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$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply 8

process to end !sers" /!e to the fact that there are vario!s opport!nities for the

composition of energy chains of f!el s!pply and di#erent +ays of energy prod!ction, it is

necessary to try to make a !ni%!e mathematical approach for this problem" @ith the

proposed s!stainability criteria and developed mathematical model, it is possible to !nify

the overall problem of energy s!pply chains optimi*ation" The proposed developed method

can be !sed for the optimi*ation of any kind of energy s!pply chains -electricity, heat, f!els

or their mi(0" All of these are enabled by proper selection criteria for the description of

overall energy transformations in energy chains and %!ality eval!ation of the energy pro

d!ced" The developed approach and mathematical model have a very practical application

in the selection of optimal variant of energy prod!ction and of co!rse in designing ne+

energy chains"

ey!or"s# energy s!pply chains, optimi*ation, e(ergy, mathematical modelling, opti

mi*ation criteria, biomass, bioenergy, rene+able energy

$% Intro"uction

The process of energy and f!el prod!ction is closely related to s!stainability" The !se of fossil

f!els ca!ses harmf!l inB!ences to the environment, +hile, on the other hand, the reserves of

fossil f!els are limited" @ith the development of h!man civili*ations, the needs for energy

gro+, +hich ca!ses an accelerated cons!mption of fossil f!el reserves" The decrease of fossil

f!el reserves and their harmf!l inB!ences to the environment have forced the mankind to

take the direction of the more intensive !se of rene+able energy so!rces as +ell" )bserved

from a thermodynamic aspect, for the analysis of an energy prod!ction process, it is

necessary to eval!ate the process both in terms of %!antity and %!ality" 3or that reason,

energy and e(ergy e'ciencies of an energy prod!ction process +ere dened, and they have

to be taken into acco!nt" The energy prod!ction chains can be dened in di#erent +ays, and

in most cases the logistics of the f!el s!pply has a signicant role" The selection of optimal

variant of energy prod!ction presents a process that has to take into acco!nt a set of the

most signicant factors and criteria, +hich can be ade%!ately !sed for the description of

energy prod!ction chains" 3rom the set of di#erent energy prod!ction chains described by

optimi*ation criteria, it is possible to select the variant of energy prod!ction +hich is optimal

for some partic!lar case, based on the c!rrent state of development of energy prod!ction

technology, economic and ecological parameters" The optimal variant of energy prod!ction

selected in this +ay is not completely s!stainable, b!t it presents a +ay and a path by +hich

+e get closer to a s!stainable energy chain of energy prod!ction" 4t is obvio!sly the best

approach method for optimi*ation of energy chains in the m!lticriteria decision making,

+hich solves the selection problem of an optimal energy prod!ction" 4n this te(t, there is a

description of m!lticriteria optimi*ation application and the V45)6 method for the selectionof optimal and s!stainable energy s!pply process"



$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply >

&% Concept of multicriteria "ecision ma'ing

2ot long ago, the concept of optimi*ation +as based mostly on the economic criteria, +hile

the other conse%!ences of s!ch a sol!tion +ere often neglected"" 4t +as tho!ght that the

increase in nancial prot not only leads to the progress and general +elfare of the society,

b!t also to the satisfaction of all h!man needs" The accompanying e#ects of this concept,

s!ch as the deterioration of %!ality of +ater and air, and the poll!tion of environment in

general, bad social inB!ences, etc", !ndo!btedly indicate a +rong basis of s!ch a model"

1eca!se of that, a ne+, still dominating, concept has been created, of the socalled

s!stainable development, that is, of s!ch a development +hich is in harmony +ith the

environment, corresponding to modern technical standards, economically and socially

acceptable from the vie+point of social dist!rbances that it may ca!se" So, s!ch an

approach enables the f!llment of the present generations needs, +itho!t dist!rbing the

opport!nity of other generations to meet their needs too" There is no !ni%!e and generally

accepted denition of the notion of s!stainable development" The most often stated

denition of s!stainable development is the one given by the Cnited 2ations @orld

.ommission on $nvironment and /evelopment -the socalled 1r!ndtland .ommission0 in

its report +ith the title D)!r .ommon 3!t!reD" The denition is& DS!stainable development

is the kind of development that meets the needs of the present +itho!t compromising the

ability of f!t!re generations to meet their o+n needs too"D 3or that reason, the need for

searching an optimal sol!tion in many criteria has been created, th!s initiating the

appearance of a ne+ branch in the eld of optimi*ation, that is, of optimal decision makingEm!lticriteria optimi*ationEas a tool for assistance in the process of m!lticriteria decision

making -M./M0" 4n the Cnited States, m!lticriteria analysis is also often called M./M, and

in $!rope, it is called m!lticriteria decision aid -M./A0 F:" M./M is a comple( process of

nding a sol!tion, and it occ!rs at a fe+ phases and a fe+ levels of decision making" There

are di#erent methods of M./M, and most of them belong to the category of discrete

methods" 4n discrete methods, the problem of decision making is dened thro!gh nite

n!mber of options" 4n this paper, the M./M methods are divided into F8&

1asic methodsEThe simplest forms of the M./M method, and it is di'c!lt to apply

them in solving the optimi*ation of energy chains d!e to the inade%!acy of their

simple preferential models"

)necriterion approachEThe methods +here all the criteria are red!ced to one

criterion for comparison" The follo+ing methods belong to this gro!p& MACT, T)PS4S,

SMA6T, AHP, etc" These methods belong to the American school of M./M"

)!tranking methodsEThe methods +here the alternatives are compared, and the

preferences of one in relation to the other are identied" They incl!de& 2A4/$,

$<$.T6$, P6)M$TH$$, etc" These methods belong to the $!ropean school of M./M"

Target method, or the referent point methodEThis method identies the options

closest to the ideal one and the f!rthest from the antiideal point" These methods

incl!de the target and compromise programming, the V45)6 method"

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I S!stainable S!pply .hain Management

$ 0 3!**y set theoryEThis !ses the approach of imprecise and insec!re information" 4t is !sed

& as a means +hich can be applied to any M./M methodology, and not e(cl!sively as a

( specic M./M methodology"

) The application of m!lticriteria optimi*ation and decision making may have a signicant role

* in the selection of technological, economical, more e'cient and ecological criteria, and of

many

+ other criteria of acceptable sol!tions" This method also provides a good opport!nity of

, application in the selection of optimal variants of energy prod!ction from biomass and the

- %!ality analysis of energy chains" $nergy prod!ction from biomass is, by its nat!re, m!ltidi

. mensional and comple(, +ith many available so!rces of biomass, technical possibilities and

a

$/ diverse set of interested parties +hich have a m!ltit!de of opposed opinions" Todevelop and

$$ r!n a s!ccessf!l option of biomass !tili*ation for energy p!rposes, there are many

re%!ire

$& ments +hich sho!ld be taken into acco!nt and met" Scott and associates have

provided an

$( overvie+ of those academic papers +hich try to deal +ith the problems occ!rring

+ithin the

$) bioenergy sector, by !sing the M./M" These methods are especially appropriate for

bioenergy

$*prod!ction, if its m!ltidimensional nat!re is taken into acco!nt as +ell, b!t they can

also be

$+ e%!ally relevant for other energy conversion technologies" The related articles +hich

occ!r in

$, international o!rnals from 8999 to 89:9 have been collected and analysed in s!ch a

+ay that

$- the ans+ers to the follo+ing t+o %!estions can be given& -:0 +hich methods are the

most

$. pop!lar onesJ -80 +hat problems attract the highest attentionJ The overvie+ discovers

that

&/ the optimi*ation methods are the most pop!lar ones among the methods +here the

selection

&$ has been made +ithin a small n!mber of alternatives, and, as s!ch, !sed in IIK of

analysed

&& papers, and among the methods +here the selection has been made +ithin many

alternatives,

&( they have been !sed in 8LK of papers" The most pop!lar application area of M./M is

in the

&) selection of technologies, +ith 8K of analysed papers, +hile the application of M./M

to the

&* decisionmaking policy participates +ith :LK F>"



$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply N

&+ (% 1easons for the application of multicriteria optimizationin the

&, selection of optimal energy supply chain

&- Generally, m!lticriteria optimi*ation presents the nding of the variant -in o!r case, of

an

&. energy chain, a dened +ay of energy prod!ction0, +hich +ill, in many +ays, meet the

(/ re%!ired sol!tion closest to the ideal one" The m!lticriteria optimi*ation method

occ!rred

($e(actly from the striving to+ards a s!stainable concept of the development of

mankind"

(&1eca!se of that, the chosen methodology for the selection of optimal variant of

energy((prod!ction from biomass is good eno!gh for the solving of this problem" The reason

for that

() is more than simple" 1iomass presents a rene+able energy so!rce and is an

important part in

(* the chain of s!stainability" 4n the overvie+ed literat!re, a fe+ papers have been

fo!nd in +hich

(+ the V5)6 optimi*ation method has been !sed" Ho+ever, the real reason +hy this

method is

(,potentially good in solving the problem of selection of an optimal chain of the

energy pro(-d!ction from biomass is the possibility of di#erent criterion +eights denition and

+eights in

(.decisionmaking strategies" 1esides that, for all the obtained sol!tions, it is possible

to check

)/ their stability mathematically as +ell, that is, +hether they +ill be good eno!gh if

some

parameters are given a greater importance in the optimi*ation than others" )f co!rse,

the forming of the criterion matri( gives a systematic overvie+ of all characteristics of

the observed energy chains, among +hich the best option has been selected" 4n this

+ay, the !niversal concept is formed, +hich can give many ans+ers on the design,installation and e(ploitation of the systems for energy prod!ction from biomass in a

m!ch more comprehensive sense"

)%2e3nition criteria for evaluation of biomass supply chain

an" approach to the optimal variant of energy

pro"uction

The energy chains modelling sho!ld be based on mod!larity" 4t practically means thatit is necessary to do a mathematical modelling of every energy chain element as an

independent entity +hich +ill present a mathematical model for itself, as an

elementary part of the energy chain" 4n literat!re, many st!dies have foc!sed on

technoeconomic assessment to eval!ate the economic feasibility of forest biomass

!tili*ation for the generation of heat FI, po+er FN, combined heat and po+er F;, and

biof!el, heat and po+er F" The previo!s st!dies have compared alternative process

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; S!stainable S!pply .hain Management

technologies that !se forest biomass to prod!ce electricity FL and alternative prod!cts

that can be generated from a specic forest biomass base FO, :9" Also, it is possible to

minimi*e the c!m!lative fossil energy demand or the cons!mption of certain types of

critical reso!rces -e"g", labo!r, materials0 associated +ith the !nit of biof!el prod!cts,

in order to achieve the ma(im!m !tili*ation of available reso!rces F::" 3or the most

economic obectives, +e often try to optimi*e the total %!antity, that is, ma(imi*e total

prot or minimi*e total cost" Ho+ever, for environmental criteria, the Denvironmental

impact per f!nctional !nitD is more critical F:8" This is beca!se, for e(ample, one may

care more abo!t the carbon footprint of prod!cing one gallon of biomassderived

gasoline, rather than the ann!al total .)8 emission of the entire biof!el s!pply chain"

Therefore, the environmental impact eval!ated based on f!nctional !nit is, in fact, the

indicator of ho+ DgreenD the s!pply chain is" All these st!dies did not nd the optimal

design of the forest biomass s!pply chain !nder analysis" $specially for conditions of optimi*ation, this incl!des several di#erent criteria s!ch as technical, logistics,

energetic, economic or environmental factors" This is a good direction for the

development of the criteria for optimi*ation of energy chains" The approach to the

modelling of all elements is based on the analysis from the aspect of cons!med energy

in every element of the chain" The calc!lation of other criteria comes do+n to the

calc!lation of prod!ction costs, .)8 emission and investment cost per installed po+er

of all energy cons!mers in the chain" Almost all the important elements of an energy

chain for biof!el and energy prod!ction can be dened by the criteria= f— f— f-, f— f—

The calc!lation of all the criteria f!nctions is di#erent for each of the chain variants (av

a8 a> """ an ). 1!t +e have similar approach to the analysis of a single element of thechain" @elldened criteria describe the overall energy chain based on biomass

completely" 3or this reason, it is necessary to properly select the set of criteria +hich

+o!ld have given a better assessment of the val!e chain of biomass energy" The

follo+ing criteria m!st be dened&

energy e'ciency of observed chain criteria f!nction noted as f— e(ergy e'ciency of chain criteria f!nction noted as f—

the coe'cient of e(ergy %!ality for di#erent prod!cts at energy chains f—

specic investment cost per total installed po+er of all machines and plants in the

energy chain, Q=k@ criteria f!nction, f

prod!ction cost of energy chain per : k@h of the lo+er heating val!e of prod!ced

biof!els or energy, Q=k@h criteria f!nction, f—

.)8 emission in the total chain d!e to the fossil f!els cons!mption for : k@h of the

lo+er heating val!e of prod!ced biof!el or energy, kg=k@h criteria f!nction, f ;"

As +e kno+, lo+er caloric val!e -or lo+er heating val!e, <HV0 of a f!el portion is dened

as the amo!nt of heat evolved +hen a !nit +eight -or vol!me in the case of gaseo!s

f!els0 of the f!el is completely b!rnt and one part of that heat is !sed for +ater

evaporation +ith the comb!stion prod!cts F:>" That is the main reason +hy +e dened

the previo!s criteria +ith lo+er heat val!e of f!els" 4t is the !sef!l heat energy given incomb!stion process from chemical energy stored in all f!els and of co!rse in biomass"

The mentioned criteria are di#erent for di#erently dened initial conditions of a problem"

Sol!tion to the problem of selecting the optim!m variant of f!els and energy prod!ction

consists of&

Mathematical model for calc!lation of optimi*ation criteria

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$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply

Mathematical method for the selection of optim!m variant of energy chain"

The signicance of energy chains analysis from the aspect of invested energy is very

important" 4n the literat!re, +e can nd the socalled $6)$4 factor -energy ret!rned on

energy invested0, +hich presents the %!otient of !tili*able energy from a certain f!el -or

from a +ay of energy prod!ction0 and the energy cons!med to convert the f!el or energy to

a !sef!l form F:I" To be able to eval!ate the total energy cons!mption in an energy chain

for f!el prod!ction at all, it is necessary to calc!late all the cons!med energies to the

primary energy form" Primary energy is the content of energy in f!el related to lo+er heating

val!e and +eight of f!el" 4n that +ay, the total s!mmation of all the cons!med energy

amo!nts in the energy chain of f!el= energy prod!ction is enabled" The principle of

calc!lation of primary energy is dened by $%!ation : -see 3ig!re :0&

+here <HVf!el -k@h0 is the primary energy related to lo+er heating val!e of f!el, R [in are

di#erent coe'cients of energy transformation" 3or e(ample, overall energy e'ciency for

conventional po+er plants +ith p!lveri*ed coal ring has e'ciencies as follo+s& >OIKEsteam t!rbine coalred po+er plant F:N"

)%$% 4unction of energy e5ciency for energy chain 6$7%

$nergy e'ciency for the Rth element of chain and th energy chain of prod!ction is the

ratio bet+een the obtained energy and the energy cons!med in the process of energy

prod!ction in dimensionless !nit, k@h=k@h" The val!e +hich is the ratio bet+een the lo+er

caloric val!e of the f!el cons!mption or any kind of energy -e(pressed in the form of

primary energy, see $%!ation :0 and lo+er heating val!e of biomass processed in every

single operation is important in the rst part of the energy chain dened for biomass f!el

prod!ction depending on the energy plant F:;" This approach to calc!lating e'ciency

involves the prod!ctivity of machines and e%!ipment for processing of biomass, as +ell as

dened energy and f!el cons!mption from certain processes -elements0 in the energy

s!pply chain F:" All cons!med energy is dened as primary energy in <HV f!el -see

3ig!re 80"

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4igure &% Part of s!pply chain for biof!els prod!ction !p to po+erplant"



L S!stainable S!pply .hain Management

Total energy e'ciency factor of the energy chain incl!ding po+er plants, transmission losses

in the net+ork, as +ell as all levels of energy transformation is dened by

- % e l: I TU k: pk 9

m b m e Rt Rg m d m end,!se -80



$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply O

+here ec% is the primary energy cons!med in one element of the bioenergy chain, e(pressed

in k@h ep% is lo+er heating val!e of processed biomass in one element of the chain,

e(pressed in k@h k is the co!nter of elements in the energy chain and q is the total

n!mber of elements in the energy chain?ab ?ae R ?ag ?

ad ?aend,!se are the factors of energy e'ciencies for

boilers, heat e(changers, t!rbines, generators, distrib!tion, end !sers, etc" F:N"

)%&% 4unction of e8ergy e5ciency for overall energy chain f

/i#erent +ays of form!lating e(ergy e'ciency -e#ectiveness, or rational e'ciency0 for

vario!s energy systems are given by .ornelissen F:L" The e(ergy performance of the

system can be eval!ated by means of the e(ergy e'ciency" T+o e(pressions of the

e(ergy e'ciency are often !sed in literat!re, the simple and the rational e(ergy e'ciency

F:O, 89" Their mathematical e(pressions are given in $%!ation >"

+here ?ae(simpie is simple e(ergy e'ciency, $(o!t is total e(ergy o!tp!t, $(in is total e(ergy

inp!t, ?ae(ral is rational e(ergy e'ciency, $(des,o!t is desired o!tp!t e(ergy" The irreversibility

of the process or e(ergy loss, I, is dened as the di#erence bet+een desired e(ergy

o!tp!ts $Wo!t and the re%!ired e(ergy inp!ts $Win to it F89" @hen +e talk abo!t thee(ergy e'ciency of the entire bioenergy chain -from the so!rce of biomass to the end

!ser0, then the individ!al e(ergy e'ciency of single chain elements m!st be taken

into acco!nt -see 3ig!re 80" The total e(ergy e'ciency of the energy chain is

+here e(ck is e(ergy cons!med in one element of chain, e(pressed in k@h e (pk is

e(ergy stored in the prod!ced f!el, in k@h k is the co!nter of elements in energy

chain q is the total n!mber

of elements in the energy chain Re(b R(e Me(t Re(g Me(d Re(,end,!se

are factors of e(ergy

e'ciencies for boilers, heat e(changers, t!rbines, generators, distrib!tion, end

!sers, etc" 3or more information abo!t energy and e(ergy e'ciencies of selected

processes, see F8:" $nergy and e(ergy analyses for three di#erent cogeneration

systems -steam cogeneration, gast!rbine cogeneration and dieselengine

cogeneration +ere performed by 5a!shik F88" 4t sho!ld be noted that the rst part

of the s!pply chain relates to the prod!ction of f!els from biomass e(ergetic

e'ciency of this part of the chain is appro(imately e%!al to the energy e'ciency"

The main reason for this is a constant chemical e(ergy of biomass" There are cases+hen it comes to the occ!rrence of chemical e(ergy destr!ction, s!ch as pyrolysis

and gasication of biomass" Then it is needed to calc!late the e(ergy e'ciency of

these processes"

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:9 S!stainable S!pply .hain Management

)%(% The coe5cient of e8ergy 9uality for "i:erent pro"ucts atenergy chains f

Vario!s forms of energy have di#erent %!alities" There are di#erent basic energy forms&

kinetic energy, potential energy, thermal energy, chemical energy, electrical energy,

electromagnetic energy, so!nd energy and n!clear energy" 4t is said that energy can be

D!sef!lD if it can be entirely transformed by an ideal system -i"e", +itho!t losses0 into any

other type of energy" Csef!l energy, other+ise kno+n as e(ergy, only represents a part of

energy" $lectrical and mechanical energies are Dhigh %!alityD forms of energy their e(ergy

inde( is :99K, since e(ergy is e%!al to energy" Table : provides an overvie+ of the

coe'cients of e(ergy %!ality for di#erent energy forms&

.oe'cients $lectricity 3!el

H ; < $ '=h > ?l @ @T@

Table $% .oe'cients of e(ergy %!ality"

+here pe(p is e(ergy e'ciency for the prod!ction of electricity from di#erent types of f!els

from dened technology F8: T 0 is environment temperat!re -50 T is temperat!re of heat

reservoir -50 $, F- and Hj are coe'cients of e(ergy %!ality for electricity, f!el and heat,

respectively" Also, +e can dene the combined coe'cient of e(ergy %!ality as

>X $ eY 3" f"Y H h",>

+here e Y f Y h X :, e, f h are percentages of sim!ltaneo!s prod!ction of electricity, f!el

and heat at the energy chain"

The main di#erence bet+een the %!ality factor of energy form -%0 and coe'cient of e(ergy

%!ality f0 is only that e(ergy %!ality factor takes into acco!nt the degree of conversion of

chemical e(ergy into electricity" This factor provides a comparison of f!el and electricity"

)%)% 4unction of speci3c investment cost for energy chain f

$ngineers and investors typically interpreted and meas!red the performance of energy

systems based on economic val!e s!ch as investment and prod!ction costs" The most

+idely !sed economic performance metrics for comparing the economic val!e energy

systems are net present val!e, total life cycle cost, rate of ret!rn, benetcost ratio and

payback period" The economic principles and applications of these techni%!es are

disc!ssed in n!mero!s standard engineering economics analyses and engineering

economy te(ts F8>, 8I" 3or energy chains, there are more elements incl!ded in their

composition" Specic investment cost in the energy chain is the ratio bet+een the total

investment cost and the total installed po+er of all the elements in the chain&

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$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply ::

%

f

IX R -;0[pkkX:

%

+here k: is the s!m of all investment in the elements of energy chain FQ k: is the

s!m of all installed po+er in the energy chain -k@, M@0 q is the n!mber of

elements in the energy chain k is the

co!nter for the n!mber of elements in

the energy chain j is the n!mber of energy chains" 4f in the energy chain there are

elements +hose f!nction cannot be e(pressed in !nits of Q= k@, it is necessary to

bring these elements in similar correlations" 3or e(ample, if the storage for biomass

e(ists, then Ij is certain val!e of investment in storage and Pk j -installed po+er0 is

e%!al to *ero"

)%*% 4unction of speci3c pro"uction cost for energy chain f

4nvestments are dened as the s!m of all inc!rred e(penses !ntil plant operation reaches

readiness, +hile operating costs occ!r d!ring operation and depend on capacity !tili*ation

F8N" The prod!ction costs -operating and maintenance0 +ere calc!lated by dividing the

total ann!al costs as a (ed and variable, +ith the net generating capacity and net ann!al

generation respectively, electricity and district heat or f!els" 3or electricitygenerating

technologies, A\: incl!ding combined heat and po+er generation, the denominator is

electric capacity and electricity generation" 3or heatonly technologies, the denominator is

heatgenerating capacity and heat generation" )ften, the reference doc!ments do not

disting!ish bet+een (ed and variable prod!ction costs" Then the total prod!ction costs

are e(pressed, typically in Q=M@h or Q=k@h" 3!nction of total prod!ction costs f- for

bioenergy plants is tf, X RRE, ]Q / k@h, Q / M@h^' $p -f!el / heat / electricity0" t < _

+here -)pk Y Mp is the s!m of all operating and

maintenance costs in all elements of energy chain per

year -Q=h0 Cr- is the cost of biomass ra+ material -Q=h0

$p-f!el=heat=electricity0 is the prod!ctivity of di#erent energy forms per chain

-k@h=year, M@h=h0" )perating and maintenance costs also incl!de labo!r costs per

k@h of energy prod!ced"

)%+% 4unction of speci3c CO& emission for energy chain f + ;

A trend in GHG emissions from fossil f!el comb!stion ill!strates the need for all

co!ntries to increase the !se of more s!stainable energy in f!t!re" The emission of

GHG of partic!lar species is often monitored beca!se of the adverse environmental

conse%!ences that can ca!se

photochemical smog, acid rain, global +arming and o*one depletion" The details of,

and standard methods !sed to meas!re, global +arming potentials -G@Ps0 are

dened by the 4P.. F8;" 3or meas!rement of an energy systems environmental

performance, the res!lts are e(pressed thro!gh a mass of carbon dio(ide e%!ivalent

emission per !nit of desired o!tp!t -e"g", kg.)8e%"=k@h elec"0" The follo+ing

%

$&

()*+,

(

.

$/

$$$&$($)$*

$+$,$-

$p k

[- ) PkY M Pk0 Y .

-0

$.

$.&$&&

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*+

,

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$)$*

$+

$,

$-

$.

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&$

&&

&(

&)

&*

&+

&,

&-

&.

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:8 S!stainable S!pply .hain Management

e%!ation can be !sed for the estimation of greenho!se gas emissions from the

comb!stion of each type of f!el per energy chain F8&

+here mk" is the %!antity of f!el type cons!mption in one element of energy chain -kg=h0

eck is the energy content factor of the f!el according to each f!el -k@h=kg0 efk" is the

emission factor for each gas type -in o!r case .)80 for di#erent f!el types according to each

f!el -k@h= kg0 F8L$p-f!el=heat=electricity0 is prod!ctivity of di#erent energy forms for each

chain per ho!r -k@h=h, M@h=h0"

*% Bathematical mo"el for the selection of optimum variant of

energy chain for energy pro"uction from !oo" biomass

4n this paper, for the act!al problem of selection optim!m variant of energy chain, V45)6

optimi*ation method is applied as a proposal and as an ade%!ate method for the sol!tion of

m!lticriteria optimi*ation related to the selection of optimal energy chain of prod!ction" This

method aims to collect all the most important factors +hich describe energy s!pply chains

from biomass and make the selection of optimal s!pply chain" The V45)6 method -m!lticri

teria compromise ranking0 has been developed for the determination of a m!lticriteria

optimal sol!tion" The V45)6 method has been developed on s!ch a methodological basis

that a decisionmaker is s!ggested as the alternative -or sol!tion0 to present a compromise

bet+een +ishes and opport!nities, the di#erent interests of the decisionmaking

participants" The V45)6 method has been developed for a m!lticriteria optimi*ation of

comple( systems" 4t is foc!sed on ranking and selection of the best sol!tion from the given

set of alternatives, +ith conBicting criteria F8O" The V45)6 method re%!ires the val!es of allthe criteria f!nctions for all the alternatives in the form of a matri( to be familiar" 1eca!se of

that, at the beginning of the optimi*ation process, a general form of the problem has been

set -eval!ation matri(0 for the specic case" The matri( of criterion f!nctions for all variants

of the prod!ction of f!els or energy from biomass is of 6 x n dimensions -; criteria and n

alternatives of energy prod!ction from biomass0, obtained from the calc!lation of di#erent

cases of energy chains composition&ai a8

a> """ a

I IC 8 Is r

I Ii I

88

I> " I8r

I Ii I8 I>>" I>r

I Ii I8 II> " IIr

I Ii I8 IN> " INr

I Ii I8 I;> .

f ,X

%% m"" ec"

e,"" y k 0 k 0kX:

>"; J

t-L0

$p-f!el / heat / electricity0" tr

3X



$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply :>

+here {av a, a! """ an", j X n are a nite set of possible alternatives for the n energy chains of

prod!ction `= , f, f >, f, f N, f ;, i X ; are a nite set of criterion f!nctions for ve dened and

adopted criteria on the basis of +hich the chains of energy prod!ction from biomass are

analysed =̀!, f :8 """ f 6n" are the set of all the criterion f!nctions val!es in matri( F. An ideal

sol!tion is determined on the basis of the criterion f!nctions val!es from the e%!ation

F8O&

X e(tf = i X :,8,""", ;" -:90

The operator e(t denotes a ma(im!m if the f!nction f describes a benet or prot, and a

minim!m if f describes damages or costs or other variables +hich are of interest to optimi*e-minimi*ation or ma(imi*ation criterion f!nctions0" This is the best +ay to dene an ideal

sol!tion for energy prod!ction from di#erent energy chains based on biomass" The

criterion f!nctions +ithin the matri( F are commonly not e(pressed in the same

meas!rement !nits -i"e", the belonging criterion space is heterogeneo!s0" 3or that reason,

in order to perform !se of m!lticriteria optimi*ation, it is necessary to convert all the

criterion f!nctions into dimensionless f!nctions +hose val!es +ill be in the interval F9, :"

This process is called the normali*ation of dimensional !nits in the area of m!lticriteria

mathematics" 3irstly, the best val!es of criterion f!nctions are determined" 4n o!r case,

those are the ma(im!m val!es of rst three criterion f!nctions -energy and e(ergye'ciency, the coe'cient of e(ergy %!ality for di#erent prod!cts at energy chains0 and

minim!m val!es of the other three criterion f!nctions -minimi*ation of .)8 emission per :

k@h energy prod!ced, prod!ction cost per : k@h energy prod!ced and specic

investment cost per kilo+att installed in the prod!ction chain0" Then +e have

mathematically F8O

ma(f : -f :0 X . ma(f 8 -f 80 X f 8 , ma(f > -f >0 X .minf I -f I0 X f I, minf N -f N0 X f N, minf ; -f ;0 X II - 0

4n the same +ay, the +orst val!es of the criterion f!nctions can be determined, +hich are

obtained by the same criterion f!nctions F8O&

Then all the elements of the matri( f are converted in the val!e domain F9, :" This is

achieved by the follo+ing form!la F8O&

ff"d X fEf, and a matri( is formed,in the form / X RdR _, for i X :,"""; and X :,En"

-:>0

.onsidering the di#erence f f in the e(pression for d" it is necessary for all elements of

the matri( / to be of the val!es in the interval -9, :0" The val!es of criterion f!nctions are

obtained by ma(imi*ation or minimi*ation of criterion f!nctions" The criterion +eights for

the specic problem related to ranking variants of energy chains, for the si( main criteria

$

&

(

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*

+

,

, .

$

/

$

$

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:I S!stainable S!pply .hain Management

dened are m!t!ally e%!al" The reason for this is very simple, beca!se +e strive for the

minimal .)8 emission %!antities, prod!ction cost and specic investment cost per totallyinstalled po+er in the energy chain" Also, at the same time, the aim is ma(imi*ation of

energy e'ciency and e(ergy e'ciency and %!ality of energy forms" All criteria f!nctions

have e%!al +eight and importance" /!e to that, it +ill be valid that the criterion +eights are

+ , X + , X + X + " X + " X + , X + " X E: 8 > I N ;

After that, the val!es of the elements of matrices #j and $j +ere calc!lated" .onsidering the

e%!ality of the criterion +eights, they are obtained as F8O&

4n this +ay, the problem is red!ced from a m!lticriteria space to a t+ocriterion problem" The

val!es of minimal and ma(imal elements are determined from the matrices #j and $j F8O"

S X minS ,S X ma(S,6 X min6 ,6 X ma(6 " d;0 _ _ _ -:;0

-:I0

-:80

m n i - i0 X r

ma(f I -f I0 X f I=

minf 8 -f 80 - f % ,

ma(f N -f N0 f

minf > -f >0 X f >

ma(f ; -f ;0 X f ;

S" , X +"Vd"" X E Vd"" X X< n _ i" i"_ ; _

iX: iX:

6 " X &. ( ma(i d" ?X

_: D _ i < _ _

; ; ; ; ; Vd i:' ; Vd i8;

Vd i' ; iX:

iX:; :Xi _ ; iX:

d,ma( d,ma( d, ma( d ma(i: _8 in

; ; ; ;

-:N0



$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply :N

A certain val!e of qj corresponds to every chain in the follo+ing matri( F8O&

The optim!m variant of prod!ction is dened by the minimal val!e" The ranking of

alternatives is formed from the lo+est val!e of qj to the highest val!e of qj, +hich is

from the best to the +orst variant" 4n o!r case, the alternatives are the mentioned

energy chains for f!els and energy prod!ction from biomass F8O"

*%$% Acceptable a"vantage an" stability of the selecte" variant of

optimal energy chain on the basis of the IO1 metho"

4n the cases +hen val!es of criterion +eights are di#erent and some criteria are given

a greater importance in relation to the others, the stability of the obtained optimal

sol!tion sho!ld be checked on the basis of the V45)6 method" The alternative -a0 is

s!ggested as a compromise sol!tion, +hich is the highest ranked val!e on the

meas!re -matri(0" Then, t+o conditions have to be met&

() *++a a1vana2

-a30\-a0 4

$- +here a3 is the secondposition alternative on the rank list -\0 4 X :=-m :0advantage$. threshold, +here 5 is the n!mber of alternatives -energy chains0"

() *++a aii7

The alternative a' sho!ld also be ranked as the best in # and=or $ rank -matri(0" 4n that

case, the sol!tion has been selected correctly F8O"

+% Enclosure of speci3c mathematical functions for elements

in !oo" biomass supply chain

3or the prod!ction of biof!el from +ood biomass, it is necessary to engage di#erent

types of mechani*ation, plants for converting biomass to !sef!l f!el, h!man and other

reso!rces" /!e to the fact that the energy chains for biof!el prod!ction +ere analysed

from the energy aspect in this paper, in the te(t that follo+s, mathematical descriptions

+ill be given for the partic!lar elements of an energy chain p!rs!ant to the previo!slyadopted concept for the calc!lation of f!nctions for the elements in s!pply chain F:;"

+%$% Diomass collection machines in a supply chain

1iomass collection machines are the rst elements in a chain from +hich the entire

biomass s!pply process starts" /i#erent operations in +ood biomass collection re%!ire

*

$ The decision strategy +eight +ill be taken as v X9, ;"" This is valid for the criterionn!mber 5& X ; F8O" 3or the other case and n!mber criterion 5 F8O, +e have

!X

9"N, m Z I

9";, N Z m Z

:9"

9", m :9

-:0

()

)n the basis of that, it is possible to calc!late the val!e of the matri( % p!rs!ant to

the e%!ation F8O&

qj89

:

( #j - # 0

S S Y -: !0

$ j- $ '$ ;-$ 3' -:L

0

.H .H8

\ X F%i %8

.H .Hn

% %n \ X min\ -:O0

+

,,

.

$/$$

$&

$(

$)

$

*

$+

$,

-890

$

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)

*

+

,

-

.

$/

$$

$&

$(

$)

$*

$+

$,

$-

$.

&/



:; S!stainable S!pply .hain Management

di#erent machines, +hose selection for !se practically depends on the application

conditions" 4n the str!ct!re of the analysed energy chains disc!ssed in this paper, thefollo+ing machines +ere !sed& chainsa+, tractor, tr!ck, hydra!lic crane, mobile chipper

and for+arder" 3or all the prod!ction machines +hose f!el cons!mption is e(pressed in

litres per ho!r -l=h0 and the labo!r prod!ctivity in vol!me !nit per ho!r -m >=h0, the

follo+ing relations +ere adopted to $%!ations 8L F:;&

- P3% Hv % :9; 0 < %

< :99 p 9% -:99 @ %H:99 Y )v%0 Pr % % (#=F 0 %

FI j >>>>>II% : 999

Hv jq

J : j D:? v

9 ,, -:9 &i ) -8 "II+ 4

4:

j ...... ;@ A--B;ji 000 : 0jq : (00 - &q )-(00 j

P r jq -( #=F

-8:0

% F+ jq- j - + jqf N n Dehv 9R

< \i%C+ : P , - 0

< :99 P 9% -:99 @ %0 -:99 Y )v%0 Pr % t % (#=F 0 %

-880

T% Hv % 9R RR F . % %f ; : ? V 9% -:99 -8 II+ %0



n

M%

I n

[PM%%Xl

$ +here q X : """ n is the n!mber of machines incl!ded in the +ork 3c % is specic f!el

con

& s!mption of the observed +orking machine, l=h Pr % is prod!ctivity of the +orking

machine,

( m>=h is +orking time of machine, h Hvq is lo+er heating val!e of f!el -gasoline or oil,

) depending on the f!el type the machine !ses0, M_=kg + % >9K +ood moist!re, K p9 %

is +ood

* density, kg=m> av% is the percentage of +ood s+elling, K -SV30% is f!llment factor of

vol!me

+ -9 """ :0 .% is the price of a litre of f!el -gasoline or oil0 p 3% is the density of f!el atatmospheric

, conditions, kg=m> e3% is coe'cient of .)8 emission for di#erent f!els in kilograms of .)8

per

- gigao!le of the f!el heating val!e, kg .)8=G_ 4M% is the cost price of a ne+ +orking

machine,

. Q PM% is the ma(imal po+er of +orking machine in kilo+atts, in +hich j X :, 8 """ n"

$/ 4t m!st be mentioned that the previo!sly +ritten e%!ations are valid only for the +orking

$$ machines +hose prod!ctivity is e(pressed in +orking ho!rs F:;" .alc!lation dened

criteria$& for tr!cks&

f, X

-8I0

f i X

ni p3" 3tc" l"

3 % % %

:999

Hv

%Xin i ehvn" -i99@" 0-8"II@" 0

o% % %

y iooMt" :999

t%

-8N0

f N

V3tc" :" ." % % % %Xi

n i ehv"9%

-l99 + % 0- 8"II+ % 0-8;0

%Xi

%:99

Mt" :999

t%

f ; X

D3ig3 % % i9;p3" Hv"

3% %h3tc" l" c"

% % %%Xi

n i ehv9" -i99 +" 0-8"II+" 0 y MRR M i999y

i99%

-80



price of a k@h of electricity e3i is coe'cient of .)8 emission for coal in kilograms

of .)8 per gigao!le of the f!el heating val!e, kg .)8=G_" 4t m!st be mentioned that

it has been ass!med that the sa+mill cons!mes the electricity prod!ced in a

thermal po+er station" The factor ncelX9, >; takes into acco!nt all the energy

losses from the thermal po+er station to the motor +hich drives the system for

+oodc!tting" The factor of loss incl!des the losses in boiler, t!rbine, generator and

electric s!pply net+ork F:N" 4t m!st be emphasi*ed that all energy losses are

red!ced to the primary energy form -heating val!e0" 4n s!ch a +ay, the

opport!nity of a simple s!mmation of heating val!es e%!ivalent to certain forms of

energy cons!mption is obtained, regardless of thermal energy or electricity in

%!estion" .onsidering $%!ation 8I, it has been previo!sly dened" 4n this case, the

po+er of motor PM% +hich drives the c!tting system is taken for the sa+mill, +hile

the price of a plant for primary processing is taken as the cost price 4M%"

+%(% Plant for pro"uction of !oo" chipsF "ryingF bri9uetting an"pelleting

3or the +ood chips, bri%!ettes or pellets prod!ction process, it is, as rst,

necessary to chop the initial +ood resid!e to a certain gran!lation, and then dry it"

4f a +ood chip is prod!ced, then the prod!ction line ends +ith machines for ro!gh

chopping of +ood to certain gran!lation" 4f +e +ant to prod!ce a +ood bri%!ette or

pellet after ro!gh chopping, the obtained +ood chips are dried in rotary dryers,

and then are additionally nechopped, to be bri%!etted or pelleted later" The

mathematical f!nctions (f j, f D j, f 6 j, fj by +hich the prod!ction of +ood chips,

bri%!ettes and pellets +ithin a plant have been described are related to electricitycons!mption d!e to the mechanical +ork of chopping of +ood resid!e" Th!s, +e

have the follo+ing relations F:;&

n+i -l Pc % n i % %: ? V%p)) l 8 II R,0

:99 F PCjq ' : 9

4t +ill be emphasi*ed again that the electricity for driving a plant has been prod!ced from

a thermal po+er station" )f co!rse, that sho!ld not be a case" 4f it is ass!med, for

e(ample, that the drive of a plant has !sed the electricity obtained from a hydroelectric

po+er station, then the .)8 emission factor is e%!al to *ero for the plant" 4n $%!ations >:

>>, +e have the follo+ing val!es introd!ced& q X : """ n is the n!mber of plants Pc% is

the electrical po+er of the plant,

$&()

*+,

( .$/$$$&

$(

$)$*$+$

,$-$.

$(&$&&

->:0'Z

%Xl

f N : ?1 ? 9%C Vj%=>; :99 F+q ' : 999 ?

%:

? V 9%-l99 -8 II+ i% ->80

e3% >;

-R: ,%r :9> l : n t i%

f ; ; - ? V 9%-:99 -8 II+ % >; I :99 ' :99 9

->>0

&(&)&

*&(&,



$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply 8:

k@ n is the sim!ltaneity factor of the operation of all electric motors in the plant -9"

9"ON0, +hich depends on +hether the plant has an installed electric po+er compensation

system or not is the +orking time of machine in ho!rs, h 3pc % is the o!tp!t prod!ctivity

of the plant, t=h . is the price of : k@h of electricity q+80, >; takes into acco!nt all theenergy losses from the thermal po+er station to the electricity !ser in a factory e 3% is the

coe'cient of .)8 emission for coal in kilograms of .)8 per gigao!le of the f!el heating

val!e, kg .)8=G_" 4n the case of +ood chips prod!ction plants, pelleting and bri%!etting

plants, the total installed electric po+er in the plant is taken as PM%, +hile the price of the

plant installation is taken as the cost price 4M%"

The o!tp!t moist!re val!e of +et +ood chips can vary signicantly depending on the inp!t

moist!re of +ood to be chopped, and is !s!ally in the interval from >9 to N9K" 4n pellets

and bri%!ettes, there is a prescribed moist!re val!e, bet+een O and :8K" 4t can be

concl!ded that the di#erences in +ood chips, pellets and bri%!ettes in prod!ction plants

are seen only in the installed po+er of a plant, prod!ctivity, and in the electric po+er

compensation factor"The mathematical f!nctions f, f, f, f0 +hich describe the drying of

chopped material before bri%!etting or pelleting process are the follo+ing ones F:;&

4n pelleting and bri%!etting plants, m!ltipass rotary dryers are !sed" /!e to the comple(ity

of the mathematical model of the rotary dryer for sa+d!st drying, this paper presents a

simplied approach to the calc!lation of the thermal energy needed for drying chopped+ood resid!e" 4t is ass!med that for the evaporation of every kilogram of +ater from a +et

material, it is necessary to invest the amo!nt of heat e%!al to the latent heat of

evaporation, increased by the coe'cient of losses in the dryer" Also, the red!ction of heat

energy cons!med for drying to primary energy has been done thro!gh the coe'cients of

losses in the boiler +hich s!pplies the dryer" @e have the follo+ing parameters !sed in

$%!ations >I>;& q X : """ n is the n!mber of dryers M % is the inp!t capacity of ra+

materials, m>=h is the dryer operation time, h + : % is the moist!re of the material at the

entrance of the dryer -9 """ :0 + % is the moist!re of the material at the e(it of the dryer -9 """

:0 eX8"II is the latent heat of evaporation for +ater F>:,

$

&(

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*

+,

-.

$/$$

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$(

$)$*

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$,

$-

$.

&/&$

&&&(

&)

&*&+&,

f C X S G

%Xl

v??

? oi%p)) &j - f8 "II 0

:99

-:99 @l%l l)) +i%

I

->I0

S+ :%+ %

id S :99 & jq : % J :f N j

: -S ? =

0jq(00 - @

%0 -8

II+

%0

>"; 4S :99%X:

-:99

@:%?

:99 +i% I

->N0

3%

f ; X

nb nd

?- ++%: 0+ % t% X0

' ; j - :99 @ :% 0> "; S :99 : jq : M:99 + %

->;0



S!stainable S!pply .hain Management

M_=kg 9O is boiler e'ciency F:N nd is rotary dryer e'ciency, !s!ally +ithin the

limits

from 9"I to 9"; F>8 .h % is the price of : k@h of thermal energy, Q=k@h e 3% is the

coe'cient of .)8 emission for di#erent f!els, in kilograms of .)8 per gigao!le of the f!elheating val!e, kg .)8=G_" 4f +ood biomass is !sed in the boiler for drying heat prod!ction,

then the .)8 emission is e%!al to *ero" 4n this paper, the data from a real pellet

prod!ction plant D$nterprise for making of +ood packaging and prod!ction of eco

bri%!ettesEpellets $C PA< factory Pale, 1osnia and Her*egovinaD has been !sed for

dening partic!lar mathematical f!nctions and logistic concept"

,% Bo"el testing results in the case of the selection of

optimal chain of energy an" fuel supply from biomass

3or the analysis and selection of an optimal chain of the prod!ction of electricity, f!el and

thermal energy, three energy chains have been taken into acco!nt& .HP -combined heat

and po+er0 facility +ith the )6. process, pellet prod!ction and hot +ater boiler" All the

facilities and processes are real, and the necessary data !sed for calc!lation are real and

present the c!rrent state in the !se of biomass for energy p!rposes in the 6ep!blic of

Srpska and 1osnia and Her*egovina" As a f!el s!pply chain for the .HP facility +ith the

)6. process and hot +ater boiler, the chain of +ood chips obtained by means of a mobile

chipper has been !sed" Table l presents the optimi*ation criteria calc!lated +ith the help

of a model made !sing Math.A/ soft+are for the analysed energy prod!ction chains" 3or

the inp!t of data +hich describe the real state of solid f!els prod!ction -+ood chips andpellet0, the data from sa+mills and companies in 6ep!blic of Srpska=1osnia

Her*egovina have been !sed" The companies are as follo+s& D.ompany for making of

+ood packaging and prod!ction of eco bri%!ettes pellets, $C PA< <"<"." PaleD, sa+mill

DG)/D <"<"." Han Piesak, sa+mill DMT5 )M)645AD <"<"." Han Piesak, company for

transportation of timbering and assortments D542G/)MD <"<"." Han Piesak, .ity heating

plant in Priedor" 3or an average f!el cons!mption and the specication of +ood

mechani*ation incl!ded in the prod!ction of +ood f!els, the res!lts from st!dy F: have

been !sed" The prod!ction of pellet is determined by a chain consisting of sa+, tractor,

lifter, tr!ck, fork lift, dryer and facility for pelleting" 4n the pellet prod!ction chain, there

are t+o transportations& the transportation of timbers -;9 km0 and the transportation of +ood resid!e to the pellet facility ->9 km0" The total distance is O9 km of transportation to

the nal prod!ct" The prod!ction of +ood chips by mobile +ood chipper is determined by

the chain +hich consists of sa+, skidder, mobile chipper and tr!ck for the transportation

of +ood chips" The +ork of skidder in the forest is predicted on a short distance of : km"

The transportation of +ood chips is performed +ith a tr!ck +ith the total tr!ck body

vol!me of ;9 m> at the distance of O9 km" )ther data related to the biomass f!el s!pply

chain are& the price of a litre of gas=oil of :Q, the price of +ood resid!e from the sa+millE

9"9N;> Q=k@h, drying of +ood resid!e from N9 to :8K for pellet prod!ction, +age of :8

:N Q=day for +orkers and +age of 8N Q=day for a tr!ck driver" 3or the calc!lation of

89

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$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply 8>

parameters from f to f +hich are related to the prod!ction of pellet and +ood chips by means

of a mobile chipper, the form!lae -:0 and -8:>;0 have been !sed"

The data on the analysed technologies for the )6. process and hot +ater boiler have been

taken from the doc!mentation for the installation of these systems in the .ity /istrict

Heating Plant from Priedor -1osnia and Her*egovina0 F>>"

eneral information about CHP plant !ith O1C processF option $#

Pn X N:I9 k@, nominal po+er of thermooil boiler

P X :999 N9 X ON9 k@, installed electric po+er of plant red!ced by o+n cons!mption

P X I9ON I99 X >;ON k@, installed heat po+er of plant red!ced by o+n cons!mption for

drying f!el

T X >N> 5, o!tlet temperat!re of +ater from .HP process to district heating

grid T9 X 8> 5, reference temperat!re of environment 5f X 8899 kg=h, f!el

cons!mption

H1 X OO8O k_=kg, lo+er heating val!e of f!el for moist!re content I>K

Energy chain# pro"uction of heat an" electricityF pro"uction of pelletsF heat generation

/escription of energy chains .HP +ith )6. processProcess of prod!ction of

+ood pellets

Hot +ater boiler

Moist!re content in +ood f!el N9K N9K N9K

Solid +ood f!els& @ood chips from mobileSa+mill +ood resid!e, r @ood chips from

chipper, r mobile chipper, r

$nergy and e(ergy e'ciency of +ood

chips prod!ced by mobile chipper

f.8 X GX9"O G X X9"O

.riteria for the selection of optimal energy chain obtained from the model developed in Mathcad soft+are

)verall energy e'ciency of chain 9"I> 9";LI 9"L9

)verall e(ergy e'ciency of chain 9"88> 9";LI 9":NN

.oe'cient of e(ergy %!ality 9">LN 9":88 9"8L

Total specic investment cost per

total installed po+er in the energy

chain,

>":IO ( :9> N"8;> ( :9> :"8>N ( :9I

Total specic prod!ction cost, $C6=k@h 9"9II 88"> ( :9> 9"9NI

Total specic emissions of .)8,

k =k@h9"9:N N:";ON ( :9> 9"9:L

Table &% 1asic parameters and res!lts of model testing at the selection of optimal variant of the energy chain"$

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I X I9L>;I"OO Q, total investment cost for plant P X

N9ON k@, total installed po+er of .HP plant eneral

information about !oo" pellet plantF option &#nCi X 9">;, the e'ciency of electrical po+er generation from thermal po+er plants to the

cons!mption

F PC X 8 t=h, pellet plant prod!ctivity

PC X N99 k@, total installed electrical po+er in pellet plant taken from real factory, $C

Pale /))

?5 X :O"IO M_=kg, lo+er heating val!e of dry +ood,

r & X :8K, moist!re content p9 X IN9 kg=m>, density

of dry +ood, r av X LK, the percentage of s+elling for

r

n X 9"L, factor of sim!ltaneity +ork of all electric drives in plant C X

9"9O Q=k@h, price of : k@h of ind!strial electrical energy f X :99 kg

.)8=G_, specic emission coe'cient of .)8 for stone coal I X ;N9,999

Q, total investment in pellet plant

P X :OI; k@, total installed po+er in pellet plant, heat Y electrical

po+er eneral information about the hot !ater boilerF option

(#

P X :9,999 k@, o!tp!t thermal po+er from heating

plant T X >L> 5, o!tlet temperat!re of +ater from boiler

T9 X 8> 5, reference temperat!re of environment 5f X

NN9 kg=h, f!el cons!mption

H1 X N99 k_=kg, lo+er heating val!e of f!el for moist!re content N9K

I X ;,LNN,OIO Q, total investment in

boiler P X :9,999 k@, thermal po+er of

boiler

The calc!lation of criteria for the optimi*ation of tested energy chains has been

performed +ith the help of the form!lae -80-;0" 3or the selection of the optimal variant of

energy chain, form!las -O0-:O0 have been !sed" The check of stability and acceptability

of the sol!tion has been performed +ith the help of $%!ation 89"

88

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$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply 8N

/!e to the optimi*ation model at the comparison of incomplete energy chains and di#erent

%!alities of energy prod!ction, the combined prod!ction of thermal energy and electricity in

the facility +ith the )6. process has been obtained -the bl!e col!mn in Table l0" This sol!tion

has both the necessary stability of the sol!tion and the s!'cient advantage in relation to the

secondranked variant" 4t is interesting to notice that pellet prod!ction is the secondrankedvariant" 4t can be concl!ded from that that, !nder the conditions of testing +ith model, the

advantage is given to pellet prod!ction in relation to heat prod!ction" Ho+ever, for a

completevalori*ation of the process, it is also necessary to take the process of pellet

transportation into acco!nt" 4n that case, m!ch clearer sit!ation is obtained on this

advantage of f!el prod!ction in relation to heat prod!ction" This case of model testing

serves for the %!ality eval!ation of di#erent forms of energy -electricity, thermal energy

and f!el0" 4n that set, there are di#erent and incomplete energy chains" S!ch analysis and

optimi*ation process are obtained by the factor of e(ergy %!ality -see Table : and $%!ation

N0" $lectricity has the highest factor of e(ergy %!ality, and it is e%!al to the n!mber :" All

other val!es of this factor for heat and f!el are smaller than the n!mber :" 4n the analysedoptimi*ation process, at the selection of an optimal variant of energy chain, in the third

case of the model testing, the factor of e(ergy %!ality for +ood pellet f!el is e%!al to the

e(ergy e'ciency of electricity prod!ction in the )6. process, and is 9":88" Generally, if

there had been several energy chains +hich prod!ce electricity, either averaged val!es of

this factor from several di#erent technologies to be compared or the factor +ith the

smallest val!e of transformation of f!el into electricity co!ld be taken as a valid factor of

e(ergy %!ality" The factor of e(ergy %!ality enables the red!ction of energy prod!ction

process per c!m!lative kilo+att ho!r of thermal energy and electricity" This e#ect has a

large application in the eval!ation of the prod!ction cost and specic emission of .) 8

red!ced per c!m!lative kilo+att ho!r of thermal energy and electricity prod!ced, :

k@htYe" A concl!sion can be made from this on the great signicance of e(ergyeconomicanalysis of energy processes" All the data for the analysed technologies have been

disclosed by the district heating plant in Priedor"

-% Conclusions an" "iscussion

/eveloped mathematical model described in this paper denes ade%!ate !niversal criteria,

+hich describe biomass energy chains and +hich are adapted to the process of

m!lticriteria optimi*ation" These criteria are related to total energy e'ciency of a

prod!ction chain, total e(ergy e'ciency of a prod!ction chain, factor of e(ergy %!ality of di#erent energy forms, total prod!ction cost per : k@h of energy prod!ced, total

investment cost per total installed po+er in an energy chain, total emission of fossil f!els

cons!med for the prod!ction of : k@h of f!el, heat or electricity" This approach combines

the most signicant specic criteria for the description of the entire chain of energy

prod!ction and gives the possibility to compare the energy chains as +ell as selection of

the optimal variant for the prod!ction of f!els and=or di#erent forms of energy from

biomass" The optimal variant is obtained on the basis of m!lticriteria optimi*ation, by !sing

the adapted V45)6 method" The verication of the developed mathematical method has

been done on the application of energy and f!el s!pply from biomass" 4n the calc!lation

$&()*+,-.

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$-$.&/

&$

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part, three energy chains have been !sed for the verication of the concept, +hose criteria

for optimi*ation are provided in Table l" These energy chains are the )6. process +ith

combined prod!ction of thermal energy and electricity, the process of +ood pellet prod!ction

-solid f!el0 and the process of thermal energy prod!ction by means of a hot +ater boiler, for

district heating p!rposes" All three variants of energy chains prod!ce di#erent energy forms

+hich have a di#erent %!ality of o!tp!t prod!cts" 3or that reason, s!ch energy chains have

been selected to demonstrate the !niversality of the model application to

the analyses of other energy and f!el prod!ction processes as +ell" 4t sho!ld be noted that

the e(ergy %!ality factor of prod!ced energy allo+s comparison of di#erent energy forms"

The proposed criteria for optimi*ation are closely related to technicaltechnological,

thermodynamic, economic and ecological characteristics +hich describe energy chains" )f

co!rse, the physical basis of the proposed criteria for the optimi*ation of energy chains isbased on the concept of s!stainability" /epending on the initial data on the basis of +hich

the criteria for the optimi*ation of energy chains are calc!lated, these criteria, at the same

time, give the information on the c!rrent state of development at +hich the applied

technologies and the +ays of energy prod!ction are" 3rom the set of di#erent chains of

energy prod!ction described +ith the s!ggested optimi*ation criteria, it is possible to select

the variant of energy prod!ction +hich is optimal" The selected optimal variant is, at the

same time, the one closest to the s!stainable +ay of prod!ction of energy and=or f!els in the

observed set of dened energy chains" The developed mathematical model and the

s!ggested concept have a large practical application in the selection of an optimal variant of

prod!ction of biof!els and=or prod!ction of energy from biomass in dened real conditions"1esides that, the model can also be !sed in the process of designing and establishing of

energy prod!ction chains, both from biomass and from some other so!rces" 3rom the aspect

of energy chains of energy prod!ction, the model is very !niversal and can be e%!ally

applied to any other energy s!pply chains"



$nergy .hains )ptimi*ation for Selection of S!stainable $nergy S!pply 8

Author "etails

Srdan Vaskovic:, Petar Gvero:, Vlado Medakovic: and Velid Halilovic8

Address all correspondence to& srdanvaskovicyahoo"com

Address all correspondence to& gvero"petargmail"com

: Cniversity of $ast Saraevo, 3ac!lty of Mechanical $ngineering, $ast Saraevo

8 Cniversity of 1ana <!ka, 3ac!lty of Mechanical $ngineering, 1ana <!ka

> Cniversity of Saraevo, 3ac!lty of 3orestry $ngineering, Saraevo, 1osnia and

Her*egovina

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8co!ntries" Thesis, /elft Cniversity, 2etherlands"

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$'ciency in

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+ood biomass processing and possibilites for energy crops and forest, .hapter 8, in

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$nergy Potential and .haracteristics of 1iomass 6esid!es and Technologies for

Application in Serbia, 1elgrade, 3ac!lty of 3orestry, P!blic .ompany, Srbias!me,

4nstit!te for Poplars, pp" 8N8;"

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Vadodara, 4vory Terrace, I9N p"

F>>Grontmi A"1", 89:I" 3inal 6eport& Heating Plant PriedorE3easibility St!dy,

.ontract 2!mber $1/6 .8L;L=S@M$89:>9O98, 3inanced by the S+edish

Agency for 4nternational /evelopment -Sida0"

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provisional chapter

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