School of GeoS ciences
Dissertation For the degree of
MSc in Ecological Economics
Lina Isabel Brand Correa*
August 2014
* Beneficiaria COLFUTURO 2013.
EXERGY AND USEFUL WORK ANALYSIS AS A TOOL FOR IMPROVED ENERGY POLICY MAKING: THE CASE OF THE
COLOMBIAN ENERGY SECTOR
Lina Isabel Brand Correa
A dissertation presented for the degree of Master of Science University of Edinburgh, 2014.
I assert my right to be identified as the author of this work in accordance with section 78 Copyright Designs and Patents Act 1988.
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THE UNIVERSITY OF EDINBURGH
(Regulation ABSTRACT OF THESIS 3.5.13)
Name of Candidate Lina Isabel Brand Correa
Address 39/5 Marchmont Crescent, EH9 1HF, Edinburgh
th Degree MSc. in Ecological Economics Date 15 of August, 2014
Title of Thesis Exergy and Useful Work Analysis as a Tool for Improved
Energy Policy Making: The Case of the Colombian Energy Sector
No. of words in the main text of Thesis 20653
Energy systems entail a dualism: they are absolutely vital for the normal functioning of societies, but the activities related to them are threatening the stability of the natural environment where societies develop (by being the main source of greenhouse gas emissions). Therefore, energy systems need to be maintained and further expanded, whilst simultaneously reducing their negative environmental impacts. In this sense, a deeper understanding of the thermodynamic concepts behind energy use and conversion processes is needed. Exergy and useful work provide such an understanding and hence their analysis can be used as a tool for improved energy policy making, particularly when dealing with efficiency improvements.
In consideration of the above, this dissertation first looks into the energy dualism, followed by the description of the conceptual framework which orientates the work. Subsequently this is applied to the analysis of Colombia as an illustrative case study, taking into account data availability and specific features of that country’s energy system, which in themselves provide special analytical interest. Finally, this dissertation discusses methodological issues and results, as well as the energy policy implications derived from the analysis, both in general/conceptual terms and in the specific case of Colombia.
As a result, it was found that exergy and useful work analysis is a tool that can complement traditional energy analysis when assessing national energy systems. Exergy and useful work provide significant conceptual improvements, as well as strengthening the comprehension of the whole flow of energy through society. Furthermore, exergy and useful work analysis leads to different energy policy recommendations when compared to the traditional energy based analysis, particularly regarding energy sources for electricity generation, efficiency dilution effects and leapfrogging opportunities.
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ACKNOWLEDGEMENTS
First and foremost I would like to extend warm thanks to Paul Brockway for his generous sharing of time, knowledge and experience, and for introducing me into the academic circle of exergy. This dissertation would not have achieved what it has without his kindness and support. I would also like to thank sincerely my supervisor, Claudio
Cattaneo, especially for his critical and opportune advice when in danger of getting carried away by my enthusiasm for the topic. Additionally, a big thank you to Oscar
Gonzalo Manrique for sharing the data for Colombia, but ever more so for awakening my interest in this topic some years ago. And to Héctor Iván Velásquez and Sergio A. Giraldo for being so patient with me while I struggled to grasp, at least partially, the thermodynamics behind it all.
On the personal side, I would like to thank especially my library buddies R and T for providing such nice study breaks, while creating our own gastronomic/cultural routine!
Also to my family and friends back in Colombia, whose support even across the distance felt so close, and the thought of seeing them again gave me strength and inspiration.
Finally, heartfelt acknowledgements both to my dad, who is a constant source of objective and loving advice, and my mom, who virtually walked home with me every late night, patiently listening to all the ups and downs of this rollercoaster experience.
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TABLE OF CONTENTS
Acknowledgements ...... i Table of Contents ...... iii Table of Tables ...... v Table of Figures ...... vii List of Abbreviations, Symbols and Units ...... ix Chapter 1. Introduction...... 1 Chapter 2. Dualism of Energy for Modern Societies ...... 5 2.1. Energy as key for economic growth ...... 5 2.2. Energy as one of main causes of climate change and resource exhaustion ...... 9 2.3. Energy transition and the role of efficiency ...... 12 Chapter 3. Exergy and Useful Work ...... 15 3.1. Definition of relevant concepts ...... 15 3.2. Literature review of exergy applications ...... 27 3.3. Rationale and research question ...... 33 Chapter 4. The Colombian Case ...... 37 4.1. Colombia and its energy sector ...... 37 4.1.1. General context ...... 37 4.1.2. Energy reserves and potential ...... 39 4.1.3. Current energy use ...... 41 4.1.4. Evolution of energy use ...... 44 4.2. Methodology ...... 44 4.3. Past exergy and useful work ...... 47 4.4. Data analysis ...... 52 4.5. Future energy projections (PENs) ...... 61 Chapter 5. Discussion ...... 65 5.1. Methodology ...... 65 5.2. Results ...... 69 5.3. Policy implications ...... 72 5.3.1. General / conceptual ...... 72 5.3.2. Colombia ...... 75 Chapter 6. Conclusions ...... 81 References ...... 85 Appendix A ...... 101
iii
TABLE OF TABLES
Table 1. Energy forms and types classification ...... 16 Table 2. Units of energy, exergy, work, heat and power in the different systems of units 17 Table 3. Sectors and Consumption Categories ...... 50 Table 4. Details of TFC-UW and TPES-UW exergy efficiencies (1975-2009) ...... 53 Table 5. Exergy coefficients for Colombia's energy sources ...... 101
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TABLE OF FIGURES
Figure 1. Energy production and GDP for the world from 1830 to 2000 ...... 6 Figure 2. Global GHG emissions and fossil fuels ...... 10 Figure 3. UK's production and consumption emissions ...... 11 Figure 4. Resource classification ...... 12 Figure 5. Energy and exergy content of different systems ...... 21 Figure 6. Energy and exergy efficiency for 4 conversion systems ...... 24 Figure 7. Energy and exergy flow diagrams of a condensing power plant ...... 25 Figure 8. Energy system levels of analysis ...... 26 Figure 9. The flow-path of exergy to energy services ...... 27 Figure 10. Map of Colombia ...... 38 Figure 11. Colombia's non-renewable energy resources in 2013 ...... 40 Figure 12. Colombia's 2012 TPES and TFC ...... 42 Figure 13. TPES/TFC ratio and share of electricity generated by hydropower ...... 43 Figure 14. Colombia’s TFC by sector as a percentage of the total (2012) ...... 43 Figure 15. Energy sources used by sector (2012) ...... 44 Figure 16. TPES by energy sources as a percentage of the total (1975-2012) ...... 44 Figure 17. Colombia's primary exergy inputs ...... 47 Figure 18. Colombia's primary exergy inputs as a share of the total primary exergy input ...... 48 Figure 19. Colombia's secondary exergy inputs ...... 49 Figure 20. Colombia's secondary exergy inputs as a share of the total secondary exergy input ...... 49 Figure 21. Total exergy inputs in Colombia (1975-2009) ...... 49 Figure 22. Colombia's total exergy inputs by sector ...... 51 Figure 23. Colombia's total exergy inputs by sector as a percentage of total exergy inputs ...... 51 Figure 24. Total useful work in Colombia (1975-2009) ...... 52 Figure 25. Colombia's aggregate exergy efficiency (1975-2009)...... 53 Figure 26. Exergy efficiency by sectors and total exergy efficiency ...... 54 Figure 27. Exergy efficiency by agriculture processes and total agriculture exergy efficiency ...... 55 Figure 28. Exergy efficiency by industry processes and total industry exergy efficiency .. 55 Figure 29. Level of activity of the sectors ...... 56 Figure 30. Industry sector share of processes ...... 57 Figure 31. Residential sector share of processes ...... 57 Figure 32. Transport sector share of processes ...... 58 Figure 33. Exergy, useful work and exergy efficiency in Colombia (1975-2009) normalized 1975=1 ...... 59 Figure 34. Comparison of several country's overall exergy efficiency ...... 60 Figure 35. Projected TFC in the BAU and alternative scenario...... 63 Figure 36. Projected GHG emissions (PEN 2010) ...... 64 Figure 37. Comparison between UPME and IEA data ...... 66
vii
Figure 38. 2010 PEN projections and hypothetical stagnated TFC-UW efficiency ...... 70 Figure 39. Exergy and useful work in relation to GDP (1975-2009) ...... 72 Figure 40. Diagram of the potential exergy efficiency improvements ...... 74
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LIST OF ABBREVIATIONS , SYMBOLS AND UNITS
ANDI National Businessmen Association of Colombia BEN National Energy Balance COMMEND Community for Energy, Environment and Development E Exergy inputs Exergy efficiency GDP Gross Domestic Product IEA International Energy Agency LEAP Long -range Energy Alternatives Planning system Mtoe Million tonnes of oil equivalent OLADE Latin American Energy Organization PEN National Energy Plan SEI Stockholm Environment Institute TCal Tera calories TFC Total Final Consumption TPES Total Primary Energy Supply UPME Energy and Mining Planning Unit URE Rational Use of Energy UW Useful Work
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Energy is important enough to become a determinant, or at least conditionant, of all human activity IDEE (1994, p. 52)
Chapter 1. INTRODUCTION
Energy is the backbone of modern societies; their normal functioning is unconceivable without a sufficient, constant and secure supply of energy. That is the reason why governments all around the world maintain and further develop energy systems that satisfy their country’s needs. Energy is also important to achieve what are now considered minimum living conditions, therefore it must be affordable by everybody.
The current context of climate change (IPCC, 2013) poses additional challenges to the energy sector, especially since the majority of global greenhouse gas (GHG) emissions are a consequence of activities related to energy systems (IEA, 2012a). Thus, besides being secure and affordable, energy supply must be low carbon emitting. Together these three objectives of energy policy (security of supply, affordability and low carbon emissions) are grouped into what has been called by the World Energy Council the “energy trilemma” (Harvey, 2014).
By taking a step back and looking at the bigger picture, the trilemma can be transformed into a dualism: energy systems are vital for societies, but at the same time they are negatively affecting the natural environment that supports human life. In this sense, it is clear that in order to solve the energy dualism, energy systems need to be maintained and expanded, but they also need to transition towards being low carbon and sustainable.
However, resolving the energy dualism is more easily said than done. Energy systems are complex and energy is not like any other commodity. It requires large infrastructure and capital investments that lead to lock-in into certain technological and fuel alternatives
(Unruh, 2000), limiting substitution possibilities. Furthermore, it needs to be delivered to
Introduction 1
final users whenever it is needed, which becomes a vital consideration when the option of storage is not yet fully developed.
In addition, history teaches us that energy transitions do not happen overnight. The past full transition from traditional energy sources to fossil fuels took around 400 years, i.e. the full diffusion of the new energy sources and associated technologies (Fouquet, 2010). The ongoing transition towards low carbon sustainable energy systems is no exception; current evidence shows that renewables are not being implemented at the pace required to avoid catastrophic climate change consequences (IEA, 2014b).
Therefore, careful planning and efficiency improvements are important while a very much needed transition towards renewable and sustainable energy sources takes place.
Moreover, efficiency improvements represent the largest and least costly alternative to reduce the emissions caused by energy systems (IEA, 2008, p. 40), hence they are being promoted by most energy related organizations both national (see for example DECC,
2012; EIA, 2014; Univerisdad Nacional de Colombia & Fundación Bariloche, 2010) and international (see for example IEA, 2008; WEC, 2010).
In order to promote the efficiency alternative, a thorough understanding of the thermodynamic concepts behind it is needed. Nonetheless, when projecting future efficiency changes and their impact on energy demand –in order to formulate policies that meet such projections- , national and international organizations tend to rely on a first law of thermodynamics approach (i.e. energy analysis). This can be complemented by a second law of thermodynamics approach (exergy and useful work analysis) which, by analysing the maximum work obtainable from a system, reveals the maximum theoretical efficiency possibilities (Rosen, 2006a) and in turn suggests different policy recommendations.
Efficiency analysis can go a step further, moving into the sphere of energy services. Here the use of energy is considered in relation to the service it provides, for instance lighting,
Introduction 2
transportation or comfortable ambient temperature. In this context, efficiency can be assessed taking into account additional technical and social elements, which also lead to alternative policy recommendations. Although the importance of this level of analysis is fully recognised, as will be acknowledged throughout the dissertation, data availability limitations make it outside the scope of the present work.
Bearing in mind the above, the main goal of this dissertation is to analyse conceptually how exergy and useful work analysis can be used as a tool for improved energy policy making, based on the acknowledgement that there is an energy dualism upon which it is important to act in the short term. The analysis will be developed through an illustrative case study: Colombia, where, as in most countries, energy and energy efficiency are the concepts used to guide projections and policy making.
The selection of Colombia as a case study was made in part on the grounds of data availability on exergy efficiencies for that country, basic data deriving from previous research but further elaborated and analysed in the context of this dissertation. There are, however, other factors that make Colombia an interesting case study. Firstly, little previous work exists on the analysis of exergy and useful work in the context of energy policy for a developing country. Secondly, energy dualism is particularly relevant for developing countries in general. Finally, Colombia has considerable potential for developing alternative energy sources and the transition to a fossil fuel based energy system is still incomplete, thereby presenting interesting opportunities for leapfrogging.
Additionally, this dissertation will discuss the energy policy implications of exergy and useful work analysis, specifically for the Colombian case, but also for energy policy in general from a conceptual point of view. Furthermore, the value of exergy and useful work analysis will be related to specific demand, supply and efficiency concerns, which are the major areas of energy policy focus.
Introduction 3
The dissertation is organised into six main chapters. Following this introduction, the second chapter addresses the aforementioned dualism, explaining the importance of energy for societies (particularly for economic growth) but also the environmental impacts of current energy systems. This leads to the justification of the urgent need to undergo an energy transition towards low carbon and sustainable energy systems, but also the need to implement efficiency measures as an intermediate step.
The third chapter provides the conceptual framework needed to understand why exergy and useful work are relevant concepts to energy policy making. In this sense, a detailed explanation of exergy and useful work is given, followed by a literature review that reveals the paucity of their application in the energy policy field, and finally the rationale and research question underlying this dissertation are laid out.
The fourth chapter addresses the case study of Colombia’s energy system. It describes the country’s energy resources and potential in order to provide context. Subsequently it describes the methodology employed to analyse it. Existing exergy and useful work data are then presented, upon which a detailed analysis is undertaken, particularly with regard to the factors behind exergy efficiency changes. The chapter concludes with the evaluation of energy scenarios constructed by the Colombian government´s Unit of Mining and
Energy Planning (UPME in Spanish).
The fifth chapter develops a discussion of the three main issues that arise from the dissertation: methodological concerns, detailed results, and policy implications. Finally, the sixth chapter presents the main conceptual and case study related conclusions, especially in relation to policy implications, which are the main goal of this work.
Introduction 4
Energy sources of various kinds heat and power human development, but also put at risk the quality and long-term viability of the biosphere Hammond (2000, p. 304)
Chapter 2. DUALISM OF ENERGY FOR MODERN SOCIETIES
Energy is vital for the normal functioning of modern societies; it is central to economic and development related issues, but it is also central to pressing environmental issues.
Both these aspects are particularly relevant for developing nations, where large shares of the population cannot yet meet their basic needs and where the most adverse consequences of climate change will be felt (IPCC, 2014).
Economic growth and societal development depend on the availability of energy and material resources, but also life on earth depends on the conservation of the fragile conditions of ecosystems. In this section, this dual role of energy, as something absolutely essential for societies but at the same time as something that currently entails serious environmental impacts, will be analysed, in order to justify the need for a transition towards renewable and sustainable energy sources and hence the role of efficiency while the transition takes place.
2.1. ENERGY AS KEY FOR ECONOMIC GROWTH
Modern societies are absolutely dependant on a constant flow of energy. This dependence becomes evident when the flow is interrupted (Verbong & Loorbach, 2012), for example during electricity blackouts or during supply cut offs of other energy carriers (such as oil and gas). The disturbances in the normal functioning of societies prove that when the flow of energy is altered societies suffer: from simple events such as people getting stuck in elevators, to more serious issues such as production processes stopping, transport systems collapsing, the flow of information being disturbed and political tensions arising.
Energy systems are the lifeblood not only of modern societies, but also of any society throughout history. Cipolla (1978) describes the history of world population based on the
Dualism of Energy for Modern Societies 5
increased control over energy sources, moving from animated energy converters in agricultural societies (human and animal muscles) towards inanimate energy converters in industrial societies (steam engine, gas turbine and electric devices, amongst others). In other words, the increased control over and use of natural resources, particularly energy carriers, has led to a steep increase in population and productive activity.
In the same line of thought, White (1943) explains the history of cultural evolution in terms of energy and the efficiency of energy conversion processes. For White (1943) culture has the purpose of satisfying human needs, therefore humanity has to continue harnessing and exploiting natural resources in order for cultural progress not to cease.
Fouquet and Pearson (1998) provide empirical evidence of the above when analysing one thousand years (1000-2000) of energy statistics for the UK, showing that energy use has increased together with population and production, more markedly in the last two centuries when energy use has increased significantly (see Figure 1).
Figure 1. Energy production and GDP for the world from 1830 to 2000 Source: Murphy and Hall (2011, p. 68).
Dualism of Energy for Modern Societies 6
Energy use is linked primarily to productive activity and therefore to economic growth when measured by Gross Domestic Product (GDP, which measures the amounts of goods and services produced in a country in a year). This link is empirically illustrated by Figure
1, and section 3.1 will conceptually support the historical evidence by demonstrating, using physics and thermodynamics, that not a single productive process can be understood without the use of energy. Therefore, although these historical accounts are very valuable, they become more explicit when there is an understanding of important physic and thermodynamic concepts.
However, energy has not formally entered mainstream economic growth theory. This theory is based on the classic economics conception of labour and capital being the main factors of production. After World War II, when empirical corroboration of economic growth theory was possible (given the availability of national accounts), almost simultaneously Solow (1956) and Swan (1956) developed a model that used the Cobb-
Douglas function to perform statistical tests. The main finding was that a third factor of production, an exogenous one, was needed to explain economic growth, namely technological change, although it was used “as a shorthand expression for any kind of shift in the production function” (Solow, 1957, p. 312).
This third factor of production has mutated over the years, both in name and conception.
It has been called technical change, technological progress, the Solow residual and Total
Factor Productivity (TFP). It has also been endogenized in some economic growth models since the 1980s, using variables such as knowledge or human capital (Romer, 1994).
However, its true meaning continues to be quite ambiguous, hence it is not surprising that it has been referred to by some authors as the “measure of our ignorance” (Abramovitz,
1956, p. 11) or even as a “black box” (Rosenberg, 1982, p. 11).
The fact that mainstream economic theory has not incorporated energy in its conceptualization of economic growth is of considerable concern in the face of a much needed energy transition. There have been efforts, however, from disciplines such as
Dualism of Energy for Modern Societies 7
ecological economics to explain the role of natural resources in general and energy in particular in economic activity. In this line of thought, the theoretical contributions since the late 19 th century of some authors must be recognized: Serhii Podolinsky in the last decades of the 19 th century, Frederick Soddy and Alfred Lotka in the first half of the 20 th century (Cleveland, 1987; Martínez-Alier, 1987).
Since the second half of the 20 th century theoretical contributions continued with Nicholas
Georgescu-Roegen (1975), Herman E. Daly (1974, 1987), Reiner Kümmel (1982, 2011),
Cutler J. Cleveland and others (Cleveland, Kaufmann, & Stern, 2000; Cleveland & Ruth,
1997), Charles E. Hall and others (Hall & Kiltgaard, 2012), Bernard Beaudreau (1999),
Vladimir Pokrovsky (2003), Benjamin Warr and Robert Ayres (Ayres, Ayres, &
Pokrovsky, 2005; Ayres, Ayres, & Warr, 2003; Ayres, Turton, & Casten, 2007; Ayres &
Voudouris, 2014; Warr, Ayres, Eisenmenger, Krausmann, & Schandl, 2010), just to mention the main ones.
The two latter authors in particular (Ayres & Warr, 2009), find that by analysing the efficiency with which energy and materials flow in the economic system, an objective measure of technological progress can be found: useful work (see section 3.1 for a detailed definition). Furthermore, they use this new measure, together with a Linear Exponential function -LINEX first derived by Kümmel (1982)- completely different from the traditional Cobb-Douglas one, to test empirically its explanatory power.
They find that the Solow residual is almost entirely explained by useful work for the period 1900-2000 in the US and Japan, i.e. they endogenize technological progress using an objective and physics based measure. But more importantly, their work provides an explanation and a quantification of the shared intuition of many ecological economists:
“[P]roduction in the real world cannot be understood without taking into account the role of materials and energy” (Ayres & Warr, 2005, p. 182).
Dualism of Energy for Modern Societies 8
Finally, energy use has also been linked with development and quality of life. Lambert et al. (2014) find that energy indices (EROI and energy use per capita, amongst others) are correlated with higher standards of living (measured by the Human Development Index, percent of children under weight, health expenditures, Gender Inequality Index, literacy rate and access to improved water). The United Nations Advisory Group on Energy and
Climate Change (2010) also considers energy a key for poverty alleviation, health improvements, education access and food security, given that all of the above need energy supply to be achieved.
Even though the relationship between energy and quality of life is more indirect and cannot be proven by physics or thermodynamic concepts, it makes the energy question even more relevant for developing countries, which already need to consider the energy issue seriously in relation to economic growth 1. If economic growth is to continue into the future and if developing countries are to catch-up with developed countries in terms of living standards, there needs to be a greater use of energy sources, and thus a greater understanding of their physical and thermodynamic properties.
The empirical and historical understanding of the vital role energy has to play in economic growth and in the normal functioning of our societies addressed in this section, must be accompanied by an assessment of the environmental consequences of its use.
Hence, this issue will be analysed in the next section.
2.2. ENERGY AS ONE OF MAIN CAUSES OF CLIMATE CHANGE AND RESOURCE
EXHAUSTION
1 This dissertation will not address the issue of whether economic growth is a positive thing for societies and for the environment, but it is acknowledged that it is a much contested issue and that from a biophysical perspective evidence points towards the contrary.
Dualism of Energy for Modern Societies 9
Globally, the energy sector is the major emitter of GHG 2: around 65% of global GHG emissions originate from activities related to the energy system, i.e. extraction, transformation, delivery and use, and this figure rises to 83% in Annex I countries 3 (IEA,
2012a). The combustion of fossil fuels entails the emission of CO 2 resulting from the oxidation of carbon, which accounts for 92% of the emissions related to the energy sector; the remaining 8% is constituted by CH 4 and N 2O originated in other processes such as mining and transmission (IEA, 2012a). In 2011 81.6% of the world’s total energy supply came from fossil fuels, namely coal, oil and natural gas (IEA, 2012b), which has implications for both climate change and resource exhaustion. Figure 2 shows the relationship between global GHG emissions and fossil fuels.
Figure 2. Global GHG emissions and fossil fuels Source: Own elaboration based on data from IEA (2012a, 2012b).
Regarding climate change, there is now a scientific consensus that increased anthropogenic GHG emissions are linked with climate change (IPCC, 2013). Given that energy accounts for most GHG emissions worldwide, that fossil fuels are the world’s main energy source and that energy use has increased dramatically since the industrial
2 The GHG are: water vapour, CO 2 (carbon dioxide), CH 4 (methane), N 2O (nitrous oxide), O 3 (ozone) and CFC (chlorofluorocarbon). 3 Annex I countries correspond to industrialized countries and economies in transition as defined by the United Nations Convention on Climate Change (UNCCC) (IEA, 2012a).
Dualism of Energy for Modern Societies 10
revolution, the implications for climate change of the world’s energy mix being dominated by fossil fuels are clear. This is illustrated by Figure 2, especially if seen from right to left.
Considering the importance of energy for economic activity discussed in section 2.1, it might then seem contradictory the recent decreasing trend of emissions in certain countries (IEA, 2012a); however, it is important to note that this trend can be deceiving.
Emissions can be reduced in a single country even as economic growth keeps rising, but when taking into account global trade this decarbonisation of certain economies is not as clear as it might seem.
In a globalized world, trade has a major role to play. This is revealed when a country’s emissions analysis is done through the lens of consumption (Barrett et al., 2013; Davis &
Caldeira, 2010), where the embedded emissions in imported goods are taken into account.
The difference between the UK’s GHG emissions from production and consumption can be seen in Figure 3.
Figure 3. UK's production and consumption emissions Source: Barrett et al. (2013, p. 454).
It is not only in terms of climate change emissions that emissions and energy system related activities affect the environment. Energy has negative impacts in other areas of
Dualism of Energy for Modern Societies 11
environmental concern which include: stratospheric ozone depletion, acid precipitation and deposition, air pollution, smog and air quality and visibility degradation, water pollution (including groundwater and surface water degradation), solid waste disposal, hazardous waste disposal, soil degradation, oil spills and other major environmental accidents, and radiation and radioactivity releases (Rosen, 2002a).
On the other hand, regarding resource exhaustion, fossil fuels are deposits that are emptied as they are used. This corresponds to a resource classification following Wall
(1977), in which there are flows and stocks (see Figure 4). The former are unlimited in time (for example sun light), whilst the latter are limited in time and subdivided into live stocks or funds (such as a forest) and dead socks or deposits (such as oil, coal and gas).
Fossil fuels are non-renewable in our time frame and therefore finite, which means that they could be exhausted if they continue to be harnessed. Out of the three main fossil fuels, oil is the one that could be exhausted first, although there is no consensus about a time where ‘peak oil’ will be reached (Bradshaw, 2010).
Figure 4. Resource classification Source: Adapted from Wall (1977, p. 28).
2.3. ENERGY TRANSITION AND THE ROLE OF EFFICIENCY
Dualism of Energy for Modern Societies 12
Taking into account the environmental and resource exhaustion consequences of current energy sources, together with the vitality of energy for societies, it becomes clear that an energy transition must take place. However, history teaches us that energy transitions are slow and led by the opportunity to develop better or cleaner energy sources (Fouquet,
2010). Although in previous transitions the role of prices and scarcity was determinant, in this transition the role of regulation and directed action towards the reduction of GHG emissions will be a key component, given the pressing concerns about climate change and the adoption of legally binding commitments to reduce GHG emissions (Fouquet, 2012;
Pearson & Foxon, 2012). Therefore, energy policy must be directed towards sustainable and least environmentally harmful energy sources, i.e. renewable energy sources.
Nonetheless, the current rate of development of sustainable renewable energy is not sufficient to meet the 2⁰C stabilisation target established by the IPCC. As the IEA (2014b, p. 14) states: “[T]oday’s policies and market signals are not strong enough to switch investment to low-carbon sources […] at the necessary scale and speed”. In parallel, there is a debate around the decoupling of economic activity from energy and material use.
Decoupling can be absolute or relative: absolute decoupling is a myth, because as was mentioned before, economic activity cannot be understood without the use of energy; relative decoupling is possible through efficiency improvements, but it has an upper limit
(Jackson, 2009).
Thus, energy efficiency improvements should only be considered as a way to ease the transition towards a low-carbon economy, not as a final solution to the dualism described above. Nonetheless, “energy efficiency improvements […] represent the largest and least costly” alternative to reduce GHG emissions caused by the energy system (IEA, 2008), besides reducing the depletion of non-renewable energy sources and decreasing energy costs (Cullen & Allwood, 2010b, p. 2059).
It is at this point where exergy and useful work analysis has an important role to play as a tool for improved energy policy making: it can be used to better understand and address
Dualism of Energy for Modern Societies 13
energy efficiency. As will be explained in the following section, exergy and useful work analysis is particularly useful in revealing where the biggest losses in energy conversion processes occur and thus where the largest potential for efficiency improvements lay
(Rosen, 2006a, 2006b). This is relevant because efficiency improvements are a feasible and cost effective way forward while a complete transition towards low carbon sustainable energy takes place. In other words, exergy and useful work analysis can be used to increase relative decoupling of energy from economic activity while an absolute decoupling of non-renewable energy resources from economic activity takes place.
Dualism of Energy for Modern Societies 14
The second law of thermodynamics is, without a doubt, one of the most perfect laws in physics. Any reproducible violation of it, however small, would bring the discoverer great riches as well as a trip to Stockholm. The world’s energy problems would be solved at one stroke Bazarov (1964)
Chapter 3. EXERGY AND USEFUL WORK
Having established the need for a transition towards renewable and sustainable energy sources, but also the importance of efficiency improvements to ease such a transition, the thermodynamics behind efficiency in energy systems will now be addressed. First an in depth definition of relevant concepts will be made. Secondly a literature review of how these concepts have been applied in different fields will be made. And finally, the rationale and research question will be established.
3.1. DEFINITION OF RELEVANT CONCEPTS
Before going into the definition of unfamiliar concepts, such as exergy and useful work, more familiar concepts such as energy, work and power, will be defined. The latter, although used more often, are not necessarily better understood by non-experts. For instance, expressions such as “I’m going for a run to get energized” are fundamentally incorrect (Smil, 2006, p. 2), as well as talking about energy production or consumption is a common mistake, and even the expressions energy crises (Rosen, 2002b) and energy conservation (Rosen, 2002c) are confusing and misleading.
Energy in particular is a concept that is abstract and difficult to understand. “We cannot understand what energy actually is, since everything we can observe is energy in different forms” (Dincer, 2002, p. 141). But at the same time, energy is something absolutely essential for life. “Energy is the cause and measure of all that there has been, is, and will be […], it is a fundamental property of existence” (Kostic, 2007, p. 1). Although energy itself cannot be easily defined, its manifestations have been clearly identified and measured. Energy can take the forms summarized in Table 1.
Exergy and Useful Work 15
Table 1. Energy forms and types classification Energy Form Energy Type 4 Example Kinetic Kinetic A bowling ball thrown down a bowling lane Mechanical Gravitational Potential A painter on a stair A distorted elastic band (stretched, Elastic Potential compressed or folded) Sensible Kinetic Warm iron piece (no change in state) Thermal Latent Potential Frozen ice cube (change in state) Chemical Potential Ignition of a fuel, food oxidation Nuclear Potential Fission of uranium atoms Electro-kinetic Kinetic Electric current travelling through a cable Electric Electro-static Potential Nylon jumper out of the tumble dryer Electromagnetic Potential Electromagnetic magnet Source: Classification taken from Kostic (2004) and examples taken from Hecht (1987).
This classification is related to the energy of a system, in its different forms, at a given moment. A system is as big as its boundaries; it can be a single cell, an industrial process or a whole economy. Therefore, the definition of the energy of a system by Kostic (2012, p.
810) is appropriate: “Energy is fundamental property of a physical system and refers to its potential to maintain a system identity or structure and to influence changes with other systems (via forced interaction) by imparting work (forced directional displacement) or heat (forced chaotic displacement/motion of a system’s molecular or related structures)”.
However, it is generally more interesting to analyse the second part of Kostic’s definition that refers to system interaction, which can be more generally stated as “energy is the capacity to cause changes in the world” (Kümmel, 2011, p. 29). That is, to analyse how the energy in a system can influence other systems. In other words, energy transformations and their related manifestations of work performed and heat transferred when two systems interact.
Heat appears when energy is transferred in a disorganized (dissipative) way (as heat transfer); work, on the other hand, appears when energy is transferred in an organized
4 Kinetic: movement; Potential: state or position with respect to a force.
Exergy and Useful Work 16
way (movement in the direction of a force 5); and finally power is the rate of energy transfer per unit of time 6 (Kostic, 2004). The units in which energy, work, heat and power are measured can be seen in Table 2.
Table 2. Units of energy, exergy, work, heat and power in the different systems of units System of Units SI Metric English Energy and Exergy Joule (J) kcal Btu Work N×m= J kg f×m lb f×ft Heat a cal kcal (1000 cal) Btu Power J/s = W (Watt) KWh hp a Heat needed to warm by one degree of temperature a unit of mass of water (cal: 1 gram, 1°C; kcal: 1kg, 1°C; Btu: 1lb, 1°F). Source: Based on Kostic (2004, p. 529) and Levenspiel (1997, p. 6).
The above is even more relevant in the context of this dissertation, because work and heat are, in general, the energy manifestations that societies need to maintain themselves and their economic systems, whichever they are. Energy transformation processes are the ones that allow everything to happen: from “simple” phenomena such as our muscles moving because chemical energy is transformed into mechanical energy; through to more complex phenomenon like our cars, buses, trains and airplanes transporting us and tonnes of goods around the world because chemical energy (mostly fossil fuels) is transformed into mechanical energy; and our lights shining and our computers turned on because some sort of energy form (kinetic, chemical, nuclear, thermal, etc.) has been transformed into electricity.
In other words, the manifestations of energy transformation processes constitute the backbone of our societies. In the specific case of economies, and by allowing change to occur, no productive activity can be undertaken without energy use (this was historically and empirically demonstrated in section 2.1). Heat is important for certain industries and
5 Work = force * distance (W=f*d) 6 Power = energy transfer / time (P=E/t). It is usually related to the rate of work (P=W/t) but the rate of heat transfer can also be obtained (Kostic, 2004, p. 528).
Exergy and Useful Work 17
chemical processes, but also to warm up our houses and offices. Work on the other hand, given that it has higher quality 7, is even more important than heat.
Work has been and is particularly important for societies at every point in time; in early societies work was done by human and animal muscles, which was replaced during the
Industrial Revolution with inanimate energy sources (Cipolla, 1978). Early energy units are still used today (e.g. horse power), and even the increased use of inanimate energy sources has been compared to the amount of people that would be needed to perform the same work if humans did not have the capacity to harvest additional energy sources: energy ‘slaves’ (Armaroli & Balzani, 2011).
Electricity is a form of energy that is very versatile and can be completely transformed into work, therefore it is usually considered as a special case. To continue with the analogy mentioned above, electricity is the most skilful slave ever, given the fact that it can be converted into all other energy forms without major losses. It can also be considered the most efficient ‘slave’ ever, given that it travels at great speed, it does not need holidays or get injured and is always available for its users at the flick of a switch
(Manrique Díaz, 2013). Even historically it has been considered as a key driver of industrial development (Beaudreau, 1995; Rosenberg, 1998) and even change in social relations (Nye, 1990). However, its storage has not been developed yet, which has serious implications for several renewable energy sources such as wind and solar.
But how does all this relate to exergy? Exergy measures the quality of energy, and can be defined as “the maximum possible work that may be obtained from a system by bringing it to the equilibrium in a process with reference surroundings” (Kostic, 2012, p. 816). As
Gaggioli & Wepfer (1980, p. 823) state, exergy “is synonymous with what the layman calls
‘energy’. It is exergy, not energy, that is the resource of value, and it this commodity, that
‘fuels’ processes, which the layman is willing to pay for”.
7 “Work is a more valuable form of energy than heat inasmuch as 100% of work can be converted to heat, but only a fraction of heat can be converted to work” (Kanoglu et al., 2012, p. 15).
Exergy and Useful Work 18
Therefore, all the energy forms listed above (Table 1) have an exergy content which describes their quality. However, the exergy content depends on the surroundings, so usually a reference or average environment needs to be defined in order to be able to carry out exergy calculations 8. The exergy content of each energy form depends on its chemical and physical properties, and how they relate to the reference environment.
Appendix A shows the exergy coefficient for each energy form used in Colombia.
Considering the above, the highest quality energy forms are those that can be transformed completely into work. In this sense, mechanical and electric energy are the highest quality energy forms; they have 100% of exergy content related to their energy content, or a quality factor of 1; chemical energy follows with a quality factor of almost 1 (or even more than 1 depending on the system definition and surroundings); nuclear energy has between 95% of exergy content related to their energy content; sunlight has a quality factor of 0.9; and finally thermal energy is the one with least quality, because it has an exergy content that varies between 60 and 0% as the temperature difference decreases and approximates to that of the environment (Dincer, 2002; Wall, 1986).
In this sense, exergy accounting, using the same units (see Table 2) of energy accounting, has an advantage over the latter. The different energy forms can be indexed based on their quality, and the issue of having a good criterion of equivalence for national energy statistics posed by (Giampietro & Sorman, 2012) is avoided9. National exergy inputs can
8 Usually, a conventional stable reference environment (SRE) is defined as temperature T0 = 298.15K (25°C), pressure p0=1atm (1.013bar) and average chemical composition of the Earth’s three subsystems (atmosphere, hydrosphere and lithosphere) (Querol, Gonzalez-Regueral, & Perez- Benedito, 2013, pp. 9–10). 9 On the other hand, it is true what Cleveland, Kaufmann, & Stern (2000) point out: that even though exergy is a good common property of all energy and materials, it is one-dimensional, and it does not capture other important attributes such as energy density, cleanliness, conductivity, resistance, etc. Nonetheless, exergy is a tool for improved energy accounting that is based on stable thermodynamic concepts, in which sense it is better than prices or other subjective criterions of equivalence.
Exergy and Useful Work 19
be calculated by multiplying the energy balances by the exergy coefficients of each energy source.
The analogy proposed by Alfvén (cited by Wall, 1986) is particularly appropriate to illustrate this. According to Alfvén, to account for energy without taking quality into consideration is to be like an accountant who adds coins irrespective of their value. It is like adding together a £2 coin (e.g. electricity) with a 5p coin (e.g. low temperature heat) as two coins that can be interchangeable, instead of adding them as £2.05 where the £2 coin can pay for more things than the 5p coin.
Furthermore, similarly with respect to energy, it is more interesting to analyse the exergy in a system and how it is manifested during transformation processes in heat and work.
Exergy is destroyed in real life processes as a system reaches thermodynamic equilibrium with its reference environment; this is due to the irreversibilities present in real processes
(as opposed to ideal processes) (Dincer, 2002), which are accounted for by the second law of thermodynamics 10 . It is exergy the one that is consumed in transformation processes, while energy is conserved 11 . The quality of energy is degraded in transformation processes
(Wall, 1977), i.e. work is performed and heat is dissipated.
When a system reaches thermodynamic equilibrium with its surroundings, it is said to be in a dead-state, i.e. the “system is at the temperature and pressure of its environment (in thermal and mechanical equilibrium), it has no kinetic or potential energy relative to the environment (zero velocity and zero elevation above a reference level), and it does not react with the environment (chemically inert). Also, there are no unbalanced magnetic,
10 The second law of thermodynamics, also referred to as the entropy law and considered the “arrow of time” (Levenspiel, 1997, p. 181), states that the entropy of an isolated system always increases (Kümmel, 2011, p. 131). Exergy is derived from a combination of both the first and second thermodynamic law and measures quantity and quality, making it a more complete concept (Dincer, 2002). 11 Energy is derived from the first law and measures quantity. The first law of thermodynamics is one of the most famous laws of physics, and it is also referred to as the energy conservation law: “energy can be neither created nor destroyed during a process; it can only change forms” (Kanoglu et al., 2012, p. 12).
Exergy and Useful Work 20
electrical, and surface tension effects between the system and its surroundings, if these are relevant to the situation at hand” (Kanoglu, Cengel, & Dincer, 2012, pp. 20–21).
A system that is in a dead-sate may have energy in it, but it will not be possible to obtain work from it. For example, an ice cube has negative energy, but if it’s located in winter time in a country from the northern hemisphere, no work can be obtained from it because it is in equilibrium with its surroundings (Gong & Wall, 2001). However, if there is a temperature difference between a system and its surroundings, a heat engine can be run in order to obtain work from it (Kanoglu et al., 2012) (see Figure 5b). Similarly, if there is a height or speed difference between the system and its surroundings, a turbine can be run and work can be extracted from that system (Kanoglu et al., 2012) (see Figure 5a).
Likewise, work can be extracted when there are differences in pressure, chemical composition, and so on.
Figure 5. Energy and exergy content of different systems In panel a) there is no energy or exergy content when there is no height difference, but when there is a height difference the energy and exergy content is the same (i.e. potential and mechanical energy, which is why hydropower is so
Exergy and Useful Work 21
efficient). In panel b) the energy content of the steam engine and the heat reservoir is the same, but the exergy content of the steam engine is higher due to the higher temperature difference in relation to the environment. Source: Domingos (2013).
Moving on to efficiency, exergy analysis, by calculating the maximum possible work obtainable from a system, can determinate the locations, types and true magnitudes of losses, and thus where the major opportunities for the improvement of energy systems, lay (Kanoglu et al., 2012). This is usually done measuring the exergy efficiency of the different parts of a system. Efficiency in general can be defined as the ratio of desired output over required input; which in the case of energy efficiency is represented by equation (1) (Kanoglu et al., 2012):
(1) =
Exergy efficiency on the other hand, measures the ratio of exergy output over exergy input (see equation (2)). However, if the main interest is to analyse energy transformation processes, the ratio should measure exergy recovered over exergy expended by an energy transforming device (Kanoglu et al., 2012). This exergy recovered has also been called
“useful work” by Ayres & Warr (2009). In other words, exergy efficiency is the “ratio of actual work (output) to maximum work (exergy) input, for any given process” (Ayres &
Warr, 2009, p. 91).
(2) = = =
Although it may seem to be a very similar concept to energy efficiency, exergy efficiency differs from it in that it measures the actual work performed 12 in a given process in relation to the exergy input. Additionally, exergy entails an important relationship with the surrounding environment and, given its origins in the second law of thermodynamics,
12 For the case when heat is the outcome of the transformation process, work performed corresponds to the capacity to obtain work (measured by the Carnot heat engine) from that heat, which is why the temperature difference is so important (i.e. higher temperature difference → more capacity to obtain mechanical work).
Exergy and Useful Work 22
it moves towards the realm of irreversible processes, which are those that actually take place in reality, in societies.
In order to give a graphical description of what has been explained above, the differences between energy and exergy efficiency can be seen in Figure 6, and the way exergy analysis reveals the true magnitude, types and location of losses compared to energy analysis can be seen in Figure 7. These two figures can be related in the case of the oil furnace: in Figure 6 the energy efficiency is 85% while the exergy efficiency is 4%, a difference that can be seen in the first part of the energy and exergy flows in Figure 7 (the ones that correspond to the furnace, where chemical energy/exergy is converted into hot steam). These figures help to visualize the relevance of exergy analysis regarding energy transformation processes, but given the scope and goal of this dissertation, will not be further developed in technical terms.
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Figure 6. Energy and exergy efficiency for 4 conversion systems η: energy efficiency (as in equation (1)); Ɛ: exergy efficiency (as in equation (2)). Source: Adapted from Wall (1977, p. 34).
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Figure 7. Energy and exergy flow diagrams of a condensing power plant Note that energy is conserved all along the process (the initial chemical or nuclear energy is equal to the sum of the final electricity plus the friction, the waste heat and the exhaust gas), with the largest amount of lost energy happening at the condenser as waste heat. On the other hand, exergy is destroyed along the process (the exergy flow ‘shrinks’), and the largest loss is in the furnace, where high temperature heat is lost through the walls of the furnace and in the exhaust gases. Source: Wall (2003, p. 128).
Finally, it is important to acknowledge that efficiency analysis of an energy system could also be undertaken at an even more detailed level than useful work, i.e. at the energy services level (see Figure 8). By doing so, efficiency could be assessed in a wider perspective which includes passive systems (Cullen & Allwood, 2010b) and further losses could be identified (see Figure 9). While useful work is obtained when exergy inputs are converted into a useful form (heat, mechanical work/drive, lighting, electrical applications and muscle work) by some end-use device, energy services appear when that useful work
Exergy and Useful Work 25
drives the activity of another system (for example a car or a house) to provide a specific service (for example passenger transport or heating) (Cullen & Allwood, 2010a).
Energy Level
Exergy Level
Useful Work Level
Energy Services
Figure 8. Energy system levels of analysis Source: Own elaboration.
Expanding on the car example provided by Cullen & Allwood (2010a), the exergy input is the petrol, the useful work output is the mechanical drive, the passive system is the car itself (excluding the engine) and the energy service is the number of people transported from point A to point B. Subsequently, with an exergy and useful work analysis, the theoretical potential for efficiency improvements would be limited to the maximum amount of mechanical drive obtained by the engine per unit of exergy input; whilst with a passive system and energy services analysis, the efficiency of the final service delivered could be improved by reducing the aerodynamic drag and friction of the car (the passive system), or even increasing the occupancy rate, and thus more energy service (passenger transport) could be obtained by using the same amount of exergy inputs.
The advantages of using this approach at a national level are clear: a greater level of detail, a better understanding of energy use and an increased knowledge of the location of losses (and therefore potential for improvements). However, the passive systems and energy services approach has only recently started to be developed. Moreover, the boundary between a conversion device and a passive system can be difficult to establish
(Cullen & Allwood, 2010a) and the energy services are measured in different units,
Exergy and Useful Work 26
making aggregation a difficult task. But perhaps more importantly, the availability of data for Colombia as a case study is limited.
Figure 9. The flow-path of exergy to energy services Source: Adapted from Cullen and Allwood (2010b, p. 2060).
3.2. LITERATURE REVIEW OF EXERGY APPLICATIONS
The term exergy was initially used by Zoran Rant in 1953 in a scientific meeting, where he gave a unique name to what others before him had already explored and defined, but expressed in different ways 13 (Sciubba & Wall, 2007, p. 6). The concept of exergy, however, has an earlier development: it was intuitively described by Carnot in 1824 for the specific case of the work that can be extracted from a heat engine, which some decades later led to the development of the second law of thermodynamics by Rudolf Clausius (Sciubba &
Wall, 2007, pp. 4–5). It was Josiah Willard Gibbs in 1873 who explicitly defined exergy, although he called it available work (Sciubba & Wall, 2007, p. 5).
From that point on, exergy continued on a theoretical development pathway, making its way into thermodynamic textbooks, but also seeing the publication of some seminal
13 For example available energy, availability, available work, potential work, useful energy, potential entropy, amongst others (Sciubba & Wall, 2007, p. 6).
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practical applications (Sciubba & Wall, 2007, pp. 5–6). It was only in the 1950s that the concept was given a unique name and a mature definition was reached. Also from the second half of the 20 th century onwards, exergy opened its way into different types of applications regarding optimization procedures for energy-conversion and industrial processes, initially mainly in the mechanical and chemical engineering fields (Sciubba &
Wall, 2007). As Sciubba (2001) points out, exergy analysis has had a profound impact on the design of energy conversion systems, up to the point that almost every design standard today makes either a direct or indirect use of exergy when searching for an optimal configuration.
Some examples of energy conversion processes that benefit from exergy analysis for their design include: power cycles and components (steam power cycles, gas turbine cycles, renewable energy cycles, combined heat and power cycles, cogeneration cycles, fuel cells, nuclear cycles, heat exchangers, cryogenics), chemical processes and distillation and desalination (Sciubba & Wall, 2007). However, exergy analysis alone only provides technical (thermodynamic) criteria for design optimization, but real optimization procedures depend on regulatory, economic and environmental constraints.
This is something that should be kept in mind when assessing a national energy system
(for example the case of Colombia studied in this dissertation), i.e. that technical criteria needs to be contextualized within economic, environmental and regulatory realities. The first two realities correspond to the energy dualism described in chapter 2, while the latter corresponds to the political context in which the policy implications will be analysed in section 5.3.
Exergy also worked its way towards microeconomic analysis, where engineering second law optimization problems are combined with cost analysis, resulting in methodologies for exergy-based microeconomic analysis of energy conversion systems. This approach has been called both thermoeconomics and exergoeconomics, and although there have
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been discussions around the differences between the two 14 and their origin 15 , their similarities are more significant in the context of this literature review of exergy and its applications.
These methodologies of exergy-based microeconomic analysis acknowledge that it is exergy, not energy, the commodity of importance in a system, and thus the one that should be assigned costs and prices before optimization (Utlu & Hepbasli, 2009). In this sense, they allocate a cost to exergy, together with the cost of other system variables (such as temperatures, pressure, equipment size, materials, etc.), and then proceed to optimize
(minimize costs) (Tsatsaronis & Valero, 1989). After the methodologies appeared in the
1980’s, there have been many applications of them, including recent applications to optimize the design of renewable energy conversion systems: for example for wind turbines (Baskut & Ozgener, 2012) and biomass trigeneration systems (Lian, Chua, &
Chou, 2010).
In this sense, exergoeconomic applications end up being the tool that gives microeconomic (financial) support to the findings obtained by exergy analysis applications in the engineering field. Furthermore, thermoeconomic methodologies have been recently expanded towards relating non-energetic expenditures (such as financial, labour and environmental costs) to exergy parameters, in what has been called extended exergy accounting (Sciubba, 2001).
Moreover, some authors extended the micro view of particular processes in isolated systems to a more macro view of multiple processes in complex systems, such as economic sectors and societies (regional, national or global systems). This type of studies
14 Tsatsaronis (2007b) points out that thermoeconomics is a more general approach, where any thermodynamic criteria can be combined with economic criteria, while exergoeconomics only uses exergy. 15 Tsatsaronis (2007a) claims he coined the term “exergoeconomics” in a conference paper in 1984, while Sciubba & Wall (2007) attribute it to Valero in 1986. However, Tsatsaronis & Valero (1989) use the alternative expression “thermoeconomics” to describe the same methodology.
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analyse the energy and exergy flows in those complex systems; there is an unavoidable loss in precision and detail, but a gain in generality, which is valuable for more general policy making. Rosen (2013) for instance, undertakes a global analysis of energy utilization efficiency in the industry sector using exergy analysis in order to compare the results with energy analysis. The author finds that the global energy efficiency of the industrial sector is 51%, while the exergy efficiency is 30%. This difference reveals that there is more room for efficiency improvements in the global industrial sector than thought of with energy analysis alone.
Reistad (1975) was the first one to analyse a society, the US, in exergy terms. Using an exergy (or available energy as he calls it) flow diagram, Reistad found that the overall exergy efficiency of the US energy sector was 22% in the year 1970, with the residential, commercial and transportation sectors being the least efficient ones. This approach analyses only energy carriers, and has been also used to analyse the exergy efficiency of a certain year in Canada (Rosen, 1992), Brazil (Schaeffer & Wirtshafter, 1992) and Turkey
(Ílerí & Gürer, 1998), and even at a global scale (Nakićenović, Gilli, & Kurz, 1996).
Similarly, Wall (1987) analysed Sweden’s exergy efficiency in 1980, finding that the overall exergy efficiency of the Swedish society was 20%. His approach, as opposed to
Reistad’s, includes all materials that a society processes, not only energy carriers. In the same way analysis for one year exergy efficiency for Japan (Wall, 1990), Italy (Wall,
Sciubba, & Naso, 1994), Norway (Ertesvag & Mielnik, 2000) and China (Chen & Qi, 2007) have been undertaken, showing generally very similar results.
Moreover, in the same way that exergy analysis has been used to analyse societies, the extended exergy accounting methodology proposed by Sciubba (2001) has also been used to analyse a society not only in thermodynamic terms, but also combining financial and environmental criteria. Some applications of the above have been done for Norway
(Ertesvag, 2005), Netherlands (Ptasinski, Koymans, & Verspagen, 2006), the UK
(Gasparatos, El-Haram, & Horner, 2009) and China (Chen & Chen, 2009).
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There have also been studies, although less abundant, that analyse exergy efficiency of societies through time, by constructing time series of exergy inputs to a society and useful work output actually used by the same society. In this line of applications, Warr et al.
(2010) analyse how exergy efficiency has evolved through the 20 th Century in the US, the
UK, Austria and Japan. An even longer study has been done for Portugal for the period
1856-2009 (Serrenho, Warr, Sousa, Ayres, & Domingos, 2012).
Williams, Warr and Ayres (2008) construct exergy and useful work time series for Japan for the period 1925-1999, and Brockway et al. (2014) analyse the UK and US exergy and useful work for the period 1960-2010. Finally, there is also a study for the UK, but for a shorter period of time (1965-2000) and only for the energy sector (Hammond & Stapleton,
2001).
Additionally, by its very own definition, in which disequilibrium from its surrounding environment is key, exergy has a role to play in environmental applications. It has been proposed as a measure of environmental impact because of three main reasons shown by
Dincer (2002) and Rosen (2002a). Firstly, exergy is a measure of order (opposite to entropy) and ordered environments are preferred than chaotic ones; secondly, improved exergy efficiency and use of external exergy sources (i.e. the sun, taking into account that the Earth is an open system) can help avoid resource degradation; and thirdly the exergy content of waste emissions can be associated with their potential to cause change
(damage).
However, this approach has been criticised (Gaudreau, Fraser, & Murphy, 2009) particularly for the third reason, on the basis that exergy does not measure other variables relevant to assess impacts on the environment, for example toxicity (Hammond, 2004a).
Another common criticism of exergy as a measure of environmental impact has been regarding the problems associated with the standardization of the reference environment
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(Romero & Linares, 2014), because the environment against which the exergy of wastes is calculated varies in time and space.
Despite the criticisms, there have been developments of several applications to use exergy as a measure of environmental impact, namely the cumulative exergy content proposed by Szargut (1986), the exergetic life cycle analysis proposed by Cornelissen (1997) and the very similar life cycle exergy analysis proposed by Gong & Wall (2001).
As a result of this link between exergy and the environment, exergy applications have extended towards the sustainability sphere. Some authors have even described exergy as a key element for a democratic society, proposing along the way exergy as a measure for taxing resource use and waste creation (Wall, 1993): a tax based on the exergy content of non-renewable resources consumed and a tax based on the exergy content released into the environment, and the income from the tax could be used to improve exergy efficiency and use. However, these approaches remain mainly in their initial stages and much more research is needed, particularly transdisciplinary research given the complex nature of the sustainability issue (Romero & Linares, 2014).
Finally, exergy and useful work have also joined the macroeconomics world. The inclusion of useful work (and thus exergy efficiency) into a production function was pioneered by Robert Ayres and his different collaborators throughout the years, and is particularly ground breaking. Although energy has been proven to be correlated to economic activity in general (see section 2.1), and the LINEX production function was already introduced by Reiner Kümmel in the 80s (Kümmel, Strassl, Gossner, & Eichhorn,
1985; Kümmel, 1982), the link to exergy and useful work had not yet been made, let alone the link with exergy efficiency as a measure of technological progress and its empirical significance as a factor of production to explain economic growth.
Energy use is said to enhance competitiveness and promote economic growth (AGECC,
2010). But it is not energy per se that explains growth dynamics, it is the efficiency
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improvements with which the exergy content of energy sources is transformed into useful work. The results form Ayres and Warr (2009) suggest that efficiency improvements are the engine behind economic growth for the US and Japan during the 20 th century. With a production function that includes useful work as a production function, Ayers and Warr
(2009) are able to explain technological progress as the increases in the conversion efficiency of exergy to useful work through time.
Ayres and Warr’s (2009) findings imply that for economic growth to continue into the future, three major requirements need to be met: a new engine of economic growth needs to be found (continued improvements in the efficiency of conversion from exergy to useful work), a new source of cheap useful work needs to be found (renewable energies) and there needs to be a deeper environmental awareness. These three requirements are in line with an energy transition, and this dissertation will focus on the first one.
3.3. RATIONALE AND RESEARCH QUESTION
As it was demonstrated in sections 2.1 and 2.2, energy is absolutely vital for societies but its current dependence on fossil fuels is very harmful for the environment, which calls for an energy transition. If the current rates of economic growth, development and living standards improvements are to continue into the future, it is important to guarantee a sustainable and sufficient energy supply. A promising alternative is to pursue, in parallel to the development of sustainable renewable energy sources, improvements in the efficiency of providing specific energy services that a society needs. That is to say, pursue ways to deliver the same useful work (or ideally energy services) with less energy expenditure.
As was demonstrated in section 3.1, it is the manifestations of energy that are purposefully extracted from transformation processes, in particular work, that are valuable for societies. And since exergy measures the maximum work obtainable from a system, exergy analysis must be a useful tool to improve the energy transformation
Exergy and Useful Work 33
system that is a society as a whole, and more specifically its energy system. This has been recognized in the theoretical sphere of energy policy.
It was also demonstrated (in section 3.2) that exergy is a concept that has contributed and been valuable for a great number of areas of application, particularly in the engineering field, but also for sustainability, micro and macro-economics. There have been a few contributions to sustainability policies, such as Wall’s (1993) exergy tax, but this dissertation focuses on energy policy making, i.e. policies towards the development of national energy systems. However, exergy has not yet entered the world of energy policy decision making tools , and thus has not been used for the planning and development of national energy systems.
In relation to the theoretical approaches to energy policy making, the contributions by
Bejan and Bejan (1982) address the issue of how to allocate different processes to the available exergy sources in order to improve overall efficiency. It is a supply-side approach to energy policy, as opposed to the demand-side approach currently used. In the latter the energy problem is to expand “energy sources in order to meet projected homogeneous demands”, while in the former the energy problem is to meet
“heterogeneous end-use needs with a minimum of energy supplied in the most effective way for each task” (M. Bejan & Bejan, 1982, p. 153). Other authors have highlighted the importance of exergy analysis to prioritize areas of action for efficiency improvements within a country’s energy system (Dincer, 2002; Hammond & Stapleton, 2001).
When it comes to the tools used for actual energy policy making, exergy is notable for its absence. It is not mentioned in the 2012 World Energy Outlook (IEA, 2012b), nor in the US
Annual Energy Outlook (EIA, 2014). It is not even mentioned in the IIASA (2014)
MESSAGE (Model for Energy Supply Strategy Alternatives and their General
Environmental Impact) model, which incorporates a bottom-up approach to modelling future energy supply and demand, and thus has a very technical approach to producing energy scenarios. The only exception the author is aware of is an academic project
Exergy and Useful Work 34
currently being undertaken by Brockway (Brockway, 2014) in which he analyses IEA’s energy scenarios for China under the light of past exergy and useful work trends.
This is even more surprising considering that energy efficiency is a key component of current energy policy. Efficiency improvements on the demand side now play an important role in many countries’ and institution’s energy policy plans and recommendations (see for example DECC, 2012; IEA, 2012), and in fact of broader political agendas such as green growth (see for example OECD, 2011; UNEP, 2011; World Bank,
2012). Thus, energy efficiency is being promoted all over the world, but it is not being complemented by modern thermodynamics, i.e. exergy efficiency analysis.
Moreover, exergy analysis has not yet entered the developing world in a substantial sense. Whilst there has been some work regarding its most common applications, nothing has yet been done in the energy policy context. Specifically in the case of Colombia, there are some studies on exergy efficiency, for example in relation to the production of unrefined sugar (Velásquez Arredondo, Agudelo, & Chejne, 2011) and ethanol production from banana fruit (Velásquez Arredondo, Ruiz Colorado, & Oliveira Junior, 2009). There is also a study on the relationship between useful work and economic growth for
Colombia (Manrique Díaz, Velásquez Arredondo, & Giraldo Arismendy, n.d.).
This gap in the literature, namely that exergy has not been applied to energy policy when constructing energy scenarios nor to developing countries, is the one that this dissertation aims to address.
Research Ques tion: How can exergy and useful work analysis be used as a tool for bet ter
energy policy decision making, using the case of Colombia as an illustrative example?
Exergy and Useful Work 35
A modern industrial society can be viewed as a complex machine for degrading high-quality energy into waste heat while extracting the energy needed for creating an enormous catalogue of goods and services Summers (1971, p. 149)
Chapter 4. THE COLOMBIAN CASE
As it was identified in section 3.3, there is a gap in the literature regarding the use of exergy and useful work concepts in energy policy decision making tools, and this gap is even larger when it comes to developing countries. In order to address this gap, Colombia was chosen as a study case considering the following three factors: i) the availability of exergy and useful work data for Colombia (Manrique Díaz et al., n.d.), ii) the country’s extraordinary natural resource richness and variety, which means that it has multiple energy policy options to explore, and iii) the fact that Colombia’s energy use is still transitioning from that of a rural country towards an industrialized or even more so towards a service based country, making it an interesting case study.
Moreover, the case of Colombia will be studied by, in the first place giving a general context of the country and its energy sector (section 4.1). The following section describes the methodology used in the subsequent section is described (section 4.2). Thirdly, past exergy and useful work data for the period 1975-2009 is presented (section 4.3). This is then followed by an analysis of the presented data (section 4.4), and finally the energy projections for Colombia a presented (section4.5), which are the background against the usefulness of exergy and useful work for policymaking will be assed in chapter 5.
4.1. COLOMBIA AND ITS ENERGY SECTOR
4.1.1. GENERAL CONTEXT
Colombia is located in South America (see Figure 10), has a population of 46,039,000 and an area of 1,141,748 square kilometres (440,831 square miles) (National Geographic, 2014).
According to the UN (2013), Colombia is a developing country, and although in economic
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terms it is considered an upper-middle-income economy (World Bank, 2014), Colombia has a GINI index of 55.9 (CIA, 2014), one of the highest in the world, which means that
Colombia’s income is distributed in a very unequal way amongst its population.
Figure 10. Map of Colombia Source: World Atlas (2014).
However, in terms of natural resources Colombia is very rich: it is the only country in the
South American subcontinent that has coastlines in both the Caribbean Sea (part of the
Atlantic Ocean) and the Pacific Ocean; it’s the world’s second largest country in biodiversity (it is host of more than 10% of the world’s known species) while having only
0.22% of the world’s terrestrial surface (MAyDS & PNUD, 2014); it has around 311 types of terrestrial and marine ecosystems divided in 7 eco-regions (5 terrestrial and 2 marine)
(MAyDS & PNUD, 2014).
Colombia’s natural resource richness is the result of a combination of geographical, climatological, ecological and evolutionary factors (MAyDS & PNUD, 2014), which also provide an abundance and variety of primary energy sources. Primary energy sources are usually divided into non-renewable (which include uranium ore and fossil fuels: coal, oil and natural gas) and renewables (which include hydropower, biomass, wind, solar,
The Colombian Case 38
wave/tidal and geothermal energy). Although Colombia has uranium ore, the country has never adopted nuclear energy.
4.1.2. ENERGY RESERVES AND POTENTIAL
Regarding fossil fuels, Colombia has the highest proved coal reserves of the South
American region, with 6746 million tonnes (4722.2 million tonnes of oil equivalent -mtoe) representing 0.8% of the world’s coal reserves in 2013 (BP, 2014). It is also by far the largest producer in South America, mining 55.6 mtoe in 2013 (1.3% share of the world’s coal production) (BP, 2014). The vast majority of Colombia’s coal is nonetheless exported, with the country only consuming 4.3 mtoe in 2013 (0.1% of the world’s total coal consumption) (BP, 2014).
Furthermore, Colombia has proven oil reserves of 2.4 billion barrels (327.36 mtoe) according to BP (2014), making it the 4 th country in South America in terms of oil reserves after Venezuela, Brazil and Argentina, with a 0.1% share of the world’s reserves.
However, in terms of production, in 2013 Colombia extracted 1,004,000 barrels of oil daily
(50 mtoe per year), being the 3 rd largest producer in South America after Venezuela and
Brazil, representing a share of 6.3% of the world’s production (BP, 2014). As in the case of coal, most of Colombia’s oil production is exported: in 2013 the country consumed 297,000 barrels of oil daily (14.79 mtoe per year), 0.3% share of the world’s total consumption (BP,
2014).
Regarding natural gas, Colombia also has this energy resource, although in small quantities when compared to the South American region reserves, and is mostly used for internal consumption. Colombia’s proven natural gas reserves amount to 0.2 trillion cubic meters (180 mtoe), 0.1% of the world’s total natural gas reserves (BP, 2014). Moreover,
Colombia produced 12.6 billion cubic meters (11.34 mtoe) in 2013, of which it consumed
10.7 billion cubic meters (9.63 mtoe) (BP, 2014). These non-renewable energy sources
(summarized in Figure 11), particularly coal and oil, are vital for Colombia’s economy in
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terms of exports, contribution to the GDP, attraction of foreign direct investment and tax revenues (Univerisdad Nacional de Colombia & Fundación Bariloche, 2010).
4750 4722.2
400
350 327.36
300
mtoe 250
200 180.00
150
100 55.60 50.00 50 4.30 14.79 11.34 9.63 0 Coal Oil Gas Reserves Production Internal Consumption
Figure 11. Colombia's non-renewable energy resources in 2013 Source: Own elaboration based on data from BP (2014).
On the other hand, and regarding renewable primary energy sources, Colombia is privileged by its geographical location. It has great hydropower potential, given its mountainous terrain, high precipitation and number of river basins (720,000), which together with other bodies of water (lakes, lagoons and dams) account for an approximate volume of 26,000 million cubic meters and a potential for 25,000 MW of power
(Univerisdad Nacional de Colombia & Fundación Bariloche, 2010). It is located near the
Equator providing almost continues sunlight throughout the year, accounting for a daily multiannual average close to 4.5 kWh/m 2 (UPME & IDEAM, 2005). In the Atlantic coast
Colombia has the greatest availability of wind, with power density between 1,000 and
1,331 W/m 2 at 20m height, and between 2,744 and 3,375 W/m 2 at 50m height (UPME &
IDEAM, 2006).
Regarding biomass, the country has a potential of 16,267 MWh/year between agroindustrial residues (11,828 MWh/year), carburant alcohol (2,640 MWh/year), residues of natural forests (698 MWh/year), combustible oil (658 MWh/year) and residues of
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planted forests (442 MWh/year) (Univerisdad Nacional de Colombia & Fundación
Bariloche, 2010). Finally, Colombia also has some geothermal potential and, although the energy flow of its wave and tidal resources is not enough for efficiently generating electricity, there are 4 places identified where the thermal gradient of ocean can be exploited for electricity generation (Univerisdad Nacional de Colombia & Fundación
Bariloche, 2010).
With the exception of hydropower, these sources have not been exploited on a large scale, but account for Colombia’s possibilities for future energy policy decisions. There is a total installed hydropower capacity of 14,559 MW (XM, 2014), 58% of the country’s potential.
On the other hand, biofuels have been developed to some extent, with a production of
1867 TCal (2.17 MWh) of bioethanol and 4689 TCal (5.45 MWh) of biodiesel in 2012. Wind and solar power have only been developed marginally. The remaining renewable sources that Colombia has potential for developing, namely geothermal and the thermal gradient of the ocean, have not yet been developed.
4.1.3. CURRENT ENERGY USE
Colombia’s current energy mix is varied. Figure 12 shows the country’s total primary energy supply (TPES), where oil plays a prominent role followed by natural gas and hydro-power. It also shows its total final consumption (TFC), where oil products become very relevant, followed by electricity and natural gas.
The difference between TPES and TFC is that in the latter the energy sector’s own use and the uses for transformation processes are discounted. In other words, TFC only considers the energy sources that are used directly for final consumption in the different economic sectors. Therefore, hydropower does not appear in TPES, since it is used entirely in transformation processes where it becomes electricity. Similarly, most of the crude oil is used in transformation process in order to obtain oil products.
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TPES
TFC
0 50000 100000 150000 200000 250000 300000 350000 400000 TCal Bagasse Coal and Coke Natural Gas Hydropower Wood and Coalwood Crude Oil Oil Products Recovery/Residues and Biofuels Electricity Non Energetic
Figure 12. Colombia's 2012 TPES and TFC Source: Own elaboration based on data from UPME (2014b).
By calculating the ratio between TFC and TPES, the overall efficiency with which the primary energy supply is transformed into final energy (ready for direct use) can be analysed. This ratio is determined principally by the transformation processes undertaken to generate electricity, and therefore by the share of electricity generated by hydropower relative to thermal power. Figure 13 confirms the above by showing that the TFC/TPES ratio and the share of electricity generated by hydropower vary very similarly.
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Figure 13. TPES/TFC ratio and share of electricity generated by hydropower Source: Own elaboration based on data from UPME (2014b). The share of electricity generated by hydropower in Colombia varies over the years depending on weather conditions. The remaining share is covered by thermal power plants, which are mainly fuelled by natural gas, with some coal also used. The latter are very important for Colombia’s energy security in the dry seasons, especially if there is
ENSO (El Niño Southern Oscillation). Therefore, it is not surprising that in 1982-83, 1991-
92, 1997-98 and 2009-10 there was ENSO affecting Colombia.
Additionally, Figure 14 shows how the TFC is distributed into the different sectors, and
Figure 15 shows in more detail which energy sources are used in each of the sectors. The most important sector in 2012 was transport, using 44% of Colombia’s TFC, followed by industry (21%) and the residential sector (19%). As expected, the transport sector mainly uses oil products, while the industry uses mainly natural gas followed by electricity and some coal and coke, and the residential sector uses mainly electricity but also some natural gas and some firewood and coal wood (particularly in the rural areas).
2% 6% Industry 21% Transport 19% Agriculture Mining 1% 1% Construction Residential 6% 44% Comm. and Pub. Sector Other Consumptions
Figure 14. Colombia’s TFC by sector as a percentage of the total (2012) Source: Own elaboration based on data from UPME (2014b).
Other Consumptions Comm. and Pub. Sector Residential Construction Mining Agriculture Transport Industry
0 20000 40000 60000 80000 100000 120000 140000 Bagasse Coal and Coke TCal Natural Gas Hydropower Wood and Coalwood Crude Oil Oil Products Recovery/Residues and Biofuels Electricity Non Energetic
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Figure 15. Energy sources used by sector (2012) Source: Own elaboration based on data from UPME (2014b).
4.1.4. EVOLUTION OF ENERGY USE
Finally, Colombia has been and still is undergoing the transition from conventional energy sources to a fossil fuel based energy system. This can be seen in Figure 16, which shows the evolution over the years of the use of the different energy sources in the TPES, where the use of firewood and coal wood has decreased as electrification (through an increased consumption of hydropower and natural gas for thermal plants) has increased in the country.
100%
80%
60%
40%
20%
0% 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 Bagasse Coal and Coke Natural Gas Hydropower Firewood and Coal wood Crude Oil Recovery/Residues and Biofuels
Figure 16. TPES by energy sources as a percentage of the total (1975-2012) Source: Own elaboration based on data from UPME (2014b).
Having described Colombia’s energy system and natural resource conditions, the next section will now move on to describing the methodology used to analyse the country in terms of exergy and useful work, within the context of energy policy.
4.2. METHODOLOGY
In order to study how exergy and useful work can be used for improved energy policy making, they must be analysed in the context where energy policy decisions are taken.
Generally, in the energy sector individual countries and international organizations
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construct energy scenarios (or projections) in order to have an idea of future energy demand and therefore supply requirements, and thus guide energy policy decisions.
Colombia is not the exception. It has a Ministry of Mining and Energy, which has a special unit called the Energy and Mining Planning Unit (UPME in Spanish). In order to guide the country’s energy policy, UPME constructs every four years a National Energy Plan
(PEN in Spanish) which must be aligned with the National Development Plan (PND in
Spanish) produced by the corresponding government. The PENs have projections of energy supply and demand in them, as well as energy policy recommendations.
Therefore, the methodology used in this dissertation will be to, in the first place, present the data of Colombia’s past exergy inputs and useful work outputs (section 4.3).
Following this a more detailed analysis of the above mentioned data is undertaken, focusing on the evolution over time of the efficiency improvements, particularly examining the drivers of such improvements (section 4.4). Finally, the most recent PEN
(Univerisdad Nacional de Colombia & Fundación Bariloche, 2010) is analysed, particularly the assumptions regarding energy efficiency (section 4.5). Now a description of each of the three aforementioned steps will be made, and in chapter 5, a discussion of the methodology, the results and the policy implications will be made.
In relation to past exergy and useful work data (section 4.3), it is important to note that this dissertation will use exergy coefficients (in order to obtain exergy inputs) and exergy efficiencies (in order to obtain useful work) provided by Manrique Díaz et al. (n.d.).
Furthermore, the baseline energy data is taken from Colombia’s National Energy Balances
(BEN in Spanish), which are published yearly since 1975 by UPME.
This data is then further elaborated in order to present exergy and useful work time series and detailed sectorial information. In particular, the exergy time series is obtained by multiplying the energy quantities of the BENs by the exergy coefficients provided by
Manrique Díaz et al. (n.d.), hence transforming them into exergy balances. Additionally,
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the useful work time series is obtained by multiplying the TFC (now in exergy terms) by the exergy efficiencies provided by Manrique Díaz et al. (n.d.). Further details on these calculations are given in section 4.3.
Regarding the data analysis (section 4.4), this focused primarily on the exergy efficiencies.
It analyses whether the underlying causes of efficiency improvements have been dilution/concentration and structural effects, or rather concrete improvements in the transformation of exergy to useful work. This is done through the observation of the evolution of efficiencies and shares of sectors in time. It is important to acknowledge that this part of the methodology was largely inspired by conversations on an exergy- economics workshop carried out in Leeds (Brockway, n.d.), and the forthcoming study of
Brockway for the case of China.
Finally, in relation to the most recent PEN (Univerisdad Nacional de Colombia &
Fundación Bariloche, 2010) 16 (section 4.5), the future projections were constructed using a model called LEAP (Long-range Energy Alternatives Planning system), which was developed by COMMEND (Community for Energy, Environment and Development), an international initiative managed by SEI (Stockholm Environment Institute) (COMMEND,
2014). The LEAP model is an energy-environment model that uses a bottom-up approach to simulate demand-driven scenarios (Di Sbroiavacca & Dubrovsky, 2011).
The LEAP model scenarios are based on the detailed representation of a country’s energy production, transformation and use patterns, which are under the control of assumptions on population, economic development, prices and available technologies (Di Sbroiavacca
& Dubrovsky, 2011). The demand is organized within a treelike hierarchical structure: sector, subsector, final use and fuel/technology (Di Sbroiavacca & Dubrovsky, 2011). The two latter variables can be set to change in time in the scenario construction, based on
16 A 2014 version will be published soon by UPME, but not in time to be included in this dissertation.
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projected changes in the level of activity (final use) and technological developments or fuel substitutions (Di Sbroiavacca & Dubrovsky, 2011).
In the specific case of Colombia, special attention is given to the assumptions on available technologies and the projected changes in the variables that determine demand in the two scenarios developed using the LEAP model in the most recent PEN (Univerisdad
Nacional de Colombia & Fundación Bariloche, 2010). By doing so, an insight into the shortcomings of energy analysis can be attained, and this will be complemented with the insights gained in the previous past exergy and useful work analysis, as described below.
4.3. PAST EXERGY AND USEFUL WORK
A time series of exergy inputs for the Colombian economy has been constructed for
Colombia for the period 1975-2009. It used the exergy coefficients provided by Manrique
Díaz et al. (n.d.), and the TFC quantities reported in the BENs, which separates primary
(raw) and secondary (processed/transformed) energy sources. The exergy coefficients used are shown in Appendix A, and, as explained in section 3.1, are based on the chemical and physical properties of Colombia’s primary and secondary energy sources; therefore they do not vary in time.
100000
80000
60000
TCal 40000
20000
0 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year Bagasse Coal Natural Gas Hydropower Wood Oil Recovered Waste
Figure 17. Colombia's primary exergy inputs Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
Figure 17 shows Colombia’s exergy inputs by primary energy sources and Figure 18 shows them as a share of the total primary exergy inputs. The use of natural gas and coal
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has increased significantly in this time period, while the use of wood has shown a substantive decrease, both in absolute and relative terms. Hydropower does not appear in these figures because it does not go straight into final consumption, but rather is entirely transformed into electricity.
100% 90% 80% 70% 60% 50%
TCal 40% 30% 20% 10% 0% 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year Bagasse Coal Natural Gas Hydropower Wood Oil Recovered Waste
Figure 18. Colombia's primary exergy inputs as a share of the total primary exergy input Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
Figure 19 shows Colombia’s exergy inputs by secondary energy sources and Figure 20 shows them as a share of the total secondary exergy inputs. The use of diesel oil and electricity has increased significantly in this time period, while the use of petrol has shown a substantive decrease, both in absolute and relative terms.
200000
150000
100000 TCal 50000
0 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year Carburant Alcohol Biodiesel Coalwood Coke Diesel Oil Electricity Fuel Oil Industrial Gases Liquified Gas Petrol Refinery Gases Kerosene and Jet Fuel Non energetic
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Figure 19. Colombia's secondary exergy inputs Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
100%
80%
60%
40% TCal
20%
0%
1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 Year1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Carburant Alcohol Biodiesel Coalwood Coke Diesel Oil Electricity Fuel Oil Industrial Gases Liquified Gas Petrol Refinery Gases Kerosene and Jet Fuel Non energetic Figure 20. Colombia's secondary exergy inputs as a share of the total secondary exergy input Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
When putting together primary (Figure 17) and secondary exergy inputs (Figure 19), a growing trend in their use in Colombia over the 34 year time period can be seen (Figure
21).
300000
250000
200000
TCal 150000
100000
50000
0 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009
Year Total Secondary Exergy Total Primary Exergy Total Exergy Inputs
Figure 21. Total exergy inputs in Colombia (1975-2009) Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
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Moreover, it is interesting to analyse in which sector or consumption category the total exergy inputs fall into. The sectors (8 in total) and consumption categories (35 in total) used in this dissertation are the same ones used in the BENs and can be seen in Table 3.
Table 3. Sectors and Consumption Categories Sector Consumption Category Industry Food, beverages and tobacco Footwear and leather Cement Iron, Steel and Non-Ferrous Woods and Furniture Machinery and Equipment Other Industrial Paper and Printing Stones, Glass and Ceramic Chemicals Textiles and Clothing Transport Air Railway River Sea Road Agriculture Fumigation Other Agriculture Farm Processing Irrigation Grain Drying Tractors Mining Motive Force Lighting Other Mining Construction Construction Residential Hot Water Air Conditioning Cooking Lighting Fridge Other Residential Rural Residential Commercial and Public Sector Commercial and Public Sector Other Consumptions Other Consumptions Source: Extracted from the structure of the BENs (UPME, 2014b).
Therefore, in Figure 22 the total exergy inputs by sector can be seen, and in Figure 23 they are shown as a share of total exergy inputs. The residential sector has reduced its share of total exergy inputs while the transport sector has increased its share.
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300000
250000
200000
150000TCal
100000
50000
0 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Year Industry Transport Agriculture Construction Residential Commercial and Public Sector Other Consumptions Mining Figure 22. Colombia's total exergy inputs by sector Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Year Industry Transport Agriculture Construction Residential Commercial and Public Sector Other Consumptions Mining Figure 23. Colombia's total exergy inputs by sector as a percentage of total exergy inputs Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
Furthermore, the time series for useful work outputs is shown in Figure 24. In order to calculate the total useful work output time series, the exergy efficiency of each consumption category was multiplied by its share of total exergy inputs for each year, and then added together to obtain the useful work output time series. This is expressed in equation (3), which is derived from equation (2) by clearing U.
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(3) ∗ =
Where E cc is exergy inputs by consumption category (aggregated by sectors in Figure 22),
Ɛcc is exergy efficiency by consumption category and U is total useful work outputs
(shown in Figure 24).
80000 70000 60000 50000 TCal 40000 30000 20000 10000 0
Year
Figure 24. Total useful work in Colombia (1975-2009) Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
Keeping this in mind, the exergy efficiencies for each consumption category will be analysed in more detail in section 4.4, together with the share of useful work used in each sector and consumption category.
4.4. DATA ANALYSIS
Colombia’s overall exergy efficiency (from TFC exergy to useful work: TFC-UW) during the 1975-2009 time period is shown in Figure 25. Colombia’s aggregate exergy efficiency increases from 23.5% to 27.17%, but it is not a steady increase. Furthermore, when calculating the exergy efficiency from TPES exergy to useful work (TPES-UW) for
Colombia (using the TFC/TPES ratio shown in Figure 13), it can be seen that Colombia’s efficiency is even more volatile, increasing slightly from 19.3% to 19.59% (see Figure 25).
Table 4 shows minimum, maximum, average and 1975-2009 increase quantities for both
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TFC-UW and TPES-UW exergy efficiencies, in absolute terms and regarding year by year variations.
33.00% 31.00% 29.00% 27.00% 25.00% 23.00% 21.00% 19.00%
Exergy efficiency Exergy 17.00% 15.00% 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year TFC Exergy Efficiency TPES Exergy Efficiency
Figure 25. Colombia's aggregate exergy efficiency (1975-2009) Source: Own elaboration based on data from UPME (2014b) and Manrique Díaz et al. (n.d.).
Table 4. Details of TFC-UW and TPES-UW exergy efficiencies (1975-2009) TFC-UW exergy efficiency TPES-UW exergy efficiency Absolute Variation Absolute Variation Minimum 23,45% -10,07% 19,30% -12,21% Maximum 30,29% 8,08% 25,46% 13,09% Average 27,95% 0,48% 22,62% 0,15% 1975-2009 Increase 3,72% 15,87% 0,29% 1,48% Source: Own elaboration.
A country’s overall exergy efficiency could be improved by different circumstances. The most straightforward circumstance is efficiency gains in specific processes, i.e. the efficiency improvement comes directly from technical progress in one or more consumption categories. However, a country’s overall exergy efficiency could also be improved if there are changes between in the level of activity of sectors towards those that are more efficient (structural effect). Furthermore, a country’s overall exergy efficiency could be improved if there are changes within economic sectors towards more efficient consumption categories (concentration effect).
As a starting point, the efficiency gains in specific processes will be looked at. Figure 26 shows the exergy efficiency of sectors and the overall exergy efficiency (in the second
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axis). The exergy efficiencies of the sectors are influenced both by the efficiency of their consumption categories and their share in total exergy inputs. The latter explains the sudden rise in the mining sector’s efficiency (it started being accounted for as a separate sector in 1992).
There seems to be a relationship between total exergy efficiency and the exergy efficiency of the agriculture sector. However, when looking in detail the exergy efficiency of the latter (Figure 27), it can be seen that its efficiency changes are not a consequence of efficiency changes in its specific processes (consumption categories).
100.0% 32.00%
80.0% 30.00% 28.00% 60.0% 26.00% 40.0% 24.00%
20.0% 22.00%
0.0% 20.00% Overall ExergyOverall efficiency Sector Sector Exergy efficiency 197519771979198119831985198719891991199319951997199920012003200520072009 Year Total Industry Efficiency Total Transport Efficiency Total Agriculture Efficiency Total Mining Efficiency Total Construction Efficiency Total Residential Efficiency Total Commercial Efficiency Total Other Consumptions Efficiency TOTAL EXERGY EFFICIENCY Figure 26. Exergy efficiency by sectors and total exergy efficiency Source: Own elaboration based on data from Manrique Díaz et al. (n.d.).
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70.0%
60.0%
50.0%
40.0%
30.0%
20.0% Exergy efficiency Exergy
10.0% 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year Total Agriculture Efficiency Fumigation Other Agriculture Farm Processing Irrigation Grain Drying
Figure 27. Exergy efficiency by agriculture processes and total agriculture exergy efficiency Source: Own elaboration based on data from Manrique Díaz et al. (n.d.). Additionally, but not as clear, there seems to be a relationship between total exergy efficiency and the exergy efficiency of the industry sector (Figure 26). Moreover, when looking in detail at the exergy efficiency of the industry sector (Figure 28), it can be seen that its efficiency changes could be influenced, at least in part, by the efficiency changes in the specific processes (consumption category) of iron, steel and non-ferrous.
90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0%
Exergy efficiency Exergy 20.0% 10.0% 0.0% 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year Total Industry Efficiency Food, beverages and tobacco Footwear and leather Cement Iron, Steel and Non -Ferrous Woods and Furniture Machinery and Equipment Other Industrial Paper and Printing Stones, Glass and Ceramic Chemicals Textiles and Clothing
Figure 28. Exergy efficiency by industry processes and total industry exergy efficiency Source: Own elaboration based on data from Manrique Díaz et al. (n.d.).
On the other hand, when looking at the level of activity of the sectors in relation to the overall exergy efficiency (Figure 29), there seems to be an inverse relationship between the
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transport and residential sectors (two of the most inefficient ones), i.e. when their share in the economy increases the total exergy efficiency decreases and vice versa. Furthermore, there seems to be a direct relationship, albeit smaller, between the total exergy efficiency and the industrial sector (one of the most efficient ones). These three sectors are in turn the ones that have had the greatest share of exergy inputs throughout the period (1975-
2009), which explains why their variations impact so strongly on the total exergy efficiency.
Furthermore, the changes within the three main economic sectors reveal again that, as expected, the consumption categories that have the largest share in the sector’s total exergy inputs are the ones that impact more strongly sectorial exergy efficiency, and the direction of their influence is determined by their relative efficiency to the rest of the processes within the sector. In this sense, it is the food, beverages and tobacco and cement processes (high relative efficiency) that directly affect industrial exergy efficiency, while it is the chemical and paper and printing processes (low relative efficiency) that inversely affect industrial exergy efficiency (Figure 30).
40% 35% 30% 25% 20% 15% 10% 5% 0%
Share of of Share sector exergy consumption 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009
Year Share of Industry Share of Transport Share of Agriculture Share of Mining Share of Construction Share of Residential Share of Commercial and Public Share of Other Figure 29. Level of activity of the sectors Source: Own elaboration based on data from Manrique Díaz et al. (n.d.).
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35%
30% 25%
20%
15%
10%
5%
0% 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009
Share of of Share process exergy consumption Year Food, beverages and tobacco Footwear and leather Cement Iron, Steel and Non-Ferrous Woods and Furniture Machinery and Equipment Other Industrial Paper and Printing Stones, Glass and Ceramic Chemicals Figure 30. Industry sector share of processes Source: Own elaboration based on data from Manrique Díaz et al. (n.d.).
In the case of the residential sector, the rural efficiency inversely affects residential exergy efficiency while cooking affects it directly (Figure 31). Finally, in the case of the transport sector it is less clear, but in general it is the air transport processes (high relative efficiency) that directly affects transport exergy efficiency, while it is sea transport processes (low relative efficiency) that inversely affects transport exergy efficiency and the road transport processes have a mixed effect (Figure 32).
90% 80% 70% 60% 50% 40% 30% 20% 10% 0%
Share of of Share process exergy consumption 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year Hot Water Air Cond. Cooking Lighting Fridge Other Residential Rural Residential
Figure 31. Residential sector share of processes Source: Own elaboration based on data from Manrique Díaz et al. (n.d.).
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100% 90% 80% 70% 60% 50% 40% 30% 20% 10%
Share of of Share process exergy consumption 0% 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year Air Railway River Sea Road
Figure 32. Transport sector share of processes Source: Own elaboration based on data from Manrique Díaz et al. (n.d.).
In summary, in this 34 year period (1975-2009) exergy efficiency changes have been driven more by structural and concentration/dilution effects than by actual efficiency improvements in the different processes (consumption categories) undertaken by the
Colombian economy. The structural effect of increased transport sector (a relatively inefficient sector) share in the use of total exergy inputs explains the decay in total exergy efficiency between 1985 and 1995. Moreover, the increase of industry’s –together with the decrease of the residential sector’s- share of total exergy inputs explains the rise in total exergy efficiency between 2001 and 2007.
Taking this into account, the almost two-fold increase in useful work outputs shown in
Figure 33 has been mainly due to increases in the exergy inputs. The small contribution due to efficiency gains, have in turn been a result of structural and concentration effects.
The implications of these results for Colombia’s energy policy will be discussed in detail in section 5.3.
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2.5
2
1.5
1
0.5
0 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Normalized Values (1975) Year TPES Exergy Inputs Total Useful Work Outputs TFC Exergy Efficiency TPES Exergy Efficiency TFC Exergy Inputs Figure 33. Exergy, useful work and exergy efficiency in Colombia (1975-2009) normalized 1975=1 Source: Own elaboration based on data from Manrique Díaz et al. (n.d.).
On the other hand, it is interesting to consider how the exergy efficiency data analysed in this section fits into the wider literature (see section 3.2). For developed countries such as the UK and the US, the overall exergy efficiencies tend to be more stable or increase more steadily than in the Colombian case, as well as being lower. Brockway et al. (2014) show that in the 1960-2010 period, overall US exergy efficiency (TPES-UW) remained stable at around 11% and overall UK exergy efficiency (TPES-UW) increased from 9% to 15% in the same time period.
Similarly, when comparing countrywide studies for a specific year, Colombia’s exergy efficiency appears to be higher. For example, the exergy efficiency (TFC-UW) of Brazil in
1987 was 22.8% (Schaeffer & Wirtshafter, 1992), while Colombia’s was 29.4%. The same can be observed in the case of the US (Reistad, 1975), Canada (Rosen, 1992), Turkey (Ílerí
& Gürer, 1998) and the world (Nakićenović et al., 1996), i.e. that Colombia’s exergy efficiency is higher. Figure 34 summarizes these comparisons 17 .
17 Single year national analysis that include non-energy uses were not included in this comparison because non-energy uses were not taken into account in this dissertation.
The Colombian Case 59
Colombia (TPES -UW) 0.35 Colombia (TFC-UW) 0.3 Canada (TFC -UW) Brazil (TFC-UW) 0.25 US (TPES -UW) UK (TPES-UW) 0.2 Turkey (TPES -UW) 0.15 World (TPES-UW) World (TFC -UW) 0.1 Exergy efficiency Exergy 0.05
0
Year
Figure 34. Comparison of several country's overall exergy efficiency Source: Own elaboration.
The above comparison shows that Colombia’s overall exergy efficiency is, in general, higher than for all the reviewed countries. It is very important to look for an explanation of this, because due to technology factors, developing countries can be expected to be behind developed ones. In this sense, it is very likely that the deep methodological differences regarding the calculations of exergy efficiency between Colombia and other developed countries explain the fact that Colombia has a higher exergy to useful work efficiency. These methodological issues will be discussed in detail in section 5.1
However, it is also worth mentioning that Colombia has a high share of hydropower for its electricity generation, which partially explains its higher TPES-UW efficiency.
Furthermore, given its geographical location, it does not need to establish heating systems, which are in general very inefficient exergetically, i.e. Colombia uses less energy sources for low temperature heat. Moreover, given its mountainous terrain, it does not need to establish air conditioning systems in the whole territory, only in the cities that are close to sea level, which also represents savings in an inefficient use of exergy.
Finally, the volatility of its overall exergy efficiency could be characteristic of developing countries, which have a more volatile economy and less established industries, hence structural and concentration/dilution effects have a larger impact on overall efficiency.
The Colombian Case 60
Given that there are no other studies of exergy efficiency for developing countries, this cannot be confirmed and further research is needed in this area.
4.5. FUTURE ENERGY PROJECTIONS (PEN S)
The 2010 PEN constructs two energy projections (scenarios) from 2008 until 2030: business as usual (BAU) and alternative. The former assumes a continuation of the recent historical evolution of Colombia’s energy system, while the latter incorporates markedly different hypothesis, particularly in the participation of alternative energy sources in the country’s energy mix (Di Sbroiavacca & Dubrovsky, 2011). Both scenarios are exploratory, which means that they can explicitly include structural changes through the hypothesis and assumptions used, which in turn were constructed based on interviews with energy sector experts (Di Sbroiavacca & Dubrovsky, 2011).
It assumes socioeconomic variables to be the drivers of energy demand, specifically population, GDP and vehicle fleet (Di Sbroiavacca & Dubrovsky, 2011). Their evolution in time was based in the projections done by other institutions. Population is assumed to grow at an annual average rate for the whole period of 1.09%, with a continuous move from the rural to the urban areas (Di Sbroiavacca & Dubrovsky, 2011). In turn, the GDP is assumed to grow at an average annual rate of 4.23% between 2008 and 2030 and the vehicle fleet is assumed to grow at an average rate of 3.4% for private vehicles, 1.6% for public transport and 4% for road freight (Di Sbroiavacca & Dubrovsky, 2011). These socioeconomic variables and their assumed evolution in time will not be discussed in the context of this dissertation.
Regarding efficiency, the 2010 PEN has implicit and explicit assumptions. The implicit assumption is imbedded in the BAU scenario, and is related to exergy efficiency. Given that exergy efficiency is not analysed in the PEN, there is an implicit assumption that the energy supplied has provided the useful work that Colombia needs, and that it will continue to do so. However, useful work is a product of both exergy inputs and exergy
The Colombian Case 61
efficiency, and the contribution of exergy efficiency gains to the supply of useful work
(see Figure 33) is not taken into account.
The explicit assumptions are related to energy efficiency gains in the alternative scenario, which in this 2010 PEN are assessed through the recent establishment of the Rational and
Efficient Use programme (URE in Spanish) in 2001, its past achievements and future potential. However, URE is largely a programme of consumer education on energy savings and demand side management. Its component on the introduction and development of more efficient technologies is based on the gradual introduction of more efficient equipment for illumination, air conditioning, cogeneration, refrigeration, engines and boilers amongst others, the economic incentives needed to achieve this (e.g. tax deductions) and some research and development encouragement.
Specifically, based on the difference between the annual average growth rates, the energy efficiencies of the alternative scenario will amount to 0.5% annually on average, and will be a consequence of both URE efficiency gains and substitution of less efficient energy sources for more efficient ones (Di Sbroiavacca & Dubrovsky, 2011). The difference in the projected TFC in both scenarios can be seen in Figure 35.
Therefore, in the BAU scenario the estimated TFC by 2030 is 66,380 TCal (a 96% increase in relation to the 2009 TFC), whereas in the alternative scenario it is 419,075 TCal (a 76% increase in relation to the 2009 TFC). This means that in the BAU scenario, there is an implicit assumption of a 0.48% annual exergy efficiency increase (average TFC-UW exergy efficiency increase for the period 1975-2009, see Table 4), and that for the alternative scenario there is an additional 0.5% annual efficiency increase (i.e. a total efficiency increase of 0.98% on average annually).
The Colombian Case 62
500,000
450,000
400,000
350,000
TFC TCal TFC 300,000
250,000
200,000 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 Year BAU Alternative
Figure 35. Projected TFC in the BAU and alternative scenario Source: Own elaboration based on data from Di Sbroiavacca & Dubrovsky (2011).
The almost doubling of TCF in both scenarios is driven, as already mentioned, by the projections in population, GDP and vehicle fleet. These in turn lead to an increase in the demand for electricity as it substitutes firewood and coal wood, and an increase in the demand for biofuels as their participation in fuel mixes with oil products increases.
Therefore, TPES is projected to have an increased participation of coal –particularly for electricity generation-, biofuels and natural gas.
The projected increase in the use of coal is justified in consideration of the fact that it is a very abundant resource in Colombia (see Figure 11) and that it would reduce the vulnerability of the country’s electricity generation in dry seasons (Di Sbroiavacca &
Dubrovsky, 2011). However, this has consequences for GHG emissions and hence the energy dualism discussed in chapter 2. Figure 36 shows how the projected GHG emissions do not differ significantly in each scenario, i.e. they more than double in the
2008-2030 period.
The Colombian Case 63
140,000
120,000
100,000
80,000
60,000
40,000
20,000 GHG emissions emissions GHG (tonnes of CO2eq) - 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 Year BAU Alternative
Figure 36. Projected GHG emissions (PEN 2010) Source: Own elaboration based on data from Di Sbroiavacca & Dubrovsky (2011).
The Colombian Case 64
For industry increased efficiency means lower production costs; for the consumer it means lower prices; for everyone it means reduced pollution of air and water Summers (1971, p. 149)
Chapter 5. DISCUSSION
This chapter will discuss three aspects of this dissertation. First and foremost, the methodological particularities and possible improvements of the Colombian dataset will be discussed, since the validity of the results obtained through the data analysis depends on the soundness of the dataset itself (section 5.1). Secondly, the results themselves will be analysed in the light of the PEN projections and energy dualism (section 5.2). Thirdly, the policy implications of the results will be assessed, both in general and for the specific case of Colombia (section 5.3).
5.1. METHODOLOGY
The IEA’s energy balances are usually the source of energy information for other studies
(for example Brockway et al., 2014; Serrenho et al., 2012). However, the IEA only has statistics for Colombia (which is not a member of this institution) from 1990 onwards. This is not a sufficiently long period to be able to construct an exergy and useful work time series, which is required in order to show significant trends in efficiency improvements.
Therefore, the primary source of energy information used in this dissertation is necessarily different for the Colombian case: the BENs elaborated by UPME.
The BENs are based on the structure developed by OLADE (Latin American Energy
Organization) for constructing energy balances and it differs slightly from the IEA’s structure. The main difference between OLADE and IEA energy balances is that OLADE’s structure subdivides energy sources under the categories of primary energy sources 18 and
18 Natural gas, oil, coal, firewood, bagasse, hydropower and recovery/residues.
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secondary energy sources 19 , while IEA uses a broader set under a single category 20 .
However, Figure 37 shows that the information from UPME and IEA do not differ significantly at an aggregate level, demonstrating that the original energy data used in the
Colombian case is generally consistent with the source used in other studies.
350000
300000
250000
200000 TCal 150000
100000
50000
0 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year BEN Final Consumption IEA TFC BEN Internal Supply IEA TPES
Figure 37. Comparison between UPME and IEA data Source: Own elaboration based on data from UPME (2014a) and IEA (2014a).
Moreover, recent work has sought to achieve methodological uniformity in the calculation of useful work national time series. Serrenho et al. (2012), for example, develop a standardised way of taking IEA energy statistics and constructing exergy and useful work series, and applies this to EU-15 countries for the period 1960-2010 21 . This approach is based on using a defined number of useful work categories 22 into which they allocate final exergy inputs depending on sector and energy source. In this way exergy inputs are, in
19 Bioethanol, biodiesel, coal wood, coke, diesel oil, electricity, fuel oil, industrial gases, liquefied gas, petrol, refinery gases, kerosene and jet fuel, and non-energetic. 20 Coal and peat; crude oil; oil products; natural gas; nuclear; hydro, geothermal, solar, etc.; biofuels and waste; electricity; and heat. 21 Brockway et al. (2014) further develop this approach by improving the level of detail on electricity and transport for the US and the UK for the same time period in order to move towards easily comparable results. 22 Heat (low, medium and high temperature), mechanical drive/work, electricity, lighting, muscle work.
Discussion 66
general, allocated to a defined number of processes, and from there proceed to calculate the exergy efficiency of each useful work category (or process).
Manrique Díaz et al. (n.d.), on the other hand, calculate the exergy efficiencies of consumption categories within each sector. This can be problematic, particularly in the case of the industry sector which has exergy inputs from many different energy sources feeding into a single consumption category 23 ; here higher or lower single source efficiencies could be hidden within general efficiency. Therefore, Colombia’s useful work time series and overall efficiencies are not directly comparable with the ones calculated for other developed countries, nonetheless they are valuable in themselves as a first approximation for a developing country.
The exergy efficiencies for each consumption category should, ideally, be calculated separately for each energy source, since the energy sources can be used for different processes in a given consumption category. Manrique Díaz et al. (n.d.) acknowledge this but to date have only been able to calculate a general efficiency for each consumption category. Their approach has considerable potential in this sense, but at the same time all macro scale studies seek a fairly high level of generalization. Therefore, the useful work categories approach could be a better alternative, since it also allows easier comparison with other studies and contributes to methodological uniformity. Also, using useful work categories enables the identification of opportunities for efficiency improvements in the general processes that transform exergy inputs into useful work.
However, a categorization based on technical conversion devices, such as the one undertaken by Cullen and Allwood (2010a), could be helpful in identifying more precisely the conversion devices with the greatest potential for efficiency improvements, especially those which would have the greatest impact (i.e. the ones that transform more exergy
23 For example, in 2009 the cement consumption category (industry sector) received exergy inputs from natural gas and electricity, amongst others, which are used for different processes and hence have different exergy efficiencies.
Discussion 67
inputs). Moreover, efficiency improvements could be assessed from the passive system perspective (see Figure 9). This is the ideal level of analysis and further research needs to be carried out in this direction.
Additionally, the different types of models available to assess efficiency warrant discussion. Following Cullen and Allwood (2010b), there are 3 types of models: top-down, bottom-up and theoretical. They vary according to which target efficiency is chosen: economic potential, technical potential and theoretical potential, respectively. The first type of model chooses its target efficiency by identifying historical trends in order to extrapolate into the future. The second type of model chooses its target efficiency by identifying the best available technologies and assessing their combined potential. The third type of model establishes a thermodynamically based absolute target efficiency.
As it was described in section 4.2, the LEAP model used by UPME to develop the 2010
PEN uses a bottom-up approach. It has the advantage of looking in detail at the available technological options, but it falls short by aggregating the potential efficiency gains into broad economic sectors and assessing only known or emerging technologies (Cullen &
Allwood, 2010b). The latter shortfall can be overcome by using exergy and useful work analysis, a theoretical model, since it establishes a target efficiency that allows for comparisons on an equivalent basis and is independent of current technical alternatives
(Cullen & Allwood, 2010b).
Finally, UPME analyses Colombia’s energy system at the energy level (see Figure 8). It makes projections of the TFC (together with projections of energy imports and exports), and from there it goes back to TPES to assess and provide policy recommendations on how to develop the energy system further so that the country can harvest enough TPES to meet such projections. However, section 3.1 argued that useful work is the most valuable concept for a country trying to meet its social needs, this being the underlying aim of all energy system development. Therefore, the analysis of an energy system should be carried out at this level of relevance.
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Analysing an energy system at the energy level could be compared to analysing the performance of a furniture factory based on the wood inputs that go in to it (TPES), and how much wood comes out of it (TFC), without looking at the type of wood inputs that go in (exergy) nor the shape and quality of the furniture outputs that come out as a result
(useful work). As has been stressed earlier, it is useful work (furniture outputs) that societies demand, and hence what should be analysed when assessing an energy system.
Society does not demand rough pieces of wood of random shapes (dissipated heat, for example) but, rather, assembled tables (mechanical drive, for example).
5.2. RESULTS
Section 4.4 analysed Colombia’s energy system at the useful work level. The main conclusions were that Colombia’s useful work has almost doubled in the 34 year period, but that this was mainly due to increases in exergy inputs and less so to efficiency gains
(which in turn were a consequence of structural and concentration effects). This could mean two things:
1. Colombia has reached a stagnation point in terms of exergy efficiency, thus any
increase in useful work must come from increases in exergy inputs.
2. Colombia has yet to start making progress in actual efficiency gains that go
beyond structural and concentration effects, thus future increases in useful work
could come from increased exergy efficiency.
Considering what was described in section 4.5, the 2010 PEN assumes that the efficiency gains in Colombia’s energy sector between 2010 and 2030 will come mainly from energy savings and demand side driven programmes, and secondly from efforts to replace technologies and energy sources towards more efficient ones. In this sense, the 2010 PEN seems very much in line with the second possible result derived from this case study, i.e. that Colombia has yet to start improving its exergy efficiency.
Discussion 69
However, by not using exergy and useful work analysis, the 2010 PEN ignores that exergy efficiency might have reached a stagnation point (first possible result), and that its projected increases in TPES might therefore need to be higher than expected. If this is the case, the consequences could be significant taking into account that energy infrastructure requires large capital and time investments. Figure 38 shows how different the projections would be if Colombia has actually reached a stagnation point and there were no more
TFC-UW exergy efficiency improvements.
550,000
500,000
450,000
400,000 TCal 350,000
300,000
250,000
200,000 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 Year BAU Alternative Stagnated TFC -UW efficiency
Figure 38. 2010 PEN projections and hypothetical stagnated TFC-UW efficiency Source: Own elaboration based on data from Di Sbroiavacca & Dubrovsky (2011) and Table 4.
In order to correctly assess which of the two results is relevant in this case, a greater understanding of the exergy efficiencies of the processes behind the most influential sectors (transport, industry and residential) is needed, so that comparisons with current efficiencies in other countries can be made and possible sources of improvements be identified. Unfortunately, this is not possible within the timeframe of this dissertation.
The information obtained from Manrique Díaz et al. (n.d.) is part of an ongoing project, and at this stage constitutes only a first approximation to the issue. Therefore, its value lies more in its illustrative use than its technical precision and validity.
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Finally, and relating the results back to the energy dualism explored in section 2, the role of government intervention will be particularly important in determining the solution for dualism, i.e. the transition towards a low carbon energy system, both in terms of incentives (Pearson & Foxon, 2012) and an increasing need for government intervention to promote investment needs (IEA, 2014b). Also the role of government intervention in relation to improved environmental quality could be a driver in this low carbon energy transition (Fouquet, 2012), something which can already be seen in recent efforts to the reduction of GHG emission 24 .
Regarding efficiency and energy dualism, on the one hand it is true that increased efficiency implies less resource use and hence a lower relative environmental impact. In this sense, efficiency improvements address directly the environmental concerns of energy use and would, therefore, help ease an energy transition.
On the other hand, exergy and useful work analysis provides the conceptual and empirical link between energy use and economic growth (Ayres and Warr, 2009), hence it highlights the key nature of energy under the current economic system. At a national level, and based on the policy recommendations of the 2010 PEN, Colombia considers the energy sector to be a vital part of the economy, through its role in exports, GDP, tax income and foreign direct investment (Univerisdad Nacional de Colombia & Fundación
Bariloche, 2010). However, it has not yet been recognized that the increased consumption of useful work has been one of the factors that has driven economic growth as a whole.
For a developing country, it is particularly important to understand all the factors that drive economic growth in order to be able to promote it.
In this sense, both exergy inputs (Figure 21) and useful work outputs (Figure 24) have increased in the 1975-2009 period. This is consistent with the importance of energy for
24 Although Colombia does not have specific commitments to reduce its emission of GHG, and it does not contribute significantly to global emissions (only 0.37%), it has promoted several policies that promote low GHG emissions (PNUD, 2010).
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economic growth described in section 2.1, taking into account that Colombia’s GDP has also increased during the period analysed. Figure 39 shows the evolution of exergy and useful work in relation to GDP. As expected, the TPES exergy/GDP and TFC exergy/GDP have decreased because of efficiency improvements, while the UW/GDP has stayed more or less stable since this is what the economy actually needs. Useful work cannot be decoupled from productive processes.
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
-
TPES exergy/GDP TFC exergy/GDP UW/GDP
Figure 39. Exergy and useful work in relation to GDP (1975-2009) Source: Own elaboration based on data from Manrique Díaz et al. (n.d.), UPME (2014a) and DANE (2013).
5.3. POLICY IMPLICATIONS
5.3.1. GENERAL / CONCEPTUAL
In general, using exergy instead of energy as a measure of TPES and TFC has the advantage of providing an objective measure for comparing all energy sources, i.e. their ability to perform work. It facilitates following the flows of energy from TPES to useful work while at the same time avoiding the problem pointed out by Giampietro and
Sorman (2012) and Cleveland et al. (2000) of identifying a relevant attribute which can be used as criterion equivalence in order to aggregate and compare different energy sources.
Discussion 72
In addition, analysing an energy system at the useful work level provides a more detailed understanding of energy use than analysing it at the energy level. By so doing, it is possible to go back to TPES in exergy –or even energy- terms, which is what policymakers are interested in. There is nonetheless an additional level of analysis that has great potential to further increase the understanding of energy use, but which needs to be fully developed before entering the energy policy sphere: the energy services level.
Additionally, exergy efficiency provides an absolute reference base for measuring progress in energy efficiency. The thermodynamic (theoretical) limit is the one against which exergy and useful work analysis is undertaken, at a device or society level, hence it provides a “useful theoretical target from which to set practical limits, and an absolute basis from which to measure progress” (Cullen & Allwood, 2010b, p. 2061). This is illustrated in Figure 40 with indicative values, where the theoretical potential is an objective equitable basis for comparison while the technical potential and the economic potential are subjective bases for comparison, given that they depend of current market and technical conditions that change over time.
Consequently, the value of exergy and useful work analysis as such can be observed even if the specific details are not fully available for Colombia. In summary, exergy and useful work analysis improve the understanding of what happens to energy beyond power generation, beyond the harnessing of energy sources and their transformation into useful forms, beyond TFC and its allocation to different economic sectors that have little to do with how the energy is used. By doing so, it opens possibilities for improved action in the planning of future energy supply.
Finally, the complexity issue that surrounds exergy and useful work analysis is vital to understanding its scarce use outside expert circles and its lack of adoption in policymaking. As Arnold Sommerfeld observes: “Thermodynamics is a funny subject. The first time you go through it, you don't understand it at all. The second time you go through it, you think you understand it, except for one or two small points. The third time
Discussion 73
you go through it, you know you don't understand it, but by that time you are so used to it, it doesn't bother you anymore” (cited by Califano, 2012, p. 22).
Theoretical potential
Technical potential
Economic potential
0% 100%
Figure 40. Diagram of the potential exergy efficiency improvements Source: Adapted from Cullen & Allwood (2010b, p. 2060).
Despite the complexity behind thermodynamics in general, its relevance cannot be underestimated. Our understanding of the physical world, and the phenomena that occur within it, is incomplete without at least a basic idea of the laws of thermodynamics. But perhaps more importantly, our knowledge of present environmental and development issues related to energy is only partial without an adequate recognition of physical reality, and adequate solutions or possible improvement pathways depend on this. As Hammond
(2004b) argues, the current dismissal of thermodynamic concepts by economists and energy policymakers is a manifestation of the “two cultures” (natural sciences and humanities) divide characterised by C.P. Snow.
On the other hand, the relevance of thermodynamics should not be overestimated either.
Insights from the natural sciences are only part of the puzzle, a very important part that should not be ignored, but only a part nonetheless. Therefore, trans-disciplinary approaches seem to be the way forward in dealing with complex issues. Even beyond academia, Rosen (2006b) insists on the need to increase knowledge of exergy by everyone: the general public, media, decision-makers and the government.
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5.3.2. COLOMBIA
In relation to the specific case study of Colombia, policy implications will be analysed in three spheres: demand, particularly how to limit it and how to avoid efficiency dilution; supply, paying special attention to the generation of electricity; and finally efficiency itself, how to improve it and the possibilities for leapfrogging.
DEMAND
A role consumers could play in solving the energy dualism would be to change their behaviour towards less wasteful energy use practices. However, this role is limited to the wasteful portion of energy use, since energy use itself is vital to living standards and economic growth, as analysed in Bejan’s (2012) paper “Why we want power”. A similar role can also be attributed to producers, but here limitations become especially evident when considering the global distribution of supply chains.
Even with these limitations, the reduction of energy demand by changing wasteful practices is important. In light of the 2010 PEN, and through the URE programme, user education on energy issues is being undertaken through partnerships between the
Ministry of Culture and Education, the private sector (social responsibility) and the media
(Univerisdad Nacional de Colombia & Fundación Bariloche, 2010). It has entered national policies, and could contribute to the management and control of demand.
In terms of energy demand, it is also important to avoid efficiency dilution effects. These types of effects were initially identified by Williams et al. (2008) and Brockway et al.
(2014) for Japan and the US respectively. Efficiency dilution happens when the net effect of the incorporation of a more efficient technology is effectively diluted because of the increased use of less efficient technologies. For example in the case of Japan (Williams et al., 2008), the efficiency of trains has increased significantly more than that of automobiles,
Discussion 75
but the demand for the latter has also increased, diluting the efficiency gain from rail transport.
In this sense, demand management in Colombia could focus on promoting efficient means of transportation, for example by reviving its abandoned rail system, in order to meet an increasing overall demand for transportation (see section 4.5). It could also focus on promoting passive cooling systems in the areas of the country that need air conditioning, since air conditioning is a very inefficient use of electricity which would lead to the dilution of possible increases in the efficiency of other conversion devices.
SUPPLY
As was shown in section 4.4, the role of hydropower is very relevant to Colombia’s overall TPES-UW exergy efficiency. It is the major energy source for electricity generation, with the remaining electricity being generated by thermal plants, powered mainly by natural gas. The 2010 PEN projects electricity demand to double over the 2010-2030 period, and how this electricity is going to be supplied is a key concern (Univerisdad
Nacional de Colombia & Fundación Bariloche, 2010).
In the light of the exergy analysis undertaken in this dissertation, it is now clear that an increase in thermal power plants would reduce TPES-UW efficiency. However, as was expressed in section 4.5, the 2010 PEN proposes to meet the increased demand for electricity by coal powered thermal plants, taking advantage of the abundance of this resource in Colombia and also reducing the vulnerability inherent in relying on hydropower generated electricity during the dry seasons.
This would have consequences for both sides of the energy dualism. It would necessarily imply more GHG emissions, and if the link between useful work and GDP is accepted, it would have limiting consequences for economic growth. Nonetheless, Colombia has a great potential for renewable energy (see section 4.1.2). Promoting these types of sources
Discussion 76
instead of coal would clearly address the environmental side of the energy dualism.
However, because renewable energy sources are not yet fully developed, it would not have immediate positive effects in terms of energy efficiency, an aspect that could be overcome in the long term as the deployment of renewables develops further (Kramer &
Haigh, 2009).
EFFICIENCY
Energy efficiency measures to ease the transition towards a low carbon energy future are not part of the main concerns of the general public. As Ayres and Ayres (2010, pp. 157–
158) put it: “[T]he conundrum we face is that, from the standpoint of public arousal and mobilization, the idea of recycling waste heat […] just doesn’t grip the public imagination the way that Al Gore’s vision of a zero-carbon, renewable energy future does. Yet the former is an essential bridge to the latter”. Hence, voluntary public pressure on governments to promote energy efficiency improvements is not likely to happen.
Moreover, current market incentives work against efficiency improvements. Extractive and energy transformation companies increase their profits if they sell more coal, oil or electricity (Ayres & Ayres, 2010), so that increasing the efficiency of conversion devices that transform such energy sources acts against the interest of the suppliers. Furthermore, it is consumers who are being left with the incentive of improving the efficiency of the conversion devices they use in order to reduce their energy costs, but in most cases consumers do not have sufficient technical knowledge to make decisions about energy efficiency (Ayres & Ayres, 2010).
One way to turn around the incentives would be for extractive and utilities companies to sell useful work (or even better, energy services) instead of energy sources; in this way, it would be in the interest of these companies to produce the greatest amount of energy services with the minimum use of energy sources (i.e. increase efficiency), and efficiency
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concerns would be transferred to the actors that have the knowledge and technical means of improving efficiency (Ayres & Ayres, 2010).
However, this is not the direction in which Colombia is moving, and so the promotion of efficiency improvements remains primarily a responsibility of the government. In this regard, the URE programme aims to incentivise the replacement of equipment through partnerships with the Ministry of Industry and Commerce, the Ministry of Transport and the ANDI (National Businessmen Association of Colombia), as well as local research and development.
Moreover, if we accept that the results for Colombia are reliable, and that the overall exergy efficiency of the country can still be improved when compared to the efficiency of developed countries, it is worthwhile considering whether there are possibilities for leapfrogging in certain energy technologies. The latter term was first introduced by
Goldemberg (1998) when stating that developing countries did not have to follow the same path of energy technologies as they closed the gap with developed countries, and that they could leapfrog over some of the technologies and directly implement the most efficient ones.
In this sense, Colombia could leapfrog certain energy technologies, particularly in the rural sector. For example, following Goldemberg (1998), photovoltaic (PV) or wind technology could be implemented in areas that are not connected to the national grid, and thus replace candles, kerosene and batteries for lighting purposes. This in turn would enable, Colombia to leapfrog traditional light bulbs by using the more efficient LED ones, once unelectrified areas have access to electricity. Furthermore, Colombia could also potentially leapfrog over some industrialized countries in the widespread adoption of PV or wind technology.
Exergy and useful work analysis can be used to identify which technologies are lagging behind and could be replaced, either with or without leapfrogging, depending on how far
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lagged they are. However, leapfrogging needs consistent government policies, private sector willingness to move towards more efficient technologies (Gallagher, 2006) and domestic technological capabilities together with an understanding of specific social, cultural and political institutions (Murphy, 2001).
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I sell here, Sir, what all the world desires to have –POWER Matthew Boulton, the business manager and partner of James Watt, to a visitor to the Boulton-Watt works in 1776 (Bejan, 2012, p. 4930)
Chapter 6. CONCLUSIONS
There is an energy dualism: energy is something absolutely essential for societies but at the same time is something that currently entails serious negative environmental impacts.
This dualism could be solved by a full energy transition from fossil fuels towards renewable and sustainable energy sources. However, this transition is not occurring as fast as needed to avoid the most negative consequences of climate change. Efficiency improvements are an alternative to ease the transition, and their importance should not be underestimated. Efficiency has been considered even as a fifth fuel (Yergin, 2011).
In this sense, exergy and useful work are important concepts that should be considered when assessing energy systems in general, but particularly when referring to energy efficiency. Firstly, they are a good criterion of equivalence when analysing energy statistics. Secondly, given that measure quality as well as quantity, they represent a better level of analysis than energy. Thirdly, they provide an absolute reference base for assessing possibilities and measuring progress in energy efficiency.
Exergy and useful work analysis are particularly useful at revealing where the biggest losses occur within an energy system and thus where the major areas of efficiency improvement lay; this is the field of exergy analysis that is widely used by engineers when assessing specific processes. When applied to a whole nation, it is a useful tool for comparing efficiency performance between economic sectors, but even better for comparing the relative impact of efficiency improvements in the conversion devices that deliver useful work in economic sectors, and hence to determine where to concentrate effort. These are the main advantages of using exergy and useful work analysis from a conceptual viewpoint.
Conclusion 81
In this dissertation a specific case study was undertaken in order to illustrate how exergy and useful work can be used as a tool for improved energy policy making in a more practical, grounded sense. In the study undertaken for Colombia, applied exergy and useful work analysis revealed several important issues concerning the future of the country’s energy sector. Firstly, with regard to energy demand, this study revealed limitations with respect to the scope for reducing wasteful energy use, but more importantly, it demonstrated the risk of efficiency dilution. When existing work, presented in this dissertation, on the cases of Japan and the US is taken into consideration, it suggests that special attention needs to be paid to the transport and residential sectors.
Secondly, regarding energy supply, this study revealed that the choice of the energy source for electricity generation should be assessed in relation to its consequences for the country’s overall exergy efficiency and its impact on GHG emissions. The coal alternative does not perform very well in either of these two aspects. . And finally, regarding efficiency, this study provides evidence concerning real possibilities for leapfrogging certain energy technologies, for example in the case of PV or wind technology for lighting unelectrified rural areas.
Therefore, more in depth understanding of energy use will necessarily affect the decisions and specific policy recommendations of national and international institutions in charge of shaping energy systems. UPME in the case of Colombia and IEA in the case of OECD countries fit into that institutional category. Although this point may seem obvious, it is worth emphasising given that energy related institutions of this kind are still lacking in understanding of energy use beyond TFC and its classification into broad economic sectors.
In particular, both the planning of future energy supply needs and the identification of where the greatest possibilities of efficiency improvement lay, would benefit from the use of exergy and useful work analysis. For these specific purposes, the use of exergy and useful work analysis on behalf of expert institutions would not imply major challenges,
Conclusion 82
given that exergy and useful work analysis is now an established methodology which has already been applied, in academic circles, at a national level and for many countries.
Finally, the application of exergy and useful work analysis to an increasing number of countries is important in the quest for methodological consistency within this particular field. Furthermore, by studying countries that are different in terms of income levels and geographical conditions, the value of exergy and useful work analysis is strengthened, both of itself and as a standard for comparing countries.
To sum up, exergy and useful work analysis can be used as a tool for improved energy policy making in various ways: as an objective measure which can be aggregated at different levels of energy analysis; as a means for deepening our understanding of energy use and enabling the study of an energy system at a relevant level; as a way of improving the construction of more accurate projections of energy demand and thus supply needs; as a facilitator for the identification of the areas with most potential for efficiency improvements; and as an aid for effective comparisons between countries.
However, further research is needed both in the specific case of Colombia and in general terms. In the former case, to overcome the methodological difficulties identified in this dissertation and obtain a clearer picture of Colombia’s energy system. And in the latter case, further work should aim at increasing the work on exergy and useful work analysis across a wider range of disciplines, but focusing on energy policy, which is where there is the strongest potential for application.
Conclusion 83
REFERENCES
Abramovitz, M. (1956). Resource and output trends in the United States since 1870. American Economic Review , 46 (2), 5–23.
AGECC. (2010). Energy for a Sustainable Future: Summary Report and Recommendations . Retrieved from http://www.unido.org/fileadmin/user_media/Publications/download/AGECCsummaryrepor t.pdf
Armaroli, N., & Balzani, V. (2011). Energy for a sustainable world: from the oil age to a sun- powered future . Weinheim: Wiley-VCH.
Ayres, R. U. (1997). Technological Progress: A Proposed Measure (No. 97/101/EPS). Fontainebleau, France.
Ayres, R. U., & Ayres, E. H. (2010). Crossing the Energy Divide: Moving from Fossil Fuel Dependence to a Clean-Energy Future . Upper Saddle River, N.J.: Wharton School Publishing.
Ayres, R. U., Ayres, L. W., & Pokrovsky, V. N. (2005). On the efficiency of US electricity usage since 1900. Energy , 30 (7), 1092–1145. doi:10.1016/j.energy.2004.07.012
Ayres, R. U., Ayres, L. W., & Warr, B. (2003). Exergy, power and work in the US economy, 1900– 1998. Energy , 28 (3), 219–273. doi:10.1016/S0360-5442(02)00089-0
Ayres, R. U., Turton, H., & Casten, T. (2007). Energy efficiency, sustainability and economic growth. Energy , 32 (5), 634–648. doi:10.1016/j.energy.2006.06.005
Ayres, R. U., & Voudouris, V. (2014). The economic growth enigma: Capital, labour and useful energy? Energy Policy , 64 , 16–28. doi:10.1016/j.enpol.2013.06.001
Ayres, R. U., & Warr, B. (2005). Accounting for growth: the role of physical work. Structural Change and Economic Dynamics , 16 (2), 181–209. doi:10.1016/j.strueco.2003.10.003
Ayres, R. U., & Warr, B. (2009). The Economic Growth Engine. How energy and work drive material prosperity . Cheltenham, UK: Edward Elgar.
85
Barrett, J., Peters, G., Wiedmann, T., Scott, K., Lenzen, M., Roelich, K., & Que, C. L. E. (2013). Consumption-based GHG emission accounting: a UK case study. Climate Policy , 13 (4), 451– 470. doi:http://dx.doi.org/10.1080/14693062.2013.788858
Baskut, O., & Ozgener, L. (2012). Exergoeconomic assessment of a wind turbine power plant (WTTP): Cesme, Izmir, example. Energy , 47 (1), 577–581. doi:10.1016/j.energy.2012.09.014
Bazarov, I. P. (1964). Thermodynamics . Oxford: Pergamon Press.
Beaudreau, B. C. (1995). The impact of electric power on productivity: A study of US manufacturing 1950-84. Energy Economics , 17 (3), 231–236.
Beaudreau, B. C. (1999). Energy and the Rise and Fall of Political Economy . London: Greenwood Press.
Bejan, A. (2012). Why we want power: Economics is physics. International Journal of Heat and Mass Transfer , 55 (19-20), 4929–4935. doi:10.1016/j.ijheatmasstransfer.2012.05.046
Bejan, M., & Bejan, A. (1982). A supply-side approach to energy policy. Energy Policy , 10 (2), 153– 157. doi:http://dx.doi.org/10.1016/0301-4215(82)90027-1
BP. (2014). BP Statistical Review of World Energy . Retrieved from http://www.bp.com/content/dam/bp/pdf/Energy-economics/statistical-review-2014/BP- statistical-review-of-world-energy-2014-full-report.pdf
Bradshaw, M. J. (2010). Global energy dilemmas: a geographical perspective. Geographical Journal , 176 (4), 275–290. doi:10.1111/j.1475-4959.2010.00375.x
Brockway, P. E. (2014). Session: Impacts of useful work and exergy results on energy scenarios. Leeds: Exergy-Economics Workshop. Retrieved from http://sure- infrastructure.leeds.ac.uk/exec/3-impacts-of-useful-work-and-exergy-results-on-energy- scenarios/
Brockway, P. E., Barrett, J. R., Foxon, T. J., & Steinberger, J. K. (2014). Divergence of trends in US and UK Aggregate Exergy Efficiencies 1960-2010. Environmental Science & Technology . doi:http://dx.doi.org/10.1021/es501217t
86
Califano, S. (2012). Pathways to Modern Chemical Physics . New York: Springer.
Chen, G. Q., & Chen, B. (2009). Extended-exergy analysis of the Chinese society. Energy , 34 (9), 1127–1144. doi:10.1016/j.energy.2009.04.023
Chen, G. Q., & Qi, Z. H. (2007). Systems account of societal exergy utilization: China 2003. Ecological Modelling , 208 (2-4), 102–118. doi:10.1016/j.ecolmodel.2007.04.017
CIA. (2014). The World Factbook. Retrieved July 10, 2014, from https://www.cia.gov/library/publications/the-world-factbook/rankorder/2172rank.html
Cipolla, C. M. (1978). The Economic History of World Population (7th ed.). Harmondsworth: Penguin Books.
Cleveland, C. J. (1987). Biophysical Economics: Historical Perspective and Current Research Trends. Ecological Modelling , 38 (1-2), 47–73. doi:http://dx.doi.org/10.1016/0304-3800(87)90044-5
Cleveland, C. J., Kaufmann, R. K., & Stern, D. I. (2000). Aggregation and the role of energy in the economy. Ecological Economics , 32 (2), 301–317. doi:10.1016/S0921-8009(99)00113-5
Cleveland, C. J., & Ruth, M. (1997). When, where, and by how much do biophysical limits constrain the economic process? A survey of Nicholas Georgescu-Roegen’s contribution to ecological economics. Ecological Economics , 22 (3), 203–223. doi:http://dx.doi.org/10.1016/S0921-8009(97)00079-7
COMMEND. (2014). COMMEND: A Community for Sustainable Energy Analysis. Retrieved July 12, 2014, from http://www.energycommunity.org/default.asp?action=67
Cornelissen, R. L. (1997). Thermodynamics and sustainable development: The use of exergy analysis and the reduction of irreversibility . University of Twente. Retrieved from http://doc.utwente.nl/32030/
Cullen, J. M., & Allwood, J. M. (2010a). The efficient use of energy: Tracing the global flow of energy from fuel to service. Energy Policy , 38 (1), 75–81. doi:10.1016/j.enpol.2009.08.054
87
Cullen, J. M., & Allwood, J. M. (2010b). Theoretical efficiency limits for energy conversion devices. Energy , 35 (5), 2059–2069. doi:10.1016/j.energy.2010.01.024
Daly, H. E. (1974). The Economics Steady State. The American Economic Review , 64 (2), 15–21.
Daly, H. E. (1987). The economic growth debate: What some economists have learned but many have not. Journal of Environmental Economics and Management , 14 (4), 323–336. doi:10.1016/0095-0696(87)90025-8
DANE. (2013). Documento metodológico y resultados de la retropolación 1975 - 2005. Base 2005 . Bogotá. Retrieved from https://www.dane.gov.co/files/investigaciones/pib/especiales/doc_met_retropolacion_base 2005_1975_2005_28_05_13.pdf
Davis, S. J., & Caldeira, K. (2010). Consumption-based accounting of CO2 emissions. Proceedings of the National Academy of Sciences of the United States of America , 107 (12), 5687–92. doi:10.1073/pnas.0906974107
DECC. (2012). The Energy Efficiency Strategy: The Energy Efficiency Opportunity in the UK . London. Retrieved from https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/65602/69 27-energy-efficiency-strategy--the-energy-efficiency.pdf
Di Sbroiavacca, N., & Dubrovsky, H. (2011). Metodología y prospectiva a partir de escenarios energéticos (2008-2030) realizados con el modelo LEAP : El caso de COLOMBIA (pp. 1–135).
Dincer, I. (2002). The role of exergy in energy policy making. Energy Policy , 30 (2), 137–149. doi:http://dx.doi.org/10.1016/S0301-4215(01)00079-9
Domingos, T. (2013). Useful work, thermodynamic efficiency & economic growth. Retrieved from https://fenix.tecnico.ulisboa.pt/downloadFile/3779580562656/Lecture 11 20131217 Energy and economic growth.pdf
EIA. (2014). 2014 Annual Energy Outlook . Retrieved from http://www.eia.gov/forecasts/aeo/pdf/0383(2014).pdf
88
Ertesvag, I. S. (2005). Energy, exergy, and extended-exergy analysis of the Norwegian society 2000. Energy , 30 (5), 649–675. doi:10.1016/j.energy.2004.05.025
Ertesvag, I. S., & Mielnik, M. (2000). Exergy analysis of the Norwegian society. Energy , 25 (10), 957–973. doi:http://dx.doi.org/10.1016/S0360-5442(00)00025-6
Fouquet, R. (2010). The slow search for solutions: Lessons from historical energy transitions by sector and service. Energy Policy , 38 (11), 6586–6596. doi:10.1016/j.enpol.2010.06.029
Fouquet, R. (2012). The demand for environmental quality in driving transitions to low-polluting energy sources. Energy Policy , 50 , 138–149. doi:10.1016/j.enpol.2012.04.068
Fouquet, R., & Pearson, P. (1998). A Thousand Years of Energy Use in the United Kingdom. The Energy Journal , 19 (4), 1–14. doi:http://dx.doi.org/10.5547/ISSN0195-6574-EJ-Vol19-No4-1
Gaggioli, R. A., & Wepfer, W. J. (1980). Exergy economics. Energy , 5(3), 823–837. doi:http://dx.doi.org/10.1016/0360-5442(80)90099-7
Gallagher, K. S. (2006). Limits to leapfrogging in energy technologies? Evidence from the Chinese automobile industry. Energy Policy , 34 (4), 383–394. doi:10.1016/j.enpol.2004.06.005
Gasparatos, A., El-Haram, M., & Horner, M. (2009). Assessing the sustainability of the UK society using thermodynamic concepts: Part 2. Renewable and Sustainable Energy Reviews , 13 (5), 956–970. doi:10.1016/j.rser.2008.03.005
Gaudreau, K., Fraser, R. a., & Murphy, S. (2009). The Tenuous Use of Exergy as a Measure of Resource Value or Waste Impact. Sustainability , 1(4), 1444–1463. doi:10.3390/su1041444
Georgescu-Roegen, N. (1975). Energy and economic myths. Southern Economic Journal , 41 (3), 347–381. doi:http://dx.doi.org/10.2307/1056148
Giampietro, M., & Sorman, A. H. (2012). Are energy statistics useful for making energy scenarios? Energy , 37 (1), 5–17. doi:10.1016/j.energy.2011.08.038
Goldemberg, J. (1998). Viewpoint. Leapfrog energy technologies. Energy Policy , 26 (10), 729–741.
89
Gong, M., & Wall, G. (2001). On exergy and sustainable development — Part 2: Indicators and methods. Exergy, An International Journal , 1(4), 217–233. doi:http://dx.doi.org/10.1016/S1164-0235(01)00030-9
Hall, C. A. S., & Kiltgaard, K. A. (2012). Energy and the Wealth of Nations. Understanding the biophysical economy . New York: Springer.
Hammond, G. P. (2000). Energy, environment and sustainable development: A UK perspective. Process Safety and Environmental Protection , 78 (4), 304–323. doi:http://dx.doi.org/10.1205/095758200530826
Hammond, G. P. (2004a). Engineering sustainability: thermodynamics, energy systems, and the environment. International Journal of Energy Research , 28 (7), 613–639. doi:10.1002/er.988
Hammond, G. P. (2004b). Towards sustainability: energy efficiency, thermodynamic analysis, and the “two cultures.” Energy Policy , 32 (16), 1789–1798. doi:10.1016/j.enpol.2003.09.015
Hammond, G. P., & Stapleton, A. J. (2001). Exergy analysis of the United Kingdom energy system. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy , 215 (2), 141–162. doi:10.1243/0957650011538424
Harvey, F. (2014, March 17). The energy “trilemma”: how did we get here? The Guardian . Retrieved from http://www.theguardian.com/big-energy-debate/energy-trilemma-how-did- we-get-here
Hecht, E. (1987). Física en Perspectiva . México D.F.: Addison Wesley Iberoamericana.
IDEE. (1994). Economía de la Energía. San Carlos de Bariloche: Instituto de Economía Energética.
IEA. (2008). Energy Technology Perspectives . Retrieved from http://www.iea.org/publications/freepublications/publication/etp2008.pdf
IEA. (2012a). CO2 Emissions from Fuel Combustion. Highlights . Retrieved from http://www.iea.org/co2highlights/co2highlights.pdf
90
IEA. (2012b). World Energy Outlook . Retrieved from http://www.worldenergyoutlook.org/media/weowebsite/2008-1994/weo2008.pdf
IEA. (2014a). Colombia Balances. Retrieved July 22, 2014, from http://www.iea.org/statistics/statisticssearch/report/?country=COLOMBIA&product=balanc es&year=2009
IEA. (2014b). World Energy Investment Outlook 2014 . Retrieved from http://www.iea.org/publications/freepublications/publication/weio2014.pdf
IIASA. (2014). Model for Energy Supply Strategy Alternatives and their General Environmental Impact (MESSAGE). Retrieved July 10, 2014, from http://webarchive.iiasa.ac.at/Research/ENE/model/message.html
Ílerí, A., & Gürer, T. (1998). Energy and exergy utilization in Turkey during 1995. Energy , 23 (12), 1099–1106. doi:http://dx.doi.org/10.1016/S0360-5442(98)00063-2
IPCC. (2013). Summary for Policymakers. In T. F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, … P. M. Midgley (Eds.), Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 3–29). Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. Retrieved from http://www.climatechange2013.org/images/report/WG1AR5_SPM_FINAL.pdf
IPCC. (2014). Summary for Policymakers. In C. B. Field, V. R. Barros, D. J. Dokken, K. J. Mach, M. D. Mastrandrea, T. E. Bilir, … L. L. White (Eds.), Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 1–32). Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.
Jackson, T. (2009). Prosperity without Growth: economics for a finite planet . London: Earthscan.
Kanoglu, M., Cengel, Y. A., & Dincer, I. (2012). Efficiency Evaluation of Energy Systems . London: Springer.
91
Kostic, M. M. (2004). Work, Power, and Energy. Encyclopedia of Energy , 6, 527–538. doi:http://dx.doi.org/10.1016/B0-12-176480-X/00075-9
Kostic, M. M. (2007). Energy: Global and Historical Background. Encyclopedia of Energy Engineering and Technology , 1–15. doi:http://dx.doi.org/10.1201/9780849338960.ch73
Kostic, M. M. (2012). Energy: Physics. Encyclopedia of Energy Engineering and Technology , 2, 808– 823. doi:http://dx.doi.org/10.1201/9780849338960.ch135
Kramer, G. J., & Haigh, M. (2009). No quick switch to low-carbon energy. Nature , 462 (7273), 568– 9. doi:10.1038/462568a
Kümmel, R. (1982). The Impact of Energy on Industrial Growth. Energy , 7(2), 189–203. doi:http://dx.doi.org/10.1016/0360-5442(82)90044-5
Kümmel, R. (2011). The Second Law of Economics. Energy, entropy, and the origins of wealth . London: Springer.
Kümmel, R., Strassl, W., Gossner, A., & Eichhorn, W. (1985). Technical Progress and Energy Dependent Production Functions. Journal of Economics , 45 (3), 285–311. doi:http://dx.doi.org/10.1007/BF01282565
Lambert, J. G., Hall, C. A. S., Balogh, S., Gupta, A., & Arnold, M. (2014). Energy, EROI and quality of life. Energy Policy , 64 , 153–167. doi:10.1016/j.enpol.2013.07.001
Levenspiel, O. (1997). Fundamentos de Termodinámica . Mexico D.F.: Prentice Hall Hispanoamericana.
Lian, Z. T., Chua, K. J., & Chou, S. K. (2010). A thermoeconomic analysis of biomass energy for trigeneration. Applied Energy , 87 (1), 84–95. doi:10.1016/j.apenergy.2009.07.003
Manrique Díaz, O. G. (2013). Personal comunication.
Manrique Díaz, O. G., Velásquez Arredondo, H. I., & Giraldo Arismendy, S. A. (n.d.). Energía y Crecimiento Económico en Colombia: Un análisis integral e interdisciplinario. Medellín. Proyecto financiado por Colciencias y la Universidad Nacional de Colombia.
92
Martínez-Alier, J. (1987). Ecological Economics: Energy, Environment and Society . New York: Basil Blackwell.
MAyDS, & PNUD. (2014). Quinto Informe Nacional de Biodiversidad de Colombia ante el Convenio de Diversidad Biológica . Retrieved from https://www.dropbox.com/s/cxmj8umzklym3x5/V INFORME NACIONAL DE BIODIVERSIDAD.pdf
Murphy, D. J., & Hall, C. A. S. (2011). Adjusting the economy to the new energy realities of the second half of the age of oil. Ecological Modelling , 223 (1), 67–71. doi:10.1016/j.ecolmodel.2011.06.022
Murphy, J. T. (2001). Making the energy transition in rural East Africa: Is leapfrogging an alternative? Technological Forecasting and Social Change , 68 (2), 173–193. doi:http://dx.doi.org/10.1016/S0040-1625(99)00091-8
Nakićenović, N., Gilli, P. V., & Kurz, R. (1996). Regional and global exergy and energy efficiencies. Energy , 21 (3), 223–237. doi:http://dx.doi.org/10.1016/0360-5442(96)00001-1
National Geographic. (2014). Colombia Facts. Retrieved July 10, 2014, from http://travel.nationalgeographic.com/travel/countries/colombia-facts/
Nye, D. (1990). Electrifying America: social meanings of a new technologies, 1880-1940 . London: The MIT Press.
OECD. (2011). Towards Green Growth . OECD Publishing. Retrieved from http://www.oecd.org/greengrowth/48224539.pdf
Pearson, P. J. G., & Foxon, T. J. (2012). A low carbon industrial revolution? Insights and challenges from past technological and economic transformations. Energy Policy , 50, 117–127. doi:10.1016/j.enpol.2012.07.061
PNUD. (2010). Educación para Enfrentar el Cambio . Retrieved from http://www.pnud.org.co/img_upload/36353463616361636163616361636163/SEGUNDA_C OMUNICACION.pdf
93
Pokrovsky, V. N. (2003). Energy in the theory of production. Energy , 28 (8), 769–788. doi:10.1016/S0360-5442(03)00031-8
Ptasinski, K. J., Koymans, M. N., & Verspagen, H. H. G. (2006). Performance of the Dutch Energy Sector based on energy, exergy and Extended Exergy Accounting. Energy , 31 (15), 3135–3144. doi:10.1016/j.energy.2006.03.010
Querol, E., Gonzalez-Regueral, B., & Perez-Benedito, J. L. (2013). Exergy Concept and Determination. In E. Querol, B. Gonzalez-Regueral, & J. L. Perez-Benedito (Eds.), Practical Approach to Exergy and Thermoeconomic Analyses of Industrial Processes (pp. 9–28). London: Springer London. doi:10.1007/978-1-4471-4622-3
Reistad, G. M. (1975). Available energy conversion and utilization in the United States. ASME Journal of Engineering for Power , 97 (3), 429–434. doi:http://dx.doi.org/10.1115/1.3446026
Romer, P. M. (1994). The Origins of Endogenous Growth. Journal of Economic Perspectives , 8(1), 3–22. doi:http://dx.doi.org/10.1257/jep.8.1.3
Romero, J. C., & Linares, P. (2014). Exergy as a global energy sustainability indicator. A review of the state of the art. Renewable and Sustainable Energy Reviews , 33 , 427–442. doi:10.1016/j.rser.2014.02.012
Rosen, M. A. (1992). Evaluation of energy utilization efficiency in Canada using energy and exergy analyses. Energy , 17 (4), 339–350. doi:http://dx.doi.org/10.1016/0360-5442(92)90109-D
Rosen, M. A. (2002a). Can exergy help us understand and address environmental concerns? Exergy, An International Journal , 2(4), 214–217. doi:http://dx.doi.org/10.1016/S1164- 0235(02)00085-7
Rosen, M. A. (2002b). Energy crisis or exergy crisis? Exergy, An International Journal , 2(3), 125– 127. doi:10.1016/S1164-0235(02)00056-0
Rosen, M. A. (2002c). Exergy conservation: An alternative to conserving the already conserved quantity energy. Exergy, An International Journal , 2(2), 59–61. doi:10.1016/S1164- 0235(02)00055-9
94
Rosen, M. A. (2006a). Benefits of exergy and needs for increased education and public understanding and applications in industry and policy - Part I: Benefits. International Journal of Exergy , 3(2), 202–218. doi:10.1504/IJEX.2006.009047
Rosen, M. A. (2006b). Benefits of exergy and needs for increased education and public understanding and applications in industry and policy - Part II: Needs. International Journal of Exergy , 3(2), 219–229. doi:10.1504/IJEX.2006.009046
Rosen, M. A. (2013). Assessing global resource utilization efficiency in the industrial sector. The Science of the Total Environment , 461-462 , 804–7. doi:10.1016/j.scitotenv.2012.11.069
Rosenberg, N. (1982). Inside the black box: technology and economics . Cambridge: Cambridge University Press.
Rosenberg, N. (1998). The Role of Electricity in Industrial Development. The Energy Journal , 19 (2), 7–24. doi:10.5547/ISSN0195-6574-EJ-Vol19-No2-2
Schaeffer, R., & Wirtshafter, R. M. (1992). An exergy analysis for the Brazilian economy: from energy production to final energy use. Energy , 17 (9), 841–855. doi:http://dx.doi.org/10.1016/0360-5442(92)90102-6
Sciubba, E. (2001). Beyond thermoeconomics? The concept of Extended Exergy Accounting and its application to the analysis and design of thermal systems. Exergy, An International Journal , 1(2), 68–84. doi:10.1016/S1164-0235(01)00012-7
Sciubba, E., & Wall, G. (2007). A brief Commented History of Exergy From the Beginnings to 2004. International Journal of Thermodynamics , 10 (1), 1–26.
Serrenho, A. C., Warr, B., Sousa, T., Ayres, R. U., & Domingos, T. (2012). Natural resource accounting: exergy-to-useful work analysis in Portugal from 1856 to 2009 (No. Working Paper) (pp. 1–26).
Smil, V. (2006). Energy . Beginners Guides . Oxford: Oneworld Publications.
Solow, R. M. (1956). A Contribution to the Theory of Economic Growth. Quarterly Journal of Economics , 70 (1), 65–94. doi:http://dx.doi.org/10.2307/1884513
95
Solow, R. M. (1957). Technical Change and the Aggregate Production Function. The Review of Economics and Statistics , 39 (3), 312–320. doi:http://dx.doi.org/10.2307/1926047
Summers, C. M. (1971). The Conversion of Energy. Scientific American , 225 (3), 148–160. doi:http://dx.doi.org/10.1038/scientificamerican0971-148
Swan, T. (1956). Economic growth and capital accumulation. The Economic Record , 32 (2), 334– 361. doi:http://dx.doi.org/10.1111/j.1475-4932.1956.tb00434.x
Szargut, J. (1986). Application of Exergy for the Calculation of Ecological Cost. Bulletin of the Polish Academy of Sciences , 34 (7-8), 475–479.
Tsatsaronis, G. (2007a). Comments on the Paper “A Brief Commented History of Exergy from the Beginnings to 2004.” International Journal of Thermodynamics , 10 (4), 187–190.
Tsatsaronis, G. (2007b). Definitions and nomenclature in exergy analysis and exergoeconomics. Energy , 32 (4), 249–253. doi:10.1016/j.energy.2006.07.002
Tsatsaronis, G., & Valero, A. (1989). Thermodynamics Meets Economics. Mechanical Engineering , 111 , 84–86.
UN. (2013). World Economic Situation and Prospects . Retrieved from http://www.un.org/en/development/desa/policy/wesp/wesp_current/2013country_class.p df
UNEP. (2011). Towards a Green Economy: Pathways to Sustainable Development and Poverty Eradication - A Synthesis for Policy Makers . Retrieved from http://www.unep.org/greeneconomy
Univerisdad Nacional de Colombia, & Fundación Bariloche. (2010). PEN 2010-2030. Informe Final (pp. 1–253). Retrieved from http://www.upme.gov.co/Docs/PEN/PEN 2010 VERSION FINAL.pdf
Unruh, G. C. (2000). Understanding carbon lock-in. Energy Policy , 28 (12), 817–830. doi:http://dx.doi.org/10.1016/S0301-4215(00)00070-7
96
UPME. (2014a). Balance Energético Nacional (BEN) 1975. Retrieved from http://www.simec.gov.co/simec/Home/Balances/tabid/62/Default.aspx
UPME. (2014b). Balance Energético Nacional (BEN) 2012. Retrieved from http://www.simec.gov.co/simec/Home/Balances/tabid/62/Default.aspx
UPME, & IDEAM. (2005). Atlas Colombiano de Radiación solar . Retrieved from http://www.si3ea.gov.co/si3ea/Home/EnergiaSolar/tabid/74/language/en-US/Default.aspx
UPME, & IDEAM. (2006). Atlas de Viento y Energía Eólica de Colombia . Retrieved from http://www.si3ea.gov.co/si3ea/Home/Energ%C3%ADaEolica/tabid/75/language/en- US/Default.aspx
Utlu, Z., & Hepbasli, A. (2009). Exergoeconomic aspects of sectoral energy utilization for Turkish industrial sector and their impact on energy policies. Energy Policy , 37 (2), 577–587. doi:10.1016/j.enpol.2008.09.078
Velásquez Arredondo, H. I., Agudelo, A., & Chejne, F. (2011). Energy use in the production of unrefined sugar in Colombia (exergy analysis). Revista Facultad de Ingeniería , 58 , 17–26. Retrieved from http://aprendeenlinea.udea.edu.co/revistas/index.php/ingenieria/article/view/14595/1275 9
Velásquez Arredondo, H. I., Ruiz Colorado, A. A., & Oliveira Junior, S. (2009). Ethanol Production from Banana Fruit and its Lignocellulosic Residues: Exergy and Renewability Analysis. International Journal of Thermodynamics , 12 (3), 155–162.
Verbong, G., & Loorbach, D. (2012). Introduction. In G. Verbong & D. Loorbach (Eds.), Governing the Energy Transition. Reality, Illussion or Necessity? (pp. 1–23). London and New York: Routledge.
Wall, G. (1977). Exergy - a useful concept within resource accounting . Göteborg, Sweden. Retrieved from http://www.exergy.se/ftp/paper1.pdf
Wall, G. (1986). Exergy – a useful concept . Chalmers University of Technology, Göteborg, Sweden. Retrieved from http://www.exergy.se/ftp/introduction.pdf
97
Wall, G. (1987). Exergy conversion in the Swedish society. Resources and Energy , 9(1), 55–73. doi:http://dx.doi.org/10.1016/0165-0572(87)90023-5
Wall, G. (1990). Exergy conversion in the Japanese society. Energy , 15 (5), 435–444. doi:http://dx.doi.org/10.1016/0360-5442(90)90040-9
Wall, G. (1993). Exergy, Ecology and Democracy - Concepts of a Vital Society or A Proposal for An Exergy Tax. In ENSEC’93, International Conference on Energy Systems and Ecology (pp. 111– 121). Krakow, Poland.
Wall, G. (2003). Exergy tools. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy , 217 (2), 125–136. doi:10.1243/09576500360611399
Wall, G., Sciubba, E., & Naso, V. (1994). Exergy use in the Italian society. Energy , 19 (12), 1267– 1274. doi:http://dx.doi.org/10.1016/0360-5442(94)90030-2
Warr, B., Ayres, R. U., Eisenmenger, N., Krausmann, F., & Schandl, H. (2010). Energy use and economic development: A comparative analysis of useful work supply in Austria, Japan, the United Kingdom and the US during 100years of economic growth. Ecological Economics , 69 (10), 1904–1917. doi:10.1016/j.ecolecon.2010.03.021
WEC. (2010). Energy Efficiency: A Recipe for Success . London. Retrieved from http://www.worldenergy.org/publications/2010/energy-efficiency-a-recipe-for-success/
White, L. A. (1943). Energy and the Evolution of Culture. American Anthropologist , 45 (3), 335–356. doi:http://dx.doi.org/10.1525/aa.1943.45.3.02a00010
Williams, E., Warr, B., & Ayres, R. U. (2008). Efficiency dilution: long-term exergy conversion trends in Japan. Environmental Science & Technology , 42 (13), 4964–70. doi:http://dx.doi.org/10.1021/es0716756
World Atlas. (2014). Colombia. Map of Colombia . Retrieved August 05, 2014, from http://www.worldatlas.com/webimage/countrys/samerica/co.htm
World Bank. (2012). Inclusive Green Growth: The Pathway to Sustainable Development . Retrieved from http://issuu.com/world.bank.publications/docs/9780821395516
98
World Bank. (2014). Country and Lending Groups. Retrieved June 04, 2014, from http://data.worldbank.org/about/country-classifications/country-and-lending-groups
XM. (2014). Descripción del Sistema Eléctrico Colombiano. Retrieved July 27, 2014, from http://www.xm.com.co/Pages/DescripciondelSistemaElectricoColombiano.aspx
Yergin, D. (2011). The Quest. Energy, Security, and the Remaking of the Modern World . London and New York: Penguin Books.
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APPENDIX A
Table 5. Exergy coefficients for Colombia's energy sources Energy Sources in Colombia Energy Form Exergy Coefficients Oil Chemical 1.08 Non- Chemical renewable Coal 1.07 Primary Natural Gas Chemical 1.04 Energy Hydro-power Mechanical 1 Sources Wood Chemical 1.11 Renewable Bagasse Chemical 1.06 Recovered waste Chemical 1 Biodiesel Chemical 1.11 Carburant alcohol Chemical 1.11 Coal wood Chemical 1 Coke Chemical 1.05 Diesel oil Chemical 1.06 Electricity Electrical 1 Secondary Energy Sources Fuel Oil Chemical 1.07 Industrial gases Chemical 1 Kerosene and jet fuel Chemical 1.06 Liquefied gas Chemical 1.06 Non-energetic Chemical 1 Petrol Chemical 1.06 Refining gas Chemical 1.06 Source: Based on data from Manrique Díaz et al. (n.d.).
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