nanotechnology for energy applications

8/12/2019 Nanotechnology for Energy Applications

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NANOTECHNOLOGY

FOR ENERGY APPLICATIONS

NANO CONNECT SCANDINAVIA www.nano-connect.org

Chalmers University of Technology | DTU | Halmstad University | ImegoLund University | University of Copenhagen | University of Gothenburg

ENERGY EFFICIENCY

ENERGY PRODUCTION & POWER TRANSMISSION

ENERGY STORAGE & CONVERSION

Sol Voltaics AB aims to produce portable, semi-conductornanowire-based solar cells using a high volume production

method based on guided self-assembly of nanowires in the

gas phase. Image: Damir Asoli.



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Thematic Area ”Nano for Energy”

Why nanotechnology matters

The world’s hunger for energy is rapidly increasing while

we at the same time face critical environmental issues as

well as dwindling resources. To manage this situation we

need to produce, transport, store and consume energy in

new and more efcient ways.

Nanotechnology promises to be the tool we need. Design-ing and developing new material properties on the na-

noscale enables new applications and solutions. We are in

fact already seeing products such as energy-efcient LED

lights, new nanomaterials for thermal insulation, low fric-

tion nanolubricants and lightweight nanocomposites on

the market. This is just the beginning.

Many exciting opportunities with huge market potential

will emerge in the decades to come. Nanotechnologies will

affect the entire eld of energy from usage to supply, con-

version and storage. Today the main focus is very much onimproving energy efciency.

With this brochure, Nano Connect Scandinavia, an EU-

nanced project representing seven universities and insti-

tutes in south-western Scandinavia, presents a few prom-

ising areas within the energy eld where nanotechnology

will have a major impact.

WHAT IS NANOTECHNOLOGY?

Nanotechnology is the understanding

and control of matter and processes

at the nanoscale, typically, but not ex-

clusively, below 100 nanometres in one

or more dimensions where the onset

of size-dependent phenomena usually

enables novel applications. Nanotech-

nology is cross-disciplinary in nature,drawing on medicine, chemistry, biol-

ogy, physics and materials science.

New properties

Modied at the nanoscale, matter be-

gins to demonstrate entirely new prop-

erties, also on a macroscopic scale. It

can become stronger, lighter, have im-

proved viscosity, increased stability or

better thermal and electrical properties.

Creating nanostructures

With a bottom-up approach, nano-

structures are formed molecule by mol-

ecule, using methods such as chemical

vapour deposition or self-assembly. By

contrast, top-down fabrication can be

likened to sculpting from a base mate-

rial, and typically involves steps such as

deposition of thin lms, patterning, and

etching

This composite image shows Earth as

seen from space at night. It illustrates

how unevenly energy use is distributed

across the globe, and it gives a taste

of how much mankind’s energy con-

sumption will rise when the “dark” ar-

eas develop. Photo courtesy of NASA.



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The Volkswagen 1-litre concept car travels 100 km on

one litre of diesel fuel. This extraordinarily high fuel

efciency is possible thanks to lightweight materials,

carefully designed aerodynamics and an engine con-trol system tuned for economy. Photograph by Rudolf

Simon via Wikimedia Commons.

LIGHTWEIGHT CONSTRUCTIONS BOOSTFUEL EFFICIENCY

Nanostructured metal or polymer matrix composites

dene new standards in lightweight design; they offerhigher strength-to-weight ratio, higher resistance against

fatigue and better formability than conventional com-

posite materials owing to the large interfacial area be-

tween matrix and reinforcement structure. They also

display interesting optical, electrical, thermal and mag-

netic properties. Lighter and smaller heat exchange

systems can be constructed by using nanouids, a new

class of heat transfer uids, where the addition of a very

small quantity (<1 % by volume) of nanoparticles to a

traditional heat transfer uid dramatically improves its

thermal properties while not signicantly affecting the

ow properties.

Energy efciencyThe International Energy Agency (IEA) estimates that energy sav -

ings corresponding to almost one fth of the current worldwide en-

ergy consumption can be achieved by improved energy efciency.Nanotechnology enables large energy and cost savings, especially

in the building, transportation and manufacturing industries.

SMART WINDOWS RECONCILE ENERGY EFFICIENCY

AND AESTHETICS

Windows create a connection to the outside world and add natu-

ral light to a building, but they also critically affect the building’s

energy balance. Nanotechnology-based smart windows change

their colour at the ick of a switch – a small applied voltage

changes the appearance of electrochromic glass from transpar-

ent to translucent (and vice versa) as lithium ions and associated

electrons migrate from the counter electrode to an electrochro-

mic electrode layer. Due to efcient heat and light management,

the need for cooling and lighting can thereby be optimally bal-

anced, and motorised shades can be partially eliminated.

AEROGELS RE-DEFINE THERMAL INSULATION

Aerogels are solid nanoporous substances with exceptionally

low density (as low as 3 kg/m3 ) and remarkable thermal insula-

tion properties (thermal conductivities down to 0.004 Wm-1K-1, i.e.

about 8–10 times lower than mineral wool). They are mechani-cally stable, translucent, non-toxic, and non-ammable. While tra-

ditionally expensive, Svenska Aerogel AB has developed a new

production method that enables the material to be produced in

a cost-effective way. Flexible aerogel blankets are available from

Aspen Aerogels.

Excellent thermal insulation can be achieved

with aerogels as illustrated by a ower not

being burnt by a Bunsen burner. Image

courtesy of NASA/Wikimedia Commons.



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Energy production and

power transmission

Nanotechnology is a key enabling technology both to exploit traditionalenergy sources in a more efcient, safe and environmentally friendly

manner, and to tap into the full potential of sustainable energy sources

such as biomass, wind, geothermal and solar power. It also offers so-

lutions to reduce energy losses in power transmission, and to manage

complex power grids with dynamically changing loads and decentral-

ised feed-in stations.

BRIGHT PERSPECTIVES FOR SOLAR ENERGY

The conversion efciency of photovoltaic and photochemical solar cells

is traditionally governed by a compromise – in order to absorb enough

light, at least micrometre-thick layers are required, while charge car-

rier collection is more efcient the thinner the active layer is. Several

types of nanomaterials that absorb light very efciently are currently

under development; they include quantum dots, plasmonically active

metallic nanoparticles and nanowires. Charge carrier collection can be

improved by designing nanostructures which exhibit short collection

paths with reduced recombination losses. Consequently, less active

material is needed and purity requirements can be relaxed. Graphene is

a promising alternative to indium tin oxide, a scarce material commonly

used to fabricate transparent electrodes in solar cells and LCD displays.

Nanotechnology-enabled solar cells can thus be produced at a lowercost and in a more resource-efcient way. Since they can be made ex-

ible, integrating them into buildings is possible.

TURNING WASTE HEAT INTO VALUABLE ELECTRICITY

Thermoelectic materials convert heat directly into electricity (and vice

versa) and can thus recycle some of the energy contained in, for in-

stance, hot exhaust streams. While low efciency has traditionally lim-

ited the use of thermoelectrics to niche markets, recently developed

nanostructured thermoelectrics, with much better performance than

bulk thermoelectrics, mark the beginning of a new era. Progress has

also been made towards inexpensive, large-scale production methods.

Beyond transport and industrial production, interesting application ar-

eas include the transformation of low-grade solar thermal or geothermal

energy, or the use of human body heat to power portable electronics.

BOOSTING POWER GENERATION FROM WIND

The energy provided by a wind turbine is proportional to the square of

the blade length. Nanocomposite materials with excellent strength-to-

weight and stiffness-to-weight ratios enable the construction of longer,

more robust blades. Low-friction coatings and nanolubricants provide

means to reduce energy losses in gearboxes and thus further increase

efciency.

Thermoelectric materials generate a current when

placed in a temperature gradient as a consequence

of charge carrier diffusion from the hot to the cold

side, thus allowing the regeneration of waste heat

into electricity. Reproduced with permission from

NPG Asia Mater. 2, 152–158 (2010) © 2010 Tokyo

Institute of Technology.



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POWERING PERSONAL ELECTRONICS WITH

YOUR OWN BODY

A nanogenerator is a device, which harvests external me-

chanical energy and converts it into electricity as a result

of bending or stretching nanostructured piezoelectric ma-terials such as zinc oxide nanowires. The mechanical en-

ergy may be provided in a countless number of ways, e.g.

virtually any body movement, a rolling tire, vibrations, or

airow. Nanogenerators capable of powering commercial

liquid-crystal displays or light-emitting diodes have been

demonstrated. Further development will result in devices

powerful enough to drive portable electronics such as a

cell phone, or to extract electricity from wind or waves on

a large scale.

LOST IN TRANSMISSION

A grid capable of massive power transmission across

continental distances with negligible energy losses is a

critical component for a sustainable energy future. Current

copper-based grids leak electricity at about 5% per 100

miles of transmission. A special type of carbon nanotubes,

so-called armchair nanotubes, which exhibit extraordi-

narily low electrical resistance (more than 10 times better

conductivity than copper) and tremendous specic tensile

strength, could revolutionise electricity transmission. The

insulation system accounts for up to 7% of the energy lossduring transmission. Dielectrics based on polymer nano-

composites (nanodielectrics) have shown advantageous

insulating properties, including enhancement of the dielec-

tric breakdown strength and improved erosion and track-

ing resistance, making them interesting candidates for high

voltage outdoor insulation applications.

Nanowires made of piezo-

electric materials can create

electricity from mechanical

motion such as a human

walking or running.

Reproduced with permission from Science

316, 102-105 (2007) Copyright © 2007 American

Association for the Advancement of Science.



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Energy storage & conversionMany sustainable energy sources like wind and solar power deliver signicant power only part of the

time. Strategies to store energy are therefore needed. While the particularly stringent requirements

posed by the transport sector are currently only met by fossil fuels, nanotechnology will make novel

types of energy stores, including electrical stores such as batteries and chemical stores such as hydro-

gen, more competitive.

This fuel cell hybrid vehicle (FCHV) bus

is powered by fuel cells, which generate

electricity from hydrogen, and a nickel-

metal hydride battery in synergy. Photo-

graph by Gnsin via Wikimedia Commons.

PUTTING PRESSURE ON HYDROGEN STORAGE

Hydrogen has a very high energy density by weight, but its low energy density by volume turns its

storage into a major challenge. Nanocomposite materials with exceptional strength-to-weight ratio

can be used to construct lightweight storage tanks with pressure ratings that exceed the perfor-

mance of traditional materials. High surface area materials such as carbon aerogels, carbon na-

nobres or graphene constitute another nanotechnology-based storage option. Current research

focuses largely on chemical methods, where hydrogen reversibly reacts with a solid-state material

such as magnesium. Reducing the dimensions of the storage medium to nanoscale dimensions

can alleviate traditional performance barriers of chemical stores, such as high release temperatures

and slow charge/discharge rates.

Scientists at the Lawrence Berkeley National

Laboratory have recently developed a new,

air-stable nanocomposite material for hy-

drogen storage, where magnesium nanopar-

ticles are embedded in a plastic matrix thatprotects the magnesium from oxidation. The

nanocomposite rapidly absorbs and releases

hydrogen at modest temperatures.



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JUICE UP YOUR MOBILE PHONE IN SECONDS

The use of nanostructured electrodes in batteries has several advantages. The rate of charge/discharge

is improved, down to a few seconds or minutes depending on storage capacity, thanks to a short ion

transport path, and the energy storage capacity benets from the large surface area. Nanostructured

electrodes are also more robust towards volume changes associated with the intercalation and de-intercalation of ions than bulk electrodes, thereby improving cycle life. These nano-approaches are

compatible with a range of battery chemistries, including lithium-ion and nickel-metal hydride batteries.

SQUEEZING THE MOST OUT OF CATALYSTS

Since the chemical reactions involved occur on the cata-

lyst surface, a catalyst is used more effectively the larger

its specic surface area. Nanoscale catalysts thereforehave a decisive advantage over catalysts made from larg-

er particles, particularly if they are made from expensive

noble metals. Nanotechnology allows the synthesis of the

catalyst particles to be steered in such a way that those

crystal facets with the highest activity grow preferential-

ly at the particle surface, and with the catalyst particles

being uniformly distributed on their support. Processes

like the electrolytic production of hydrogen from water or

the conversion of hydrogen to electricity in a fuel cell can

consequently be run more economically and with more

efcient use of resources. Commercial catalysts for the

aforementioned reactions are developed by Quantum-

Sphere Inc. and 3M respectively.

Pt nanowires grown on carbon nanospheres

show a 50% higher mass activity for the ox-

ygen reduction reaction than a commercial-

ly available fuel cell cathode. Reproduced

with permission from Adv. Mat. 20, 3900-

3904 (2008) © 2008 John Wiley and Sons.

Would you like to know more?

This brochure is part of a series, covering different application areas of nanotechnology, including life

science, materials, electronics & sensors, and the regulatory framework for nanomaterials. Please visit

www.nano-connect.org for more information.

This work was supported by the EU through its Interreg IVA Programme. It reects only the author’s views. The Community

is not liable for any use that may be made of the information contained therein.

Simulated quasispherical amorphous carbon

used as the anode material for intercalation in

lithium ion energy storage. Image courtesy of

Argonne National

Laboratory /ickr



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Chalmers University of Technology

Halmstad University

Imego

Lund University

Technical University of Denmark

University of Copenhagen

University of Gothenburg

Halland Regional Development Council

Region Skåne

Region Västra Götaland

Region Zealand

The Capital Region of Denmark

Nano Connect Scandinaviawww.nano-connect.org

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