113
Chapter 4
4. Methodological Instruments for Multidimensional
Analysis of Energy Systems
4.1. Introduction
How long will researchers working in adjoining fields, such as demography, sociology, and political science on the one hand and ecology, biology, health sciences, engineering, and other applied physical sciences on the other, abstain from expressing serious concern about the state of stable, stationary equilibrium and the splendid isolation in which academic economics now finds itself?1
This question that was formulated more than tow decades ago by Leontief (1982) and still applicable emphasizes the need to include natural science into economics analysis in order to introduce more realistic models base on the biophysical world and the laws governing it.
With respect to energy systems, it emphasizes the extremely grow in complexity experimented during the last century and its understanding. Three factors driven this
114
grow, fossil fuel scarcity, environmental concerns, and increasing world population at rising standard of life. This three factors underline the need to include into the classical economic approach the different aspects involved in the energy process that, up until now, have been not taken into account, calling for more intensive and extensive methodology analysis. Thus, the analysis becomes multi-disciplinary. Also even with fossil fuel abundance, the other two factors maintain the constrains2.
Therefore, the different aspects regarding energy conversion systems as the fuel scarcity or environmental concerns turn to be fundamental questions into the analysis, without leaving behind social or geopolitical aspects, that even faraway form engineering considerations are doubtless implicated into the energy production processes. This “new-requirements” claim for new instruments of analysis setting aside fragmented studies. Indeed, what can be called a multidimensional analysis -including different dimensions affecting the studied systems-, must contribute to new discourses about the means, methods, and ends of economics hegemony3.
A fundamental step in integrating the environment is the definition of a framework, where environment means all the in-situ resources, energy resources, land used, water etc. and the capacity of the environment to assimilate the waste products. Conventionally economic analyses ignore or are not sufficiently consistent with the basic laws of thermodynamic or with the environment preservation. Indeed, this designedly withdrawal leads to the failure of any analysis that can successfully meet any challenges of pollutions reductions or resources scarcity endangering the environment. Therefore, the economic function of the environment as a waste sink or as a source has been impaired, with the indiscriminate used of narrow economic analysis.
In order to examine the environment preservation problems in detail, some considerations must be point out. Certainly, the natural resources merit some recognition in the economic production function because of their associated discovery and extraction costs. But the question is rather that the economics assigns a low value to natural resources found always on prices consideration based on “economy of scale”
115
that usually does not reflect how scarce is the resources but only its economics-geopolitical situations. Besides, there are other uses of the environment, for which there is no cost at all, left completely out. For example, the free use of the environment as a sink for waste materials does not figure in the production function even though production clearly depends on the availability of this service. Without this service (and many others provided at zero direct cost by the environment), producers would be forced to find others, surely more costly means of dealing with their wastes. Of course, in that case wastes would represent direct costs to producers and enter the production function.
Policy and industrial decision-makers at all levels may need to know energy system performances under many complementary points of view. Hence, nowadays decisions concerning energy systems analyses must been based on multidimensional assessments. This multidisciplinary point of view is found on the idea that all the dimensions involving the system need to be introduced into the analysis, in order to take into account the different factors acting on the energy systems. Thus, beyond the long established disjoined thermodynamic and economic analysis. New criterion that are going to influence the evolution of energy production; concepts as the depletion of resources associated with highly intensive use of energy, the need to preserve the environment or the social issues related to investment decisions and political actions (taxes, incentives, etc.) are also significant subjects concerning the energy power generation4.
However, it is very difficult in a multidimensional analysis to join the different dimensions involved without failing into any arbitrariness, beginning from the description of the system per se and its boundaries. Nevertheless, in the meantime it is clear that the view that focuses mainly on the economic dimension of the system needs to be abandoned3.
The present chapter introduces an overview of the most remarkable multi-criteria methodologies of energy analysis present in literature.
116
4.2. Goals and boundaries definitions. Spatial and time scales
In order to describe the different methodologies approaching the energy generation system, a brief outline of the various possible goals and boundaries of the system are here explained. An energy system is a complex system and can be defined by different boundaries depending of the problem. In simplest analysis where the only function of the energy system designed is the conversion of energy resources into the final energy form. Therefore, the interaction of the energy system can be defined only by its thermodynamic efficiency, where the use of technical analyses turns the most suitable. Adding respectively complexity to the energy analysis satisfy the holistic aporaches, which can allow the examination of the different interaction between the energy system and the environment. For instance, the definition of the pollution problems as emissions of energy or material waste resulting from the energy conversion. Obviously, additional increase in complexity can be considered taking into account the social interaction between the system and the environment.
According to the set up goals and the specific task that each approach is able to accomplish, accurate design of the boundaries of the investigated system is required. Space and time scale definitions are crucial for a correct application of each approach and the reliability of results. The first step of any evaluation (energetic, economic or environmental) is therefore a clear identification of the space-time windows of interest, see figure 4.1. While the spatial scale is related to the choice of boundaries, the time scale is related, in its most general sense, to the nature resources and the actual goals of the investigation. Some approaches are focused on the process, while others are concentrated on the relation between the plant and the ecosystem in which the process takes place.
117 Physical boundary Regional level Biosphere Life cycle Operating life Present conditions TIME SPACE
Figure 4.1: Boundary definitions for the space-time scale involving the plant5
In accordance with the Fig. 4.1, short time and long time, small scale and large scale consequence of policy decisions can be fully assessed. Therefore, depending of the purpose and specific task of the approach a first classification among the different multi-criteria methodology can be made among Reductionist and non-reductionist approaches.
4.3. Reductionist and Non- Reductionist Approaches
All the methodologies discussed in the literature to analyze the energy systems under a multi-criteria point of view can be reconnected to reductionist and non- reductionist approaches.
Technical
Approaches
118
4.3.1. Reductionist approaches
The reductionist approaches can involve technical and holistic methodologies where all the different aspect of the analysis, represented by means of indicators, are aggregated in a unique synthetic indicator. All the indicators must be accumulated in a synthetic indicator. The reducionist approach needs of a criterion that defines the way the synthetic indicator is aggregated. This gives rise to all the different methodologies to perform the different task and investigation related to the energy systems.
For the reductionist approaches, the number of indicators must be quite low, (e.g. Environomic analysis) in order to have the possibility of a not questionable aggregation.
One of the main problems, which this approach is confronting, is the comparison between inhomogeneous energy systems. Many of these methodologies are used for comparing very different electricity generation systems6,7, which yield to very
inaccurate results, raising a number of questions concerning its application.
The practical implications can be seen in many analysis including renewable energy conversion systems for their introduction in the energy market, an area that has become increasingly important. These analysis suffer of misunderstand for a number of reasons. First of all, we believe in the importance of compare homogeneous energy systems with about similar sizes. It is misconceived to compare a 600 MW nuclear power plant with a 20 kW Photovoltaic solar plant because there are no common indicators that can really yield to a reliable analysis. Furthermore, the same can be applied for energy systems using different energetic density fuels. For example, the analyses that compare energy conversion systems using fossil fuels with renewable energy conversion systems lead to erroneous results, since the well-established fossil fuels relish of the “economy of scale” factor, while the renewable sources ( wind, solar or biomass among other), are physical limited and, for instance, have no possibility of escalation. Also as an important check on referred to the type of resource used, the area needed per kW produced, which obtain a leading role in the renewable energy systems, while for the fossil fuels energy systems is an irrelevant indicator.
119
4.3.2. Non- Reductionist approaches
For the non-reductionist approaches a set of indicators describing the different aspect of the analysed systems is required. In this case the higher the number of indicators the detailer is the analysis.
This approach does not need of an aggregation of the different indicators, therefore the decision is not based on a pre-constructed criteria, otherwise it rests on the disaggregated information gave by the different indicators, which will be interpreted by the decision-makers and politics.
The holistic approaches are the one using this type of analysis, since it will have non sense its application in a technical approach. The information by means of the disaggregated indicators encloses many different aspects affecting the energy systems as the societal and environmental dynamics, where the boundaries of the system go beyond the physical border.
4.4. Technical and Holistic Approaches
Technical approaches are restricted approaches usually based on Thermodynamic principles When the purpose of the assessment is to minimize the amount of input (energy, material or money) required per unit output, a system boundary might well be its physical borders. The boundaries of the system are well defined, usually limited to its own system and present conditions. The technical analyses involve, basically, Thermoeconomics and Environomics analyses with their multiples variables as the exergy-based approaches8,9, the “Analysis of cumulative exergy consumption”10, or the
“Embodied energy analysis”11.
On the other side, when the generation and supply of resources or the uptake of pollutants has to be evaluated according to diverse criteria than minimization, trying to assess the dynamic of the environment, the boundary might be expanded to the local/regional or even to the biosphere scale in order to include the chain of processes. These are the holistic approaches such as the “Emergy analysis”12, “life cycle
120
assessment”13, “Extended exergy analysis”14 or “integrated environmental assessment
based on a representative set of indicators”15.
The different assumptions are the basis of the different methodologies, making them capable to perform different tasks and answers to different kinds of questions related to the goals of the analysis. These assumptions are described below for each multi-criteria methodology, technical or holistic.
4.4.1. Technical approaches
In order to analyze, improve and optimize energy system analysis, the technical approach is an attempt to propose, in its widest possible sense, a structured connection between the thermodynamic performance of the power plant and its economic dimension. Further on, environmental concerns are also considered, introducing the environomic analysis, which represents a natural evolution of the thermoeconomics analysis.
4.4.1.1. Historical review of the main technical analysis
A brief historical review of the main technical approaches is shown in figure 4.2. In the seventies, the relationship between energy and economics was principal concern. Even if the interaction between cost and efficiency has always been recognized qualitatively. However till the seventies engineering analysis was basically based on the two laws of thermodynamic. During the eighties, the dominant criterion was the monetarism as economic criteria, introducing the concept of cost per produced energy.
Furthermore, the environment protection becomes of concern in the nineties, where the environmental impacts of energy conversion systems started to be considered. A new awareness of environmental problems launched to receive much attention, as global climate change, ozone depletion or acid rain among others. Hence, the link between energy processes (production, conversion, transport and use) and their environmental implications becomes more recognized16
121
Figure 4.2: historical review of the main technical approaches
Thermoeconomics was structurally developed as a general theory in the late eighties by Valero et al.17,18
. Although it is right to say that the birth of a general vision of the concept thermoeconomics was first used for Evans and Tribus in 196519
. The functional analysis was also developed at the early eighties by Tribus and El-Sayed20,21,22. Later in the early eighties, the interest in further development of
Thermoeconomics to handle energy intensive systems was initiated by professor Gaggioli23,24. Many researches responded positively to the initiation. In the last 25 years, the development of Thermoeconomics has been extraordinary in more that one direction. The development by Valero et al. 25, was also followed by El-sayed26, and
Thermodynamic 1° Law Thermodynamic 2° law Economic (monetarism) Exergy Exergoeconomic Thermoeconomic Extended Exergy Accounting Environomic Economy and Environment Technical approaches Engineering point of view
1850~1960-70 1974-75 1980 1985
-
1986 1997 2000 years tendencyOne possible way To integrate economy into complex energy analysis Thermodynamic 1° Law Thermodynamic 2° law Economic (monetarism) Exergy Exergoeconomic Thermoeconomic Extended Exergy Accounting Environomic Economy and Environment Technical approaches Engineering point of view
1850~1960-70 1974-75 1980 1985
-
1986 1997 2000 years tendencyOne possible way To integrate economy
into complex energy analysis
122
Lazzaretto and Tsataronis27 may adequately represent the different directions of
development
Thermoeconomics is an effective tool to reveal opportunities for achievement of increased efficiency and lower cost of energy conversion system, admitting, that the energy transformation systems are determined by the physical environment and the economic environment. In consequence, thermoeconomics analysis tries to provide physical roots for economics introducing the Laws of thermodynamics in the economic analysis of energy systems. Anyway, the final evaluation of any process is carried out in monetary terms, incorporating each resources used into the internal flows and products cost. It is also fair to say that increasing efficiency also has environmental benefits as it lengthens the lives of existing resource reserves and reduce pollutants reject to the ambient.
Unfortunately, these directions are not yet free from inconsistencies. The transition from thermodynamics to economics is not a smooth path; and has hindered the creation of the necessary common principles, which would unify and clarify the concept and methods typical for each of them25.
Further on in the late eighties, as mentioned above, resources scarcity and environmental issues have made apparent that some “limits to growth” indeed exist. Thus, the problem to consider the environmental dimension into the design of energy systems appear to be crucial, being one the foremost complex issue for energy system assessment. Accordingly, the thermoeconomics as thermal-economical design for energy systems, whose fundamentals were largely discussed in the literature28,29, is
presented as the thermodynamic-mathematical-economic background for energy-economic-ecological analyses called “Environomics”30,31,32.
Environomics unites the monetary cost with the processes thermodynamics where the sacrifice of physical resources or the generation of inevitable waste affecting the environment are located and quantified into the analysis.
123
4.4.1.2. Second law efficiency in the technical analysis
In the present days, there is universal agreement on the fact that a “conversion efficiency” based solely on first law consideration is misleading, because the scale of energy quality can be quantified only by an entropy analysis. The second law perspective has proven to be extremely useful for the optimization of energy systems. Significant attention has been directed towards the use of exergy analysis in the assessment of thermal and other industrial processes and their environmental impacts since exergy analysis is an effective tool both for achieving efficient energy utilization with minimum environmental impact and for understanding environmental issues. Even if, the method of exergy analyses, based on the second law of thermodynamics and the irreversible production of entropy, is neither new nor modern, its practical use has been very limited. The early fundamentals were already stated by Carnot in 1824 and Clausius in 1865 but the term "exergy", first used by Rant in 1956, has been connected to the capability to do work or the available work from a process, and the Carnot efficiency of thermal systems. The second law of thermodynamics states that there is no natural reversible process. This means that each process entails the degradation of energy resources. Therefore, no energy conversion happens in the world without producing entropy, with the consequences, in particular, that every energy process requiring the input of energy, will unavoidably produce useful energy (exergy) and will dissipate entropy and usually matters too. This results in thermal and chemical pollution and, eventually, the exhaustion of the resources of no renewable fuels and raw materials.
Consequently, “exergy analysis8,28,33, as a revival of the classic method “availability
analysis” proposed by Gibbs and applied by Keenan assumes a rising special significance in the analysis of environmental impact34,35, emphasizing the linkages
between exergy input (scarcity of the resources), exergy output (energy production )and the exergy reject to the environment as environmental damages account (waste emissions and exergetic losses),36. The reason is the close connection between energy
124
policy and energy losses. Such a direct relation between thermodynamic function and needs of society is rather unusual37.
Second law considerations analysis generated more precise and useful information for the designer Engineer; likewise, the Environomics analyses become Exergoeconomics analyses, where the no-energetic expenditures like financial, or environment cost are expresses as functions of the technical and thermodynamic parameters of the process under consideration.
Exergoeconomics has been also used in the analysis for optimum energy-economic design of thermal systems based on the theory of exergy cost9
. This theory comes into the world at the lately eighties by Profs. Valero, Muñoz and Lozano, this is a concept close to that of embodied energy or cumulative exergy consumption of Szargut38.
4.4.1.3. Technical approaches by means of suitable indicators
All this technical methods discussed in the literature are based on the optimization of the energy systems design under a multi-dimensional point of view including its interaction with its environment. Once flows to and from the system are carefully described, their energetic, economic and environmental quality can be specified by means of suitable indicators (cost, efficiency, pollutant emissions etc.), where multi-criteria analysis of energy systems can be reconnected to cumulative index methods. Cumulative index methods take into account the different feature of energy production by means of defined indicators, reflecting the combined effect of all the criteria under consideration and are expressed in the form of a general Index. A selected number of indicators are taken as the measure of the criteria comprising specific information of the option under consideration. The procedure is aimed to express option properties by the aggregation under specific criteria of a set of indicators. The simplest form of aggregation is to add up the individual indicators according for example with their thermal equivalents (BTUs, Joules, etc.), assuming for this case, that each indicator is in the same units.
Nevertheless, for more complex multi-criteria analysis of energy systems, a selection among a heterogeneous group of indicators permits to aggregate indicators with
125
different units, which in some general case can expand the boundary of the analyzed system to regional or biosphere space scale, addressing concerns that go beyond the process. This assumption made of the cumulative index methods for multi-criteria assessments a mixed method that can be reallocated amongst technical and holistic approaches, depending of the selected indicators used for describing the system. In any case, all the relevant dimensions of the system are aggregated in a unique cumulative index, including among others; resource, environment, technical, economic, social and efficiency indicators, but in this case, naturally, the aggregation become very much complicated.
Different multi-criteria assessments have been recently proposed in the literature to compare different energy production technologies in the field of fossil fuels and renewable energy power plants6,7,39
. Those analyses assumed that the energy system is a complex system, which may interact with its surrounding by utilizing resources, exchanging conversion system products, utilizing economic benefits from the conversion process and absorbing the social consequences for the conversion process.
4.4.1.4. A critical review of Environomic Analyses.
Technical multidimensional approaches of energy systems have been developed as a result of considering the multidisciplinary aspect of the analysis, basing on the aggregation of thermodynamic, economic and environmental criteria40,41,42.
As a natural evolution of the Thermoeconomic analysis, Environomic methodologies30,31 that
aggregate different dimension interacting in the energy analysis in a synthetic utility function under an economic common base, have been already proposed in literature for the analysis, improvement and optimization of energy systems introducing environmental concern. This is a technical approach that, unfortunately, has been applied in a satisfactory way only with reference to some particular systems.
The unified environomic approach optimizes the plant in order to minimize the total costs of the system, by searching for the minimum of a utility function that is based on thermodynamic, economic an environmental criteria, which can be expressed as costs
126
of the fuel, investment and a quantification in monetary terms of the negative impact of the pollution.
This technical analysis required to be applied to an open system, where the environmental is represented by the immediate surrounding of the energy system, remaining into the border of the technical approaches, physical boundary and present conditions. This optimization minimizes the overall monetary cost, under a proper set of financial normatives, environmental and technical constrains, by searching for the minimum of a utility function U cost based, eq. 4.1.
∑
∑
∑
∑
∑
∑
∑
∑
++++∑
∑
∑
∑ ∑
∑
∑
∑
++++∑
∑
∑
∑
−−−− ==== ==== r ro r r k e e r , ok r Z K U Γ Γ Γ (4.1)where Zr is the capital cost related to the r-th unit of the system, including charges and maintenance cost, Гok,r is the cost of resource and services, Гro is the revenue from products or services that the system furnish (energy, steam etc.), Гe is the generic environmental costs. In fact, this term distinguishes the environomic from the Thermoeconomic theory43,44,45.
The environmental costs Гe can estimate the external cost of pollutant emissions, the cost of the resources depletion or any general environmental degeneration, internalizing them into the economic evaluation of the system for an environomic optimization. It is a very controversial term that can generate inaccuracy into the analysis. The more interesting approaches to this term are exposed below.
4.4.1.4.1 Environmental cost
Some costs related to the environmental protection of energy production systems activities are included in the price paid by the consumer; these are the “internalized environmental cost”. Other environmental costs related to the activity are cover by society in general rather than be paid in electricity bills; these are the external environmental costs. According to the framework of environomic analysis, every environmental impact of the energy production systems should be evaluated.
127
But still a great deal of disagreement subsists in the estimation of the environmental costs, the great uncertainty of the data yields to very difficult analyses and the result suffers from considerable inaccuracy. Nevertheless, an attempt has been given to estimate the external costs of energy production by employing three different approaches.
1) The indirect methods aim to measure the value of goods in an independent way as the one trade in formal markets.
2) Proxy (avoidance) methods measure the necessary costs to return to the initial conditions. For energy systems e.g., these methods can be based on pollution mitigation methodologies. The analysis uses unit cost for evaluating the reduction in energetic or monetary terms [kg pollutant removed/kWh or kg pollutant removed/cent€].
Mitigation methodologies can be typically capture technologies, but also measures as a proper design of the combustion chamber, an adjustment of the combustion temperature, catalytic converters etc.
3) Damage costs are an attempt to evaluate the repairing cost of the environment. They are used to measure goods for which economic cost can be readily assessed.
Accordingly, the environomic analyses attempt to furnish interesting elements for the economic quantification of the environmental costs. Various measures have been suggested in the literature in order to evaluate them, as a challenge to quantify in monetary terms the negative impact of pollution on the environment, resources scarcity or any other type of environmental impact.
4.4.1.4.2. Different efforts to account for the environmental pollution costs
Many studies have been performed in the attempt to estimate the pollutant costs, but difficulties and limitations have been found. However, an attempt to derive reasonable costs analysis can make far more sense that to ignore external effect of energy systems. A possible form for the pollutant cost function, Гe(pe), was given by Spakovsky et al.
46,47
128 e e p e f k p Γ = (4.2)
Where fp is a pollution penalty factor related to the pollutant, ke is an environmental unit cost and pe is a pollution measure.
The pollution measure pe can take any number or forms. The simplest measure could be the quantity of the pollutant reject to the environment for thermal or chemical pollution. But this measure avoids deliberately any further consideration about the relation among the pollutant quantity and the damage associated to it, namely, the pollutant quantity/impact relation, which it is not always linear. Another measure for pe can be derived from the disturbance that the pollutants cause to the environment. Thus, exergy or entropy as a measure of departure from equilibrium can be considered, and since resources consumed can also be measured in terms of exergy, a uniform measure can be established for both the inputs and the outputs of the system43
Also the used of the exergy reject by system to the environment can also be a measure of the irreversibility of the system, which increase the entropy of the environment. However, as has been pointed out by Szargut10 the assumption that the harmful effects
of rejecting waste products can be expressed only in terms of its exergy seems to be oversimplified. Further investigations should be made on determining the harmful effects of pollutant on the nature and on the society.
Moreover, the difficulty in the economic quantification of pollutant emissions and in particular for the definition of the environmental unit cost and of the penalty factor is a great source of inaccuracy, causing an ambiguous and a difficult use of the environomic analysis for the optimization of the energy system.
A simple measure of the pollution penalty factor related to the pollutants is shown in equation 4.3, which attends to be adapted to the system emissions and to the local and global pollutant conditions43,46.
129 o o p f
α
α
α
α
− − = (4.3)where α is an intensive property characterising the pollutant (quantity, entropy, exergy etc.), αοis the intensive property of the same pollutant in the environment, α is the harmfulness limit of the intensive property: if it is exceeded, the pollution becomes particularly harmful to the environment
Some examples for thermal and chemical pollution can be given by the two following expressions. Q T T T T p o o Q − − = (4.4) v o o m o o ch c c c c c p −−−− −−−− ==== −−−− −−−− ==== χ χ χ χ χ (4.5)
Where T is the temperature at which heat is rejected to the environment, χ and c are the mass content or the concentration of the pollutant in the rejected stream.
Careful environmental studies must be conducted to define the harmfulness limit for T, χ and c respectively.
The environmental unit cost can comprise pollutant unit cost and energy/exergy unit cost among others. The energy/exergy unit cost can be referred in their simplest form to the fuel or the electricity unit prices (cent/kWh) produced or consumed, but in general the energy/exergy unit cost is able to integrate diverse aspects of the analyzed systems where no absolute values can be taken.
4.4.1.4.3. Different efforts to account for the natural resources costs.
Degradation of the environment can be taken into consideration by treating the environment as a consumed resource. The extraction of depleted natural resources not only requires energy and produces wastes but also decreases the concentration of
130
resources, which in turn increases the energy required for extraction and makes the resources not available for future generations. Even considering that the market prices may reflect the extraction costs and current or near-term supply and demand, they do not in general account for long term local or global scarcity or the ensuing difficulties and cost for further generation.
Concerns about these realities due scarcity, future supplies or geopolitical considerations are very difficult if not impossible to be introduced into the analysis, revealing that an environomic optimization of energetic systems based on traditional economic terms is very questionable and not wholly accurate.
Nevertheless, a possible form for the resource cost function, Г0k,r(y0k,r), was given by Spakovsky et al.46,47 and formulated in eq. 4.6.
r , ok r ok, r s0k, r pok, r 0k, f f c y Γ = (4.6)
Where fp0k,r is a penalty factor related to the resource 0k,r, fs0k,r scarcity factor for the resource ok,r, cok,r is an resource unit cost (e.g. market price) and y0k,r is a resource entering unit r.
4.4.2. Holistic Approaches
The complexity of the problem that should be taken into account when evaluating energy system within societal and environmental dynamics suggests the use of holistic approaches, where the energy systems analyses are not presented in the way engineering are accustomed to, since these approaches address concerns that go beyond the process and considers large scale of the biosphere.
As any other complex system the energy system is defined with constrains. Thus, the criteria for a holistic approach have to reflect namely; resources, environmental, social, technological and economic constrains. In this respect, the holistic approach of energy system will comprise the evaluation of those parameters, which are the reflection of an interdisciplinary approach. Obviously, additional complexity is added, since explicit
131
relations between different aspects of the same process are very hard (if not impossible) to find. Useful indications about systems can be obtained by comparing empirical and calculated parameters supply by different but complementary sciences. Accordingly, beside engineers, scientists and economists are involved in energy and environmental issues.
Except for the Life cycle assessment, very few examples of holistic approaches application have been published, due to the relative recent introduction of most of them5. An overview of the most representative holistic approaches is presented below.
They may be criticized, and one may be disagree with the conclusion or even with the methodologies, but not discounted acritically, since they represent a noticeable effort on the part of their proponents to systematize the phenomenological complexity under which we perceive nature48
.
The integrated environmental assessment methodologies5 for energy conversion
process are procedures to arrive at an informed judgment on different courses of action with regard to energetic problems. This analysis involves interdisciplinary and social processes, linking knowledge and action in public policy/decision context The information required refers to physical, chemical, biological, psychological, socio-economic and institutional phenomena, including the relevant decision making processes15. Thus, it facilitates the framing and implementation of policies and
strategies. Models aiming at structuring these cross-boundary problems of an economic and environmental nature are usually called environmental' or 'economic-ecological' models49.
This multi-criteria assessment is an effective tool for evaluating the performance of energy conversion systems from different points of view, where a set of suitable performance indicators within the proposed methodological framework must be developed and defined accordingly. The parameters must be carefully selected and normalized to facilitate the interpretation of the results.
132
4.4.2.1. The use of indicators in the holistic approaches
Indicators are important tools to communicate ideas, thoughts and values. The procedure is aimed to express option properties by a respective set of suitable intensity indicators as the measure of the criteria comprising specific information of the option under consideration. The energetic, economic and environmental quality can be described by means indicators. A number of studies have been conducted in this field, raising to different type of indicator groups. Very interesting studies have been carried out by different Environmental agencies, see figure 4.3, giving different frameworks for sustainable development indicators, which measure progress toward a sustainable economy, society and environment5051,52,53.
For each dimension, different indicator data based are proposed. The economic indicators provide information about the investments, human resources, energy unit cost, financial status etc., used in generating profits for the plant shareholders and benefit for the overall society. Energy indicators evaluate the interaction among the system and the flows interacting with the system, how resources are exploited, first and second law conversion efficiency, fuel exergy content etc.
Similarly, the environmental aspects should be investigated considering both the environment as a source of resources and as a sink for the pollutant and by-products associated with the production process. The main indicators are the air pollution, the water pollution, the heat reject to the environment and the non-renewable resources utilization.
In addition, social indicators can be selected, which reflect the interaction between the energy system and the society. Some representative social indicators among others are; society welfare, jobs, toxicity in the environment, living conditions, etc.
133
4 Dimensions:
Socio-economics, environmental, institutions (Agenda 21, Indicators UN, Indicators Eurostat)
3 Dimensions:
Ecological, economics, social
2 Dimensions:
Nature and human being, social systems, natural systems “Man and the Biosphere“, UNESCO, 1975
“People and Ecosystems“, UNDP/UNEP/WB/WIR, 2001 “Egg of wellbeing / Barometer of sustainability“, IUCN 2001
Pyramid mediums and goals:54,55
Ultimate Ends:WELL-BEING
happiness, harmony, identity, fufillement
Intermediate Ends: HUMAN CAPITAL & SOCIAL CAPITAL
health, wealth, leisure, mobility, knowledge, communication, consumer goods
Intermediate Means: BUILT CAPITAL & HUMAN CAPITAL
labour, tools, factories, processed raw materials
Ultimate Means: NATURAL CAPITAL
Solar energy, biosphere, earth materials, biogeochemical cycles
Figure 4.3: Diverse studies taking in to account the different dimension of a sustainable development
UE IE
IM UM
134 4.4.2.2. Emergy Analysis
A Further interesting “holistic” methodology is the Emergy analysis. According to
Laganisa and Debeljakb56, the emergy synthesis method was introduced from Odum in
the 1980s12, with the aim of taking into account the different quality of driving forces
supporting a process and allowing their comparison on the same basis. This analysis attempts to solve the problem of multi-quality inputs by transforming them to an equivalent of energy of a single quality, which is usually solar energy. Emergy is therefore promoted as a concept that is useful for establishing the metric for a rigorous and quantitative sustainability index.
Emergy refers to several concepts at the same time. It was originally coined by Dr. David M. Scienceman in collaboration with the late Professor Howard T. Odum as a means of making of the term "embodied energy". However, Scienceman also used emergy to refer to the concept of energy memory57, and H.T.Odum used it to mean
both sequestered energy and emergent property of energy use. Some researchers
maintain that it can be expressed as a scientific unit, which is called the "emjoule", a contraction of "emergy joule", or "embodied energy joule".
Emergy can be defined as the total solar equivalent available energy of one form that was used up directly and indirectly in the work of making a product or service58,59.
Emergy analysis sought to ordered energy form conversions according to their quality; however, its hierarchical scale for ranking was based on extending ecological system food chain concepts to thermodynamics rather than simply relative ease of transformation. For H.T.Odum energy quality rank is based on the amount of energy of one form required to generate a unit of another energy form. The ratio of one energy form input to a different energy form output was what H.T.Odum and colleagues called transformity, defined as the Emergy per unit energy in units of emjoules per joule12.
However the emergy methodology is still very controversial, depending on plausible but arbitrary choice of the “transformities”. This yields doubts about precision and
135
reliability on the emergy calculations. Also little attention is paid to the sensibility of the results to the data quality and uncertainties.
4.4.2.3. Life Cycle Assessments
Life Cycle Assessments (LCA), included into the holistic approaches, are interdisciplinary appraisals. The life-cycle assessment is a methodology for analyzing
the environmental interactions of a technological system with the environment. The concept emerged in the seventies as a way to assess the overall use of energy and materials by products or services, from "cradle to grave" (creation of raw materials to final disposal). Later on, the method was extended to include environmental emissions to air, water, and solid waste as defined in document by the Society of Environmental Toxicology and Chemistry (SETAC 1991)13. In 1997, the International Standards
Organization (ISO)60 completed work on a series of standards that have become the
general benchmark for the technique. LCA emerged as a worldwide environmental management tool in the form of the ISO 14040 series. For example, LCA can be used to assess different technologies in order to identify the best environmental option; alternatively, it can be used to provide a scientific basis for developing sound environmental strategies and policies in government or industry.
Life Cycle Assessment is divided into four basic stages: Defining the goal, scope and boundaries of the assessment. "Life Cycle inventory" (LCI) -a database of energy/materials use and emissions, relative to some "functional unit" (e.g., for a detergent, emissions per 1000 loads of laundry washed; for an automobile, emissions per 1000 personkilometres travelled). "Life Cycle impact assessment" (LCIA) -translation of inventory data into potential impacts on the environment. “Exergetic Life cycle Analysis” (ELCA)61 used to accomplish the proposed LCA with an exergy
136 4.4.2.4. A critical review Life cycle analyses.
Life cycle analyses (LCA) appear very interesting to assess the environmental impact of product systems and services, accounting for the emissions and resource used during the production distribution, use and disposal of a product, based on a physical description of the processes involved in a product live cycle. But it is clearly recognised that these analyses are still in a developed phase.
This analysis continues to face very important challenges, firs of all, the reliability of the data, i.e., for the analysis of energy system with a live time bigger that 35 years, the data must be consistent for the whole period of the analysis. Energy/exergy data, for example, can support its values in time, while for monetary values the same cannot be said, since a temporal reference must be given. However as will be detailed in chapter 6, exergy accounts are needed of an environmental reference state, which is a very difficult task for this type of analysis. The unavoidable theoretical simplification, that withstands the exergy analysis, yields to an inaccuracy of the LCA in absolute values terms. Therefore, energy base analyses are more recommendable for the LCA.
In LCA analyses, the definition of a temporal and physical reference scale is particularly extensive, yielding to very complicate, if not impossible, analysis of the system’s boundaries. Figure 4.4 illustrates a global ecosystem where the only system’s input is the solar energy. Questions can rise when addressing the origin of the natural resources. For instance, fossil fuels accounts, -should be evaluated by ascending till their geological formation time? And then, how to do it? These questions are, so far, by no means clarified by the LCA.
Furthermore, the process is inherently complex, time consuming, and costly. It requires considerable data and relies on a variety of assumptions. Second, there are continuing questions about impact assessment, especially for "local" issues such as eco-toxicity, human health, or nutrient enrichment (eutrophication). Finally, communicating the results of a Life Cycle Assessment is a considerable challenge, given the complexity of the method.
137
Figure 4.4: Global Ecosystem for LCA
More concretely, the LCA can be used to compare different energy generation systems. The energy systems should be made to last in time, since their investment costs are especially high. So we are comparing, e.g., similar fossil fuel power plants, which live time are similar, using the variables of the LCA that give a priority to the environment. In this case the results reflect the mass/energy inputs-outputs, which for similar plants became practically indiscernible. This is explained because; this type of analysis despises, to a certain extent, the thermodynamic variables of the studied system, which for energy systems analysis are extraordinarily important. This fact made of the LCA a not quite appropriate analysis for energy systems, seeing that in order to reflect the main thermodynamic variables of the system environomic analyses appears to be more appropriated.
Economic subsystem Ene rgy
Materials
Degraded energy Degraded mate rial Solar energy
Low g rade the rmal energy Nature Resources Environmental Waste assimilation Recycled materials Economic subsystem Ene rgy Materials Degraded energy Degraded mate rial Solar energy
Low g rade the rmal energy Nature Resources Environmental Waste assimilation Recycled materials
138
References
1
Leontief, W., 1982, Academic economics, Science 217, pp.104-107
2 El-Sayed, Y.M., 2002, “Application of exergy to design” Eng. Conv. Mang. 43, pp. 1165-1185. 3 Herring H., 2006, “Energy efficiency – a critical view”, Energy 31, pp. 10-20
4 Hall, C.A.S., Lindenberger, D., Kummel, R., Kroeger, T., Eichhorn, W., 2001, “The need to reintegrate the natural sciences into economics”, BioScience, 51, pp. 663–67
5 Tonon, S., Brown, M.T.; Luchi, F., Mirandola, A., Stoppato, A., Ulgiati, S., 2005, “An integrated assessment of energy conversion processes by means of thermodynamic, economic and environmental parameters” Energy, Inpress corrected proof.
6
Afgan NH, Carvalho MG, Hovanov N.V., 2000. “Energy system assessment with sustainability indicators”, Energy policy; 28: 603-612
7 Afgan NH, Carvalho MG. 2002 “Multi-criteria assessment of new and renewable energy power plants”, Energy; 27:739-755.
8 Ahren, J. 1980, “The exergy method of energy systems analysis” J. Wiley.
9 Lozano, M.A:, Valero, A., 1993, “Theory of the exergetic cost”, Energy,Vol 9, pp. 939-960
10 Szargut, J., Morris, D.R., Steward, F.R., 1988, “Exergy analysis of thermal, chemical and metallurgical processes” Hemisphere Pub. Co., New York.
11
Berry, R.S., Fels, M., 1973, “Energy cost of automobiles” Bull. Atom. Sci.; 29.
12 Odum, H.T., 1988, “Self organization, transformity and Information” Sciense, vol. 242, pp. 1132-1139
13 Fava, J., Denison, R., Jones, B, Curran, M., Vigon, B., Selke, S., Barnum, J., 1991, “A Technical Framework for Life Cycle Assessment”. Pub. by SETAC, Pensacola, Fla.
14 Sciubba, E., 2003, “Cost analysis of energy conversion systems via novel resource-ased quantifier”, Energy, 28, pp. 457-477.
15 Munda, G., 1996, “Cost-benefit analysis in integrated environmental assessment: methodological issues”, Ecological Economics, 19, pp. 157-168
16 Hafele, W., 1981, “Energy in a finite world: global systems analysis” Toronto: Ballinger.
17Valero, A., M.A. Lozano, M. Muñoz, 1986,.”A General Theory of Exergy Saving” ASME Book H0
341A. WAM 1986 AES, vol. 2-3, pp. 1-22.
18Valero A., L. Serra, and C. Torres, 1992, “A General Theory of Thermoeconomics”: Part I: Structural Analysis.International Symposium ECOS’92. ASME Book I00331, 137-145.Zaragoza, Spain.
139
19 Evans, R.B., Tribus, M., 1965, “Thermo-economics of saline water conversion” Ind. Eng. Chem. Process Des. Dev. Vol. 4, pp. 195-206
20 El-Sayed Y., Evans, R., 1970 “Thermoeconomics and design of heat systems”. Journal of Engineering Power 92:27, 35
21 Tribus, M., El-Sated, Y.M., 1980, “Themoeconomis Analysis of an Industrial process” Center for advanced Engineering Study, MIT, Cambridge, MA
22
El-Sayed Y. M., 1988,.”A Decomposition Strategy for Thermoeconomics Optimization of a Given New Configuration Approaches to the Design and Optimization of Thermal Systems”. Wepfer and Moran eds., 41-47. ASME. New Yrk,USA.
23 Gaggioli, R., editor, 1980, “Thermodynamics: second law analysis” ACS Symposium series, No. 122. 24 Gaggioli, R., editor, 1983, “Efficiency ans costing” ACS Symposium series, No. 235.
25 Valero, A., Torres, C., Lozano, M.A., 1989, “On the unification of Thermoeconomics Theories”, Simulation of thermal energy systems, pp.63-74, The ASME
26 El-Sayed, Y., 1996, “A second law based optimization,” part 1 and 2. J. Eng. Gas turbine power, 118,pp. 693-70
27 Lazzaretto, A., Tasatronis, G., 1997, “On the quest for objective equations in exergy costing” ASME Advanced energy system division, AES vol. 37. pp. 197-210
28 Bejan, A., Tsatsaronis, G., Moran, M., 1996, “Thermal Design and Optimization”. New York: John Wiley and Sons,
29 Valero, A., 1995, “Thermoeconomics: the Meeting Point of Thermodynamics, Economics and Ecology” in (E. Sciubba and M. Moran Editions) Second Law Analysis of Energy Systems: Towards the 21st Century, pp. 293-305, Circus, Rome.
30
Frangopoulos, C.A., and Caralis Y.C., 1997, “A Method for taking into account environmental impacts in the economic evaluation of energy system”, Energy Conversion and Management, 38, pp. 1751-1763
31 Pelster, S., Favrat, D., von Spakovsky, M.R., 2001, “Thermoeconomic and environomic modelling and optimisation of the synthesis, design, and operation of Combined Cycle with advanced options” ASME Journal of Engineering for Gas Turbines and Power, 123, pp. 717-726.
32 Valero, A., 1998, “Thermoeconomics as a conceptual basis for energy-ecological analysis” proceedings of the International Workshop on Advances in Energy Studies, Porto Venere, italy
33
Gaggioli, R.A., Wepfer, W.J., 1980, “Exergy Economics” Energy; 5.
34 Tastsaronis, G., Park M.,H., 2002, “On avoidable and unavoidable exergy destruction and investment cost in thermal systems”Enr. Conv. Mang., vol. 43,pp. 1259-1270
140
35 Dincer, I., Cengel, Y.A., 2001, “Energy, entropy and exergy concepts; and their roles in thermal engineering” Entropy, vol. 3, pp. 116-149
36 Rosen, M.A., Dincer, I., 1999, “Exergy analysis of waste emissions” Int. J. Energy, vol. 23, pp. 1153-1163
37 Van Gool, W., 1998,“Thermodynamics of chemical references for exergy analysis”, Energy Conversion Management, vol. 39, pp. 1719-1728
38
Szargut J., 1988, “Exergy losses in the chains of technological processes”, Bull. Pol. Acad. Ser. Techn. 36 (7–9) pp.513–521.
39 Rao S. 1996, “Engineering Optimization Theory and Practice”. New York: John Wiley & Sons, 40 Von Spakovsky MR., 1994, “Application of engineering functional analysis to the analysis and optimization of the CGAM problem”. Energy;19(3):343-64
41 Dincer, I., Rosen, M.A., 2005, “Thermodynamic aspects of renewable and sustainable development”. Renewable and Sustainable Energy Reviews;. 9, pp. 169-189.
42 Frangopoulos C.A., 1994, “Application of the thermodynamic functional approach to the CGAM problem”. Energy;19 (3): 323-42
43
Frangopoulos C.A., 1992 “An introduction to environomic analysis and optimisation of energy-intensive systems”. In: Proc. of ECOS ’92, 231-239.
44 Curti, V., von Spakovsky, M.R., Favrat, D., 2000, “An Environomic Approach for the Modelling and Optimization of a District Heating Network Based on Centralized and Decentralized Heat Pumps, Cogeneration and/or Gas Furnace (Part I: Methodology)”, International Journal of Thermal Sciences , vol. 39, no. 6, June, Elsevier, France.
45 Curti, V., Favrat, D., von Spakovsky, M.R., 2000, “An Environomic Approach for the Modeling and Optimization of a District Heating Network Based on Centralized and Decentralized Heat Pumps, Cogeneration and/or Gas Furnace (Part II: Application)”, International Journal of Thermal Sciences , vol. 39, no. 6, June, Elsevier, France.
46 Von Spakowski M.R., Frangopoulos C.A., 1993, “A global environomic approach for Energy Systems analysis and optimization, Part I”, Energy systems and Ecology. ENSEC'93, Cracow Poland
47 Von Spakovsky M.R Frangopoulos C.A., 1993, “A global environomic approach for Energy Systems
analysis and optimization, Part II”, Energy systems and Ecology, ENSEC'93, Cracow Poland
48 Sciubba, E., Ulgiati, S., Lior, N., 2006, “Editorial introduction” for the second biennial International workshop “advanced in Energy Studied”Porto Venere, Italy 2000, Energy, 31, pp. 1-2
49 Pearce D.W., Turner R.K., 1991, “Economics of Natural Resources and the Environment”. Baltimore: The Johns Hopkins University Press.
141
50 Funtowicz, S.O., Munda, G., Paruccini, M., 1990, The aggregation of environmental data using multi-criterial methods“ Envirometrics, 1:pp. 353-368
51 Morosini, M., Schneider,C., Roehm, M., Gruenert, A., Ballshmiter, K., 2002, “Umweltindikatoren – Grundlagen, Methodik, Relevanz” Arbeitsbericht Nr. 185, Band 1, ISBN 3-934629-37-7, Akademie fuer Technikfolgenabshaetzung, Stuttgart.
52 Morosini, M., Schneider,C., Kochte-Clemens, B., Losert, C., Ballshmiter, K., 2001,
“Umweltindikatoren –Gegenueberstellung, Bewertung, ud Auswahl” Arbeitsbericht Nr. 185, Band 2, ISBN 3-934629-37-7, Akademie fuer Technikfolgenabshaetzung, Stuttgart.
53 Morosini, M., Fiebe, E., Schneider, C., Roehm, M., Ballshmiter, K., 2001, “Umwelt und nachhaltigkeitsberichte, 61 Profile” Arbeitsbericht Nr. 185, Band 3, ISBN 3-934629-37-7, Akademie fuer Technikfolgenabshaetzung, Stuttgart.
54 Daly, H. E., 1974, “The Economics of the Steady State” The American Economic Review, Vol. 64,
No. 2, Papers of the Eighty-sixth Annual Meeting of the American Economic Association, pp. 15-21 55 Meadows, D., 1998, “Indicators and Information Systems for Sustainable Development” Report to the Balaton Group. Published by the Sustainability Institute. Hartland Four Corners VT.
56
Laganisa, J., Debeljakb, M., 2006 “Sensitivity analysis of the emergy flows at the solar salt production process in Slovenia”, Journal of Ecological Modelling, 194, pp. 287–295
57.Scienceman, D.M., 1987 “Energy and Emergy” In G. Pillet and T. Murota (eds), Environmental Economics: The Analysis of a Major Interface. Geneva: R. Leimgruber. pp. 257-276. (CFW-86-26)
58 Odum, H.T., 1986, “Ecosystem Theory and Application”, in N.Polunin, Ed Wiley, New York.
59 Odum, H.T. and Odum E.C., 2000, “A Prosperous way Down: Principles and Policies”, Colorado University Press, Colorado
60
ISO 14040, 1997, “Environmental Management –Life cycle Assessment- Principles and Framework International Organization for Standardization”, Geneva.
61 Cornelissen, R.L., 1997, “Therodynamics and sustainable development, The use of exergy analysis and the reduction of irreversibility” PhD Thesis, by R.L. Cornelissen, Enschede, The Netherlands
