causing great concern due to the potential

toxicity of nanomaterial (AOL 2010). Science is just beginning to explore the feasibility to

remediate waste streams containing nanocomponents or recycle nanomaterials.

Example of Appling LCA to Nanotechnology:

Few LCA studies have until now been performed for nanoproducts. International organizations

such as the International Standards Organization and the Organization for Economic Co-

operation and Development are engaged in nanotechnology issues. A two day workshop on LCA

of nanotechnology organized by the USEPA and the European Commission concluded that the

15

current ISO-standard on LCA (LCA ISO-14040:2006) is fully suitable to analyze the life cycle

impact of nanocomponents and nanoproducts (Klöpffer et al. 2007). However, there are a

number of operational issues that need to be addressed, such as system boundary definition,

functional unit selection, inventory data collection and/or estimation, allocation, and toxicity

assessment. A large number of data gaps exist when considering application of LCA to

nanoproducts. Minimal data exist on material inputs and environmental releases related to the

manufacture, release, transport, and ultimate fate of nanocomponents (Figure 8).

Bio-Accumulation

Water Treatment

Incineration

Landfill

Disposal

Other

Manufactured Goods

Medical

Environmental

Com

posit

e

Disp

ersiv

e

Application

Recycle

Dry

Wet

Bott

om U

p

Top

Dow

n

Manufacturing

Surface Function/Charge

Composition

Shape

Size

Geom

etry

Chem

istry

Material

Selection

Figure 7: Aspects of nanotechnology that can be addressed when performing a Life Cycle Assessment. The choices make the application of LCA tools challenging (Source: Meyer, et al. 2009).

16

How Will Nanotechnology Develop?

Nanotechnology has created great potential for science to develop new technologies due to an

increased understanding of natural phenomenon and holds the promise increased the efficiency

in traditional industries. A coherent model for that predicts how nanotechnology will develop is

provided by Roco, et al. (2004) as seen in Figure 8. Nanotechnology will evolve in four

overlapping generations of new nanotechnology products.

First Generation Products (~2000) are “passive nanostructures” used to tailor macroscale

properties and functions. Examples are nanostructured coatings, dispersion of

nanoparticles, and bulk materials, nanostructured metals, polymers, and ceramics.

Second Generation Products (~2005) are “active nanostructures” for mechanical,

electronic, magnetic, photonic, biological, and other effects. These nanoproducts are

typically integrated into microscale devices and systems such as transistors, amplifiers,

actuators, drugs and chemicals, actuators, etc.

Third Generation (~2010) will be “systems of nanosystems” with three-dimensional

networks using various syntheses and assembling techniques. A key challenge is

networking at the nanoscale. Research will focus on directed multiscale selfassembling,

artificial tissues and senroial systems, quantum interactions, processing of information

using photons or electron spin, assemblies of nano electromechanical systems (NEMS),

and converging technologyies (nano-bio-info-cogno) platforms integrated at the

nanoscale.

17

1st Generation Products—Passive Nanostructures Dispersed and contact nanostructures: aerosols, colloids Products incorporating nanostrucutes: coatings, nanoparticle reinforced

composites, nanostructured metals, polymers, and ceramics

2nd Generation Products—Active Nanostructures Bioactive health effects: targeted drugs, biodevices Physico-chemical active: 3D transistors, amplifiers, actuators

3rd Generation Products—Systems of Nanosystems Guided assembling, 3D networking and new hierarchical

architectures, robotics, evolutionary technology

4th Generation Products—Molecular Nanosystems Molecular devices ‘by design,’ atomic design,

emerging functions

~2000

~2005

~2010

~2015 - 2020

Risk

Gov

erna

nce

Figure 8: Timeline for the development of nanotechnology (Roco, et al., 2004).

Fourth Generation (~2015 – 2020) will bring “heterogeneous molecular nanosystems”

where each molecule in the nanosystem has a specific structure and plays a different role.

Products and new technologies will be derived from research in topics such as atomic

manipulation to engineer macromolecules, controlled interaction and conversion between

energy and matter, exploitation of quantum controlled mechanical-chemical molecular

processes, nanosystem biology for healthcare and agricultural systems, and human-

machine interface at the tissue and nervous system level.

Demand for Nanotechnology

The Woodrow Wilson International Center for Scholar’s “Project on Emerging

Nanotechnologies” is an online database that tracks the use of nanotechnology in consumer

goods. As of 2008, there were 1012 products that contain nanomaterials. In order to make the

18

list, a consumer product must list a nanomaterial in advertizing or as an ingredient. Therefore,

the list is not comprehensive because it does not account for possible products that incorporate

nanocomponents without specifically referencing them.

Consumer products that have the most exposure to nanomaterials are the “health and fitness”

category that include clothing, cosmetics, filtration, personal care products (toothpaste, razors,

wound dressings), sporting goods, and sunscreens. Many of the products utilize the UV

protection of titanium dioxide or the antimicrobial properties of silver. These materials are also

found in “food and beverage” products and in products designed for children including

sunscreens, fabric softeners, toys, pacifiers, and toothbrushes. The four-year growth of these

products since 2005 is shown in Figure 9. Also shown is a compilation of product categories,

region of origin, and most common nanomaterials used, comparing 2006 to 2009 data.

While the market demand has not matched the considerable hype that nanotechnology has

generated over the past decade and a half, nanomaterials have managed to attain an appreciable

commercial presence in recent years. Global nanomaterial demand will continue to rise, posting

robust 21 percent annual gains to $3.6 billion in 2013. By 2025, nanomaterials are expected to

reach over $34 billion in sales, having still only scratched the surface of their immense market

potential (Freedonia Group 2010).2

Many of the initial uses for nanomaterials which have had the greatest commercial impact have

involved relatively low-tech materials and applications. These include nanoscale versions of

conventional materials, including silica, alumina, titanium dioxide, clays and metals such as gold

2 Information on the nanotechnology market in this section was obtained from a 2010 study of current and future market trends for products derived from nanotechnology performed by The Freedonia Group, Inc.

19

and silver. These nanomaterials have found widespread applications as wafer polishing slurries

for semiconductor processing, personal care products such as sunscreen, and antibacterial

treatments for consumer products. In the next decade or two, however, some of the relatively

novel nanomaterials, particularly carbon nanotubes, will account for a larger share of overall

nanomaterial demand, as these products find increasing use in electronics and motor vehicle

components (Figure 10).

54

356

580

803

1015R² = 0.9949

0

400

800

1200

1600

2005 2006 2007 2008 2009 2010 2011

Total Products Listed that Incorporate Nanotechology 605

15257 98 55 68 37 19

0

175

350

525

700

Num

ber o

f Pro

duct

s

Product Categories

20062009

0

100

200

300

400

500

600

USA East Asia Europe Other

Region of Origin

2006

2009

0

75

150

225

300

Most Common Nanomaterial Ingredients

2006

2009

Figure 9: Summary of information available through the Project on Emerging Nanotechnology (PEN) website (PEN 2010).

Health care was the second largest market for nanomaterials in 2008, but is expected to overtake

electronics as the leading outlet in 2013 and beyond. Nanomaterial-based pharmaceuticals,

which include nanoscale drug delivery systems as well as nanosized drug active ingredients,

have enjoyed a significant degree of commercial success to date. Among the best selling drugs

20

employing nanomaterials are Abraxane (breast cancer), Copaxone (multiple sclerosis), Doxil &

Caelyx (metastatic ovarian and breast cancer), Rapamune (kidney transplant therapy), Renagel

(kidney dialysis), and Ticor (treats high cholesterol). In the future, it is expected that

nanomaterials will expand from pharmaceuticals into other medical product and health care

applications, including diagnostics, imaging and dental care. Additionally, the range of

nanomaterials used will broaden as well, encompassing nanotubes, nanoscale metals and new

materials such as dendrimers and quantum dots.

0

2000

4000

6000

8000

10000

12000

14000

2008 2013 2018 2023

Mill

ion

$

World Nanomaterial Demand by Market

Electronics

Health Care

Construction

Energy

Other

0

2000

4000

6000

8000

10000

12000

14000

2008 2013 2018 2023

Mill

ion

$

World Nanomaterial Demand by Region

United States

Western Europe

Japan

China

Other Asia/Pacific

Other Regions

600

800

1000

1200

1400

1600

1800

2000

2004 2005 2006 2007 2008

Mill

ion

$

World Nanotechnology Government R&D Spending

United States

European Union

Japan

Other

0

2000

4000

6000

8000

10000

12000

2000 2005 2010 2015 2020 2025 2030

Mill

ions

$

World Nanomaterial Demand by Type

Metal Oxides

Chemicals & Polymers

Metals

Nanotubes

Other

Figure 10: A forecast of world nanomaterial demand by type, region and market. Also included is a forecast of world nanomaterial government Research and Development (R&D) spending (data source: Freedonia 2010)

In 2008, the nanomaterial market was overwhelmingly concentrated in the developed world. The

US and Japan combined to account for over half of world demand, while Western Europe and

two high-income Asian nations, Taiwan and South Korea, represented an additional 34 percent.

21

While virtually all nanomaterial markets will experience robust double-digit gains in demand,

the fastest gains are forecast for the rapidly industrializing countries of China and India. By

2025, it is expected that China will rise to overtake Japan as the second largest market for

nanomaterials in the world behind the United States, accounting for twelve percent of global

demand.

While the outlook for nanomaterials is generally bright, a number of potential complications

exist. In some instances, technical issues such as agglomeration of nanotubes in plastic

composites are still a challenge. Perhaps more fundamentally, concerns about the safety and

environmental effect of nanomaterials may be impediments to commercial success. Consumer

and other groups have voiced concerns about the relative lack of caution in the adoption of

nanomaterials, which may be inhalation hazards and may cause environmental problems. Should

these concerns spread to broader consumer populations, the world nanomaterial industry could

be hampered and the commercial potential of these products delayed further.

The nanomaterial industry is populated by a wide range of companies. Large international

materials suppliers, such as Arkema, BASF and DuPont have added nanoscale materials to their

product offerings. Interest in nanomaterials has also created a wave of new companies focusing

on nanomaterial production as their primary business, including Nanocyl, Nanophase

Technologies and StarPharma.

Although numerous nanoscale materials have become commercially viable over the last decade,

much of the great market potential for nanomaterials lies in products which have not yet been

brought to market, or become commercially significant. In other instances, all the technical

issues associated with the uses of nanomaterials in specific applications have not been fully

22

resolved. As such, research and development (R&D) activity in this nascent industry is

particularly important. Governments around the world, including those in Japan, the US,

European Union nations, South Korea, Taiwan, China, Russia, Brazil and elsewhere, have been

relatively quick to realize this, and have placed a substantial degree of resources into funding

nanotechnology R&D activity.

From an economic standpoint, cost considerations and production scalability are among the

primary factors holding back the further commercialization of nanomaterials. This is true in both

economically developed regions and areas that are continuing to modernize. However, another

key barrier to market growth, one that has taken on increased prominence in recent years, is the

resolution of environmental and safety issues that surround nanomaterials. Not only will these

materials need to meet regulatory standards for environmental suitability and workplace safety,

producers of nanomaterials and of the products which feature them will have to assuage concerns

by environmental groups and consumers. There is considerable wariness about nanomaterials,

because just as they offer heretofore unseen performance potential in a myriad of applications,

they may also present similarly novel difficulties in terms of safe use and environmental impact.

Embodied Energy

Decisions need data. The engineering data used to design a bridge must be precise to ensure that

the bridge does not fail. The precision of much of the data used in analyzing environmental

impact (ecodata) can be low. However, how much precision is needed to deal with a given

environmental problem? The answer: just enough to distinguish the viable alternatives. The

engineering properties of materials—their mechanical, thermal, and electrical attributes—are

well characterized and many are known to three-figure accuracy. Additional properties are

23

needed to incorporate environmental objectives into decisions. They include measures of the

energy committed and carbon released into the atmosphere when a material is extracted or

synthesized—the embodied energy and carbon footprint. Embodied energy is the energy to

produce a unit mass (usually 1 kilogram) of a material from whatever it is made. Unlike

engineering properties, there are no sophisticated test machines to measure it and the procedures

used to determine it are vague and not easily applied. An analysis suggests a precision of ±10%

at best (Ashby 2009). This is not necessarily bad news because what is important is how one uses

the ecodata. Significant and justifiable decisions can still be made despite the imprecision of the

data on which they are base. Additional definitions of embodied energy include:

Embodied Energy refers to the quantity of energy required to manufacture, and supply to

the point of use, a product, material or service.

Embodied energy accounts for all the energy required to make a material, such as a clay

brick. This includes the energy to extract the clay, transport it to the brick-works, mould

the brick, fire it in the kiln, transport it to the building site and put the brick into place. It

also includes all the indirect energy required, i.e., that required to manufacture the

equipment and materials needed to make a brick, e.g. trucks, a kiln, mining equipment,

etc. All have a proportion of their energy invested in that brick.

Embodied energy accounts for all the energy required to make a material. If we have

available energy, we may maintain life and produce every material. That is why the flow

of energy should be the primary concern of economics (Soddy 1933).

24

The method used here assumes that market-determined production volume (the market) and

embodied energy values are proportional. The required perspective is an ecological or “systems”

view that considers humans to be part of, and not apart from, their environment. A few

economists have already taken this perspective, and the implications for a new ecological

economics that links the natural and social sciences are great (Odom 1977). The concept of

embodied energy may help provide such a link as an empirically accurate common denominator

in ecological and economic systems. With the appropriate boundaries, embodied energy values

are more accurate indicators of market values where markets exist.

The implication on national policy is that the physical dimensions of economic activity are not

separable from limitations of energy supply. The universally appealing notion of unlimited

economic growth with reduced energy consumption must be put firmly to rest beside the equally

appealing bit impossible idea of perpetual motion. It is easy to think you can get a “free lunch”

by looking only at small parts of the system in isolation. When the whole system is analyzed,

however, it becomes clear that all you can do is transfer the cost of your lunch to another

segment of the system. If we are to manage our future wisely, we must be aware of the physical

limitations on economic activity and learn to live well within our energy budget (Costanza

1980).

Methods and Other Considerations

Production Volume Calculations

This study analyzes current and future production of several nanomaterials that are currently or

will soon be in the market. The nanoproducts include titania (nano-TiO2), cerium oxide (nano-

25

CeO2), nano-zero valent iron (nZVI), nanoparticles of silver (nano-Ag), quantum dots (QD), and

single - and multi-walled carbon nanotubes (SWCNT, MWCNT). These nanomaterials were

chosen because it is likely that they will experience high demand due to the unique attributes that

they impart when used in a suspension or as nano-ingredients.

Information on production volume that is available in mature technologies and industries, such as

revenues and market share, are not available for assessing nanotechnology. In fact, there is no

US or international private or governmental source available that currently collects such data for

nanotechnology. Without this information, an authoritative assessment of the production volume

of nanomaterials is not possible. Alternatively, indicators of the production of nanomaterials can

be derived from factors such as the level of academic publications, market research reports,

articles from trade journals, and data provided by governmental organizations. The general

procedure was to determine current production volumes in order to provide a baseline for a

production function. The production over time was then estimated based on material and market

information along with a method that combines observations from scientific articles and patents

as predictive indicators of the rate of innovative transformation. The estimation of production

volumes included a conservative bias toward the highest potential value. This was done in order

to provide a worst-case estimation when determining potential environmental, health and safety

impact.

Nano-Cerium Oxide

The compression ignition or diesel engine is widely used due to its reliable operation and

economy. As petroleum reserves are depleted there is a need to optimize the efficiencies of diesel

engines to, for example, improve mileage and reduce emissions. Among the techniques available

26

to optimize diesel engines, the uses of fuel-born catalyst particles have been under investigation

(Selvan et al. 2009). Envirox is a scientifically and commercially proven diesel fuel combustion

catalyst based on nanoparticulate cerium oxide and has been demonstrated to reduce fuel

consumption by 10% and lower harmful emissions such as carbon dioxide, nitrous oxides, and

soot (Wakefield et al. 2008). Envirox can be used at only five parts per million to the diesel fuel

—one tenth of the concentration of previous additives. The smaller particles also remain more

evenly distributed in suspension than larger particles (Fox 2003). As a catalyst, the cerium oxide

essentially remains intact and is emitted with the exhaust after performing its function within the

diesel engine.

One concern is the health impact of adding a stream of nanoparticulate cerium oxide directly to

the atmosphere. An industry-sponsored study has shown that exposure to nano-size cerium

oxide as a result of the addition of Envirox to diesel fuel is unlikely to lead to respiratory and

cardiac heath problems (Park 2008).

The production volume of nanoparticulate cerium oxide was determined by assuming that its use

as an additive would follow the consumption of diesel fuel. Based on a report authored by the US

Department of Energy, world diesel fuel consumption was 2.7 million barrels per day in 2000

and will rise linearly to 4.4 million barrels per day by 2035 (USEIA 2010). Because of the

positive effects of nanoparticulate cerium oxide on fuel economy and emissions, and the

indications that its use low risk, it was assumed likely to be well received and quickly achieve

market saturation. Therefore, it was assumed that 3% of diesel fuel used nanoparticulate cerium

27

oxide in 2007, a level that increased to 100% in 2030. In order to determine the mass of

particulate cerium oxide, it was assumed that the level of addition was 10 parts per million.

Nano-Titanium Oxide

Two of the most widely used nanoparticles in consumer products are silver and titanium dioxide.

Nano-silver will be covered in a later section. Nano-titanium dioxide is produced on a large

scale as an ingredient in paints and coatings for its self cleaning, antifouling, and antimicrobial

properties and in cosmetics as a UV-absorber. Titanium dioxide is found in cosmetic products

(sunscreens, lipsticks, body powder, soap, pearl essence pigments) and also in specialty

pharmaceutics. It also has wide application in the foods industry, for instance in salami

wrapping. Small amounts added to cigar tobacco are the cause of the white ash cherished by

cigar smokers.

Nano-titanium oxide is a potent photocatalyst that can break down organic compounds when

exposed to sunlight, a characteristic used for self-cleaning fabrics, auto body finishes, and

ceramic tiles. Titanium dioxide's photocatalytic characteristics are greatly enhanced when

reduced to the size of nanoparticles caused by an increase in surface area of the smaller particles.

In some cases, energy from any ambient light source can be used effectively as the energy source

of photocatalysis instead of UV light. Technologies using nano-TiO2 remove the ripening

hormone ethylene from areas where perishable fruits, vegetables, and cut flowers are stored;

stripping organic pollutants such as trichloroethylene and methyl-tert-butyl ether from water; and

degrading toxins produced by blue-green algae. Also in development is a paving stone that uses

the catalytic properties of TiO2 to remove nitrogen oxides from the air.

28

How safe is nano-titanium oxide? One recent study suggested that exposure to nano-titanium

oxide could increase cancer risk based on a mouse study that suggested ingestion of the

nanoparticles led to genetic damage (Trouiller 2009). In a 2007 assessment the European Union

found no evidence of nano-scale particles absorbing through pig skin, healthy human skin, or the

skin of patients suffering from skin disorders (NanoDerm 2007).

R² = 0.98

3.0

4.0

5.0

6.0

7.0

2000 2005 2010 2015 2020 2025

Wor

ld Ti

O2

Prod

uctio

n (m

illio

n m

etric

tons

)

Figure 11: World production of TiO2 showing a generally constant increase in level over time (Data source: USGS Minerals Commodity Summary 2010).

In this analysis, it was assumed that all bulk TiO2 production will convert over to the nano-TiO2

product, which will occur because nano-TiO2 enhances practically all applications of bulk TiO2.

The assumption is that this fact will place market pressure on TiO2 users to convert to the

nanoparticle ingredient. Therefore, in order to determine an upper bound of nano-TiO2

production, it was assumed that eventually all production of bulk TiO2 will eventually shift to the

nano-TiO2 product. World production of TiO2 was obtained by combining data from by United

States Geological Survey reports (USGS 2010) and world production data from Grant, et al.

29

(2004). It was found that the trend in the production of TiO2 has generally increased at a constant

rate over the last several decades (Figure 11). Using this as a guideline, a linear trend lined was

used to forecast world TiO2 production out to the year 2025.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

2002 2006 2010 2014 2018 2022

Annu

al W

orld

Pro

ducti

on (m

illio

n m

etric

tons

)

nano-TiO2 TiO2

Figure 12: A forecast of nano-TiO2 production as a portion of total annual world TiO2 production (Ogilvie-Robichaud, et al. 2009).

In order to estimate the growth in nano-TiO2 production, I used a method similar to that used by

Ogilvie-Robichaud, et al. (2009). In my analysis, it was assumed that nano-TiO2 production can

be described by an exponential growth function in the form of Y = A∙expg(t-2002). The assumption

of exponential growth is in line with both standard economic practice and with typical patterns of

economies of scale. In this function, Y is the nano-TiO2 per year in metric tons, t is the year to be

estimated, and g is the exponential growth factor. In this scenario, 2002 is the start year (zero

production) and it was assumed the time span for complete conversion would take the same

amount of time as taken in the biotech industry for full conversion. This meant that complete

30

conversion to the nanomaterial would occur in 2025 with a total world production of around 5.5

million metric tons per year (Figure 12).

Nano-Zero Valent Iron

Zero-valent iron nanoparticle technology is becoming an increasingly popular choice for

treatment of hazardous and toxic wastes, and for remediation of contaminated sites. In the US

alone, more than 20 projects have been completed since 2001, with more are planned or ongoing

in North America, Europe, and Asia (Li, et al. 2006). The diminutive size of the iron

nanoparticles helps to foster effective subsurface dispersion whereas their large specific surface

area corresponds to enhanced reactivity for rapid contaminant transformation. Recent

innovations in nanoparticle synthesis and production have resulted in substantial cost reductions

and increased availability of nanoscale zero-valent iron (nZVI) for large scale applications.

As shown in Table 2, nZVI has a potential to effectively remediate groundwater contaminated

with many common pollutants including chlorinated organic contaminants (polychlorinated

biphenyls, trichloroethylene, TCA, 1,1,1-trichloroethane), pesticides, and dissolved toxic metals

such as hexavalent chromium (Nano Patents and Innovation 2009).

Table 2: Pollutants remediated by nano-zero valent iron (nZVI) technology.

Carbon tetrachlorideChloroformDichloromethaneChloromethaneHexachlorobenzenePentachlorobenzeneTetrachlorobenzenesTrichlorobenzenesDichlorobenzenesChlorobenzeneDDTLindaneOrange II

ChrysoidineTropaeolinAcid OrangeAcid RedMercuryNickelSilverCadmiumBromoformDibromochloromethaneDichlorobromomethaneTetrachloroetheneTrichloroethene

Cis-DichloroetheneTrans-Dichloroethene1,1-DichloroetheneVinyl ChloridePCBsDioxinesPentachlorophenolNDMATNTDichromateArsenicPerchlorateNitrate

31

Application of nZVI technology to clean up toxic sites involves in situ degradation of

contaminants. In situ remediation involves delivery of the treatment to the contamination zone

and nanotechnology has the potential for injecting nanosized reactive or absorptive particles into

contaminated porous media such as soils, sediments, and aquifers. In this manner, it should be

possible to create either: (i) reactive nanoparticle plumes that migrate to contaminated zones if

the nanoparticles are sufficiently mobile or (ii) underground reactive zones with nanoparticles

that are relatively immobile (Figure 13) (Tratnyek & Johnson 2006).

Figure 13: The figure depicts a permeable barrier of nZVI that has been injected into the ground in front of a plume of contaminants. The nZVI disperses and cleans toxins from water as the contaminated water flows through a wall of NZVI particles.

nZVI particles used for remediation are usually about 50-300 nm in diameter (USEPA

2005). Due to the fast aggregation process, it is difficult to get aggregates smaller than 1 μm in

the field despite mixing. It has been found that there is a tradeoff between injection velocity and

injected concentration. One study found injected concentration of 1-2 g/L to be sufficient for

32

plume treatment and to ensure particle mobility (Muller & Nowack 2010). Other studies have

found higher concentrations (10-30g /L) to be more mobile. A slurry of nZVI can be introduced

into the subsurface using a variety of carrying fluids such as water, nitrogen gas or vegetable oil

(US Navy Website). nZVI has a relatively short lifetime which typically requires more than one

treatment to remediate a site. The required total mass of nZVI and is site specific and depends on

several factors including the volume of contaminated soil and groundwater, contaminant

concentration, phase (separate or dissolved) and total mass, aquifer characteristics including

permeability and anisotropy, groundwater chemistry, and incidental biodegradation rates.

The procedure used to determine a production function was to identify the amount of nZVI used

per site and then multiply by the number of sites. Three full-scale remediation projects were used

as templates to determine the nZVI-loading required to treat a toxic site (Muller & Nowack,

2010).

Bornheim (Rhein-Sieg-Kreis, Germany) was the first contaminated site in Europe where

nZVI was used for full-scale remediation (Friedl, 2006). The site was contaminated with

several tons of perchloroethylene (PCE) from an industrial laundry/dry cleaner which had

spread over several kilometers and up to 20 meters in depth. For 14 years the

groundwater had been treated by “pump and treat” technology in a process that would

need to continue for another 50 years at a cost of about $1.3 million to remove the

estimated 1 to 2 tons of PCE still left in the ground. Instead, in July of 2007, 1 ton of

nZVI (70 nm particles stabilized with polycarboxylic acid) and 2 tons of were injected

using 10 wells at a cost of around $0.4 million. The results of the project are an

approximately 90% reduction of the PCE concentration. Two years after the injection no

33

rebound has been observed but there is still a trend for declining contaminant

concentration (Figure 14).

Figure 14: Contaminant concentration on the site in Bornheim. Monitoring results over 2 years (Source:Alenco GmbH, Germany (Muller & Nowack, 2010).

In Horice (Czech Republic) in November of 2008, 300 kilograms of nZVI were injected

to remediate an area 120 x 60 meters contaminated with PCE at a depth of 3 to 10 meters.

Testing indicated a 25 to 40% reduction in contaminants. Another 300 kilograms of nZVI

was injected in November of 2009 and final results have not yet been evaluated. The total

cost of this project was $0.27 million.

Prisecna, Czech Republic, 1.3 tons of nZVI was used to clean up about 1 ton of

chlorinated ethenes at a depth of 20 to 30 meters below ground. The total costs were

around $0.48 million.

34

Based on these tests it was assumed that an nZVI loading of 1.5 tons would be required to

decontaminate each toxic site. There are between 235,000 to 355,000 sites that require cleanup in

the United States (US EPA 2005). An estimated 20,000 sites need to be remediated In Europe

and the European Environmental Agency has identified and another 350,000 potentially

contaminated sites (Prokop et al., 2000). I assumed all of these sites would be candidates for

nZVI treatment in order to obtain a upper limit estimate of nZVI usage. In addition, the total

world contaminations sites was assumed to be twice the number of sites in the US and Europe

for a total estimated number of toxic sites of approximately 1.45 million. Using the estimated

nZVI loading per site and the total number of sites indicated that 2.2 million tons of nZVI would

need to be produced in order to remediate all of the world’s toxic sites if they all used nZVI. This

total usage was projected over a period of 16 years for an approximate total usage of 2.2 million

metric ton per year beginning in 2007.

Quantum Dots

Nanocrystals called quantum dots have promise to revolutionize display technologies, solar

power and biological imaging. Most commercially available dots have a semiconductor core,

often a crystal of cadmium selenide, measuring about 2 to 10 nanometers in diameter. This core

is surrounded by a shell, usually another semiconductor material, and an outer polymer or

inorganic layer. The small size of the dots gives them unique properties. Photons hitting a

quantum dots excite an electron from the it’s ground state in a semiconductor material, creating a

positively charged ‘hole’ The excited electron and positive hole are called an exiton. When an

electron falls back into the hole, it emits energy in the form of light. In bulk semiconductor

material, the range of energies released exitons lies within a continuous band. But in quantum

35

dots, excitons occupy distinct, quantized energy states determined by their size, giving designers

exact control at the molecular level. Smaller dots give of blue light, whereas larger dots of the

same material appear red (Figure 15).

Figure 15: Semiconductor nanocrystals, which emit different colors based on the size of the particles, as shown in the rainbow above, are useful for researching technologies ranging from fluorescent labels to novel light sources (Source: Andrey Rogach at http://www.scienceprogress.org/2010/03/unintended-consequences/).

The market for quantum dots remains small even though they have been in development for ten

years. A handful of companies sell directly to researchers who use the particles to develop their

own products or licensing their technologies to partners. A key constraint to market development

has been the high price with quantum dots going anywhere from $3,000 to $10,000 per gram

(Sanderson, K., 2009). Recently, several newer production methods have been developed that

promise to lower the price. For example, a company called Voxtel, based in Beaverton, Oregon,

recently started trials on a continuous manufacturing process that can manufacture kilogram

36

quantities a week of most types of quantum dots for less than $10 per gram.3 In addition, there is

a possible solution to a long standing but poorly understood problem. Some quantum dots,

particularly those prepared by wet chemistry methods, tend to blink on and off at random, a

problem that can be eliminated by careful adjustment of the boundary between the core and

surface coating of the quantum dot (Wang et al., 2009).

0

50

100

150

200

250

2008 2009 2010 2011 2012 2013

Mill

ions

(US

$)

Stand Alone quantum dots

Electronics (including flash memory products)

Optoelectronics (including lighting and displays)

Optics (including lasers)

Solar energy

Figure 16: Projected growth in the Quantum Dot Market—in September 2008, market-research company BCC Research of Wellesley, Massachusetts, predicted that the market for products relying on quantum dots would grow from $28.6 million in 2008 to $721 million by 2013, with particularly rapid growth in the optoelectronics sector from 2010.

Industry analysts are now predicting extremely rapid growth for the market over the next few

years, driven by demand for energy-efficient displays and lighting, and enabled by cheaper, more

3 Voxtel Corporate Website, “Voxtel in the News: Nature News on the upcoming quantum dot boom,” http://www.voxtel-inc.com/index.php/2009/06/11/voxtel-in-nature-news/, last accessed August 8, 2010.

37

efficient manufacturing processes. It is projected that the market for products relying on quantum

dots would grow from $28.6 million in 2008 to $712 million by 2013 (Figure 16). These

projections are based on the total value of products that contain nanoparticles, not on the

individual nanoparticle component. While the projections do give an indication of how much and

how fast the market will expand, they give no information on the amount of nanoparticles used.

In order to determine projected production volume of quantum dots and estimation was made

based on the amount of nanoparticles contained in products that contain quantum dots. Quantum

dot consumption was calculated using data from Scher et al. (2007). According to Sher et al.

(2007), 56 grams of quantum dots are required per square meter of quantum dot film. I combined

this value with market growth statistics to obtain a forecast for annual production volume. I

based my calculations on the following assumptions:

The average size of an LED surface in a product that uses quantum dots is 1square meter

(similar to the display surface of the typical television). The average retail cost of the

typical television is $600.

The average area of a solar panels used in a typical solar array is 30 square meters. The

average retail cost of a solar panels used in a solar installation is $10,000.

The average price of quantum dots drops from $8000 per gram in 2008 to $10 per gram

in 2015 and remains at this value until 2025.

Using these assumptions, I created an estimated production volume of quantum dots used in the

different market sectors (Figure 17). Using the trend provided by this analysis, I calculated a

forecast of quantum dot production volume to 2025.

38

0

2000

4000

6000

8000

2007 2008 2009 2010 2011 2012 2013 2014

Met

ric To

ns

Figure 17: Estimated growth in the production volume of quantum dots to 2013. The forecast includes all quantum dot market segments included in Figure16.

Nano-Silver

Nano-silver is one of the most promising nanoparticles for future applications due to its

antimicrobial, antifungal and partially antiviral properties (SME NanoRoad, 2005) and one of the

most widely used nanoparticles in consumer products (AmericanElements, 2010). There are

currently three types of silver products that consumers may find labeled “colloidal silver.” These

products can be categorized as ionic silver solutions, silver protein, and true colloidal silver.4

Ionic Silver Products: The majority of products labeled and sold as colloidal silver fall

into this category due to the low degree of manufacturing complexity and resulting low

4 Silver Colloids website: http://www.silver-colloids.com/Reports/reports.html last accessed on August 2, 2010.

39

cost of production. The silver content in these products consists of both silver ions and

silver particles. Typically, 90% of the silver content is in the form of ionic silver and the

remaining 10% of the silver content is in the form of silver particles. The silver ions are

produced by electrolysis and may be described as “dissolved silver.”

Silver Protein: Silver protein products are the second most prevalent type of so-called

colloidal silver products on the market. These products consist of a combination of

metallic silver particles and a protein binder, and can easily be produced by simply

adding water to silver protein powder sold by various chemical companies. Silver protein

products generally have very large silver particles, so large that they would not remain

suspended as colloidal particles without protein additives. Protein additives help to keep

the large particles from settling.

True Colloidal Silver: True colloidal silver products are the least prevalent type of

colloidal silver on the market due to high degree of manufacturing complexity and the

resulting high cost of production. In true colloidal silver, the majority of the silver content

is in the form of silver particles. True colloids will typically contain more than 50%

particles (often 50 – 80%), while the balance (20% to 49%) will be silver ions.

While not comprehensive, the Project on Emerging Nanotechnologies tracks the introduction of

consumer products that contain nanoparticles as ingredients.5 The inventory is based on

manufacturer –identified nanotechnology-based consumer products that are currently on the

market. The inventory indicates products that contain nano-silver particles are far more

numerous than those that contain other types of nanoparticles (Figure 18).

5 The Project on Emerging Nanotechnologies website: http://www.nanotechproject.org/inventories/, last accessed on August 9, 2010.

40

259

82

30 3550

27

0

75

150

225

300

Silver Carbon Zinc Silicon/Silica Titanium Gold

Num

ber o

f Pro

duct

s

2006 2009

Silver54%

Carbon17%

Zinc6%

Silicon/Silica7%

Titanium10%

Gold6%

Inset: The percent of products that contain the indicated class of nanoparticles.

Figure 18: The most common nanomaterial mentioned in product descriptions is now silver at 54% of products in the inventory (see inset). Carbon, which includes fullerenes, is the second most referenced at 17% (Project on Emerging Nanotechnologies, 2010).

The market for products that contain particulate silver is undergoing rapid expansion due to the

antimicrobial effect based on silver nanoparticles. The European market for silver-containing

products is projected to reach 110 to 230 tons of silver by 2010 with stabilization occurring

around 2015. In 2010, plastics and textiles that contain a nano-silver component are predicted to

account for up to 15% of the total silver released into water in the European Union. The majority

of silver released into wastewater is incorporated into sewage sludge and may be spread on

agricultural fields. The amount of silver reaching natural waters depends on the fraction of

wastewater that is effectively treated. Only limited inferences can be made about the risk of this

41

waste stream on the environment because complete characterization of the toxicity of silver to

the environment is lacking (Blaser 2008).

Nearly one-third of products that contained a nano-silver ingredient on the market in September

2007 had the potential to disperse silver or silver nanoparticles into the environment. The mass

of silver dispersed to the environment from new products could be substantial if use of these

nano-silver containing products becomes widespread. Silver is classified as an environmental

hazard because it is toxic, persistent and bioaccumulative under some circumstances. Silver is

highly toxic to bacteria, and that toxicity seems to be accentuated when silver is delivered by a

nanoparticle (Tolaymat, T., 2010). The ionic form of silver is more toxic to aquatic organisms

than any other metal except mercury. But no comparable body of information is available for

nano-silver. Silver is not known as a systemic toxin to humans except at extreme doses. There

are no examples of adverse effects from nano-silver technologies occurring in the environment at

the presence. However, the toxicity of silver to the environment became apparent when people

developed silver-based film for traditional photography and the release of silver solutions caused

adverse ecological effects. Silver contamination of natural waters, even that due to human

activities, ranges from 0.03 to 500 nanograms per liter (ng/L) and sensitive toxicity tests and

environmental case studies have shown that silver metal is toxic at concentrations equal or

greater than 50 ng/L (Luoma 2008).

In order to conduct a risk assessment for the environmental impact of nano-silver it is necessary

to identify its current and future production volume. Currently, such information is not available

and little work has been done to determine current and future loading of nano-silver on the

42

environment. One attempt to determine the level of world production of nano-silver was a study

done by Mueller & Nowack (2008) in which they modeled the release of nano-silver, nano-

titanium oxide, and carbon nanotubes into the environment based on an estimate of worldwide

production volume, allocation of the production volume to product categories, particle release

from the products, and flow coefficients within the environmental compartments. Their best

guess for worldwide production of nano-silver was between 500 to 1230 metric tons per year. I

used this value to develop a linear forecast of future production, starting with 150 metric tons in

2004 and growing to over 7,500 metric tons by 2025. While is a “shot in the dark” estimate, it

seems to be realistic that the production volume will increase significantly in the coming years.

Usage is based on consumer products so there seems little chance that production will plateau as

long as the world’s population continues to expand.

Carbon Nanoparticles

There are several types of carbon nanoparticles that have recently been commercialized. These

materials can be categorized as the carbon nanotube (CNT), the carbon nanofiber (CNF) and the

graphene platelet. The properties of these materials are derived from carbon that is joined in a

three-way sp2 hybrid covalent bond that resembles chicken wire. This structure gives rise to

unique strength and electrical properties, such as those ranging from metallic conductors to

semiconductors, sustainable high current densities, and high thermal conductivities (see Table 3).

With these properties, carbon nanoparticles show promise in a variety of applications, such as

structural polymers, super capacitors, hydrogen storage, energy conversion, batteries,

nanoprobes, sensors, and shielding.

43

CNTs are tubular structures that come in two forms, defined by the number of tube walls. Single-

wall carbon nanotubes (SWCNTs) are single tubes with a diameter of 1 nanometer (nm). Multi-

wall carbon nanotubes (MWCNT) are made up of several (5 to 15) concentric tubes. This “tubes-

within-tubes” arrangement typically has a diameter of about 20 nm. CNFs consist of a “stacked

cup” fiber configuration, with a diameter varying between 70 and 200 nm and a length of 50 to

100 μm. Graphene is in the form of flat, one-atom thick planar sheets. Table 3 compares these

materials with conventional fibers and steel.

Table 3: A comparison of the mechanical properties of the different types of carbon nanoparticles with conventional fibers and steel. Carbon-containing materials have significantly higher strength-to-weight rations and electrical properties (source: Pilato 2010).Material Modulus

(GPa)Tensile Strength(GPa)

Density(g/cm3)

Diameter

SWCNT/MWCNT ~1,000 ~100-200 ~0.7-1.7 1/~20 nmCarbon Nanofibers ~500 3-4 1.8-2.1 20-200 nmGraphene ~1,000 ~100-400 1.8-2.2 PlateletHigh Tensile Steel 210 1.3 7.9 --Carbon Fiber 230 3.5 1.75 5-10 μmAramid Fiber (Kevlar) 60 3.6 1.44 5-10 μmGlass Fiber 22 3.4 2.6 5-10 μm

There are three manufacturing methods that are primarily used to produce carbon nanoparticles:

arc ablation (arc), chemical vapor deposition (CVD), and high-pressure carbon monoxide

(HiPco). Each method consists of process steps that include catalyst preparation, synthesis,

purification, inspection, and packaging. There are significant differences in the synthesis step

among these processes but little difference between them in the purification, inspection, and

packaging steps. The yield of these processes is low (Table 4). In a comparison of the three

SWNT production processes, the HiPco process demonstrated the highest throughput (0.45 g/hr)

44

and lowest environmental impact (Healy, 2008), primarily because the HiPco process operates as

a continuous process whereas the arc and CVD processes are batch processes.

Table 4: Yield parameters, environmental impact, and throughput for three methods used to manufacture carbon nanoparticles (the HiPco process is continuous and the current yield is that for one cycle).Parameter Arc CVD HiPcoCurrent synthesis yield (%) 4.5 2.95 0.08 (single pass)Est. best case yield (%) 20 20 46Purification yield (%) 70 90 90Environmental impact 5.8 2.4 1 (basis)Throughput (g/hr) 0.034 0.008 0.45

Initial studies on the interaction of nanoparticles with biological systems are not conclusive.

Recent studies report that SWNTs appear to damage lung tissue in mice (Lam et al. 2004;

Shvedova et al. 2005; Donaldson et al. 2006; Lam et al. 2006; Poland et al. 2008), whereas

others imply they have little effect (Fiorito et al. 2005; Warheit 2005). Researchers indicate that

additional studies are essential to fully understand the toxicology of these compounds due to

inhalation, ingestion, dermal exposure and the effects of bioaccumulation of nanoparticles in the

environment (Healy 2008).

At present, carbon nanoparticles are primarily used commercially in composite materials.

Nanotubes offer the best method to make a plastic conductive while maintaining acceptable

mechanical properties. Two examples are major resin manufacturers that use MWCNTs in

composites to enable electrostatic painting of lightweight exterior auto body panels without the

need for a special conductive primer. MWCNTs also are used in composite electronics

applications. MWCNT-enhanced PEEK (polyetheretherketone), PEI (polyetherimide) and PC

(polycarbonate) have been used in clean rooms for the manufacture of computer chips and hard

45

drives, because they dissipate static electricity and, therefore, won’t attract airborne

contaminants. The potential applications of carbon nanoparticles are varied with potential use in

fields such as electronics, optics, materials science, and architecture. An application expected to

consume large amounts of CNTs is the $30 billion rechargeable battery market. Although metal

hydride batteries are used in current hybrid electric vehicles, such as Toyota’s Prius, lithium-ion

batteries (presently used for portable electronics) are expected to dominate in emerging plug-in

hybrid vehicles and the all-electric vehicles that will follow. The latter exhibit high specific

capacity, high specific energy and long cycle life, and should be available at moderate cost when

compared to other battery systems. Production volumes for carbon nanoparticles are based on a

2009 market analysis of companies that manufacture carbon nanotubes The study (Table 5)

included major producers, recent plant expansions and future commitments reported by potential

customers (Pilato, 2009). In order to obtain and estimated production volume, I used a linear

forecast of the CNT production capacities given in Table 5, extrapolating the production curves

out to 2025.

Table 5: Estimated capacity of carbon nanoparticles based on analysis of current carbon nanotube manufactures, plant expansions and future commitments and potential new applications (Pilato 2009).

2009 2010 2015MWCNT 2,380 4,000 10,000SWCNT 10 12 30CNF 120 150 550Graphene <10 40 250

Steel and Aluminum

The production statistics for steel and aluminum were included in order to provide a comparison

to a traditional material. Over the course of the 20th century, production of crude steel has risen

46

at an astounding rate, now fast approaching a production level of 800 million tons per year.

Today, it is difficult to imagine a world without steel. Like steel, aluminum is among the most

essential materials for the U.S. transportation, packaging, and construction industries. The US

produces more than 20 billion pounds of ingot and fabricated mill products, 7 billion of which is

secondary recycled metal. Sources of data for the steel and aluminum production volume come

from the mineral statistics publications of the U.S. Bureau of Mines and the U.S. Geological

Survey—Minerals Yearbook.

Embodied Energy Calculations

All materials consume energy in when they are manufactured, in the conversion to components

and products, and subsequently in transportation to the user. During use, additional energy is

expended for maintenance and ultimately, in disposal. From the perspective of sustainability it is

necessary to analyze the entire life-cycle costs of materials in order to provide a basis for rational

choices in materials selection and usage.

It is also useful to estimate of the embodied carbon (carbon dioxide), embodied water or other

environmental resource costs required to make a material. Because of the potential for global

warming, embodied carbon is particularly useful when comparing the carbon footprint of

materials and, as shown in Figure 19, there is a direct relationship between the embodied energy

and embodied carbon. Portland cement, whose embodied energy is 5.2 MJ/kg cement, provides

an important illustration. Large quantities of carbon dioxide are produced as a by-product when

clays and limestone are heated to produce cement and additional energy is used to heat the kiln

from the burning of fossil fuels. Estimated embodied carbon is about 0.80 kg CO2/kg cement

47

produced. The world uses large quantities of cement (about 2.55 billion tons in 2006) and,

consequently, about 3% of the total anthropogenic CO2 (carbon footprint) is caused by cement

manufacture (Hall 2009).

Materials

Embodied Energy(MJ/kg)

Embodied Carbon

(kg CO2/kg)Aluminum (virgin) 218.0 11.5Rubber 101.7 3.2Plastics 80.5 2.5Carpet 74.4 3.9Zinc (virgin) 72.0 3.9Paint 68.0 3.6Lead (virgin) 49.0 2.6Bitumen 47.0 0.5Steel (virgin) 35.3 2.8Aluminum (recycle) 28.8 1.7Iron 25.0 1.9Paper 24.8 1.3Glass 15.0 0.9Ceramics 10.0 0.7Steel (recycle) 9.5 0.4Timber 8.5 0.5Cement 4.6 0.8Bricks 3.0 0.2Asphalt 2.6 0.0Concrete 1.0 0.1

Trend: R² = 0.8089

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

Embo

died

Ener

gy, l

og(M

J/kg

)

Embodied Carbon, log(kg CO2/kg)

Aluminum(virgin)

Asphalt

Aluminum(recycle)

Steel (virgin)

Steel(recycle)

Concrete

Figure 19: Embodied energy of materials plotted against their embodied carbon (carbon footprint). The embodied energy is directly related to the environmental impact of materials. The plot demonstrates how the energy usage is a good proxy for environmental impact. (source: Hammond & Jones 2008)

The embodied energy of materials used to manufacture engineered materials is shown in Figure

20. Among metals, the light alloys based on aluminum, magnesium, and titanium have the

highest values, approaching 1000 MJ/kg. Polymers all cluster around 100 MJ/kg, and steels and

cast irons that lie between 20 MJ/kg and 40KJ/kg. Technical ceramics such as aluminum nitride

have high energies; those for glass, cement, brick, and concrete are much lower. Composites,

too, have a wide spread. High performance composites lie at the top, well above most metals. It

should be noted that if the basis of comparison were changed to embodied energy per volume,

48

the metals family would lie completely above the others. Therefore, it is important to base

comparisons per “unit of function” (Ashby 2009). However, most compilations of embodied

ecodata are based on unit mass.

Figure 20: Embodied energy per unit mass of various materials used to manufacture products (Ashby 2009).

There are strong incentives to recycle some materials. For example, huge amounts of energy are

needed to make aluminum metal from its ores. This provides a strong incentive to recycle as

processing recycled material requires only 12% of the energy needed to refine aluminum from its

ores. A whole new industry has developed around aluminum recycling; the high value of

aluminum for recycling drives the development of new technologies for product recovery,

dismantling, preparation, melting and ingot casting. This recycling business now contributes

49

about one-third of the U.S. annual production of aluminum, a figure that will increase as more

aluminum is inevitably used in transportation applications (Figure 21).

0.0E+00

1.0E+06

2.0E+06

3.0E+06

4.0E+06

5.0E+06

6.0E+06

7.0E+06

8.0E+06

1950 1960 1970 1980 1990 2000 2010 2020

Met

ric To

ns

Al Primary Production Al Secondary Production Total

Figure 21: Production volume of aluminum metal showing primary, secondary, and total production values. The production trend is forecast to 2020 using a linear extrapolation. The recycle of aluminum became the major source of aluminum after 2000. (Source: USGS Minerals Report 2010)

One goal of this research is to compare the embodied energies of nanomaterials with traditional

materials used in the manufacture of products. However, there is little information is available on

the embodied energy of nanomaterials. In addition, the embodied energy of a particular material

tends to decline principally because of the need for companies to lower costs due to global

competition. In the aggregate, energy used to manufacture a given amount of product has fallen

by as much as 50% since 1973. One reason is that companies have lowered the energy cost using

better technology and improved processes. But also, the mix of what is produced within

manufacturing, i.e. the structure, has changed, moving away from energy-intensive products and

leading to lower energy use. The net effect of structural changes accounted for more than a third

50

of the reduction in total manufacturing energy-use per unit of output between 1973 and 1998

(Unander 2007).

Unlike more conventional manufacturing, nanomanufacturing techniques require unique facility

and process design as well as operation and control. Accordingly, the environmental burden may

be greater. Energy intensive aspects used in nanomanufacturing include strict material purity

requirements, low tolerance for defects, low process yields, low material utilization efficiencies,

repetitive processing steps, the need for specialized environments, the use of toxic chemicals and

solvents, the need for moderate to high vacuum, the use or generation of greenhouse gases, high

energy and water consumption, and the potential for chemical exposure (Sengul, et al., 2008).

As shown in Figure 21, the new manufacturing systems used to make CNTs and QDs require

orders of magnitude more energy per mass to make material compared to traditional processes.

Figure 22: Energy requirements of several materials (adapted from Gutowski et al. 2007, and Sengul and Theis 2008).

51

Making microchips uses much more energy than making steel, for example, and the newer

processes are huge users of materials and energy. Early estimates by Isaacs (2006) indicated the

large value of the specific energy requirements for carbon nanotubes. More recently, energy

estimates have been performed for a variety of carbon fibers (SWNTs, multiwall carbon

nanotubes – MWNT, and carbon fibers) and a variety of manufacturing processes (Arc,

CVD and HiPco) (Healy et al. 2008, Kushnir & Sanden 2008, Khanna et al. 2008). Because

some of these processes are so new, they will be optimized and improved over time (Figure 22).

But as things stand now, over the last several decades as traditional processes such as machining

and casting have increasingly given way to the advanced processes used to produce

semiconductors, MEMS and nanomaterials and devices, there has been an increase in the energy

and materials consumption by three to six orders of magnitude (Gutowski et al. 2009).

Figure 23: Evolution of the HiPco Process development over time in terms of the calculated minimum theoretical physical exergy (electricity) requirements and estimated actual exergy over a nine year period (Gutowski 2010).

52

Results

Estimates of the world production for several nanomaterials and two traditional materials (steel

and aluminum) over a time range from 1990 to 2025 are shown in Figure 24. Note that the

production volume is displayed in log10 format in order to fit in all of the data. Approximately

800 billion tons of steel and 6.4 million tons of aluminum were produced in 1990, changing to

1.3 billion tons and 6 million tons by 2008, respectively. It is forecast that production of these

materials will remain flat, based on a liner trend line going back to 1965 (R2>0.9). The

production of the nanomaterials start well below that of steel and aluminum, but it is forecast that

they will all experience dramatic climb in production out to 2025. In particular, it is forecast that

world production of nano-TiO2 will approach that of aluminum.

0

1

2

3

4

5

6

7

8

9

10

1985 1990 1995 2000 2005 2010 2015 2020 2025 2030

Log (

met

ric to

nnes

)

Steel

Al

nano-TiO2

MWCNT

SWCNT

QD

nano-Ag

nZVI

nano-CeO2

Figure 24: A forecast of world production of nanomaterials compared to past and future production of steel and aluminum.

53

Estimates of current and future embodied energy change over time of 1990 to 2025 are shown in

Figure 25. Again the embodied energy is shown in log10 format in order to fit the data into one

plot for a comparison. The embodied energy of steel fell from 36 MJ/kg in 1980 to 31 MJ/kg in

2010. It is forecast that this trend will continue, falling to 23 KJ/kg in 2025. Similarly, the

embodied energy of aluminum drops to 117 MJ/kg in 2025 from 237 MJ/kg in 1980. These

trends are seen to be the result of process improvements and recycling, the latter true particularly

for aluminum. The embodied energies of nano-TiO2 and nZVI are both near that of steel. It is

estimated that the embodied energies of QDs and CNTs start three orders of magnitude higher

than aluminum, but the forecast is that they will lower as lower cost processes are implemented

and efficiencies of scale are realized.

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

5.50

6.00

1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030

Log (

MJ/

kg)

Steel Al nano-TiO2 CNT QD nZVIFigure 25: An estimate of the future embodied energy (per kg) used to manufacture several nanomaterials compared to that used to make steel and aluminum.

54

Figure 26 shows the total estimated embodied energies needed to support current and anticipated

world production volumes of steel, aluminum and several types of nanomaterials, obtained by

combining information from Figures 24 and 25, over a time range from 1990 to 2025. Again, the

numbers are plotted on a log10 scale in order to see all of the data together. Total energy needed

to support aluminum production starts at 8.5 x 108 GJ and lowers to 2.5 x 108. Both nZVI and

nano-TiO2 are less energy intensive than aluminum then increase out the entire time period to

end close to aluminum. Steel stays fairly constant, requiring around 3.0 x 1010 GJ. The total

energy needed to produce QDs and CNTs start roughly two orders of magnitude higher than

steel, but then they both steadily decrease throughout the time period. The total energy needed to

produce QDs falls fairly dramatically to a value close to aluminum. The total energy needed to

make CNTs falls more slowly, ending up to about 1 order of magnitude above that energy

needed to make steel.

6

7

8

9

10

11

12

13

1985 1990 1995 2000 2005 2010 2015 2020 2025 2030

Embo

died

Enge

rgy (

GJ)

Steel Al nano-TiO2 CNT QD nZVIFigure 26: An estimate of the total future embodied energy used to manufacture several nanomaterials compared to that used to make steel and aluminum.

55

Conclusions

The modeled concentrations of NP in the environment are only as good as the raw data. For

nano-Ag and nano-TiO2 the range between the estimations for the worldwide production is wide.

In order to address the uncertainty of data in this thesis, two scenarios were modeled: a realistic

exposure scenario based on the most reliable data and a high exposure scenario including the

worst-case assumptions. A future scenario was not conducted, as the predictions for the

development of the production volumes of the NP are too vague. It seems to be realistic, though,

that the production volumes of all three substances will increase significantly in the coming years

(UNEP 2007). So far there has been no exhaustive inventory that lists all NP containing products

and their nano-ingredients. Scientific reports usually address the application areas only on an

abstract level and do not mention concrete products. Furthermore only very little trustworthy

information is given by companies. Many producers do not advertise nanocomponents. It can be

expected that more data on the production and use of nanoparticles in consumer products will

become available in a few years when ongoing governmental projects on nanomaterials are

completed.

In The Royal Academy of Engineering’s 2004 report, “Nanoscience and

Nanotechnologies: Opportunities and Uncertainties,” projected worldwide production of

nanomaterials at 104 to 105 metric tons per annum for the years 2011 to 1020 (p. 27). Six

years on, my forecast matches this fairly closely, rising from 0.2 metric tons in 2011 to

4.5 metric tons in 2025

56

This is the first research to forecast the total annual production of nanomaterials into the

near-term future. The projections show that a large amount of energy will be devoted to

the production of carbon nanotube material, on the order of that used to product steel and

aluminum. This could be a limiting factor in the production of carbon nanotube materials.

The embodied energies needed to produce several nanomaterials converge to the same

amount needed for aluminum production.

Nanomaterials are being produced at an increasing rate. This research provides an

estimate of the energy that will be needed to manufacture these materials into the near-

term future. However, there is a strong likelihood that nanotechnology will make the

production of energy more efficient and promote the use of non-fossil fuel forms of

energy.

The average research scientist involved in nanotechnology has not thought about the

potential global energy signature of particular nanomaterials. The information provide by

this report is useful in performing Life Cycle Assessments, which can guide and inform is

public and private policy decisions.

References

AOL News, Inc, “Amid Nanotech’s Dazzling Promise, Health Risks Grow,” 2010, http://www.aolnews.com/nanotech/article/amid-nanotechs-dazzling-promise-health-risks-grow/19401235, last accessed on August 11, 2010.

AmericanElements. Silver Nanoparticles. http://www.americanelements.com/agnp.html, last accessed August 10, 2007.

Ashby, M.F., Materials and the Environment: Eco-Informed Material Choice, Elsevier, Burlington, MA, 2009.

Costanza, R., “Embodied Energy and Economic Valuation,” Science Magazine, Vol. 210, No. 4475 (Dec. 12, 1980), 1219-1224.

57

Berger, M., “Debunking the trillion dollar nanotechnology market size hype,” Nanowerk LLC, April 18, 2007, http://www.nanowerk.com/spotlight/spotid=1792.php, last accessed on August 11, 2010.

Blaser, S.A., et al., “Estimation of cumulative aquatic exposure and risk due to silver: Contribution of nano-functionalized plastics and textiles,” Science of the Total Environment, Vol. 390, No. 2, 2008), 396-409.

Costanza, R., “Embodied Energy and Economic Valuation,” Science Magazine, Vol. 210, No. 4475, December 12, 1980, 1219-1224.

EPA, “Nanotechnology White Paper,” Report 100/B-07/001, February 2007, www.epa.gov/osa.

Fox, B., “Nano fuel additive enters efficiency trials,” New Scientist, October 15, 2003, http://www.newscientist.com/article/dn4271-nano-fuel-additive-enters-efficiency-trials.html, last accessed August 6, 2010.

Freedonia Group, Inc. Study, “World nanomaterials to 2013,” Publication date: March 3, 2010.

Friedl C. (2006) AAV und Rhein-Sieg-Kreis sanieren CKW-Altlast in-situ mit Nano-technik.Online http://www.aav-nrw.de/aav/dokumente/projektinformation/bornheim_ferster.pdf

Grant, S., et al., “An undergraduate teaching exercise that explores contemporary issues in the manufacture of titanium dioxide on the industrial scale,” Green Chemistry Journal, Vol. 6, No. 1, 2004, 25-32.

Gutowski, T.G., et al., “Thermodynamic Analysis of Resources Used in Manufacturing Processes,” Environmental Science Technology, Vol. 43, No. 5, 2009, 1584-1590.

Gutowski, T.G., et al., “Minimum Exergy Requirements for the Manufacturing of Carbon Nanotubes,” IEEE, International Symposium on Sustainable Systems and Technologies, Washington D.C., May 16-19, 2010.

Hammond, G., Jones, C., Inventory of Carbon & energy (ICE), version 1.6a, University of Bath, 2008, Available from: www.bath.ac.uk/mech-eng/sert/embodied/.

Hall, C., ICE Manual of Construction Materials, (chapter 1), Institution of Civil Engineers, 2009, www.icemanuals.com.

Healy, M.L., et al., “Environmental Assessment of Single-Walled Carbon Nanotube Processes,” Journal of Industrial Ecology, Vol. 12, No. 3, 2008, 376-393.

Isaacs, J.A., et al., “Environmental assessment of SWNT production.” Proceedings of the 2006 IEEE International Symposium on Electronics and the Environment. 8-11 May 2006, 38-41.

58

Klöpffer, W. et al., “Nanotechnology and Lifecycle Assessment: Synthesis of Results Obtained at a Workshop,Washington, DC, 2-3 October 2006” Woodrow Wilson International Center for Scholars, Project on Emerging Nanotechnologies, March 2007, http://www.nanotechproject.org/file_download/files/NanoLCA_3.07.pdf.

Khanna V., et al., “Carbon nanofiber production – life cycle energy consumption and environmental impact”, Journal of Industrial Ecology, Vol. 12, No. 3, June 2008, 394 -410.

Kushnir D. & Sanden B.A., “Energy requirements of carbon nanoparticle production,” Journal of Industrial Ecology, Vol. 12, No. 3, June 2008, 360 -375.

Li, et al., “Zero-Valent Iron nanoparticles for Abatement of Environmental Pollutants: Materials and Engineering Aspects,” Critical Reviews in Solid State and materials Sciences, Vol. 31, 2006, 111-122.

Luoma, S.N., “Silver nanotechnologies and the Environment: Old problems or new challenges?” Project on Emerging Nanotechnologies, PEN 15, September 2008.

Meyer, D.E., et al., “An Examination of Existing Data for the Industrial Manufacture and Use of Nanocomponents and Their Role in the Life Cycle Impact of Nanoproducts,” Environmental Science & Technology, Vol. 42, No. 5, 2009, 1256-1263.

Muller, N.C., Nowack, B., “Nano zero valent iron—THE solution for water and soil remediation?” ObservatoryNANO focus report 2010, document available for downloading at http://www.observatorynano.eu/project/document/3290/, last accessed on August 8, 2010

Nano Patents and Innovation, “$250 Billion Cost Estimate to Clean 350,000 Toxic Sites in the US, Nano Zero Valent Iron May Be Cheaper Solution,” posted by Parrish, A., December 29, 2009, http://nanopatentsandinnovations.blogspot.com/2009/12/250-billion-cost-estimate-to-clean.html, last accessed on August 8, 2010.

Nanoderm, “Quality of Skin as a Barrier to ultra-fine Particles: Final Report,” 2007, http://www.uni-leipzig.de/~nanoderm/Downloads/Nanoderm_Final_Report.pdf .

Ogilvie Robichaud, C., et al., “trends in nano-TiO2 Production as a Basis for Exposure Assessment,” Environmental Science & Technology, Vol. 43, No. 12, 2009, 4227-4233.

Osterwalder, et al., “Energy Consumption during Nanoparticle Production: How Economic is Dry Synthesis?” Journal of Nanoparticle Research, Vol. 8, 2006, 1-9.

Park, B., et al., “Hazard and Risk Assessment of nanoparticulate Cerium Oxide-based Diesel fuel Additive—A Case Study,” Inhalation Toxicology, Vol. 20, 2008, 547-566.

PEN, The Project on Emerging Technologies, Woodrow Wilson Center for Scholarship, The PEW Charitable Trust, http://www.nanotechproject.org, last accessed on August 10, 2010.

59

Pilato, L., “CNTs ride a rising tide of nanotech optimism,” High-Performance Composites magazine, March 2010, http://www.compositesworld.com/articles/cnts-ride-a-rising-tide-of-nanotech-optimism, last accessed August 9, 2010.

Prokop G., et al., “Management of contaminated sites in Western Europe. Topic report No 13(2000),” European Environment Agency, 1999.

Roco, M., “National Nanotechnology Initiative—Past, Present, and Future,” Handbook on Nanoscience, Engineering and Technology, 2nd ed., Taylor and Francis (2007).

Sanderson, K., “Quantum dots go larger—a small industry could be on the verge of a boom,” Nature, Vol. 459, June 11, 2009, 760-761.

Sargent, J.F., “Nanotechnology and US Competitiveness: Issues and Options,” Congressional Research Service, Order Code RL34493, May 15, 2008.

Selvan, V. et al., “Effects of Cerium Oxide Nanoparticle Addition in Diesel and Diesel-Biodiesel-Ethanol Blends on the Performance and Emission Characteristics of a CI Engine,” ARPN Journal of Engineering and Applied Sciences, Vol. 4, No. 7, September 2009.

Sengul, H., et al., “Toward Sustainable Nanoproducts,” Journal of Industrial Ecology, Vol. 12, No. 3, 2008, 329-359.

Shur M.S., Zukauskas A., “Solid-state lighting: Toward superior illumination,” Proceedings of the IEEE, Vol. 93, No. 10, October 2005, 1691-1703

Soddy, F., Wealth, virtual Wealth and Debt: The solution of the Economic Paradox, Dutton, New York, 1933.

Tolaymat, T.M., et al., “An evidence-based environmental perspective of manufactured silver nanoparticle in syntheses and applications: A systematic review and critical appraisal of peer-reviewed scientific papers,” Science of the Total Environment, Vol. 408, No. 5, February 2010, 999-1006.

Tratnyek, P.G., Johnson, R. L., “Nanotechnologies for environmental cleanup,” nano Today, Vol. 1, No. 2, May 2006, 44-48.

Trouiller, B., et al., “Titanium Dioxide Nanoparticles Induce DNA Damage and Genetic Instability in vivo in Mice,” J. Cancer Research, Vol. 69, No. 22, (2009).

Truhaut, R., “Eco-Toxicology—Objectives, Principles and Perspectives,” Ecotoxicology and Environmental Safety, Vol. 1, No. 2, 197, 151-173.

Odum, E. P., “The Emergence of Ecology as a New Integrative Discipline,” Science, Vol. 195, No. 4284, March 25, 1977, 1289-1293.

60

Unander, F., “Decomposition of manufacturing energy-use in IEA countries: How do recent developments compare with historical long-term trends?” Applied Energy, Vol. 84, 2007, 771-780.

UNEP, “Emerging Challenges—Nanotechnology and the Environment,” Geo Yearbook 2007; UNEP: Nairobi, Kenya, 2007.

USEIA (US Energy Information Administration), “Annual Energy Outlook 2010 With Projections to 2035,” US Department of Energy, April 2010, publication available at www.eia.doe.gov/oiaf/aeo/.

USEPA. (2005) US EPA Workshop on Nanotechnology for Site Remediation. http://epa.gov/ncer/publications/workshop/pdf/10_20_05_nanosummary.pdf, site last accessed on August 8, 2010.

USGS Periodic Publications: Minerals Commodity Summaries, Minerals Yearbook, Mineral Industry Surveys, 2010, http://minerals.usgs.gov/minerals/pubs/, last accessed on August 7, 2010.

US Navy Website on nZVI, “Nanoscale Zero Valent Iron,” https://portal.navfac.navy.mil/portal/page/portal/navfac/navfac_ww_pp/navfac_nfesc_pp/environmental/erb/nzvi, site last accessed on August 8, 2010.

Wakefield, et al., “Envirox™ fuel-borne catalyst: Developing and Launching a nano-fuel additive,” Technology Analysis & Strategic Management, Vol. 20, No. 1, January 2008, 127-136.

Wang, X., et al., “Non-blinking semiconductor nanocrystals,” Nature, Vol. 459, June 4, 2009, 686-680.

61