Report in reference to Trends in Sustainable Energy

1876-6102 © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of Applied Energy Innovation Institute doi: 10.1016/j.egypro.2015.07.671

Energy Procedia 75 ( 2015 ) 2683 – 2693

ScienceDirect

The 7th International Conference on Applied Energy – ICAE2015

Transitions to sustainable energy and material systems – outline of principles for scenarios

Ziyi Wanga, Qinxing Wanga, Ronald Wennerstena, Qie Suna, * a Institute of Thermal Science and Technology, Shandong University, Jingshi Road No.17923, Jinan and 250061, China

Abstract

There is more or less consensus around the problems related to the existing energy systems in the world. Most focus has been on the negative environmental effects of using fossil fuels. However, looking at the development there seems to be important barriers for change. Many papers and reports conclude that the renewable energy sources have the potential to run the world and the technology needed to do so is available. A relevant and important question in this paper is then why is this potential only marginally utilized? Often the high prices of renewables are said to be one barrier and that technology change will gradually increase the advantages of renewable energy. However considerations based solely on thermodynamics and energy systems analysis, no matter how simple they are, lead to a very serious conclusion, namely that the utilization of renewable energy does not support continuous growth as we know it. In order to develop pathways for change, scenarios can be used to support decision making involving all key actors in society. In this paper we outline the driving forces why we ended up in the energy systems we have today. The competition between fossil fuels and renewable energy must be analyzed at a more fundamental thermodynamic level. This analysis has also to include the links between energy and material transformation. Understanding this we can outline possible roadmaps for transitions to more sustainable energy and material systems starting from primary energy sources. The strong dependence on fossil fuels now will require long transitions periods for change. However it is important to start the transitions taking small steps forward. The problem related to fossil fuels and climate change will not be solved in due time. The only realistic options here is Carbon Capture and storage together with climate change adaption. One difficulty in making scenarios is to handle changes in technology and people’s behavior. By developing evolutionary forecasting scenarios (EFS) different roadmaps can be evaluated, including continuous and discontinuous technology change. The key parameter that will determine the inevitable transitions in energy use and the future of our civilization is the emergy yield ratio we can obtain from the renewable energy sources. For material transformation conservation of low entropy states will be of high importance. © 2015 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of ICAE Keywords Energy system; sustainable energy; material transformation; energy scenarios; evolutionary forecasting scenarios; thermodynamics; emergy; entropy; transformity

* Corresponding author. Tel.: +86-188-8833-1818. E-mail address: [email protected].

Available online at www.sciencedirect.com

© 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of Applied Energy Innovation Institute

2684 Ziyi Wang et al. / Energy Procedia 75 ( 2015 ) 2683 – 2693

1. Introduction

Since the start of the second industrial revolution more than 100 years ago, the global dependence on fossil fuels has steadily increased. The second industrial revolution was also a technical revolution, which led to fast electrification, mass production and development of infrastructure like railways and communication systems [1]. The high energy density in fossil fuels was an important and necessary condition for the second industrial revolution as well as a high urbanization rate. Earlier, the development was hindered by low energy intensity in the form of wind and flowing water. The dominance of fossil fuels is still prevailing and this historical background is important to have in mind in order to understand the dominance of fossil fuels today.

Ever since the first report from the IPCC in 1990, much focus has been on the relation between burning of fossil fuels and CO2 emissions. Scenarios show that the combustion of fossil fuels will increase in the future, while the development of renewables is still too marginal to stop this increase. The possibility that countries will leave fossil resources underground does not seem realistic. The present economic growth models require large amounts of intensive energy that only fossil fuels can deliver, and it is likely that large amounts fossil fuel will continue to be consumed in a predictable future. In the central scenario from the IEA, where planned national policies to reduce the use of fossil energy have been implemented, global energy demand will still grow by one-third from 2011 to 2035. Emerging economies account for more than 90% of the net growth [2]. The only option in the short run to slow down CO2 emissions is the large-scale application of carbon capture and storage (CCS) in combination with increased energy efficiency [3]. In the long run, we have to explore more radical transformations of our societal metabolism and growth models before renewables can play a significant role. The key issue is how to cope with humanity's growing energy needs, including the combat of poverty, while limiting environmental impacts in the long run. The debate today around sustainable energy systems is in many ways confusing and somewhat blind for facts. It mixes short terms considerations around energy prices with long-term considerations of environmental effects. This often leads politicians to introduce temporary subsidies for technologies and energy carriers, which can lead to technological lock-in effects. A typical example of this might be the use of bioethanol as a fuel for transport. Many reports stated that we can convert our energy systems to rely on renewable energy, without drastic changes in structure and function of our society [4]. However, these scenarios lack fundamental understanding of how strong the link between the societal metabolism and fossil fuels really is. The central question is, as fossil energy sources decline, how does society return to a new position in the earth system without collapse. What is needed includes more comprehensive analysis of short-, medium- and long-term potential and consequences of using different primary energy sources, energy carriers and energy technologies. The transition has to start with small steps, which can be motivated among key actors in a short-term. We also have to include in the analysis the links between energy and material transformation. Few might understand today that cheap food, clothing, and housing depend on cheap energy and that the food we eat is really made from fossil fuel. This paper will outline how a more comprehensive analysis can form the basis for different scenarios for transitions of energy and materials. This paper is part of a research project to develop scenarios for, and transition states towards, more energy and resource efficient urban development.

2. Aim, objectives and method

The central aim of this paper is to analyze how fundamental scientific properties can be used to formulate sustainability principles regarding primary energy sources. These principles can be used later in creating scenarios for transitions of energy systems and material transformations, where other more subjective sustainability criteria will also be applied. These subjective criteria, referred to as secondary criteria, are also discussed briefly in the paper.

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Specific objectives of the paper include: Analysis of the existing situation on energy systems and global primary energy sources, how this

situation has developed, what problems there are, and what barriers for transition exist; To develop a productive definition of primary energy sources, which can be used in developing

scenarios for transitions to more sustainable energy and material systems; Analysis of using fundamental properties in understanding the future potential of different primary

energy sources; To discuss principles for scenarios for transitions to more sustainable energy systems and material

transformation combining first principles and secondary criteria. This paper is partly based on a literature review and also on experiences with scenario development in

practice for urban development. This experience has revealed the need for more structured background material, which in part is general, but also in part specific for each case.

3. Key problems with today’s energy systems on local and global level

Several key problems related to sustainability can be identified in the present energy and material systems, where primary energy is mainly based on fossil fuels. The key problems to be addressed in the criteria and transition scenarios for more sustainable energy and material systems include:

Exploitation and use of primary fossil energy sources creates pollution on local, regional and global scales. The most highlighted pollution is CO2, but also local particle emissions and water pollution are in many cases a serious problem. The problems with pollution are connected to combustion of fossil fuels but also to the extraction of the energy resource and to the transformation from primary energy to other types of energy carriers. In principle, many of these problems can technically be solved using different environmental technologies including CCS. However, this would raise national economic costs and considerations over industrial competitiveness that would often hinder economic growth in the short-term perspective.

The reserves of fossil fuels are in principle finite, but the total known reserves are much larger than the global demand [3]. It is reasonable that the more accessible deposits are extracted first and then the extraction shifts to harder assets such as reservoirs under deep seas, in oil sands or in deep shale rocks. It is thus expected that, with stronger environmental regulations, significant cost on extraction would be charged in the future. This development will make renewable energy solutions more competitive. However, renewable energy sources cannot compete with fossil fuels in terms of energy density, which is important for the existing growth models.

The reserves of fossil energy resource are geographically unevenly distributed. This causes problems because political unrest can cause fast disturbances in the trade. Countries, which are relying on import, thus face a risk, when it comes to energy security. It is likely that this will increase international conflicts, which can be seen already today. This situation will be more pronounced when new fossil sources with lower net energy output have to be utilized. The price mechanism thus favors the countries sitting on more available and more easy-to-extract sources.

Energy transition is linked to material transformation and waste handling. Scenarios for energy transitions thus have to include future ways for material transformation and waste handling. The hope for a society with zero waste might not turn out to be an optimal solution from a resource point of view.

4. Primary energy sources

In order to compare different scenarios regarding primary energy sources, it is important to start with energy embodied in these sources. In this way, the accumulated energy needed to extract and reform the energy sources should be included. Therefore, processes like separation from contiguous material, cleaning or grading, to make the energy available for trade, use or transformation into secondary energy sources or

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energy carriers should be taken into account. Each alternative proposed as a primary energy source ought to be evaluated for its potential to yield net benefit. We will later discuss how the net benefit can be expressed in fundamental property.

Primary energy is here defined as an energy form found in nature that has not been subjected to any conversion or transformation process by humans. Different kinds of statistics around energy are often based on primary energy. A problem is that primary energies are not calculated according to a consistent methodology. Instead, several approaches are available and used in practice [5].

Depending on if energy sources are renewed on human timescales, primary energy sources are divided into renewable and non-renewable energy (Table 1). Energy carriers are energy forms, which have been transformed from primary energy sources, to suit human purposes. Examples of energy carriers are electricity, gasoline, refined oil and coal, hydrogen, natural gas etc.

Table 1. Primary energy sources [6]

Non-renewable energy sources Renewable energy sources Combustibles Non-combustibles Combustibles Non-combustibles

Hard coal Coal gases

Lignite Peat

Oil based fuels Natural gas

Waste (fossil part)

Nuclear Biomass (solid, liquid, gaseous) Waste (biogenic part)

Hydro (storage, run-of-river, tide, wave and ocean)

Wind Solar (photovoltaic, solar thermal

including surface energy) Geothermal

5. Basic principles for scenario development

Traditional scenario techniques can be generally divided into predictive, explorative and normative scenarios. Another distinction is between qualitative and quantitative scenarios [7]. Forecasting scenarios start with the existing situation and prognoses different changes that would occur in future, under the assumptions about endogenous and exogenous factors. Backcasting scenario techniques are in principle normative, where desirable images of the future are developed as well as roadmaps from the present to the future.

Developing backcasting scenarios according to sustainability principles has been reported several times before. Some scenarios are built upon general qualitative sustainability criteria [8]. Starting from these criteria, the actors in the scenarios can include other criteria, which are more based on subjective values. One problem with backcasting is that one has to formulate images of the future out of existing knowledge today. Different key actors often have biased ideas about one or another solution as being the ”only possible” or ”only realistic”. If these key actors are the most powerful and influential actors, it will create severe problems when generating participative scenarios. This is also why it is important to have a well-structured “objective” background material using a systems perspective as input for the scenarios. All scenarios have difficulties in handling discontinuities in technological development and also future changes in human behaviour and future global political situations.

In our research, the aim is to develop scenario techniques, which we name evolutionary forecasting scenarios (EFS) combined with backcasting scenarios. Instead of starting with images of the future, different roadmaps are first developed through evolutionary modeling, where the fundamental criteria are applied. These scenarios can include continuous and discontinuous technology development and can identify important bottlenecks and potentials of technology development. The evolutionary scenarios will develop into different branches depending on the optimization criteria used. Optimization is generally regarded to be finding an alternative with the most cost effective or highest achievable performance under the given constraints, by maximizing desired factors and minimizing undesired ones. Practice of optimization is restricted by the lack of full information, and the lack of time to evaluate what information is available. In computer modelling of business problems, optimization is achieved usually by using linear programming

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techniques. In this project we apply agent-based modelling techniques and the optimization criteria described in section 6.3.

With these models, different images, roadmaps and consequences can be explored using both primary, fundamental scientific, criteria, as well as also secondary, more value-based, criteria described later. Sustainability and the roads towards it, which may be called sustainable development, is in principle a value- based process involving many key actors. Consequences from models using primary together with secondary criteria will be used in dialogue processes with key actors. The aim is to determine the theoretical constraints of future resource potentials and restrictions defined by today’s technologies and cultural conditions will also be taken into account.

6. Criteria for evaluation of sustainable primary energy resources

6.1. Basic criteria needed

In order to develop scenarios for long-term transitions towards more sustainable energy and material systems, we need in principle two sets of criteria. The first set, here referred to as primary criteria, is derived from the first principle of thermodynamics and will be used in exploring transition scenarios. The other set, referred to as secondary criteria, can be used together with primary criteria to evaluate different scenario options. The secondary criteria are basically value-based criteria, which have to be decided in dialogue processes involving key actors.

6.2. Primary criteria derived from the first principle of thermodynamics

When comparing different opportunities for replacing fossil fuels with renewable energy sources, it is often different kind of net energy calculations and energy prices that are used for evaluation. However, these net energy calculations do not consider the total energy inputs, since there are numerous feedbacks from inputs from fossil fuels. The fluctuations in fossil fuel prices reflect more geopolitical status than the fundamental facts of primary energy sources. In the long run, when easy-to-extract fossil fuels get scarcer, fundamental facts around primary energy sources will play a more significant role. These facts are related to energy intensity, total availability and accumulated energy need to transform the primary energy sources to final energy carriers.

The first set of criteria, primary criteria, should be based on the properties developed out of the first principles, which include the first and the second law of thermodynamics, laying the scientific foundation for energy transformation. The first law of thermodynamics is simply an expression of the conservation of energy. It asserts that energy is a thermodynamic property and that, during an interaction, energy can change from one form to another, while the total amount of energy remains constant. The second law of thermodynamics asserts that energy has quality as well as quantity and that actual processes occur in the direction of decreasing quality of energy. The attempts to quantify the quality or “work potential” of energy in the light of the second law of thermodynamics have resulted in the definition of the properties entropy and exergy. The fourth fundamental property to be used is emergy, which is defined as energy used to make a product or a service. More information around the four properties is given in Appendix A.

Energy and material transformations in our society form a series, in which the output of one is the input to the next starting from primary energy and material sources. One can also relate all the forms of energy in a series of energy transformations to one form of energy by calculating their transformities. Transformity is defined as the joules of available energy of one form previously required directly and indirectly to generate one joule of another form of energy. Transformity increases with every energy transformation. Fossil fuels are concentrations of available energy of moderately high transformity, which has been accumulated by the earth’s emergy for millions of years.

In order to analyse the efficiency of these transformations, energy, exergy and emergy analysis have been used. Sciubba and Ulgiati compared emergy and exergy analysis and used bioethanol production as a

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case study [9]. The conclusion was that “the two approaches appear to be characterized not much as different (and therefore competing) tools, but as different paradigms, whose meta-levels (their ‘philosophies’) substantially differ”. Emergy analysis expands the evaluation to the larger scale of the biosphere and properly accounts for the global aspects of the energy and resource flows that support complex living systems. One problem with exergy is that it is not a state variable but is dependent on the definition of environment. We will continue to explore the use of emergy and entropy as an evaluation criteria.

6.3. Using emergy in evolutionary scenarios

Human societies try to maximize parameters such as efficiency, short time-scale return on investment, employment, profit etc. Quite on the opposite, natural processes are stochastic and system-oriented and seem to maximize the utility of the total flow of resources processed through optimization of efficiencies and feedback reinforcement. As environmental conditions change, it appears that the response of the system adapts so that maximum power output can be maintained. In this way, systems tune their thermodynamic performance to the changing environment. The central concept addressed by emergy analyses is that of energy quality. The emergy concept supports the idea that something has a value according to what was invested into making it along with a generative ‘trial and error’ process (Maximum Power Principle) [10]. The higher the investment requires under maximum power-output selection, the higher the quality is assigned to the item. It is postulated that either a system ‘learns’ how to maximize its output for success against competing alternatives or is displaced. Implicit in this concept is a thermodynamic approach to natural selection and evolution patterns.

The key parameter that will fundamentally determine the transitions to more sustainable energy and material systems should be emergy yield ratio of renewable energy sources [11]. Examples of criteria for optimization include minimum exergy destruction (entropy generation) [12], maximum entropy production [13], emergy yield ratio [14], as well as maximum empower and maximum dissipation. Emergy yield together with entropy change can be used for investigating long-term transitions for energy and material systems. By modelling “natural selection”, it is possible to study how a system ‘learns’ how to maximize its output for success against competing alternatives.

6.4. Secondary criteria

The above primary criteria form a scientific base for evolutionary forecasting scenarios (EFS) starting from primary energy sources. Referring to the general problems related to the existing energy and material systems, there are other criteria that also have to be used in developing sustainable roadmaps for energy systems. The main difference between the primary and secondary criteria is that the first set is built on firm scientific principles, while the second involves people’s values. This will be discussed more in detail in section 7. From a sustainability point of view, the second set of criteria has to be used to evaluate economic growth models, impacts on the environment and ecosystem services, and social effects.

Important secondary criteria include: Environmental effects

Environmental effects related to using different primary energy sources depend on their whole life-cycle processes. It is therefore important to evaluate different options using a life-cycle approach. Many of the environmental effects can be actually handled using environmental technologies, which will have influence on cost and efficiency. Attempts have been made in order to include environmental costs and correct subsidies to get the “real” price of energy sources [15]. It is highly unlikely that nations will develop a price mechanism taking these factors into account. This is because of the risk of decreasing competitiveness of their domestic industries. However, it can indicate how long-term transitions of energy systems will develop.

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Geographical availability of primary energy sources Reserves of fossil fuels are unevenly distributed. This is likely to cause more international conflicts in

the future, which can seriously affect some countries’ energy security. Critical raw materials

Availability of materials can seriously affect sectors like advanced energy technologies and agriculture. EU has developed a list of such materials [16].

Social effects Social issues such as employment and health care will become more important during energy and

economic transitions. In an economy that is growing, the key drivers are more, faster and more competitive. In a descending economy, social factors can seriously destabilize a society. One way to evaluate social effects is to adopt social life-cycle analyses (LCAs) [17].

Risk factors Risk can have possible effects on economy, human health and the environment. Risk factors are

important in the energy sector, since different actors perceive risk in very different way. Risk factors are thus not objective, but has to be possible to communicate and evaluate in dialogue processes with all concerned actors [3]. An analysis of risk factors can be included into LCAs.

Depending on which level the scenarios are developed for, local, regional, or national, the back-ground material for secondary criteria have to be developed more in detail for scenario building in dialogue processes with key actors.

7. Scenario development in practice

7.1. Characteristics of the development of resource scenarios

The scenarios have to handle short-, medium- and long-term energy transition and material transformation. From the scenarios, roadmaps can be developed, where incentives from key actors are included. In order to be effectively implemented and followed up, the roadmaps have to be developed in a broad dialogue process involving all key actors to establish a context and ownership in development processes. Our experience from all kinds of areas, where the methodology has been applied, is that it is very satisfactory to work towards shared visions, when participants have access to a shared mental model informing dialogues and creativity and group dynamics.

It is also important to develop indicators for setting targets and following up during implementation. In this research project, the focus is on sustainable urban development. The scenarios must handle different sectors and dimensions of urban systems like primary energy and energy carriers, material transformation, technological change, key actors, behavioral changes and growth models. For scenario building of urban development, we have chosen to divide the city into sectors like transport, built environment, utility sector including water, waste and energy. These sectors can cover a whole city or parts of the city, e.g. a residential area.

7.2. Example of structuring of scenarios

Each sector is divided into sub-systems1. Appendix B is one example of this for building environment. Within each of the subsystems, we identify critical aspects that are relevant for the development of a more sustainable building environment. In relation to each sector, we also define key actors, which in this case can be inhabitants, constructors, developers, local, regional and governmental authorities, city planners and energy companies.

1 P ers onal c ommunic ation with R obèrt, K H in 2014.

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Appendix B starts with defining the existing situation for each sub-system. The scenarios will the generate transitions states towards long-term sustainability.

8. Conclusions

Human settlements are getting more and more complex through urbanization and globalization. The development of these systems is in principle not deterministic but can be characterized as more chaotic and self-organizing on different levels. In this way, the development resembles that of eco-system development. One of the fundamental sustainability problems today is in how we should use energy and materials. More sustainable pathways for sustainable energy systems will require step-wise changes in an evolutionary way, which might be difficult to fit into traditional long-term planning practice. Models for this kind of evolution can partly be found in the field of ecology.

There is sometimes a belief that we will find new energy technologies or energy sources in the future to support the growth, just as what has occurred in the past. However, considerations, based solely on thermodynamics and energy systems analysis, however simple they are, lead to a very serious conclusion, namely that utilization of renewable energy is not enough to support continuous growth. This fact will make any conscious decision on energy transition extremely difficult, meanwhile the fact that the present system is not sustainable has not been given deserving attention.

Much focus is now on combustion of fossil fuels and global warming. However, it seems more and more inevitable that the trends of CO2 emissions will continue. Research and practice on global warming will have to focus more on adaptation and preparedness to reduce damages from extreme weather events.

We propose the use of evolutionary forecasting scenarios (EFS) with two sets of criteria. Primary criteria are based on the first and second law of thermodynamics. They can be used to model evolutionary roadmaps starting with primary energy sources and including different technological improvements. The secondary criteria should be used for evaluating different roadmaps obtained from these simulations.

There are two options. The world will either slowly run out of fossil fuels or exceed the capacity of environment to absorb the products of their combustion. The uneven distribution of resources will cause global conflicts over the remaining reserves, or they will become unaffordable. The key parameter, i.e. the emergy yield ratio of the renewable energy sources, will determine the inevitable transitions in energy use and the future of our civilization. For material transformation, conservation of low entropy states will be of high importance.

Considerations, based solely on thermodynamics and energy systems diagram, no matter how simple they are, lead to a very serious conclusion, namely that utilization of renewable energy does not support continuous growth the way we know it today. There has to be gradual changes also in the societal metabolism during transition periods. Scenarios can develop consciousness how this can be done. Once the economy starts declining it will not be able to afford transition to a more expensive energy system, and transition would only accelerate the decline.

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Qie Sun

PhD in Industrial Ecology, KTH, Sweden. He has the background of Economics, Management and Environmental Engineering. Together with Ronald Wennersten and other colleague, they are working with Energy Systems, especially on energy transition in urban cities. In addition, his research interests cover many other disciplines, e.g. Industrial Ecology, Environmental Economics, Climate Change and Sustainable Urbanization.

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Appendix A. Some fundamental information around energy, exergy, emergy and entropy

Properties Energy Exergy Emergy Entropy

Definition Energy is a prime concept in thermodynamics. It is defined as the ability of a system to cause change. Energy is conserved in all processes, measured in Joules.

Exergy is the maximum amount of energy that can be extracted from a system by bringing it into equilibrium with its environment. Exergy is generally decreasing in a transformation process, measured in Joules.

Emergy is the availability of energy of one kind that is used up in transformations directly and indirectly to make a product or service [18]. Emergy is generally increasing in a transformation process, usually measured in emjoule.

Entropy is a measure of the amount of molecular disorder in a system. Entropy is increasing in all real processes, measured in the unit for entropy is Joules per Kelvin (J/K).

Description Energy is a source that comes in a variety of forms basically as macroscopic or microscopic energy. Macroscopic energy can be e.g. kinetic and potential energy and microscopic energy or chemical energy is what is found in many primary sources like fossil fuels.

In processes, exergy is lost mostly as low temperature heat as well as in chemically and physically reactive materials. The exergy content of a natural resource input can be interpreted as a measure of its quality or potential usefulness, or its ability to perform “useful work” Consequently, exergy can measure resource quality as well as quantity and is applicable for both material and energy transformations.

Emergy is a universal measure of real wealth of the work of nature and society made on a common basis.The emergy definition includes both natural processes for resource generation over time and human-dominated activities for resource extraction, manufacturing and delivery. Consequently the time involved in resource generation becomes an important parameter for their quality evaluation[19].

The entropy of a state of a system is proportional to its probability. Mineral found in nature with higher content of a substance than the surroundings has lower entropy. By further processing the mineral to enrich the substance, entropy is decreased by exergy consumption. Dissipating materials as waste increases entropy.

Analysis Methodology

Various types of measurement methods are used in energy analysis to determine the direct and indirect energy inputs that a system uses to deliver a product or services [15].

Basically three different methods can be used to perform an energy analysis: Process, Statistical, and input- output analyses[20].

Many controversies around energy from different sources stems from different use of references like Primary energy, Net energy, EROI etc [21].

Exergy analysis reveals more completely the system energy loss distribution than the traditional method of thermodynamics analysis, indicating the research direction for improving the system design and the efficiency of system use[22]. Exergy analysis is a useful tool for measuring the quantity and quality of energy sources and analysing sustainability, which includes material and energy flows. The methodology consists of four steps, including establishing system boundaries, breaking the process down into operation units, balancing the in- and out-flows for each process, and calculating the exergy of pure substances, mixtures and utilities [23].

Emergy analysis normalizes all products and services to equivalents of one form of energy – solar emergy – that enables all of these resources to be compared on a common basis. Emergy analysis is an eco-centred valuation method that compensates for the inability of money and traditional embodied energy analysis to fairly assess the true, total value of various products, and services.

The main steps of an emergy analysis include identifying the system boundary, drawing the system diagram, quantifying the matter and energy flows, converting different flows into emergy units, and calculating the total emergy and other performance indicators [19].

The destroyed exergy in a system is proportional to the generated entropy. In actual systems, exergy is always partially or totally destroyed and entropy increases. The destroyed exergy, or the generated entropy is responsible for the less-than- theoretical efficiency of the system.

The relation between entropy and exergy can be used to evaluate more long term sustainable strategies for waste handling.

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Appendix B. An example of scenario structure for the sector built environment

Resource bases energy

Coal, oil, natural gas, nuclear, hydro Transition states Short term

Transition states Medium term

Transition states Long term

Geothermal

Solar

Wave

Wind

New nuclear

Resource bases material

Concrete from virgin materials

Bricks from clay

Wood

Transition states Short term

Transition states Medium term

Transition states Long term

Prefabricated units Reuse of material New types of materials

Energy carriers

Gasoline, diesel, natural gas, electricity

Transition states Short term

Transition states Medium term

Transition states Long term

Electricity

Hydrogen

District heating

New types of storage

Energy systems

Centralized systems for nuclear, hydro, coal

Transition states Short term

Transition states Medium term

Transition states Long term

Combination of centralized systems for hydro, wind etc. with distributed, local systems

Infrastructure

Separated residential areas and other functions

Dominance of new concrete houses

Transition states Short term

Transition states Medium term

Transition states Long term

New types of building shells with low heat transfer

Urban farming

Urban eco-system services

Mixed areas

The social system

Increasing environmental awareness but lack of alternatives for change

Conflicting perspectives between key actors

Transition states Short term

Transition states Medium term

Transition states Long term

Participative and transparent community building

Cross sectoral solutions

Flexible housing

New family constellations

Higher mobility

Smart use of energy and material