Energy Systems in the Era of Energy Vectors: A Key to Define, Analyze and Design Energy Systems Beyond Fossil Fuels

365 Pages·2012·6.53 MB·English

by  Fabio Orecchini

Green Energy and Technology
For furthervolumes:
http://www.springer.com/series/8059
Fabio Orecchini Vincenzo Naso
•
Energy Systems in the Era
of Energy Vectors
A Key to Define, Analyze and Design Energy
Systems Beyond Fossil Fuels
123
Prof.FabioOrecchini Prof.Vincenzo Naso
CentroInteruniversitario diRicerca CentroInteruniversitario diRicerca
Per SviluppoSostenibile (CIRPS) Per SviluppoSostenibile (CIRPS)
Sapienza Università diRoma Sapienza Università diRoma
Piazza San PietroinVincoli 10 Piazza San PietroinVincoli 10
00184Rome 00184Rome
Italy Italy
e-mail: [email protected] e-mail: [email protected]
ISSN 1865-3529 e-ISSN1865-3537
ISBN 978-0-85729-243-8 e-ISBN978-0-85729-244-5
DOI 10.1007/978-0-85729-244-5
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Contents
1 Energy Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 The Energy Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.2 Energy and Power: Natural Forms of Energy. . . . . . . . . 3
1.1.3 Units of Measurement in Energy Systems . . . . . . . . . . . 6
1.1.4 Energy Availability in Nature. . . . . . . . . . . . . . . . . . . . 8
1.1.5 Classification of Energy Sources. . . . . . . . . . . . . . . . . . 11
1.2 Closed Cycles of Energy Resources. . . . . . . . . . . . . . . . . . . . . 13
1.2.1 The ‘‘Measurable’’ Definition of Sustainability. . . . . . . . 14
1.2.2 The Earth, as an ‘‘Open’’ Energy System, Allows
the Realisation of Closed Cycles. . . . . . . . . . . . . . . . . . 19
1.3 Energy Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2 Energy Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.1 Definition of Energy Potential. . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2 The Earth’s Energy Balance. . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.3 Renewable Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.3.1 Solar Energy (Direct) . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.3.2 Hydropower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.3.3 Wind. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.3.4 Biomass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
2.3.5 Geothermal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
2.3.6 Other. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.3.7 Current Renewable Energy Use . . . . . . . . . . . . . . . . . . 62
2.4 Non-renewable Energy Sources. . . . . . . . . . . . . . . . . . . . . . . . 63
2.4.1 Coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
2.4.2 Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
v
vi Contents
2.4.3 Tar Sands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
2.4.4 Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
2.4.5 Nuclear Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3 Energy Vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
3.1 The Need for Energy Transportation and Storage . . . . . . . . . . . 97
3.2 Attitude to Energy Transportation in Space and Time
and Range of Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
3.3 Duration and Range of Transfers. . . . . . . . . . . . . . . . . . . . . . . 100
3.4 Characteristics of Energy Vectors . . . . . . . . . . . . . . . . . . . . . . 102
3.4.1 Ways and Means of Storage, Transportation
and Distribution of Vectors . . . . . . . . . . . . . . . . . . . . . 102
3.5 Analysis of the Main Energy Vectors. . . . . . . . . . . . . . . . . . . . 105
3.5.1 Oil as Energy Vector. . . . . . . . . . . . . . . . . . . . . . . . . . 105
3.5.2 Coal as Energy Vector. . . . . . . . . . . . . . . . . . . . . . . . . 114
3.5.3 Natural Gas as Energy Vector . . . . . . . . . . . . . . . . . . . 115
3.5.4 Electricity as Energy Vector. . . . . . . . . . . . . . . . . . . . . 120
3.5.5 Hydrogen as Energy Vector. . . . . . . . . . . . . . . . . . . . . 143
3.5.6 Synthetic Fuels as Energy Vectors . . . . . . . . . . . . . . . . 164
3.5.7 Heat-Transfer Fluids as Energy Vectors. . . . . . . . . . . . . 168
3.5.8 Mechanic Energy as Energy Vector . . . . . . . . . . . . . . . 170
3.5.9 Radiant Energy as Energy Vector. . . . . . . . . . . . . . . . . 173
3.6 The Era of Energy Vectors. . . . . . . . . . . . . . . . . . . . . . . . . . . 174
3.6.1 Possible Production from Different Primary Sources. . . . 175
3.6.2 Environmental Compatibility During Use. . . . . . . . . . . . 176
3.6.3 Conversion Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . 176
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
4 Energy Conversion and Transformation Plants. . . . . . . . . . . . . . . 179
4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
4.2 Energy Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
4.2.1 Mechanical Energy-to-Electric Power
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
4.2.2 Radiant Energy-to-Electric Power Conversion Plants. . . . 197
4.2.3 Chemical Energy-to-Electric Power
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
4.2.4 Chemical Energy-to-Mechanical Energy
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
4.2.5 Radiant Energy-to-Thermal Energy
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
4.2.6 Thermal Energy-to-Chemical Energy
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Contents vii
4.2.7 Electric Power-to-Chemical Energy
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
4.2.8 Radiant Energy-to-Chemical Energy
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
4.2.9 Electric Energy-to-Thermal Energy
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
4.2.10 Electric Power-to-Radiant (Luminous) Energy
Conversion Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
4.3 Energy Transformation Plants. . . . . . . . . . . . . . . . . . . . . . . . . 277
4.3.1 Chemical Energy Transformation Plants . . . . . . . . . . . . 277
4.3.2 Thermal Energy Transformation Plants . . . . . . . . . . . . . 283
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
5 Distributed Generation and Cogeneration. . . . . . . . . . . . . . . . . . . 291
5.1 Distributed Generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
5.1.1 General Features of Conversion Plants . . . . . . . . . . . . . 291
5.1.2 Scale Economies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
5.1.3 Energy Sources and Distributed
Generation Technologies . . . . . . . . . . . . . . . . . . . . . . . 293
5.1.4 From Concentrated Production to
Distributed Production. . . . . . . . . . . . . . . . . . . . . . . . . 294
5.1.5 Type One and Two Distributed Generation . . . . . . . . . . 297
5.2 Combined Production of Electric Power and Heat:
Cogeneration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
5.2.1 Cogeneration Technologies . . . . . . . . . . . . . . . . . . . . . 302
5.2.2 Typical Indexes of Cogeneration Plants. . . . . . . . . . . . . 311
5.2.3 District Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
6 Energy Useful Effect and End Use . . . . . . . . . . . . . . . . . . . . . . . . 321
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
6.2 Thermal End Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
6.2.1 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
6.2.2 Thermal End Use with Heat Pump . . . . . . . . . . . . . . . . 333
6.3 Luminous End Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
6.3.1 Interior Lighting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
6.3.2 Elements of Photometry. . . . . . . . . . . . . . . . . . . . . . . . 337
6.3.3 Natural Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
6.3.4 Artificial Light. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
6.4 Mechanic End Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346
6.5 Electric/Electronic End Use . . . . . . . . . . . . . . . . . . . . . . . . . . 350
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
Chapter 1
Energy Systems
1.1 The Energy Cycle
1.1.1 Introduction
Theenergycycleconcernsenergyevolutioninitspassagefromnaturalavailability
to the most suitable form for end use, meaning the form that allows the desired
useful effect and entails the disposal of its unexploited portion.
Energetics is the branch of learning that studies the forms and quantities
through which nature provides energy to human beings, and the sources (called
primarysources)throughwhichthisavailabilityiscarriedout.Energysystemsare
those devices in which, through transformation and conversion processes and
flows, energy is processed until reaching end uses and thence the useful effect.
Obviously, as shown in Fig. 1.1, the energy cycle—in its form commonly used
nowadays—entails an interaction with the environment as well as the production
of waste and pollutants.
This cycle is shown in detail in Fig. 1.1, with the general reference scheme. It
shows the so-called primary (or natural) forms of energy, the energy flows,
which include the transformation from primary energy into secondary forms
of energy, through their processing and physical or chemical transformation, that
is to say the transformation into electric energy and the energy of end use, until
achieving the useful effect.
By following the indications of the arrows shown in the figure, the possible
pathwaysoftheenergycyclecanbeidentified.Itisthereforeshownhowsomesources
of primary energy are directly employable for end use (line (a); for instance: the
naturalgasorcoalusedfordomesticheating,thewindenergyorhydropowerdirectly
usedinmillssinceancienttimes,orthewindenergyusedforsailingpurposes).
More often, the forms of energy available in nature must be adapted to the
demandcomingfromendusersthatis,tosaytransformedand/orconverted.Inthis
F.OrecchiniandV.Naso,EnergySystemsintheEraofEnergyVectors, 1
GreenEnergyandTechnology,DOI:10.1007/978-0-85729-244-5_1,
(cid:2)Springer-VerlagLondonLimited2012
2 1 EnergySystem
Fig.1.1 Generalreference
diagramoftheenergycycle
way, a passage occurs from primary forms (i.e., the potential chemical energy
contained in liquid hydrocarbons) to secondary forms (line (b); i.e.: oil refining
products) and they are directly employed for end use (line (c)).
Inothercases,someprimarysources(line(d)),suchasnaturalgasandcoal,or
secondary sources, can supply the thermoelectric plants that generate electric
power(line(e)).Inturn,thelatterisemployedbyendusers(line(f));inthisfinal
process of the cycle, energy allows the achievement of the desired useful effect,
whereas the portion not used is generally released into the environment.
Inthischart,particularattentionispaidtoelectricpower,duetoitspeculiarity
andthepriorityitisgainingintheentireenergyframework,comparedtotheother
forms of energy used.
It is appropriate to underline that the definitions herein introduced differ from
those that several authors adopted on the basis of other nomenclatures. For
instance, some prefer to define ‘‘secondary energies’’ those types of energy that
allow to transfer energy in space or in time, with a view to make it available
wherever and whenever needed. In this framework, the name energy vector is
ascribed to this type offunction.
Forinstance,whenhydrogenproductionisfinallyobtained—havingconsidered
that it is a very good fuel not directly available for use in nature—by using the
waste heat of thermoelectric power plants, a sort of energy recovery through heat
‘‘accumulation’’ in hydrogen is carried out. In fact, the hydrogen energy vector
willcollectthewastethermalenergythatwouldotherwisebelost.Theavailability
of hydrogen so produced, in fact, will make energy available wherever and
1.1 TheEnergyCycle 3
whenever needed. As a matter of fact, through this process, the waste thermal
energy will be transferred over time by means of the hydrogen energy vector.
Inthenextfewparagraphs,ananalysisismadeofthemainusablenaturalforms
of energy. Subsequently, the units of measurement used in the energy sector will
be dealt with, since some of them—although commonly used among operators—
are not the ones adopted by the International System. As a matter offact, as we
will see more in detail afterwards, these particular units were selected for their
characteristics and size, which make their use handy in the analysis of energy
flows.
Finally,ananalysisofnaturalenergysourceswillbemade,precededbygeneral
considerations on global energy flows on the Earth, seen as an energy system
interacting with the surrounding space.
1.1.2 Energy and Power: Natural Forms of Energy
Energy,accordingtothemostwidespreaddefinition,isthecapacityofasystemtodo
work.Asregardstheunitoftime,powerissimilarlydefined.The‘‘energyproblem’’
consistsinmakingenergyavailableattheplace,timeandconditionsrequestedby
users;andthisfortheentiretimeneeded.Itisthereforeevenmoredifficulttofinda
solution to the ‘‘power problem’’, having considered that the quantity of energy
demanded may vary minute after minute. Solving the energy problem from the
quantityviewpointandinagivenperiodoftimemaynotbesufficient.1
The energy available in nature—and which human beings avail themselves
of—canbedistinguishedintodifferentheterogeneousforms.Theformsofenergy
presently used are the following:
• Chemical
• Electrical
• Electromagnetic
• Mechanical
– Kinetic
– Potential and pressure
• Nuclear
• Thermal
This classification is important since it provides the choice of the form of
energy to be employed, according to its intended use.
1 Thisconceptcanbemoreeasilyunderstoodbymeansofanexample.Let’sconsiderthecaseof
electricutilities:sinceitisknownthatelectricpowerisstoredwithdifficultyandexpensively,it
is not easy for Utilities to avail themselves of all the necessary energy. Supplying the electric
power demanded by users will entail the ability of providing, moment by moment, the exact
quantityofenergyrequestedthatis,tosaysupplyingthepowerdemandedsecondaftersecond.
4 1 EnergySystem
Infact, accordingtothecharacteristics andtheattitudeofeachformofenergy
that is converted into useful work to be destined to a particular end use, it is
possible to adopt each time the most convenient energy source, that is to say the
conversion process that is most suitable to pursue the objectives set.
For instance, in all the applications in environments with no free oxygen—as
space and submarine applications—it is little convenient, if not impossible, to
use the chemical energy developed from conventional combustion reactions,
namely those that develop heat through exothermic oxidation reactions,
entailing the availability of oxygen. In these cases, other conversion processes
are privileged or, alternatively, other forms of energy: a technically interesting
solution may be represented by nuclear power, supported by closed-cycle
thermodynamic plants, or by the resort to special systems for energy conver-
sion, such as some so-called direct conversion devices that will be described
below.
Here it follows a brief description of the characteristics and properties of the
different forms of energy available in nature.
1.1.2.1 Chemical Energy
Itisinborninthebondstrengthsexistingatamolecularandatomiclevelinsome
particularsubstances.Itcanbedefinedeitheraspotential,underliningtheintrinsic
character that can be expressed through suitable reactions in the form of thermal
energy,orelectric.Intheformercase,exothermicreactions(ingeneral,oxidation)
occur, and the quantity of heat provided, called reaction energy or reaction heat,
corresponds, in an absolute terms, to the enthalpy variation pertaining to each
reaction.Conversely,thegenerationofelectricpowerisduetothevariationoffree
energyrelatingtooxidation–reductionreactionsortotheconcentrationgradientof
different substances in given solutions (in this case, reference is made to free
energyofmixing).Thechemicalenergythatismainlyusedistheonecontainedin
fossil fuels.
1.1.2.2 Electric Power
This form of energy, utterly linked to the development of the human society,
is produced by the movement of free electrons in conductors. Although it is
incorrect to refer to ‘‘electric power’’—since, in addition to the electric field, a
magnetic field is always involved and therefore the definition of ‘‘electromag-
netic energy’’ should apply—this distinction is however suitable to define the
type of energy used for its electric features only. The electric power available in
nature (for example through the phenomenon of thunderbolts) is not directly
exploitable at the present state of technology; it is therefore necessary to pro-
duce electricity artificially, converting other forms of energy available in nature
into electric power.