Emergy Index Research Articles

Emergy-based sustainability assessment of an integrated production system of cattle, biogas, and greenhouse vegetables: Insight into the comprehensive utilization of wastes on a large-scale farm in Northwest China

Based on the concept of comprehensive utilization of wastes, an eco-agricultural integrated production system of cattle, biogas, and greenhouse vegetables (IPSCBV) was constructed for a large-scale farm in Northwest China. In the present study, the production efficiency, environmental impact, economic viability, and sustainability of the IPSCBV were evaluated using emergy and economic analyses. The performance of the IPSCBV was compared with that of independent production systems for cattle and greenhouse vegetables using a variety of emergy indices, including the joint indices (transformity, emergy yield ratio, environmental loading ratio, and emergy sustainable index) calculated for the IPSCBV with multiple outputs and the weighted average indices for the independent production systems. The self-organization ability, emergy exchange status, and economic and environmental benefits of the integrated and independent production systems were evaluated using the feedback ratio of yield (FYR), emergy exchange ratio (EER), and greenhouse gases emission mitigation intensity (GEMI). The evaluation results using the new emergy-based indices showed that the IPSCBV had better emergy efficiency and higher sustainability, which resulted in less environmental stress than the independent production systems for cattle and greenhouse vegetables. The FYR of the IPSCBV system was 10.50% while that of the independent systems was only 0%. The GEMI in the IPSCBV reached 2.12kgCO2-eq/1014sej. The EER of the IPSCBV (0.62) was significantly lower than that of the independent greenhouse vegetable production system (3.02). That is, the price of the products underestimated their real (emergy-based) value which includes the free environmental resources and the system's inherent feedbacks. From an economic point of view, the IPSCBV may not provide a competitive economic input–output ratio in the short run. However, it serves as a promising eco-agricultural model for comprehensive utilization of wastes on large-scale farms associated with intensive management because of its better performance with respect to resource utilization, environmental emission mitigation, and sustainability.

Integrated emergy and economic evaluation of tea production chains in Anxi, China

Emergy and economic methods were used to evaluate and compare tea production systems in Anxi, China. Tea production was classified into three phases, i.e., the nursery, the plantation and tea processing, and each phase was evaluated. The results showed that the nursery subsystems were profitable with an economic output/input ratio of 2.86. However, the inclusion of a nursery had no significant influence on the sustainability of the tea plantation system, because it was a small part of the total input to the system. Applying organic fertilizer to replace 66% of the chemical fertilizer decreased the pressure of chemical loading on the environment, and as a result the cultivation phase's emergy sustainability index (ESI) increased 2.10 times. However, due to the relatively high price of organic fertilizer and the labor to spread it, the economic output/input ratio (1.61) of the mixed organic and chemical fertilizer mode was less than that of the chemical fertilizer mode (1.80). If all the tea leaves used in the processing phase were produced on the farm, instead of purchased from outside, about 30% of the economic cost of processing could be saved, and as a result the economic output/input ratio would increase by 41%; the ESI would increase 5.48 times and the emergy index for sustainable development (EISD) would increase 11.05 times. The overuse of chemical fertilizer and low productivity of labor are key problems that need to be solved for further optimization of the Anxi tea plantation systems.

Emergy-based dynamic mechanisms of urban development, resource consumption and environmental impacts

As the center of human activities and social civilization, cities have developed at the cost of serious environmental degradation and huge eco-environmental pressure, which further lower human living standards and impede the sustainable development of urban ecosystems. Current urban dynamic methods have broader views and focus more on ecological aspects, e.g., the impact of emissions and resource consumption, but they lack a rigorous thermodynamic framework. Consequently, there is a need to modify existing processes and develop new technologies that minimize environmental impact while stimulating ecological flow. This paper describes the development of a forecasting model, named the emergy-based urban dynamic model, capable of accurately simulating the observed resource consumption, economic growth, and environmental impact of Beijing from 1999 to 2039. This model differs from previous urban emergy models by monitoring the negative effects to human well-being and ecosystem integrity in the developing urban system. A fresh perspective focuses on urban comprehensive performance, linking such impacts to a supply-side environmental cost evaluation (including ecological service supply, ecological and economic losses, and investment for treatment). In this introductory paper, we present the conceptual considerations of the most important components of the emergy-based urban dynamic model: the urban assets, lands, capitals, population, water resources, and economic and environmental loss. Each subsystem in this model will enrich the feedback dynamics, policy levers, and post-scenario analyses. Statistical information and calibration were also considered in this dynamic emergy accounting. The simulation revealed that water resources will be the most important limiting factor for the sustainable development of Beijing. A better approach would not be more engineering projects to deliver new supplies but to curb demand through efficiency improvements in water supply and consumption using the rule of law and economic incentives. The results of the simulation revealed that after the year 2015, many emergy indicators will collapse. The results of our study will enable urban policy planners to understand these inter-linkages by addressing specific damages to human health and the ecosystem's integrity, as well as by linking such impacts to a supply-side environmental cost evaluation.

Emergy diagnosis and reflections towards Brazilian sustainable development

This paper presents an environmental emergy-based diagnosis of Brazil compared with Russia, India, China, South Africa and United States. Reflections on the Brazilian sustainable development are presented and discussed based on the evaluations published since 1979. The variation of the emergy per capita for Brazil from 1979 to 2007 indicates that the country's growth is tied to the exploitation of non renewable natural resources which do not directly reflect in the welfare of the population. The total emergy exported per unit of gross domestic product increased in the period, suggesting that the country exports more emergy than that contained in the money received for the exportation. With the help of the emergy indices, the future development of Brazil is explored and discussed. The comparison among the BRICS (Brazil, Russia, India, China and South Africa) countries and United States indicates that what may be appropriate and usable within one country may not be within another and that to achieve the global sustainability two concomitant actions may occur: (i) the reduction of the total emergy use in developed economies, and (ii) the reduction of indigenous resources exportation in developing economies.

Emergy Analysis of Protected Grape Production System in China

This paper evaluated the energy and emergy characters and indicators of the protected grape production system in the five major producing areas in China based on the emergy analysis. The research results indicate that the total emergy input in the Northwest region is the largest. The protected cultivation in all the five regions is heavily dependent on the purchased resource and nonrenewable resource emergy. The Southwest region is found to have the lowest environmental pressure and the highest sustainability.

Monitoring and evaluating the sustainability of Italian agricultural system. An emergy decomposition analysis

The agricultural sector is critical for the achievement of sustainable development worldwide. Its present and future sustainability relies on the difficult balance of food production and environmental impact. The need for resource use optimization and increasing reliance on renewable energy, calls for increased development and integration of its supporting, provisioning, regulating and social services (multifunctionality) worldwide, in agreement with the global framework of the Millennium Ecosystem Assessment, the European Union Objectives and other international assessment studies (e.g. the United Nations International Assessment of Agricultural Knowledge, Science and Technology for Development).The performance of the Italian agricultural system is monitored and evaluated in this paper by means of the emergy accounting method coupled to decomposition analysis techniques, applied to a 25 year time series (1985–2010). The aim of this study is to assess the sustainability of these systems over time as well as to identify the major drivers of performance change, to serve as the basis for future policy scenarios. Two Italian regional agricultural systems (Emilia Romagna, in Northern Italy, and Campania, in Southern Italy) are selected as case studies representative of the Italian agriculture. Results show a steady decrease of cropped land, an increase of the fraction of renewable resource use, an overall increase of sustainability (expressed by emergy indicators) in both regions. The fraction of renewable emergy use increased from 14% to 21% in the Emilia Romagna region and from 23% to 27% in the Campania region, compared to the year 1985, with oscillating behavior over time. The overall Emergy Sustainability Index increased from 14% to 16% in the Emilia Romagna region and from 15% to 19% in the Campania region, recently. The results of decomposition analysis highlight the important role of land use change and labor productivity as major drivers of total emergy use in both agricultural systems. The approach applied in this paper is applicable to the study of other national and regional agricultural sectors wordwide, provided suitable time series of input and output flows are available.

How to manage co-product inputs in emergy accounting exemplified by willow production for bioenergy

Assessments of environmental performance are challenged by multifunctionality of production systems where impacts cannot be assigned to any one specific output. In the assessment method emergy accounting, all available energy used up for a process is summed up after being converted to solar equivalent Joules. In emergy accounting each output carries the resource use burden of all co-produced outputs. When comparing emergy indicators on a product-to-product basis (reference approach), products from single-output processes tend to be favoured. This constitutes a method bias. Building on emergy algebra rules, we describe approaches to calculate solar transformities when co-production is involved and give guidelines on how to compare products and systems. The approaches are exemplified in a comparison between willow biomass, fertilised with manure, and natural gas used as feedstock for combined heat and power (CHP) production. A Danish willow-based CHP model system was assessed whereas data for the fossil-based system was from literature. When compared on a product-to-product basis using the reference approach, bio-based CHP production is inferior to fossil-based CHP with respect to resource use (transformities of 2.31 E+05seJ/J and 0.88 E+05seJ/J, respectively). If the manure is considered as a waste and modelled as heat loss, the single-product transformity for biobased production is only 0.37 E+05seJ/J. When compared on a system-to-system basis, bio-based production is competitive with fossil-based production (transformities of 2.21 E+05seJ/J and 2.29 E+05seJ/J, respectively). The paper evaluates compatibility of suggested approaches with emergy theory and practices and presents a discussion of the distinction between waste and resource.

Emergy accounting for regional studies: Case study of Canada and its provinces

Sustainable regional management (development) requires an understanding of interactions between the social, economic, and ecological systems within the boundaries of a region. In this paper, application of emergy (an environmental accounting method) for regional planning is discussed through a case study. Emergy (spelled with an “m”) methodology is an environmental accounting technique that evaluates the energy system for the thermodynamics of an open system. Major renewable and non-renewable resource fluxes to a region, including energy, matter, human activities, and money can be converted to emergy by using corresponding transformity functions.As a case study, this paper discusses the emergy accounting of Canada and its provinces with various emergy-based indicators. Moreover, emergy maps were generated in a form of emergy geography. These maps are multi-dimensional illustrations that show resource consumption, emergy per person, and emergy density across Canada under two parameters: (1) the quantities of resources consumed and (2) the location of consumption. Emergy analysis also highlights concentrations of renewable and natural resources in Canada and distinguishes the provinces with the highest resource consumption. Analysis of emergy indicator for Canadian provinces shows that Alberta with the highest EYR (7.35) provides energy to the economy of Canada. However, ELR value of Alberta (8.5) indicates that the province's current economic approach is not sustainable as it relies mainly on non-renewable emergy inputs (mainly from fossil fuels). ELR of British Columbia and Manitoba indicates that these two provinces created a firm balance between emergy use of renewable and non-renewable resources. The characterizations of regions provided in this paper can be used for future land planning and management both in federal and provincial levels.

Provincial level-based emergy evaluation of crop production system and development modes in China

This paper presented a multi-objective indicator system for the performance evaluation of crop production system based on emergy method. Eight emergy indicators were selected to analyze the crop production system in the 31 provinces of mainland China to compare intensive use, scale management, investment density, environmental pressure, output benefit, output density, output per capita, and economic benefit. This paper conducted a comparison of each indicator in different provinces, and divided the 31 provinces into 10 groups by cluster analysis. The results show that: the crop production system among provinces has a significant difference and it is summarized into 10 development modes; with the development of modern agriculture, Chinese crop production system still complies with the input–output balance; the majority of provinces cannot achieve win-win between economic investment and environmental health; most of the underdeveloped provinces with high productivity may not be able to obtain good economic benefit; there is a significant positive correlation between the scale management degree and emergy output per capita in the crop production system; 10 development modes and policy suggestions are deduced. It is concluded that emergy-based multi-objective indicators can serve as an effective method in the evaluation of crop production system.

Application of Modified Ecological Footprint Model: A Case Study of Tibet, China

To improve the ecological footprint model in aspect of reflecting sustainability of the economic, social and technological, the emergy analysis and socio-economic system development index were introduced into the model. The modified ecological footprint model was applied in the calculation of ecological carrying capacity and ecological footprint in Tibet, China. The ecological carrying capacity/cap is 19.13hm2, and the ecological footprint/cap is 8.96hm2. The result shows that the Tibet region is under the condition of ecological surplus and it is suitable for further programs development to some extent. But the high proportion of energy resources, cement and fertilizer utility should draw attention during the exploitation or construction progress.

Emergy analysis of cassava vinasse treatment

Vinasse has great pollution to the environment. A number of technologies have been explored for reducing the pollution of vinasse. Sustainability has become an important factor when discussing wastewater treatment techniques. Emergy analysis was used to evaluate the treatment of cassava vinasse in this paper. Cr (emergy consumption ratio) as a new emergy index was proposed to measure the impact of waste treatment to the society. Centrifugal solid–liquid separation, UASB (up-flow anaerobic sludge bed), and SBR (sequencing batch reactor activated sludge process) are used in the treatment process. The emergy indices for cassava vinasse treatment system were as follows: EYR (emergy yield ratio) was 6.20, ELR (environmental loading ratio) was 5.81, ESI (emergy sustainability index) was 1.07, and Cr was 4.60E+12sej/m3. The emergy of coal electricity accounts for 46% of all purchased inputs. It is necessary to improve the treatment technology to reduce the electricity used.

Emergy Evaluation of a Production and Utilization Process of Irrigation Water in China

Sustainability evaluation of the process of water abstraction, distribution, and use for irrigation can contribute to the policy of decision making in irrigation development. Emergy theory and method are used to evaluate a pumping irrigation district in China. A corresponding framework for its emergy evaluation is proposed. Its emergy evaluation shows that water is the major component of inputs into the irrigation water production and utilization systems (24.7% and 47.9% of the total inputs, resp.) and that the transformities of irrigation water and rice as the systems' products (1.72E + 05 sej/J and 1.42E + 05 sej/J, resp.; sej/J = solar emjoules per joule) represent their different emergy efficiencies. The irrigated agriculture production subsystem has a higher sustainability than the irrigation water production subsystem and the integrated production system, according to several emergy indices: renewability ratio (%R), emergy yield ratio (EYR), emergy investment ratio (EIR), environmental load ratio (ELR), and environmental sustainability index (ESI). The results show that the performance of this irrigation district could be further improved by increasing the utilization efficiencies of the main inputs in both the production and utilization process of irrigation water.

Study on the Sustainability of Hefei City Economic Ecosystem Based on Emergy Analysis

From the theory of urban ecosystem, using emergy analysis method founded by Odum, this paper analyzed the emergy flow of Hefei city systematically, and evaluated the status of the natural environment of its ecosystem and its socioeconomic sustainable development through a series of emergy indices. The results showed that the environment loading ratio of Hefei urban ecosystem was 19.71, emergy sustainable indices(ESI) and emergy index for sustainable development (EISD) was 0.0425, 0.0507, respectively in 2010, slightly higher than the neighboring capital cities. This indicated that Hefei had strong sustainable development ability. In 2010, the input emergy of eco-economic system of Hefei city was 2.35×1022sej, the output emergy was 1.95×1022sej, the surplus emergy was 0.40×1022sej, which indicated that the emergy of Hefei city continued to increase and accumulate, and this was the real reason of the rapid development of Hefei city in recent years.

Emergy synthesis of a combined food and energy production system compared to a conventional wheat (Triticum aestivum) production system

It is a major challenge to produce food and energy sustainably for the ever increasing world population as today's conventional food production and energy needs are met by the fossil based resources, causing enormous environmental load. A novel, combined food and energy (CFE) agro-ecosystem, was designed for sustainable production of food, fodder and energy without chemical inputs (fertiliser, herbicide and fungicide). The objective was an emergy synthesis of the CFE system compared to a conventional wheat (Triticum aestivum) production system to assess resource use efficiency. The emergy indices, used to assess the environmental performance and sustainability, exhibited contrasting differences between the two production systems in terms of outputs (Y), total emergy use, solar transformity, relative use of local renewable resources, environmental loading ratio (ELR), emergy yield ratio (EYR) and emergy sustainability index (ESI). The Y in the CFE consisted of grain, straw, fodder and woodchip production of 4020, 3580, 6100 and 10,000kg/ha/yr respectively whereas Y in the conventional wheat consisted of 7250 and 3770kg grain and straw/ha/yr respectively. The Y in the CFE was 81% (2.80E+11J/ha/yr) higher with 13.5 times (6.40E+03seJ/J) lower solar transformity compared to the Y (1.54E+11J/ha/yr) and solar transformity (8.63E+04seJ/J) in the conventional wheat, exhibiting highly resource intensive production in conventional wheat. The local renewables constituted 19.2% and 2.6% of the total emergy input in the CFE and the conventional wheat respectively with a corresponding lower ELR (4.21) and 22.5% higher EYR (1.26) in CFE compared to conventional wheat. CFE was more reliant on local renewable emergy flows and compatible with the local environment with higher ESI (0.30) compared to conventional wheat (0.03), where 64.5% of the total emergy input constituted chemical inputs. The study demonstrated that the innovative agro-ecosystem, exemplified by CFE, is considerably less resource demanding and more amenable to sustainable production, whether defined in terms of outputs, solar transformity, relative use of local renewable resources, EYR, ELR or ESI.

Assessing the health of agricultural land with emergy analysis and fuzzy logic in the major grain-producing region

Agricultural land is a complex system that combines natural ecology and social economy, and the health of agricultural land directly influences regional economic development and national food security. Emergy analysis is an effective method for value analysis of ecosystems, assessment of the health of ecosystems, which is based on principles of systems ecology and energy. And fuzzy logic is a generalization tools to operate with vaguely defined parameters or concepts, which has been extensively applied in the quality evaluation of soil and land. The health of agricultural land as an aggregate that takes into account the quality and productivity of land as well as the soil environment. This paper presents an integrated evaluation model based on emergy analysis and fuzzy logic and using the geographic information system (GIS) to evaluate the health of agricultural land. An evaluation system is developed, which includes quality, productivity and the soil environment. A major grain-producing region in the North China Plain, namely Luancheng County, was selected for the case study. Field survey, household inquiry, sampling, and experimental analysis were conducted in the study area. The health of agricultural land expressed as the emergy index ranged from 0.471 to 0.763; as the fuzzy index, from 0.603 to 0.878; and as a composite index, from 0.284 to 0.666. Based on the composite index, the agricultural land was divided into four classes, namely in perfect health (which accounted for 7.6% of the agricultural land), in normal health (54.3%), in sub-health (32.9%), and in poor health (5.2%). Overall, agricultural land in Luancheng County is healthy, although 89.00 km 2 of the farmland – mainly in Douyu, Nangao, and Liulintun – is in sub-health and 14.22 km 2 in Douyu is in poor health because of poor productivity and unfavorable soil environment. ► A concept of agricultural land health was introduced. ► The health of agricultural land was assessed by integrated evaluation model. ► An integrated evaluation model was established using emergy analysis and fuzzy logic. ► Land quality, productivity and soil environment were proposed as evaluation system. ► Agricultural Land was divided into perfect, normal, sub-health and poor in Luancheng.

Impact of building material recycle or reuse on selected emergy ratios

While the emergy evaluation method has been used successfully in recycling processes, this area of application still requires further development. One of such is developing emergy ratios or indices that reflect changes depending on the number of times a material is recycled. Some of these materials may either have been recycled or reused continuously as inputs to a building, for example, and thus could have various impacts on the emergy evaluation of the building. The paper focuses on reuse building materials in the context of environmental protection and sustainable development. It presents the results of an emergy evaluation of a low-energy building (LEB) in which a percentage of input materials are from recycled sources. The corresponding impacts on the emergy yield ratio (EYRB) and the environmental loading ratio (ELRB) are studied. The EYR which is the total emergy used up per unit of emergy invested, is a measure of how much an investment enables a process to exploit local resources in order to further contribute to the economy. The ELR however, is the total nonrenewable and imported emergy used up per unit of local renewable resource and indicates the stress a process exhibits on the environment. The evaluation provides values for the selected ratios based on different recycle times. Results show that values of the emergy indices vary, even more, when greater amounts of material is recycled with higher amount of additional emergy required for recycling. This provides relevant information prioritizing the selection of materials for recycling or reuse in a building, and the optimum number of reuse or recycle times of a specific material.

Emergy-based sustainability assessment of Inner Mongolia

An integrated environmental accounting of the Inner Mongolia Autonomous Region (IMAR) is presented in this paper based on emergy analysis with data from 1987 to 2007. Through calculating environmental and economic inputs and a series of emergy indicators, this paper discusses IMAR’s resource use structure, economic situation, and trade status. The results show that more than 85% of the emergy used in IMAR was derived from home sources, indicating a strong capacity for self-sufficiency. Concentrated-used local non-renewable emergy, which provides IMAR economy with most of the driving forces, took the largest share in total emergy use after 2004 and reached 58% in 2007. The Western China Development Plan of 2000 ushered in a rapid growth of coal and electricity production and exportation to other regions of China from IMAR. The export/import emergy ratio of IMAR reached 3.46 in 2007, with the coal exported (3.44×1023 sej in 2007) without being used by IMAR itself, accounting for almost 100% of the difference between the imports and exports. The results also show that from 1987 to 1998, EmSI values remained higher than 10, suggesting underdevelopment in IMAR; after 1998, EmSI values decreased sharply from 19.07 in 1998 to 1.88 in 2007, indicating that IMAR is characterized by medium-run sustainability and is relying more on non-renewable resources and imports.

Monitoring the sustainability and equity of socioeconomic development: A comparison of emergy indices using Macao, Italy and Sweden as examples

The concept of sustainability involves factors related to society, economy, and ecology. The modern context of sustainability also includes a requirement for equitable consumption of materials and energy to sustain the quality of life while still protecting the environment. To evaluate the environmental sustainability of socioeconomic activities, emergy (embodied energy) is an important tool because it can measure real wealth by accounting for both natural and socioeconomic flows using a common set of units. However, different emergy indices provide different insights, and not all are equally suitable for every situation. Using traditional emergy-based indices, an integrated environmental sustainability index (ESI), and two measures of emergy storage, we analyzed emergy flows and related indices for three typical human-influenced ecosystems: those of Macao, Italy, and Sweden. The performance of each ecosystem was compared using several emergy-based indices to assess their levels of sustainable development and demonstrate how different indices provide different insights. Based on the principle that equitability is an essential component of sustainability, we suggest that a positive and low net emergy ratio is desirable, since this means that the system does not capture excessive amounts of resources from external systems and thereby damage its external life-support systems.

Emergy evaluation of organic and conventional marine shrimp farms in Guaraíra Lagoon, Brazil

Organic products are often appreciated by the consumers as being more environmentally friendly and sustainable compared to their conventional counterparts. However, in the case of aquaculture, scientific information regarding environmental impacts and costs of conventional and organic farming systems is scarce. Scientific methods able to measure the sustainability of production systems are of great relevance to identify best management practices and ensure consumers the sustainability of the production process of aquaculture products. The objective of this study was to compare organic and conventional marine shrimp farms located in Guaraira Lagoon, Brazil, using emergy analysis. The principle of emergy analysis is to express all costs of a process or product in solar energy units (sej), making it possible to compare systems with different inputs, outputs and environmental impacts. Emergy accounting was used at this study to integrate ecological and human dimensions of conventional and organic marine shrimp farms systems located at Brazilian northeast in order to better discuss and understand the multiple dimensions of the sustainability in such systems. The results showed several emergy indicators in favor of organic farming system: the renewability indicator, the emergy yield ratio indicator and the emergy investment ratio indicator. Both systems (organic and conventional) showed large flows of concentrated non-renewable emergy. Further improvements of the organic system are needed to increase the efficiency and to ensure its economic sustainability.

An Evaluation of the Sustainability of Thermal Power Plants Based on Emergy and Exergy Theory

Emergy analysis and exergy analysis as scientific analysis are widely used to assess the development of industrial systems. This article attempts to combine the characteristics of emergy and exergy analysis in order to evaluate the sustainable development level of three thermal power plants. It establishes an exergy/emergy indicator to amend the system yield ratio, while introducing emergy waste ratio and economic indicators to calculate the economic, environmental, and social benefits of thermal power plants. The results of the three plants' sustainability evaluation show that the revised indicators are suitable for evaluating the sustainable development of the thermal power plant.