Does nanotechnology
have the energy?
From new kinds of solar cells and improved wind turbines to supercapacitors and novel
hydrogen-storage techniques, developments in nanotechnology could transform the energy industry,
as Alan Smith and David Tolfree explain
Alan Smith is
managing director of
AZ- TECH Ltd and
David Tolfree is vice-president of the Micro
and Nanotechnology
Commercialisation
and Education
Foundation,
Manchester, UK,
e-mail dtolfree@
gmail.com
The single most important problem facing humanity
today is the need to secure a supply of sustainable
energy to meet the world’s current and future demands. It is indeed the greatest challenge of the 21st
century and how we deal with it will determine the path
of our civilization and dictate the course of the world’s
future economic development. The aim is simple: to
provide clean, cheap and abundant energy to the six
billion people who live on the planet today – a figure
that is expected to rise to over 10 billion by the middle
of this century.
Our best hope lies in exploiting new technology – and
nanotechnology in particular. Nano-scale materials are
not, of course, new. Blood is a nanofluid, milk contains
the nanoparticulate casein, millions of adhesive nano-scale “hairs” on a gecko’s foot let it dash upside down
along ceilings, while the colour of a butterfly’s wings
arises from light diffracting off crystalline nanostructures. Nanomaterials have also been used in commercial products for decades, despite not being so named –
photographic paper and printing inks, for example,
contain nanoparticles, as the relatively large surface
area allows the solvent to evaporate off rapidly.
In the last decade, however, research into nanoscience and nanotechnology has led to over 1000 new
nanomaterials – many with unique properties – coming onto the market, according to data from the Wood-row Wilson International Center for Scholars. Tennis
superstar Roger Federer uses a racket made from a
composite material containing nanotubes – tiny, rolled-up sheets of carbon – while you can now buy sunscreens
At a Glance: Nanotechnology and energy
● Nanotechnology is set to play a big role in the energy industry – from conversion
and storage to transmission and distribution
● The renewable sector will be a particular beneficiary through, for example, new
kinds of high-efficiency “third generation” solar cells that use quantum dots,
quantum wells and molecular dyes, while new nanostructured materials could
lead to bigger, stronger but lighter wind turbines
● Energy-storage devices like supercapacitors and batteries will benefit from
developments in nanotechnology too
● Durable, highly insulating and light-but-strong nanomaterials could help to reduce
carbon-dioxide emissions by lowering energy consumption
containing titanium-dioxide nanoparticles that help
protect against skin cancer. It is even possible to produce strong, thin coloured plastic films where the
colour comes not from pigments but from the diffractive properties of the film’s nanostructure.
The challenge now is to harness such developments
in nanotechnology for the benefit of the world’s energy
supply. Indeed, in 2006 when the Nanotechnology Law
and Business Journal published a list of the top 10 ways
in which nanotechnology will affect our lives ( 4 401),
four were concerned with different aspects of energy:
solar energy; new batteries; lighter, stronger and more
conductive materials; and clean water.
Look on the sunny side
Where nanotechnology will have the biggest impact is
on renewables, which currently account for about 16%
of the world’s primary energy supply. Although the UK
now generates only 4% of its energy from renewables,
it and other members of the European Union together
plan to increase this proportion to 20% by 2020 as part
of a binding target agreed in March 2007. Solar energy,
in particular, is set to benefit from the nanotech revolution. We know that about 89 PW (89 × 1015 W) of solar
power continuously hits the Earth’s surface, and capturing just 0.02% of that radiation would be more than
enough to satisfy the world’s current energy requirements of about 16 T W ( 16 × 1012 W).
Most of the Sun’s energy is currently captured by
“first generation” solar cells, which in 2007 accounted
for 90% of solar-generated electricity. They are so common that even the Vatican now has an array of 2000
solar panels on the roof of one of its buildings, which
were installed in 2007 by the German firm Solar World,
generating over 315 k Wh of electricity each year. In
these cells (figure 1a), part of the silicon is doped to create an excess of holes (i.e. a p-type semiconductor),
while another is doped to contain an excess of electrons
(an n-type semiconductor). When photons of sufficient
energy strike the cell, they promote electrons from the
valence to the conduction band, thus creating electron–
hole pairs. Pairs formed on or near the p–n junction
separate, with electrons flowing in one direction and
holes in the other to create a DC current.
First-generation devices can convert up to 31% of
