Emergy Index Research Articles

Improving the sustainability of tilapia cage farming in Brazil: An emergy approach

The accelerated and disorderly expansion of aquaculture can lead to economic, social, and environmental problems. In this sense, it is necessary to prioritize the adoption of practices that aim for sustainable production. The aims of the present study were to identify the contributions from nature and economy in the system of tilapia cage farming. In addition, emergy accounting was utilized to evaluate whether the use of periphyton as a complementary food and the reduction of storage density improve the sustainability of this production system. Three different production managements were evaluated and compared: using traditional stocking density adopted by farmers (80 kg/m3) with 100% of the daily recommended feed and without substrates for periphyton (TRAD); traditional stocking density (80 kg/m3) with 50% of the daily recommended feed and with substrates for periphyton (TDS); lower density (40 kg/m3) with 50% of the daily recommended feed and with substrates for periphyton (LDS). We calculated using emergy accounting the transformity (Tr), renewability (%R), emergy yield ratio (EYR), emergy investment ratio (EIR), emergy loading ratio (ELR), emergy exchange ratio (EER), and emergy sustainability index (ESI) of the distinct production managements. The results showed that tilapia cage farming is highly dependent on resources from economy, and feed is mainly responsible for this. Thus, the decrease in stocking density and feed rate, combined with the use of periphyton, improved all emergy indices evaluated. This occurred because there was a decrease in the use of resources from economy and increase in the use of renewable natural resources. The study shows through the emergy accounting that the use of periphyton to feed cultured fish combined with a reduction in artificial feed use and a decrease in the stocking density should be encouraged to promote the sustainability on tilapia cage farming.

Comprehensive sustainability assessment of a biogas-linked agro-ecosystem: a case study in China

The biogas-linked agro-ecosystem plays a critical role in the sustainable development of rural China. In this study, emergy analysis was performed to assess the sustainability of a biogas-linked ecological orchard system in the Loess Plateau area. To analyze the system more comprehensively, the overall orchard system was divided into three subsystems, including the biogas subsystem, the greenhouse subsystem, and the orchard subsystem. Other than the conventional indicators, two novel indicators suitable for orchard ecosystems, the system production dominance and index of system stability, were developed to evaluate the overall performance of the system and subsystems. The results showed significant variations in multiple performances of the subsystems regarding resource utilization, renewability, and production capacity. The circulation of emergy flows among different subsystems revealed a promising renewable capacity and self-organizing ability for the overall system, which further suggests the advantage of this mode in terms of sustainability. As revealed by the emergy indicators, the biogas-linked ecological orchard as an ecological practice is feasible for modern agriculture involving intensive fruit production and breeding, as it can guarantee highly efficient resource recycling and energy conservation without destroying the local environment.

Analysis of Environmental Carrying Capacity with Emergy Perspective of Jeju Island

Jeju Island experienced an approximately 42% increase in energy consumption from 2006 to 2015 and the demand for energy consumption is expected to continue to increase. Thus, Jeju Island is planning a project entitled “Carbon Free Island by 2030” to promote sustainable development and is required to estimate the environmental carrying capacity for future energy demand changes. The purpose of this study was to calculate the emergy inherent in Jeju Island’s energy, materials, and information in 2015 using the emergy analysis method and local characteristics. In addition, this study aimed to estimate the emergy indices to evaluate the environmental carrying capacity for sustainable development in 2005, 2015, and 2030 considering the future energy demand. This study’s outputs provide the environmental carrying capacity with emergy indices, such as the percent renewable (%Renew), emergy yield ratio (EYR), environmental loading ratio (ELR), sustainability index (SI), and carrying capacity of the population (CCP) for social and economic activities on Jeju Island, which are expected to be saturated. These findings show regions with heavy tourism require development strategies, including the concept of environmental carrying capacity.

Emergy-based sustainability assessment of a loblolly pine (Pinus taeda) production system in southern Brazil

The world’s wood demand from planted forests is expected to drastically increase in the following decades. Brazil displays very high levels of forest productivity for Pinus and Eucalyptus planted forests. Loblolly pine (Pinus taeda) is the most important species in terms of planted forest area in southern Brazil. There, it is mainly used for paper and pulpwood production, but also allows for multi-purpose and high quality wood production. Of particular interest is whether loblolly pine management in southern Brazil comprises a sustainable alternative to world’s wood demand. A promising tool to assess forest sustainability is named emergy synthesis (or emergy accounting). It is a top-down environmental accounting approach set out to assess holistically nature and society’s contributions toward a production process. It converts all forms of energy, materials, and human services into equivalents of one form of energy: Emergy, expressed in solar emjoules (seJ). This study aimed to assess the emergy-based sustainability of a loblolly pine wood production system practiced by a private forest company in southern Brazil (municipality of Rio Negrinho, Santa Catarina State). Data on society’s input (materials, fuels and labor) were provided by the company itself and subsequently checked through field measurements and personal communication with the forestry staff. Nature’s input was segregated into renewable and non-renewable resources, with their estimates being derived from literature information. Renewable natural resources in the form of rainfall comprised 82.4% of total emergy. The organic fraction of soil loss represented the emergy flow of non-renewable natural resources and accounted for 0.85% of total emergy. The remaining 16.75% of total emergy comprised society’s contribution. The loblolly pine system outperformed large-scale, intensively managed agriculture and eucalyptus production systems in Brazil as regards the emergy index of renewability. In relation to planted forests worldwide, this loblolly pine system displayed the lowest transformity, indicating that it was the most efficient system at producing a joule of wood per emergy investment. From the perspective of emergy synthesis, this loblolly pine production system is a feasible alternative to world’s wood demand and to sustainable land use in southern Brazil. While we perceived emergy synthesis to be an important tool to assess forest sustainability, we strongly argue that it should be complemented by other assessment approaches in order to consider, inter alia, short-term adverse impacts on soils and the socioeconomic benefits of providing job opportunities and ecosystem services.

Emergy analysis of Organic Rankine Cycle (ORC) for waste heat power generation

Abstract Converting the low grade energy into electric energy can effectively reduce the environmental pollution and improve the efficiency of energy utilization. Evaluating this kind of energy conversion is important. The sustainability evaluation of Organic Rankine Cycle (ORC) for the waste heat power generation is carried out using emergy analysis and life cycle method. The relationship to determine the transformity of the waste heat is presented. In the life cycle boundary, working fluid R134a in the ORC is firstly analyzed by emergy analysis. All the input flows including renewable resources, non-renewable resources and purchased investments in the whole life cycle of electricity produced by the ORC system have been calculated. The results show that the emergy yield ratio (EYR) and emergy index of sustainability (ESI) of an ORC are 197.52 and 3.97, respectively. The sustainability of the ORC system is less than that of wind, hydro and geothermal power plant, but much greater than that of fossil fuel power plants. The emergy proportion of the working fluid R134a accounts for 13.3% to the total input flows in the construction phase. The working fluid in an ORC system cannot be neglected in the life cycle analysis.

An assessment of emergy, energy, and cost-benefits of grain production over 6years following a biochar amendment in a rice paddy from China.

Biochar soil amendment had been increasingly advocated for improving crop productivity and reducing carbon footprint in agriculture worldwide. However, the long-term benefits of biochar application with farming systems had not been thoroughly understood. This study quantified and assessed emergy, energy, and economic benefits of rice and wheat production throughout 6 rotation years following a single biochar amendment in a rice paddy from Southeastern China. Using the data from farm inventory, the quantified emergy indices included grain outputs, unit emergy value, and relative percentage of free renewable resources, environmental loading ratio, emergy yield ratio, and emergy sustainability index (ESI). The results indicated contrasting differences in these emergy values between biochar-amended and unamended production systems over the 6years. The overall emergy efficiency of rice and wheat productions in biochar-amended system were higher by 11-28 and 15-47%, respectively, than that of unamended one of which the production being highly resource intensive. Moreover, ESI on average was 0.46 for rice and 0.63 for wheat in amended system, compared to 0.35 for rice and 0.39 for wheat in unamended one. Furthermore, over the 6years following a single application, the ESI values showed considerable variation in the unamended system but consistently increasing in the amended system. Again, the biochar-amended system exerted significantly higher energy and economic return than the unamended one. Nonetheless, there was a tradeoff between rice and wheat in grain yield and net economic gain. Overall, biochar amendment could be a viable measure to improve the resilience of grain production while to reduce resource intensity and environment impacts in paddy soil from China.

Efficiency and sustainability indicators for papermaking from virgin pulp—An emergy-based case study

The pulp and paper sector is the fourth-largest industrial sector worldwide in terms of energy use, accounting for approximately 6% of the total industrial energy consumption and contributing to 2% of direct carbon dioxide (CO2) emissions produced by industries. The definition of the environmental profile of this industrial sector is crucial, due to the high market demand of paper and the increasing concern for the environmental costs of the whole papermaking process. A sustainability perspective should rely on a wider and holistic viewpoint, properly including all direct and indirect interactions with the environment. To this purpose, the Emergy (spelled with “m”) Accounting method (EMA) is very appropriate for the evaluation of the efficiency, effectiveness and sustainability of the papermaking process under different perspectives (resource quality, fossil energy and material consumption, environmental and human-driven support). Several studies concerning environmental impacts, eco-efficiency, and cleaner technologies in the pulp and paper sector have already been carried out, but none of them addressed resource quality and resource generation costs from a supply-side point of view. This study aims to fill this gap in the literature by highlighting the direct and indirect contribution in terms of natural capital and ecosystem services to the pulp and paper production process.By means of EMA performance indices, this paper aims to assess the environmental sustainability associated to the production of pulp and paper, so as to identify those process steps that entail the highest environmental costs and require improvements. Three forest management scenarios − based on Spruce/Pine, Eucalyptus and Poplar production for raw material supply − were evaluated to assess the sustainability and the efficiency of each species. Moreover, the marginal costs of achieving higher energy and material efficiency are investigated, with a special focus placed on the identification of the effects of energy input flows on additional demand for environmental services.The research results show that the largest supply-side environmental costs are generated by the industrial processing activities, due to high energy, water and chemicals consumption. Only a minor role is played by forestry activities that supply the raw feedstock, although forestry management practices certainly affect both the final productivity and the energy balance, through the amount and use efficiency of the farm inputs. Additionally, among the three forest systems under study, Spruce/Pine forest management displays the most sustainable option for paper production because, basing on the emergy indices, it presents the best sustainable contribution to both the economy and the environment of the investigated region. In conclusion, the application of EMA approach allowed a more comprehensive assessment of forestry and industrial operations, contributing to assist decision makers in implementing the best environmental management of papermaking process.

Emergy synthesis of conventional fodder maize (Zea mays L.) production in Denmark

With the demand for animal protein on the rise, there is need for phenomenal increase in production of animal feed to meet the increasing demand. Among the feed production systems, conventional fodder maize acreage is increasing due to high yields and nutritional value of maize silage over other feeds. However, conventional fodder maize production systems are input intensive and there is a need to assess resource use in fodder maize production in Danish agriculture and in Europe in general. Hence, the objective of the study was to carry out emergy synthesis to evaluate the resource use in conventional fodder maize production. Among the renewables, rain input (3.08E + 14 seJ/ha) was the largest renewable component input and considered as the total renewable input into the production system. The purchased resources was the significant input constituting 80.5% (1.54E + 15 seJ/ha) of the total emergy. Among the purchased inputs, nitrogen consisted of the bulk of the input of 37.6% (7.18E + 14 seJ/ha), followed by phosphorus (19.5%) and diesel input (16.4%). The fodder maize yield was 3.12E + 7 kg ha−1 equivalent to output (Y) of 4.60E + 11 J/ha. The solar transformity was 4.15E + 03 seJ/J and the fraction of local renewables was 16%. Emergy yield ratio was 1.24 and environmental loading ratio was 5.2 whereas emergy sustainability index was 0.24. The study quantified the different inputs of renewables, local non-renewables and purchased inputs and used a range of emergy indicators to identify the gaps in resource use in fodder maize production. It was evident that purchased resources were the bulk of the input and management measures to improve the use efficiency of these inputs will enhance the emergy use efficiency. Hence, the study outputs are a useful resource for informed decision making to devise management measures by farmers, agricultural advisors and policy makers to optimize the inputs for sustainable production of fodder maize.

Bamboo vs. crops: An integrated emergy and economic evaluation of using bamboo to replace crops in south Sichuan Province, China

Based on long-term monitoring conducted in Chang-ning county, a pilot site of the 'Grain for Green Program' (GFGP), an integrated emergy and economic method was applied to evaluate the dynamic ecological-economic performance of 3 kinds of bamboo systems planted on sloping farmland. The results confirmed the positive effects of all 3 kinds of bamboo systems on water conservation and soil erosion control. The benefits gained progressively increased during the first 8 years after conversion, going from 4639 to 16127 EMyuan/ha/yr on average. All three bamboo plantations were much more sustainable than common agricultural crops planted on sloping land (CP) on both the short and long-term scales with their Emergy Sustainability Index (ESI) and Emergy Index for Sustainable Development (EISD), respectively, being 14.07-325.71 and 80.35-265.80 times that of CP. However, all 3 bamboo plantations had a Net Economic Benefit (NEB) less than that of CP during the first 8 years after conversion. Even with the government-mandated ecological compensation applied, the annual NEBECs of the Bambusa rigida (BR) and Phyllostachys pubescense (PP) plantations were, respectively, 3922.03 and 7422.77 yuan/ha/yr lower than the NEB of CP. Emergy-based evaluation of ecosystem services provides an objective reference for applying ecological compensation in strategy-making, but it cannot wholly solve the economic viability problem faced by all bamboo plantations. Inter-planting annual herbs or edible fungus, such as Dictyophora echinovolvata, within bamboo forests, especially in young bamboo plantations, might be a direction for optimizing bamboo cultivation that would improve its economic viability.

Emergy evaluation of Yaghuti grape of Sistan

The present study uses emergy methodology to assess environmental performance of Yaghuti grape production of Sistan. In Sistan, grape production is very important for the region in terms of both export to other provinces of Iran and domestic consumption. The renewable resources comprising free renewable local resources including sunlight, rain and wind and non-renewable including soil, and renewable purchased inputs embracing human labor, chemical fertilizer including nitrogen, phosphorous and potassium, and chemicals were the input used to estimate emergy indices. The analyses showed that the total emergy input was 1.94 × 1016 seJ, and approximately 43.41% and 23.16% were from human labor and irrigation water, respectively and followed by nitrogen fertilizer with quota of 11.32%. Emergy indices of grape production are as follow; emergy yield ratio: 1.31, emergy investment ratio: 3.25, environmental loading ratio: 0.541 and emergy sustainability index: 2.42, indicating that grape production system is sustainable and is less stressful on the environment in comparison with other research. It could be suggested with greater energy use efficiency through optimization of human labor, irrigation water and nitrogen fertilizer grape production could be recommended as suitable crop for Sistan region.

Emergy based carbon footprinting of household solid waste management scenarios in Pakistan

Waste management is a serious challenge across many resource constrained countries of the world leading to environmental issues such as pollution and high rates of soil occupation, health issues induced by poor hygienic conditions, and financial problems linked to the high costs associated to waste management, which have high impacts on municipal budget. In this study we determined the environmental impact of different waste disposal scenarios in a major city of Pakistan. Existing studies on the subject of waste management in Pakistan fail to account for the environmental burden of waste processing technologies. To counter this, in this paper we used Emergy based accounting procedures to obtain a donor or nature based perspective for environmental footprinting. Three scenarios were considered for the analysis consisting of the current practice of open dumping as Scenario A; sanitary landfilling with composting and material recycling as Scenario B and incineration with composting and recycling as Scenario C. Results were presented in the form of Emergy based input-output tables as well as greenhouse gas emissions as measured in kg CO2 equivalent (kCO2eq/t) per tonne of waste. Scenario A was the worst option due to its high emissions and lack of any useful output. Scenario B was identified as the best alternative as it resulted in similar amount of net emissions as Scenario C but with relatively lower stress on the environment as indicated by the Emergy indicators. In view of the subject city’s resource constraints we recommend inducing waste reduction and minimization practices through public awareness campaigns. Resource contributions from the civic society are also suggested for erecting the necessary waste disposal infrastructure. The results and suggestions presented herein need to be highlighted in a timely manner in order to resolve environmental and public health risks posed by the current practices.

Emergy analysis for transportation fuels produced from corn stover in China

In order to provide more useful information for the decision makers in China to implement sustainable energy policies and to identify which region in China is most suitable to build the biofuel production plants for fast pyrolysis and hydroprocessing of corn stover, the present study has evaluated the production efficiency and sustainability of large-scale transportation fuel production via fast pyrolysis and hydroprocessing of corn stover in China using emergy analysis approach. Both the hydrogen production scenario (i.e. oil hydroprocessing using the hydrogen derived from bio-oil reforming) and the hydrogen purchase scenario (i.e. oil hydroprocessing using the hydrogen purchased from market) in three regions of China (Northeast China Plain (NECP), North China Plain (NCP) and Shaanxi Province (SXP)) have been investigated. The results have shown that maize production, and fast pyrolysis and hydroprocessing are the two biggest emergy input stages of the biofuel production system. The comparison of the emergy indices of all of the six cases investigated indicates that the hydrogen purchase scenario in NCP is the best biofuel production case due to its second best sustainability and the second highest production efficiency. In comparison to bioethanol from cassava chips and wheat and biodiesel from jatropha curcas L, the hydrogen purchase scenario in NCP is also the most sustainable plan for a biofuel production plant in China. As water, fertilizer and hydrogen are the three biggest emergy inputs in this case, improvements on the water management, fertilizer management and hydrogen production technology have been discussed. In order to further increase the efficiency and sustainability of the hydrogen purchase scenario in NCP, some of the necessary efforts required from the relevant sectors have also been put forward based on the results of the emergy analysis.

Towards more sustainable social housing projects: Recognizing the importance of using local resources

The social housing projects of Brazil are focused on providing shelter for families with low income and on reaching the ultimate objective of more sustainable development of the nation. The Brazilian program, in supporting these families, is carried out through three main standardized housing projects: popular housing (R1), popular building (PP4), and building for social interest (PIS). Decisions regarding the choice of one project instead of another are usually based on economic considerations, disregarding environmental issues important for achieving sustainable development. The main goal of this work is to assess which social housing projects should be promoted in each Brazilian state, aiming for higher sustainability. For this purpose, emergy accounting is used to quantify the environmental sustainability index (ESI*) and the emergy index for construction productivity (EICP, in m2/sej). Results show the existence of different degrees of ESI* and EICP values among the three types of social housing projects, when considering the state in which projects are implemented. Analysis of the results identified the social housing projects that should be promoted to maximize ESI* and EICP aiming for higher sustainability. Choosing a project exclusively based on economic considerations could be premature, because it may forgo the opportunity to maximize sustainability of the national social housing program. This study also provides a scientific contribution to the emergy accounting method with regard to the scales of analysis that support the criteria used to count a resource as local or imported and in considering the partial renewabilities of resources according to regional characteristics.

Integrated Emergy and Economic Performance Assessments of Maize Production in Semiarid Tropics: Comparing Tillage Systems

Owing to a combination of factors like improved genotypes, closeness to consuming markets, good infrastructure to production outlets and a rainy period that occurs during the off-season, maize production in the Eastern part of the semiarid tropics (SAT) in Brazil is undergoing a shift towards a farming systems with intensive use of chemical inputs, tillage and high yielding genetically-modified (GMO) hybrids. However, the region is highly prone to desertification, and the intensive tillage accelerates the soil degradation process. Although conservation tillage has been reported to improve soil protection and quality and, consequently, sustainability of cereal production in many environments, farmers are still reluctant to adopt it, fearing yield declines as documented in early studies in SAT. Recent findings however, have shown that no-till can be instrumental for improving soil fertility and crop yields also in semiarid environments. The goals of this study are to assess the environmental and economic performances of conservation tillage in SAT and to compare the environmental performance of maize production in SAT and in more favorable environments for agricultural production in South America. Emergy accounting was used for assessing the environmental performance, and classical economic indicators for assessing the economic performances. Indicators for both environmental and economic aspects showed that no-till improves environmental performance, while it reduces costs and increases profits when compared to reduced and conventional tillage systems for maize production in SAT. Although some emergy indicators are slightly poorer in SAT than in the Atlantic Rainforest, the transformity of maize grains allow us to infer that maize production in SAT makes use of environmental resources more efficiently than in the South of Brazil or in the Argentinean Pampas. Further analysis shows that the higher prices obtained for maize grains in the region seem to pay off for the higher climate risks of Brazilian SAT.

EVALUASI EMERGY PENGEMBANGAN SISTEM BUDIDAYA UDANG SUPRA INTENSIF DI KAWASAN PESISIR MAMBORO, KOTA PALU, PROVINSI SULAWESI TENGAH

Indonesia should pay greater attention on aquaculture due to a continous decrease in capture fisheries production. Shrimp is an excellent fishery commodity consumption in the global market, but the availability of supply is not yet fulfilled. The supra intensive aquaculture system has believed as a solution method for shrimp production. This study was trying to analyze the energy and emergy flow inside the supra intensive aquaculture system. Further analysis was done with emergy indices calculation to predict the future application of supra intensive system. The result of study shows the energy required in shrimp harvested from supra intensive system (transformity) was 1,12E+10 sej/g shrimps. This number represents it is needed more energy to produce per gram shrimps in supra intensive system compared to conventional shrimp pond in Ecuador and in Brazil. System more likely depend on purchased input which was indicated by very high EIR and ELR but in contrary relatively low EYR. Supra intensive aquaculture systems tend to be unsustainable in the long term by the very low value of ESI.

Emergy-based environmental accounting toward a sustainable Mongolia

An emergy-based environmental accounting of Mongolia is presented based on the data from 1995 to 2012. By calculating natural and economic inputs and a series of emergy indicators, this paper discusses Mongolia’s resource use structure, economic situation, trade status and societal sustainability. The results show that the total emergy use for Mongolia changed from 2.83×1022 sej in 1995 to 4.96×1022 sej in 2012, representing a 75% increase over the 18 years of this study, yet its emergy per capita remains one of the lowest in the world (1.74×1016 sej/capita). The emergy money ratio (EMR) of Mongolia during 1995–2012 decreased from 1.99×1013 sej/USD to 7.75×1012 sej/USD, which indicates that the power of a dollar for purchasing real wealth in Mongolia was declining, while the relatively high absolute values compared to its trading partners and even the world average EMR suggests that Mongolia is continuing a trade disadvantage. Mongolia’s emergy exchange ratio is increasingly less than one to the point that in 2012 the ratio was 0.3 suggesting that the exported emergy was over 3.3 times greater than the imported emergy. The growing dependence on imports and the dramatic increase in exports suggests that Mongolia’s economy is increasingly vulnerable to downturns in the world economy.

The solar transformity of heat and power in coproduction

Emergy analysis is a method for environmental accounting which presents the solar energy footprint of products. Processes with multiple products involve special calculation rules. If the co-products cannot be produced separately, the total input emergy is allocated on both products. Therefore an inseparable coproduction is penalized by the method. Yet, if the product can be produced separately in the system, the input emergy can be split for the products.Combined heat and power production (CHP) is a typical multi-production process, which is designed to meet the needs for the heat and power both. In earlier cogeneration emergy studies heat and power were treated as inseparable byproducts. As a result the transformity of electricity was often lower than the transformity of steam, which is not logical. Neither the approach could describe the co-production benefits to the independent production.Different alternatives of CHP are elaborated in this paper from emergy perspective. It was found that heat & power can be coproduced semi-independently employing condensing turbines with steam reduction but not by back pressure turbines. Therefore emergy allocation is possible only in condensing turbine systems. The choice of allocation method depends on the scope and purpose of study. Efficiency based allocation methods are recommended for general and local studies.As a case study two types of biomass CHP plants were analyzed. Work and alternative production emergy allocations were employed. In the reduction type of coproduction the transformities were the same as in independent production. Therefore no coproduction benefits were gained in this case. If steam extraction from the turbine is employed, the transformities vary as a function of the power to heat ratio. Minimum transformities appear at full extraction, which corresponds to employment of a back-pressure turbine. This is the most emergy efficient way of coproduction since any steam condensation is avoided.In the end main emergy contributors of biomass based coproduction were also discussed together with emergy indices.

The impact of renovation measures on building environmental performance: An emergy approach

Approximately 30–40% of the total natural resources that are used in industrialized countries are exploited by the building sector, and almost 40% of the world’s consumption of materials converts into the built environment. Thus, improving the environmental performance of building sector could be crucial for reaching the sustainability of urban environment.The main scope of this paper is to highlight the interest of building renovation as an adequate measure for improving building environmental performance in term of emergy and identify processes that cause significant environmental stress on a local ecosystem. To enable the comparison of all phases and processes for the studied system, an emergy evaluation was performed. A multi-apartment building located in the city of Šabac, Serbia, was used as case study. Several building renovation scenarios were considered, which include different measures for building envelope thermal performance improvements, as well as installation of local renewable energy heat production system. Different renovation timelines were also compared.The overall results showed that 68% of the emergy flow is caused during the building operation phase, 24% during the construction phase and only 8% during the end-of-life phase. All renovation measures proved to be beneficial from the environmental point of view, and the use of additional materials and resources to conduct renovation measures considered did not have a negative impact on the building overall environmental performance. The effect of conducting renovation measures after the first decade of building lifetime improved the overall building environmental performance by almost 50% when compared to the same renovation measures conducted in the last decade of the lifetime (for all measures considered). Finally, based on the emergy indices analysis, it can be concluded that the application of building renovation measures improves the overall building environmental performance, enables higher efficiency in indigenous resource use, and lowers the pressure on a local ecosystem.

Integrated emergy and economic evaluation of lotus-root production systems on reclaimed wetlands surrounding the Pearl River Estuary, China

Lotus (Neumbo nucifera, Gaertn) is the most important aquatic vegetable in China, with a cultivation history of over 3000 years. The emergy, energy, material, and money flows of three lotus root cultivation modes in Wanqingsha, Nansha District, Guangzhou, China were examined using Energy Systems Language models and emergy evaluation to better understand their ecological and economic characteristics on multiple spatial and temporal scales. The natural resource foundations, economic characteristics and sustainability of these modes were evaluated and compared. The results showed that although all three modes were highly dependent on purchased emergy inputs, their potential impacts as measured by the local (ELRL) and global (ELRW) environmental loading ratios were less than 1.2 and 0.7, respectively. The lotus-fish mode was the most sustainable with its emergy index of sustainable development (EISD) 2.09 and 2.13 times that of the pure lotus and lotus-shrimp modes, respectively. All three lotus-root production modes had superior economic viability, since their Output/Input ratio ranged from 2.56 to 4.95. The results indicated that agricultural systems may have different environmental impacts and sustainability characteristics at different spatial and temporal scales, and that these impacts and characteristics can be simultaneously explored using integrated emergy and economic evaluations.

Does intensification result in higher efficiency and sustainability? An emergy analysis of Mediterranean sheep-crop farming systems

The embodiment of resources in agricultural products depends on the way they are made, i.e., the production system. We applied emergy analysis on three contrasting sheep-crop farming systems according to different degrees of specialization, integration and intensification of production in Mediterranean Spain. We studied emergy flows, transformity values and emergy indices at the system level and per product (lamb meat; permanent crops: rainfed olive and almond; arable crops: rainfed barley, irrigated barley, alfalfa and sunflower). We found that the specialized pasture-based sheep system had the lowest intensity and efficiency and the highest sustainability, as opposite to the partially-integrated mixed system, while the fully-integrated mixed system obtained a balanced position. Lamb meat production was 1.9 and 1.3 times more intensive and efficient, respectively, in the partially-integrated mixed system than in the pasture-based sheep system, but 5.1 times less sustainable. All sheep sub-systems had comparatively lower intensity and higher sustainability than crops due to their higher capacity to use local and renewable natural resources. Our findings suggest that further support of agricultural development based on local and renewable natural resources and best practices is necessary to ensure long-term farming sustainability and social welfare.