Table Of ContentICT - Energy - Concepts Towards Zero
Power Information and Communication Technology
Edited by Giorgos Fagas, Luca Gammaitoni
Douglas Paul and Gabriel Abadal Berini
ICT - Energy - Concepts Towards Zero - Power Information and Communication Technology
Edited by Giorgos Fagas, Luca Gammaitoni, Douglas Paul and Gabriel Abadal Berini
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First published February 12, 2014
ISBN 953-51-1218-X 978-953-51-1218-1
Contents
Preface
Chapter 1 Energy Management at the Nanoscale
by Luca Gammaitoni
Chapter 2 Kinetic Energy Harvesting
by Helios Vocca and Francesco Cottone
Chapter 3 Electronics for Power and Energy Management
by Naser Khosro Po ur, Franÿois Krummenacher
and Maher Kayal
Chapter 4 Energy Storage: Battery Materials and
Architectures at the Nanoscale
by James F. Rohan, Maksudul Hasan, Sanjay Patil,
Declan P. Casey and Tomÿs Clancy
Chapter 5 Minimum Energy of Computing, Fundamental
Considerations
by Victor Zhirnov, Ralph Cavin and Luca Gammaitoni
Chapter 6 Po wer consumption Assessment in
Wireless Sensor Networks
by Antonio Moschitta and Igo r Neri
Chapter 7 A R esearch Agenda Towards Zero-Power ICT
by Gabriel Abadal Berini, Giorgos Fagas,
Luca Gammaitoni and Douglas Paul
Chapter 8 Au tonomous Sensors: Existing and
Prospective Applications
by Francesco Orfei
Chapter 9 Thermoelectric Energy Harvesting
by Douglas Paul
Chapter 10 Electromagnetic Radiation Energy Harvesting –
The Rectenna Based Approach
by Gabr iel Abadal, Javier Alda and Jordi Agustÿ
Preface
A sustainable future for our information society relies on bridging
the gap between the energy required to operate portable ICT devices
with the energy available from portable/mobile sources.
The only viable solution is attacking the gap from both sides, i.e.
to reduce the amount of energy dissipated during computation and
to improve the efficiency in energy harvesting technologies.
This requires deeper and broader knowledge of fundamental processes and
thorough understanding of how they apply to materials and engineering at
the nanoscale, all the way up to the design of energy-efficient electronics.
This textbook is a first attempt to discuss such concepts towards
Zero-Power ICT. The content is accessible to advanced undergraduates and
early year researchers fascinated by this topic.
The book is realized through the EU-funded ZEROPOWER project.
Chapter 1
Energy Management at the Nanoscale
Luca Gammaitoni
Additional information is available at the end of the chapter
http://dx.doi.org/10.5772/57345
1. Introduction
Energy management is considered a task of strategic importance in contemporary society. It
is a common fact that the most successful economies of the planet are the economies that can
transform and use large quantities of energy. In this chapter we will discuss the role of energy
with specific attention to the processes that happens at micro and nanoscale, that are the scales
where the modern ICT devices are built and operated.
2. Energy and its transformation
We start our journey toward the role of energy in ICT devices by addressing the most funda‐
mental question of what energy is. According to Richard Feynman1 we do not know much
about energy apart from the fact that “energy is conserved”. We usually define energy as the
“capability of performing work” and define work as the activity performed by a force applied
to some mass that, as a consequence of this application, changes its position. Energy, in the
International System of Units, is measured in Joule (symbol J). 1 J is equal to the work done by
applying a force of one Newton through a distance of one metre. 1 J is the energy that it takes
to raise an apple (100 g) for 1 m above the ground. It is also relevant how much time it takes
to do some work. This is taken into account by the concept of power. Given a certain amount
of work done, the power is equal to the work divided by the time that it takes to do it. Physical
unit of power is Watt (symbol W; 1W = 1J /1s). Multiples or sub multiples of J or W are what
we are used to deal with in our everyday life: one kilowatt or kW is equal to 1000 W and it is
the power required to cook a cake in a microwave oven. Given that the cake takes about one
1 “It is important to realize that in Physics today, we have no knowledge of what energy is”. The Feynman Lectures on
Physics Volume I, 4-1.
2 ICT - Energy - Concepts Towards Zero - Power Information and Communication Technology
hour to be properly cooked, the amount of energy used at this aim is approximately 3600 x
1000 = 3.6 million J or 1 kWh (kilowatt-hour).
In the following table we list few examples of how much power is required to perform some
common tasks.
Task Power (W)
Average power of a Boing 747 airplane 108
Full power aircraft fighter 106
Full power car engine 105
Operate a microwave oven 103
Being alive for an average adult human 102
Brain functioning for an average human 10
mobile phone calling 1
Emission of a standard WI-FI router 10-1
Functioning of a LED light 10-2
Functioning of a miniature FM receiver 10-3
Functioning o a wireless sensor node 10-4
Low power radio module 10-5
Functioning of a quartz wristwatch 10-6
Operation of a quartz oscillator 10-7
Sleep mode of a microcontroller 10-8
1 bit information erasure at room T (min) 10-21
Table 1. Order of magnitude of the power required to perform some common activities.
From our everyday experience we know that energy is used for many different tasks and comes
in many different forms. We know that it is energy because we can use it to perform work, like
moving a car or a train. Thus energy is a property of physical systems that can be used to
perform work and usually comes inside physical objects like a hot gas or a gasoline tank.
Thinking about it we can ask questions like: how can we make the energy contained in a litre
of gasoline to push forward a car or how can we use the heat produced by burning coal to
make the train run?
Questions like these were at the very base of the activities performed in the early seventeen
hundreds by the first inventors of the so-called thermal machines. People like Thomas
Newcomen (1664-1729) who built the first practical steam engine for pumping water and James
Watt (1736-1819) who few decades after proposed an improved version of the same machine.
It is thanks to the work of scientists like Sadi Carnot (1796-1832) and subsequently of Émile
Energy Management at the Nanoscale 3
http://dx.doi.org/10.5772/57345
Clapeyron (1799 - 1864), Rudolf Clausius (1822 - 1888) and William Thomson (Lord Kelvin)
(1824 – 1907) that studies on the efficiency of these machines aimed at transforming heat (just
a form of energy) into work brought us the notion of entropy and the laws of thermodynamics.
These laws do not tell us much about what energy is but they are very good in ruling what
can we do and what we cannot do with energy. Let’s briefly review them.
The first law of thermodynamics states that the total energy of an isolated physical system is
conserved during any transformation the system can go through.
It was initially formulated by Julius Robert von Mayer (1814 - 1878) and subsequently reviewed
by James Prescot Joule (1818-1889) and Hermann Ludwig Ferdinand von Helmholtz2
(1821-1894). It is strongly believed to be true but, to some extent is a self-supporting law: as a
matter of fact it is so strongly believed that in every instance we observe a possible violation
we think harder to discover some way in which energy can be hidden and overlooked. Last
time in history this happened was at the beginning of 1900 when Albert Einstein proposed the
mass-energy equivalence to account for the “missing mass” during a nuclear transformation.
The second law states that there are limitations to how much work we can get from a given
amount of energy present in the form of heat. There exist different formulations that are all
equivalent. The two most popular are ascribed to Clausius and Kelvin:
Clausius formulation: “No process is possible whose sole result is the transfer of heat from a
body of lower temperature to a body of higher temperature”.
Kelvin formulation: “No process is possible in which the sole result is the absorption of heat
from a reservoir and its complete conversion into work”.
An important consequence of the second law is that there is a limit to the efficiency of a thermal
machine. This limit was discovered by Sadi Carnot in 1824 when he was only 28. In the
publication entitled Réflexions sur la Puissance Motrice du Feu ("Reflections on the Motive Power
of Fire") he introduced the concept of thermal machine, generalizing the concept popular at
that time of “steam engine”, and showing that the efficiency of any thermal machine operating
between two temperatures is bounded by a quantity that is a function of the two temperatures
only.
Few years after the work of Carnot, Clausius used this result to introduce a quantity that is
useful in describing how much heat can be changed into work during a transformation. He
proposed the name “entropy” for his quantity. The idea is the following: if you want to operate
a thermal machine you have to find a cyclic transformation during which heat is changed into
work. The cycle is necessary because you want to operate the machine continuously and not
just once. Clausius proved a theorem that states that during a cyclic transformation, if you do
the transformation carefully enough not to loose any energy in other ways (like friction), then
2 Feynman assertion that the notion of energy has never been very clear is testified by the fact that the key publication
of Helmholtz, considered the father of the conservation of energy, is entitled “Über die Erhaltung der Kraft”, “On the
conservation of the strength”. On the other hand the kinetic energy has been called for a long time “vis viva”, Latin
expression for “living strength”.
