EMERGY SYNTHESIS 6: Theory and Applications of the Emergy Methodology

Transcription

1 EMERGY SYNTHESIS 6: Theory and Applications of the Emergy Methodology Proceedings from the Sixth Biennial Emergy Conference, January 14 16, 2010, Gainesville, Florida Edited by Mark T. Brown University of Florida Gainesville, Florida Managing Editor Sharlynn Sweeney University of Florida Gainesville, Florida Associate Editors Daniel E. Campbell US EPA Narragansett, Rhode Island Shu-Li Huang National Taipei University Taipei, Taiwan Enrique Ortega State University of Campinas Campinas, Brazil Torbjörn Rydberg Centre for Sustainable Agriculture Uppsala, Sweden David Tilley University of Maryland College Park, Maryland Sergio Ulgiati Parthenope University of Napoli Napoli, Italy iii December 2011 The Center for Environmental Policy Department of Environmental Engineering Sciences University of Florida Gainesville, FL

2 ABSTRACT 8 SolarShare: An Emergy Derived Index of Human Demand on Environment Mark Brown SolarShare is the term derived to express an index of the emergy intensity of products or services. One SolarShare is equal to the global renewable input to the geobiosphere (15.83 sej/yr) divided by the current (2009) world population (6.8 E9 people). Since the global renewable input (Global Renewable Emergy Constant, GREC) is constant and population is increasing, the SolarShare is not constant but is continuously decreasing (as long as population is increasing). The SolarShare is used to evaluate several products and processes as examples of its applicability for highlighting the energy intensity of human activities and the unequal share of the world s wealth enjoyed by western civilization. INTRODUCTION SolarShare was developed to make two concepts more understandable by the general public in the hopes of driving home the concept of global carrying capacity. The first is that the long-term carrying capacity of the planet is related to the renewable income of the planet; a constant 15.2 E24 sej/yr that we term the Global Renewable Emergy Constant ( ; uppercase theta). The is the basis for all productivity of environmental systems and ultimately for all the economic affairs of humans. The second concept is that each individual is entitled to his/her fair share of this income and anything more is compromising another individual s living standard and quality of life. In addition to the above, it is critical to differentiate between flux and storage in building a case for global carrying capacity. In the past, human societies were built on the storages of slowly renewable and nonrenewable sources such as wood, soils, fossil fuels and minerals. As these storages are now being depleted it is becoming increasingly evident that the long-term carrying capacity of Earth will depend on the flux of renewable energy that is transformed through combined technoecosystems of humans. Since living off the flux of renewable emergy will require a different way of thinking, a new renewable, no growth ethic, it will be essential to forge new ways of communicating the concept of living off fluxes rather than storages. Ecological Footprint The Ecological Footprint (Wakernagel and Reese, 1996) has garnered significant global attention, as most people can understand the concept that area (of the planet) is required to make things. Yet land area is a storage, not a flow, and most of what the ecological footprint method evaluates results from the flux of energy through processes, not just the static land area occupied by the process. It is suggested that ecological footprint represents the amount of biologically productive land and sea area needed to regenerate the resources a human population consumes and to absorb and render harmless the corresponding waste that is generated. The accounting procedure converts the consumption of energy, biomass (food, fiber), building materials, water and other resources into a normalized measure of land area called 'global hectares'. 87

3 The footprint methods have undergone considerable refinement in the last decade, with refinements to the calculation methods, conversion factors, and best practices. Quoting the 2008 edition of Calculation Methodology for the National Footprint Accounts (Ewing, et al., 2008) The area of land or sea available to serve a particular use is called biocapacity, and represents the biosphere s ability to meet human demand for material consumption and waste disposal. The Ecological Footprint and biocapacity accounts cover six land use types: cropland, grazing land, fishing ground, forest land, built-up land and carbon uptake land (to accommodate the Carbon Footprint). For each component, the demand for ecological services is divided by the yield for those ecological services to arrive at the Footprint of each land use type. Ecological Footprint and biocapacity are scaled with yield factors and equivalence factors to convert this physical land demanded to world average biologically productive land called global hectares. The assumption with the footprint methodology is that biocapacity and ecological services are synonymous and with appropriate yield factors they can be computed. The yield factors and productivities of land are intertwined with numerous relatively obscure coefficients including: technical conversion factors, footprint allocation factors, market prices, equivalence factors, suitability scores, etc. So while the concept of ecological footprint is attractive, primarily because the phrase that describes it is easily understood, the methodology is not so easy to comprehend and not accessible nor transparent. SolarShare The solar emergy income of Earth (i.e. renewable income) may be a way for people to grasp the magnitude of our use of energy and resources and at the same time get the idea across that we are using more than our share. It is especially important to alert the general population that the ultimate carrying capacity of the Earth will be determined by the flux of renewable, quality corrected, energy and that the ecological services humans use and enjoy can be easily measured by the quality corrected energy required to make them. SolarShare is a concept that relates carrying capacity to the flux of renewable emergy. It can be used as an indicator of environmental sustainability or to highlight the use of resources throughout an economy. It can be used to explore the energy intensity of individual lifestyles, goods and services, organizations, industrial sectors, urban areas, regions or even nations. Since it uses emergy as the basis, it relates the intensity of processes or goods on a common scale that is quality corrected. There are two ways of expressing SolarShare. The first is as a global average and the second is a national average. Since different nations are endowed with differing fluxes of renewable emergy, each nation has a different SolarShare. Nations with large area (e.g. Canada or Australia) and relatively small populations have larger percapita renewable emergy flux. Also nations located along continental margins have larger renewable fluxes since the emergy methodology includes land areas as well as the continental shelf when computing renewable flux. Land locked countries or those with large populations relative to their land area tend to have smaller SolarShares. METHODS Using the global renewable emergy constant (Θ), the SolarShare is calculated by dividing the Θ by the global population as follows: Θ SolarShare (1) GlobalPopulation 88

4 The GREC is equal to 15.2 E24 sej/yr and current global population (2011) is 7.0 E9 people, therefore the Global SolarShare is as follows: 15.2E24 sej / yr SolarShare G 7.0E9 people 2.2E15 sej / capita / yr (2) SolarShare G 2.2E15 sej / capita / yr 365 da / yr 6.0E12 sej / capita / da (3) The ultimate carrying capacity of the planet can be calculated for a given per capita emergy standard of living (Em PC ) by dividing the Θ by the Em PC as follows: Θ Carrying Capacity G Q (4) Em PC A SolarShare can be computed for each country and compared to other countries or the global SolarShare as a means of indexing national economies one to another relative to their endowment of renewable emergy flux. The National Renewable Emergy Constant, (, lower case theta) is divided by the national population to obtain a National SolarShare as follows: q SolarShare N θ National Population A SolarShare Index (SSI) can be calculated which places in perspective how the per capita total emergy use in individual economies compares with their National Solar Share as follows: (5) SolarShare Index(SSI) National Per Capita Total Emergy Use National SolarShare (6) A SolarCost Index (SCI) of any good or service can be computed by dividing the emergy of the good or service by the global solar share as follows: Solar Cost Index(SCI) Emergy of good or service SolarShare G (7) This index relates the emergy of a good or service to the average share of renewable global emergy. Thus if the emergy content of a product is 12.0 E12seJ, it utilizes twice the SolarShare G of one individual (12.0 E12 sej / 6.0 E12 sej/da 2). RESULTS National SolarShare Table 1 presents the renewable emergy, population and per capita SolarShare for selected countries and the world in 2008 from the National Emergy Accounting Database (NEAD). The SolarShare is expressed on a daily basis. Countries with large populations relative to their land areas and those with minor coastal ecosystems have the smallest per capita SolarShare, while countries with large land area (e.g. Australia) or large continental shelf areas (e.g. Papua New Guinea) or comparably small population (e.g. Iceland) have the largest per capita SolarShare. The average global SolarShare is shown (World Total) as 6.2 E12 sej/da. Average national SolarShare can be compared to the average per capita total emergy consumption to provide perspective on the relative ability of each nation to support it current 89

5 Table 1. SolarShare for Selected Countries. Country Renewable Emergy 1 Population 1 SolarShare (sej/yr) (E12 sej/da) Germany 5.2E E Kuwait 3.0E E Italy 6.8E E India 1.5E E Japan 2.0E E Cuba 2.4E E World Total 1.52E E Spain 1.1E E China 3.4E E Thailand 1.9E E Saudi Arabia 8.0E E South Africa 1.6E E Kenya 1.3E E Portugal 3.9E E Mexico 4.1E E Finland 2.0E E Sweden 4.2E E Netherlands 9.2E E Zimbabwe 6.1E E United States 2.3E E Costa Rica 4.7E E Paraguay 7.8E E Venezuela 3.9E E Brazil 3.5E E Russia 2.6E E South Korea 9.8E E Congo 8.4E E Botswana 4.5E E Mozambique 4.1E E United Kingdom 2.4E E Argentina 2.3E E Papua New Guinea 4.1E E Canada 3.1E E New Zealand 3.9E E Australia 2.4E E Iceland 3.2E E Data are from (NEAD, 2011) population at its current standard of living. Table 2 provides a listing of the same countries in Table 1 showing their total per capita emergy use, per capita emergy use and relationship to the national SolarShare. The last column is expressed as a ratio of use per capita to SolarShare per capita and thus the values are the number of times above renewable carrying capacity each nations current population and standard of living is. For instance, the population of Iceland is living at a standard that is 1.2 times 90

6 Table 2. Total emergy use as it relates to SolarShare. Country Total Use per capita 1 SolarShare U per capita/ (E12 sej/da) SolarShare (E12 sej/capita/da) Mozambique Iceland Papua New Guinea Argentina Congo New Zealand Kenya Paraguay Brazil Australia Canada United Kingdom Costa Rica India Botswana Venezuela Russia Cuba South Korea China South Africa United States Thailand Zimbabwe Mexico Sweden Portugal Finland Japan Netherlands Saudi Arabia Spain Italy Kuwait Germany Data are from (NEAD, 2011) their long term SolarShare carrying capacity, despite the fact that they are one of the most richly endowed countries as a far as renewable emergy flux is concerned. The numbers in the final column indicate how much each country is exceeding its long term renewable carrying capacity and thus the reductions that will be necessary to live within their SolarShare carrying capacity. For instance the population of the United States consumes nearly 15 times their SolarShare. 91

7 Evaluating the SolarShare of Products The Big Mac hamburger produced by McDonalds restaurants worldwide requires significant quantities of emergy to produce, transport, market, and prepare. Using an estimated transformity of 3.4 E6 sej/j for processed food and the energy information given in Figure 1, we can calculate the SolarShare of one Big Mac. The energy content of the sandwich is 704 Calories, which translates into 2.9 E6 J. Using the transformity of processed food given above the emergy in a Big Mac is equal to 9.9 E 12 sej/ sandwich (2.9 E6 J * 3.4 E6 sej/j 9.9 E12 sej). By dividing by the SolarShare for US population (21 E12 sej/day) we see that one Big Mac is equivalent to 43% of a daily SolarShare. For an Italian citizen a Big Mac is equivalent to almost 3 days of his/her SolarShare (9.9 E12 sej/ 3.2 E12 sej/day). All in all the Big Mac is a relatively expensive luxury when expressed in SolarShares. Figure 1. Food label, including energy content. DISCUSSION As the world depends more and more on its renewable emergy flux, national SolarShare data will become more and more important. It is possible that in the years to come, populations will seek out those areas of the globe where the renewable fluxes are the greatest since capitalizing on them will decrease dependence on nonrenewable energy. We can envision a future where living standards are determined by the renewable energy flux transformed by appropriate techno-ecological systems into products and services. Those places on the planet where the renewable emergy is the greatest will prosper while areas lacking in renewable emergy will decrease in ability to support current populations. When the SolarShare is computed for a product or service it can easily be compared to an individual s average daily solar share. In this way it may help to bring to the attention of consumes the energy costs of their lifestyle choices in a way that is more understandable than emergy or even the ecological footprint. REFERENCES Ewing B., A. Reed, S.M. Rizk, A. Galli, M. Wackernagel, and J. Kitzes Calculation Methodology for the National Footprint Accounts, 2008 Edition. Oakland: Global Footprint Network. NEAD, National Emergy Analysis Database. Center for Environmental Policy, University of Florida, Gainesville, FL. Downloaded from on 6/11/11. Wackernagel, M. and W. Rees, Our Ecological Footprint. New Society Press. New York. 92