Evaluating renewable energy options for small islands using emergy methodology: A case study of coconut biodiesel in the Fiji Islands

The Pacific Island Countries including the Fiji Islands are heavily dependent on imported petroleum fuels for their energy needs. This is a major cause of environmental vulnerability as well as economic vulnerability due to high and volatile crude oil prices. A combination of Demand Side Management (DSM) to reduce energy consumption and optimize usage, and Renewable Energy Technologies (RET) to substitute fossil fuels can reduce their vulnerability. DSM consists of Smart Grids, Energy Efficiency and Storage, while RETs substitute fossil fuels by harnessing solar, wind, small hydro, biomass, geothermal and ocean energies. Comparative costs of electricity from RETs show that most of them are cheaper than the typical price of electricity in Pacific island countries. Nearly half of Fiji’s electricity is generated using petroleum fuels that can be substituted by biodiesel produced from locally grown coconuts. To evaluate the sustainability of coconut biodiesel, two different Environmental Accounting methods have been used: i) Emergy Analysis, and ii) Embodied Energy Analysis. Emergy Analysis is a holistic methodology that integrates all major inputs from the human economy and those coming ‘free’ from the environment, to evaluate complex systems. Emergy Performance Indicators for coconut biodiesel are: i) Emergy Yield Ratio is 1.32 indicating a low ability to exploit local resources efficiently; ii) Environmental Loading Ratio is 8.57 implying that biodiesel production causes significant environmental or ecosystem stress; and iii) Emergy Index of Sustainability is 0.15 indicating a low contribution to the economy per unit of environmental loading and a very high degree of environmental stress per unit of Emergy yield. Embodied Energy Analysis is a complimentary methodology that accounts for only the commercial energy (in kgs oil equivalent) required directly or indirectly to provide all the inputs (goods and services) for the entire biodiesel production process. Embodied Energy Performance Indicators are: i) Energy Return on Energy Invested is 2.47 which means that it is not worth the effort in energetic terms; and ii) Carbon dioxide Emissions during the production of coconut biodiesel is 1.38 kg CO2 per kg biodiesel showing that biodiesel is not climate neutral. This thesis adds to the growing body of knowledge that uses Emergy Analysis to evaluate sustainability of biofuels and other renewable energy options in a holistic manner. This is the first time in reported literature that Emergy Analysis has been used to determine the sustainability of coconut biodiesel. The Emergy and Embodied Energy performance indicators clearly show that coconut biodiesel is not a sustainable alternate source of energy for the Fiji Islands

Exergy and Exergy Cost Analysis of production systems incorporating renewable energy sources

Exergy is a thermodynamic quantity capable of measuring the conversion of material and energy flows into comparable terms based on the capacity of such flows to generate mechanical work as a useful effect and identifying and quantifying the thermodynamic inefficiencies of a generic process by means of the exergy destruction term. Because of its properties, an exergy is a convenient tool for the calculation of the global resource consumption of both natural and engineering processes. Therefore, there are different exergy-based approaches. Every exergy-based approach has its advantages and its drawbacks. It even has its own spatial and temporal domain [1]. There are different exergy-based approaches that have been reviewed which are EMergy, Extended Exergy, Cumulative Exergy Consumption, Exergetic life cycle assessment, and Thermoeconomics. Reviewing different exergy approaches, especially the approaches that introduce the externalities like Labour, Capital, and environmental cost with their equivalent exergy values will help to develop an approach that avoids the drawbacks and take advantage of other approaches. Exergy-based account methodologies do not account for the ecological processes and products. This is something savior if sustainability is the aim and the goal. The indirect cost of resource consumption must be counted. The exergy cost of mineral resources which are not renewable is not their chemical exergy embodied in them only but also the cost of exergy that has been to be spent to reconcentrate these resources to be available for the upcoming generations [2]. As it is a matter of sustainability, considering the indirect exergy cost is very important. Each exergy-based methodology has its own spatial and temporal boundary. Some of them account only for the exergy consumed during the operation phase like the basic exergy analysis and some of them extend its spatial boundary to include the ecological cumulative exergy cost of a specific product [3]. The ecological cumulative exergy consumption ECEC approach has been introduced by Szarjut. Another approach extends its spatial boundary including the economy of the region or a country where the analysis takes place. This allows some other externalities like money and labor to be accounted in form of exergy. This approach is the extended exergy analysis EEA. This thesis presents a conceptual development of sustainability evaluation, through an exergy-based Indicator, by using the new concept of the Thermoeconomic Environment (TEE). The exergy-based accounting methods here considered as a background are the Extended Exergy Accounting (EEA), which can be used to quantify the exergy cost of externalities like labor, monetary inputs, and pollutants, and the Cumulative Exergy Consumption (CExC), which can be used to quantify the consumption of primary resources “embodied” in a final product or service. Also, the new concept of bioresource stock replacement cost is presented, highlighting how the framework of the TEE offers an option for evaluating the exergy cost of products of biological systems. The sustainability indicator is defined based on the exergy cost of all resources directly and indirectly consumed by the system, the equivalent exergy cost of all externalities implied in the production process and, the exergy cost of the final product.Exergy is a thermodynamic quantity capable of measuring the conversion of material and energy flows into comparable terms based on the capacity of such flows to generate mechanical work as a useful effect and identifying and quantifying the thermodynamic inefficiencies of a generic process by means of the exergy destruction term. Because of its properties, an exergy is a convenient tool for the calculation of the global resource consumption of both natural and engineering processes. Therefore, there are different exergy-based approaches. Every exergy-based approach has its advantages and its drawbacks. It even has its own spatial and temporal domain [1]. There are different exergy-based approaches that have been reviewed which are EMergy, Extended Exergy, Cumulative Exergy Consumption, Exergetic life cycle assessment, and Thermoeconomics. Reviewing different exergy approaches, especially the approaches that introduce the externalities like Labour, Capital, and environmental cost with their equivalent exergy values will help to develop an approach that avoids the drawbacks and take advantage of other approaches. Exergy-based account methodologies do not account for the ecological processes and products. This is something savior if sustainability is the aim and the goal. The indirect cost of resource consumption must be counted. The exergy cost of mineral resources which are not renewable is not their chemical exergy embodied in them only but also the cost of exergy that has been to be spent to reconcentrate these resources to be available for the upcoming generations [2]. As it is a matter of sustainability, considering the indirect exergy cost is very important. Each exergy-based methodology has its own spatial and temporal boundary. Some of them account only for the exergy consumed during the operation phase like the basic exergy analysis and some of them extend its spatial boundary to include the ecological cumulative exergy cost of a specific product [3]. The ecological cumulative exergy consumption ECEC approach has been introduced by Szarjut. Another approach extends its spatial boundary including the economy of the region or a country where the analysis takes place. This allows some other externalities like money and labor to be accounted for in form of exergy. This approach is the extended exergy analysis EEA. This thesis presents a conceptual development of sustainability evaluation, through an exergy-based Indicator, by using the new concept of the Thermoeconomic Environment (TEE). The exergy-based accounting methods here considered as a background are the Extended Exergy Accounting (EEA), which can be used to quantify the exergy cost of externalities like labor, monetary inputs, and pollutants, and the Cumulative Exergy Consumption (CExC), which can be used to quantify the consumption of primary resources “embodied” in a final product or service. Also, the new concept of bioresource stock replacement cost is presented, highlighting how the framework of the TEE offers an option for evaluating the exergy cost of products of biological systems. The sustainability indicator is defined based on the exergy cost of all resources directly and indirectly consumed by the system, the equivalent exergy cost of all externalities implied in the production process and, the exergy cost of the final product

Sustainability and ecological efficiency of low-carbon power system: A concentrating solar power plant in China

Low-carbon power generation has been proposed as the key to address climate change. However, the sustainability and ecological efficiency of the generating plants have not been fully understood. This study applies emergy analysis and systems accounting to a pilot solar power tower plant in China for the first time to elaborate its sustainable and ecological performances. Emergy analysis covers virtually all aspects of sustainability and ecological efficiency by considering different forms of materials inputs, environmental support and human labor on the same unit of "solar joule". The input-output analysis based systems accounting is applied to trace the complete emergy embodied in the supply chain for all product materials of the given plant against the back ground of complex economic network, which improved the accuracy of accounting. This analysis illustrated unexpectedly low sustainability and ecological efficiency of this particular plant compared with the emergy analysis based on the primary materials (steel, iron, cement, etc.). Purchased emergy responses more than 95% of the total and emergy input in the construction phase is more than twice as much as that in the operation phase. Comparisons with other kinds of clean energy technologies indicate previous studies may have overestimated the sustainability and ecological benefits of low-carbon power plants. Thus, it is necessary to establish this kind of unified accounting framework. In addition, sensitivity analysis suggests that strictly controlling monetary costs of purchased inputs, extending service lifetime and improving power generation efficiency can promote higher sustainability and ecological efficiency for solar power tower plants. This study provides a more comprehensive framework for quantitative emergy-based evaluation of the sustainability and ecological efficiency for low-carbon power systems

Carbon footprint and emergy combination for eco-environmental assessment of cleaner heat production

cited By (since 1996)0; Article in PressInternational audienceThe aim of this paper is to study via environmental indicators to which extent, replacing fossil fuel with biomass for heating is an environmentally friendly solution. The environmental impact of using biomass depends mostly on the transportation process. Authors define the notion of maximum supply distance, beyond which biomass transportation becomes too environmentally intensive compared to a fossil fuel fired heating system. In this work a carbon footprint analysis and an emergy evaluation, has been chosen to study the substitution of wood for natural gas. The comparative study seeks to examine, via the two approaches, two heating systems: one is fired with wood, transported by trucks and the other one is fired with natural gas transported by pipelines. The results are expressed in terms of maximum supply distance of wood. In the emergy evaluation it represents the maximum supply distance permitting wood to be more emergy saving than natural gas. In the carbon footprint analysis, it represents the maximum supply distance permitting wood to be a carbon saving alternative to natural gas. Furthermore, the unification of carbon footprint and emergy evaluation permits to define, for both approaches, the minimum theoretical wood burner first law efficiency that allows, CO 2 or emergy to be saved, when there is no wood transport. In order to identify the impacts of the main parameters of the study a sensitivity analysis has been carried out. The case study investigated in this paper shows that there is a large gap between the results. The maximum supply distances calculated via carbon footprint and emergy evaluation are about 5000 km and 1000 km, respectively, anthe minimum theoretical wood burner efficiencies are about 5% and 54%, respectively. © 2012 Elsevier Ltd. All rights reserved

Ecological sustainability of aquafeed: an emergy assessment of novel or underexploited ingredients

Fishmeal is the optimal source of protein for fed fish and crustacean species, but the increase in market demand and prices is pushing the aquaculture industry to test alternative protein sources. This paper provides the results of an emergy assessment performed on four partial substitutes for fishmeal – dried microalgae biomass from Tetraselmis suecica and Tisochrysis lutea, insect meal from Hermetia illucens larvae, and poultry by-product meal – and then compares them with the findings of a previously published Life Cycle Assessment (LCA) on the same topic. By quantifying their degree of dependence on natural resources, the research offers a complementary perspective to that of LCA, thus allowing to obtain a complete picture on the sustainability of the four production systems. Firstly, the results reveal that insect meal has the highest environmental efficiency in terms of total emergy per unit of product, followed by poultry by-product meal. The two closed microalgae cultivation systems are penalized by a low productivity, combined with a high quantity of seawater imported. Secondly, several critical aspects are highlighted by the five emergy-based indicators: in brief, all systems appear to be based on intensive industrial processes, with the imported inputs from the economy representing 99% of total emergy flow (high level of ecosystem stress). Since local renewable inputs are not significantly exploited, higher levels of production amplify the ratio between these resources and the inputs imported from the outer economies (no economies of scale are observed). Finally, the comparison with LCA results confirms a critical point already detected by the emergy assessment (i.e. the crucial contribution of the feed provided to insect and poultry) but also reveals new ones: (i) in the two microalgae systems, the high emergy contribution from seawater versus the high impacts of carbon dioxide and energy needs; (ii) in the insect meal system, the high emergy share represented by human labour and energy needs. In light of the numerous problems found, possible approaches are proposed to increase the environmental performance through changes to each production system and the processes that support it upstream

Biofuel - opportunities and challenges for the poor in Cameroon : what can Cameroon learn from Brazil and South Africa?

Ever since the shell geologist M. King Hubbert came up with his prophesy predicting the depletion of peak oil (regarded as "Hubbert peak" in the 1940s and 1950s), several countries in the world including Brazil, Sweden and the United States of America have been looking for alternative energy means with more emphasis on renewable energy such as bio-energy. The emphasis on bio-energy which to a large extent involves the use of energy crops to fulfil global energy demand and to establish a renewable energy system has resulted in debates where questions are raised regarding the clash between the use of land for food production for human consumption and land for energy production. Other question raised relate to the impact bio-energy will have on the poor most especially as it is ‘linked’ to rising food prices. Cameroon is a country rich in natural resources and also has rich oil potentials but most of the rural areas are map out of energy systems and this pose a development problem among others. This study seeks to investigate what impact biofuels can have on the poor as well as the benefit Cameroon can have if engage on biofuels as an alternative means of energy. A livelihood approach was used to understand the strategies which poor rural people use to make a living which in this case centred in agriculture. Embodied Energy Analysis was used to evaluate the energy requirements involved in the production of biofuels and Emergy Synthesis (ES) method was used to further show the extent to which biofuel production depends on humans and the environment

Can we break the addiction to fossil energy? : Proceedings of the 7th Biennial International Workshop Advances in Energy Studies

Sponsored by Obra Social "la Caixa", Norwegian Ministry of Petroleum and Energy, Universitat Autònoma de Barcelona and LIPHE4 Scientific Association, Generalitat de Catalunya.From 1998 onwards, every other two years, the Biennial International Workshop "Advances in Energy Studies" (BIWAES) gathers experts in what can be called energy analysis to present and discuss advances, innovations and visions in energy and energy-related environmental and socioeconomic issues and models. Renowned energy experts and ecologists, such as H.T. Odum, James Kay, Charles Hall, Tim Allen, Vaclav Smil, Robert Herendeen, Jan Szargut, Joseph Tainter and Robert Ulanowicz among others, have discussed at the BIWAES the importance of energy in our society and ecosystems and the ways to better analyze and model their complex relationships. Previous editions of BIWAES have focused on energy flows in ecology and economy; analysis of the supply side; the ecological consequences of energy sources exploitation; and the role of renewable energy sources and new energy carriers. The present Book of Proceedings refers to the seventh Edition, which took place in the month of October 2010 in Barcelona and addressed society's addiction to fossil energy

Ecosystem properties and principles of living systems as foundation for sustainable agriculture – Critical reviews of environmental assessment tools, key findings and questions from a course process

With increasing demands on limited resources worldwide, there is a growing interest in sustainable patterns of utilisation and production. Ecological agriculture is a response to these concerns. To assess progress and compliance, standard and comprehensive measures of resource requirements, impacts and agro-ecological health are needed. Assessment tools should also be rapid, standardized, userfriendly, meaningful to public policy and applicable to management. Fully considering these requirements confounds the development of integrated methods. Currently, there are many methodologies for monitoring performance, each with its own foundations, assumptions, goals, and outcomes, dependent upon agency agenda or academic orientation. Clearly, a concept of sustainability must address biophysical, ecological, economic, and sociocultural foundations. Assessment indicators and criteria, however, are generally limited, lacking integration, and at times in conflict with one another. A result is that certification criteria, indicators, and assessment methods are not based on a consistent, underlying conceptual framework and often lack a management focus. Ecosystem properties and principles of living systems, including self-organisation, renewal, embeddedness, emergence and commensurate response provide foundation for sustainability assessments and may be appropriate focal points for critical thinking in an evaluation of current methods and standards. A systems framework may also help facilitate a comprehensive approach and promote a context for meaningful discourse. Without holistic accounts, sustainable progress remains an illdefined concept and an elusive goal. Our intent, in the work with this report, was to use systems ecology as a pedagogic basis for learning and discussion to: - Articulate general and common characteristics of living systems. - Identify principles, properties and patterns inherent in natural ecosystems. - Use these findings as foci in a dialogue about attributes of sustainability to: a. develop a model for communicating scientific rationale. b. critically evaluate environmental assessment tools for application in land-use. c. propose appropriate criteria for a comprehensive assessment and expanded definition of ecological land use