Emergy Yield Ratio Research Articles

Quantifying the environmental support to wild catch Alaskan sockeye salmon and farmed Norwegian Atlantic Salmon: An emergy approach

Understanding the relative contributions of the environment to commercial fisheries and aquaculture systems is an area of intense importance as it quantifies the dependence these human dominated systems have on healthy and productive ecosystems. Measures of sustainability are required that include environmental support, use of nonrenewable resources, and labor & services. This work draws on primary and secondary data used in an emergy analysis approach to assess environmental support and sustainability of a wild catch sockeye salmon fishery in Bristol Bay, Alaska and Atlantic salmon aquaculture in Norway. The analyses ended at the processing gate for both production systems. Environmental support of the sockeye fishery amounted to 69% of total inputs for landed fish and 37% for processed fish, while the environmental support for farm raised Atlantic salmon was 60% and 42% for landed and processed fish respectively. Labor and services contributed 53% of total inputs for processed sockeye and 44% for Atlantic salmon. The emergy indices for the wild caught sockeye and farmed Atlantic salmon systems were relatively high having emergy yield ratios for landed fish of 3.2 (wild caught sockeye) and 2.3 (farmed Atlantic salmon). After processing emergy yields of both systems were 1.6 (sockeye) and 1.7 (Atlantic salmon). Environmental loading ratios for the sockeye fishery were 0.45 and 1.69 for landed salmon and processed fish respectively, while for Atlantic salmon they were 0.76 and 1.40 for harvested and processed fish respectively. Emergy sustainability indexes (ESI) for both production systems were much higher than other aquaculture systems. Landed sockeye salmon had an ESI of 7.2, while that of farmed raised Atlantic salmon was 3.0, somewhat lower, but still a relatively sustainable source of high-quality protein.

Precision Feeding in Ecological Pig-Raising Systems with Maize Silage.

Simple SummaryGenerally, ecological farming is regarded as an environmentally friendly production process with high costs. The plant fiber source (e.g., maize silage) has become a common practice to reduce the cost during the fattening period to gain more profit, which means a precision feed component is needed in ecological pig-raising systems (EPRS) for achieving the balance between environment and economic profit. This manuscript provided a suitable and easy-operated ratio of sun-dried maize silage added to the feed. Meanwhile, we tried to reveal the trends of the pig growth, environmental impacts, and economic profits with the sun-dried maize silage percentage and raising period increasing. Results showed that the best balance point between environmental impact and economic performance was 20% sun-dried maize silage added to the feed with a 360-day raising period.Ecological pig-raising systems (EPRSs) differ from conventional breeding systems, focusing more on environmental consequences, human health, and food safety during production processes. Thus productions from EPRSs have undergone significant development in China. Thus far, adding plant fiber sources (e.g., sweet potato leaves, maize or wheat straw, potato, alfalfa, and vinasse) to feed has become a common practice to reduce the cost during the fattening period. Under such a context, it is necessary to choose the precision EPRS diet components and fattening period with low environmental consequences and high economic benefits. This study set up a database via pig growth models to predict environmental and economic performance based on two trials with 0%, 10%, 40%, 60%, and 80% maize silage (dry weight) added to the feed. A continuous curve about plant fiber concentration was built through the generated database. Our results showed that, with increased plant fiber concentration, the environmental performance of the EPRSs exhibited an “increase-decrease-increase” trend, and the economic performance firstly increased and then decreased. The best maize silage added percentages of emergy yield ratio (EYR), environmental loading ratio (ELR), unit emergy value (UEV), and emergy sustainability index (ESI), and the economic profits were 19.0%, 34.3%, 24.6%, 19.9%, and 18.0%, respectively. Besides, the 19.9% sun-dried maize silage added to the feed with a 360-day raising period had the best balance for environmental impact and economic performance. At the balance point, the performances of EYR, ELR, UEV, ESI, and the economic profit were only 0.04%, 3.0%, 0.8%, 0.0%, and 0.1%, respectively, lower than their maximum values. Therefore, we recommended the feed added 20% sun-dried maize silage is suitable for practical pig raising systems.

Sustainability Analysis of a Municipal Wastewater Treatment Plant through Emergy Evaluation

Water and wastewater treatment plants are essential for the supply of drinking water for consumption and the treatment of effluents produced by human/industrial activities. However, few studies deal with the investments and sustainability of these services, which consider both the contribution of nature and society. This study uses the emergy approach to evaluate a wastewater treatment plant located in the northeastern part of Romania, in Iași city. An assessment of the environmental costs of natural fluxes required for the treatment processes was performed, considering that the treated effluent is, still, loaded with contaminants that have to be absorbed by the receiving water natural system. The work done by nature to assimilate this load, generally considered free, is esteemed as a further cost in the total emergy budget of the wastewater treatment processes. The sustainability perspective was approached by calculating and analyzing the emergy yield ratio (EYR), environmental load rate (ELR), and emergy sustainability development index (ESI). The use of local renewable natural resources in Iași municipal wastewater treatment plants is negligible (1.71% of the total plant emergy budget), as compared to that of the purchased resources (98.29% of the total plant emergy budget) mainly processed with the support of fossil fuels’ generated energy. The unit emegy value was, also, calculated and compared to other studies relevant for wastewater treatment plants. The analysis suggests that the large amount of emergy that wastewater contains is proportional to the number of resources employed for wastewater treatment and the extensive effects on surrounding ecosystems, where wastewater is discharged.

Sustainability Assessment of Family Agricultural Properties: The Importance of Homeopathy

Family farming is a lifestyle and agricultural base that has ensured food for the world’s growing population in addition to the family’s own subsistence. However, the intensification of production processes to primarily generate exportable surpluses is based on the constant input of industrial inputs of low local socioeconomic viability. This study aims to evaluate the sustainability of family farms and their impact on the adoption of homeopathy instead of traditional/conventional intensification techniques. The study was conducted at six family farms located in the Serrana Mesoregion, Santa Catarina, Brazil, and include farms were classified according to the management and representativeness of their agricultural activity, i.e., conventional grains-cattle, milk-grains, grains and diversified, and according to their ecological basis, i.e., agroecological and organic. To discuss the sustainability of the family farms that were evaluated, the of metrics emergy synthesis, ecotoxicity potential and socioeconomic indicators are used. The results indicate that conventional diversified property has the best overall performance with regard to sustainability, including emergy yield ratio (EYR 1.88), emergy investment ratio (EIR 1.13), return on assets (1.22), hourly income of work (36.6 BRL/h) and income sufficiency (3.3). Agroecological and organic properties have better performance in renewability (76% and 75%), environmental load (ELR = 0.32 and 0.34), sustainability (ESI = 4.78 and 3.5) and potential ecotoxicity (1.736 and 1.579 kg 1.4 DCB-eq/ha). The contribution of homeopathy in an alternative scenario results in a 19% reduction in nonrenewable flows in conventional management properties and a decrease of up to 91% in ecotoxicity in grain + cattle properties. Using homeopathy, the return on assets and profit margin can be increased by up to 43% and income per hour of work and income sufficiency can be increased by 20% and 16%, respectively. This study contributes to discussions about the importance of using homeopathic therapies as a viable strategy that can be used in strategic public policy plans to improve the sustainability of family farms.

Sustainability assessment in the anthropocentric watershed based on emergy and decomposition methods: A case study of Erhai Lake Basin, southwest China

Assessment of anthropocentric watersheds’ sustainability and its driving forces is important for regional natural resources management and sustainable development. However, the impact of natural resources use on watersheds’ sustainability needs deeper exploration. This study employs emergy accounting and decomposition analysis methods to evaluate the sustainability and related key factors of Erhai Lake Basin (ELB) of Yunnan province in China -- a watershed facing urgently sustainable issues. Major results show that the environmental sustainability index (ESI) of ELB decreased with low production efficiency -- emergy yield ratio (EYR), and high environmental pressure -- environmental loading ratio (ELR) from 2000 to 2015. Four factors within the decomposition analysis have been identified, namely the emergy intensity factor (ΔUG), resource factor (ΔRF), water supporting factor (ΔWN) and water efficiency factor (ΔPW), as the major drivers of ESI changes. The economic development in ELB highly exceeded the carrying capacity of natural water resources, relying on imported resources and, in so doing, affecting sustainability levels. Accordingly, several suggestions are proposed which are helpful for sustainable watersheds governance.

Sustainability Evaluation of Immobilized Acid-Adapted Microalgal Technology in Acid Mine Drainage Remediation following Emergy and Carbon Footprint Analysis.

Sustainability evaluation of wastewater treatment helps to reduce greenhouse gas emissions, as it emphasizes the development of green technologies and optimum resource use rather than the end-of-pipe treatment. The conventional approaches for treating acid mine drainages (AMDs) are efficient; however, they need enormous amounts of energy, making them less sustainable and causing greater environmental concern. We recently demonstrated the potential of immobilized acid-adapted microalgal technology for AMD remediation. Here, this novel approach has been evaluated following emergy and carbon footprint analysis for its sustainability in AMD treatment. Our results showed that imported energy inputs contributed significantly (>90%) to the overall emergy and were much lower than in passive and active treatment systems. The microalgal treatment required 2–15 times more renewable inputs than the other two treatment systems. Additionally, the emergy indices indicated higher environmental loading ratio and lower per cent renewability, suggesting the need for adequate renewable inputs in the immobilized microalgal system. The emergy yield ratio for biodiesel production from the microalgal biomass after AMD treatment was >1.0, which indicates a better emergy return on total emergy spent. Based on greenhouse gas emissions, carbon footprint analysis (CFA), was performed using default emission factors, in accordance with the IPCC standards and the National Greenhouse Energy Reporting (NGER) program of Australia. Interestingly, CFA of acid-adapted microalgal technology revealed significant greenhouse gas emissions due to usage of various construction materials as per IPCC, while SCOPE 2 emissions from purchased electricity were evident as per NGER. Our findings indicate that the immobilized microalgal technology is highly sustainable in AMD treatment, and its potential could be realized further by including solar energy into the overall treatment system.

Assessing the sustainability of ecosystems over fourteen years of cultivation in Longnan City of China based on emergy analysis method

Currently, the contradiction between the limited resources of China's cultivated ecosystems and population growth is becoming increasingly evident, and the negative impacts on the environment and human activities need to be curbed. Therefore, it is crucial to quantify the sustainability of cultivated ecosystems and determine these driving factors that affect their development. This study used the emergy method to quantify the input/output flow and sustainable development of the cultivated land ecosystem in Longnan City, combined with the logarithmic mean divisia index decomposition analysis (LMDI) method to evaluate the driving factors of sustainable development in the region. The results demonstrate that from 2004 to 2017, the total emergy input and output of Longnan City showed an upward trend, and non-renewable resources (N) were always in a dominant state in the total emergy (T) input, and their proportion rose from 59.69% to 66.92%. The emergy sustainability index (ESI) is less than 1, and the environmental pressure of the system is relatively higher. Comprehensive emergy production ratio (EPR), emergy investment ratio (EIR), the renewable fraction (R%), emergy yield ratio (EYR) and environmental load ratio (ELR), showed that the agricultural ecological economy in Longnan still has great development potential, and clean energy should be developed as far as possible to replace fossil fuels in future planning. LMDI results showed that the intensity factor ΔY′A is the main driving factor for the positive development of ESI. The government's ecological protection requirements can reduce waste emissions through reasonable farming system and advocating the use of organic fertilizer, so as to achieve the purpose of improving crop yield. Vigorous development of green ecological agricultural production patterns can improve the sustainability of arable ecosystems. This study can provide a theoretical basis for the sustainable development of cultivated ecosystems and the formulation of related agricultural production measures.

Emergy-based comparative analysis of an ecological economy in the Yangtze River Delta

The Yangtze River Delta (YRD) has abundant regional advantages. Its rapid economic development plays an essential strategic role in China's overall growth; however, this place significantly pressurized on resources and the environment. Accordingly, this study developed an evaluation index and system of sustainable development for a green economic system based on the emergy theory. Moreover, comparative analyses were made according to the present ecological–socioeconomic systems of the YRD. The results indicated a large gap between the production efficiencies of the three provinces and a single city in the YRD. The highest emergy yield ratio was in Anhui Province, but the corresponding emergy yield per capita and emergy output density was the lowest; the environmental load ratios were all > 10, which is considered a high load; the sustainable development indices were all < 1, which represents a state of unsustainable development. According to the present research results, suggestions for the sustainable development of the YRD were put forth here. This research provides theoretical and methodological support for the sustainable development of an ecological economy in the YRD. It can serve as a decision-making reference for China to achieve the goal of carbon peak and carbon neutralization.

The effect of farm size on the sustainability of wheat production using emergy approach

The effect of three farm areas, including small, medium, and large, on the sustainability of wheat production was studied using the emergy technique in 2018–19 in Jovein, Iran. By increasing the size of the farm, the share of renewable natural resources decreased and the share of purchased resources increased. The total emergy supporting small, medium, and large farms, was 1.39 × 1016, 1.95 × 1016, and 2.16 × 1016 sej ha−1 yr−1, respectively. In small farms, the share of renewable natural inputs, non-renewable natural inputs, and purchased inputs of total input emergy were 55.6 × 1013, 63.01 × 1014, and 70.30 × 1014 sej ha−1 yr−1, respectively. However, the share of renewable natural inputs, non-renewable natural inputs, and purchased inputs on large farms were 50.9 × 1013, 11.38 × 1016, and 98.03 × 1015 sej ha−1 yr−1, respectively. As the farm size increased from small to large, the emergy yield ratio and emergy investment ratio increased by 11.11% and 101%, respectively, while the unit emergy value, renewable emergy ratio, emergy investment ratio, and environmental sustainability index decreased by 27.31, 50.61, 45.45, and 18.65%, respectively. According to the results, although cultivation in large farms uses less renewable environmental resources and more purchased resources, a higher yield is produced per unit area.

Evaluation of suppliers in the tannery industry based on emergy accounting analysis: implications for resource conservation in emerging economies

ABSTRACT Emergy Accounting (EMA) has gained attention in recent times as an environmental accounting tool. So far, it has been used for analysis at national and regional levels; however, the EMA has not been utilised in a business performance analysis context. When used in a business context, EMA reveals the interface between industrial activity and the environment. EMA analysis can provide opportunities in measuring the social, economic, and environmental performance of the industry in a sustainability context. Unlike other evaluation methods, which are ‘demand-side’ or ‘user-side’ concerned, EMA analysis is a ‘donor-side’ approach. This research work illustrates the selection of suppliers based on the amount of emergy consumption. Emergy indicators, such as Emergy Yield Ratio (EYR), Emergy Sustainability Index (ESI), Environmental Loading Ratio (ELR), Emergy Self-support Ratio (ESR), Renewability percent (%R), Emergy flow Density (ED), and Emergy Investment Ratio (EIR) are estimated. The results show that there is enough room for improving emergy performance in the tannery industry. The result also highlights a significant variance in the input of indigenous renewable and non-renewable resources and imported resources among the investigated tanneries. Based on the outcomes, the study provides insights on the industries’ consumption of renewable and non-renewable resources.

Livelihood consequences of the Grain for Green Programme across regional and household scales: A case study in the Loess Plateau

In 2018, the Chinese government issued a “Work Plan of Eco-poverty Alleviation” aimed at reducing rural poverty by implementing a new round of ecological construction programmes. The Grain for Green Programme (GGP), one of the largest ecological construction programmes in the world, is reconsidered and included in the tasks of the work plan. However, the first round of the GGP has controversial effects on rural livelihood and remains to be further investigated. This study focuses on a farm-pastoral county in the Loess Plateau to explore the impacts of the GGP on rural livelihood consequences across regional and household scales based on the Difference-in-Differences (DID) model and the emergy analysis method. The results indicate that the GGP has negative effects on rural livelihood outcomes in Jungar Banner, especially in the farmland-retiring period. On the regional scale, the GGP actually reduced rural households’ net income and livelihood diversity due to the substantial decrease in graziery income and insufficient compensation, the industrial failure of economic forest schemes, and invalid labour training. On the household scale, the smallholder agro-pastoral system transitioned from an extreme dependence on the environment to another extreme prohibition against grassland grazing. Although the GGP alleviated the environment load ratio, it lowered the emergy yield ratios and undermined the sustainability of the smallholder agro-pastoral system. The failure of the GGP to improve rural livelihoods is deeply rooted in policy that still puts ecological goals ahead of economic goals and thereby hinders rural households’ access to land resources. This study indicates that the government should be cautious about the policy expectations of eco-poverty alleviation and, in future ecological construction, must activate farmers' land use and balance both the economic effectiveness and ecological friendliness.

Study on the Choice of Wastewater Treatment Process Based on the Emergy Theory

With the increase in industrialization and urbanization, water pollution has become increasingly serious, and wastewater treatment has become a common step in preventing this. For a greater understanding of the sustainability of different wastewater treatment systems, two processes, Anaerobic Baffled Reactor + Anaerobic-Anoxic-Oxic and Anaerobic Baffled Reactor + Cyclic Activated Sludge System, were selected, and their sustainability was evaluated based on three indicators, namely emergy yield ratio, environmental load rate, and emergy sustainability development index, according to emergy theory. The results show that the emergy yield ratio and environmental load rate of the ABR + CASS process were lower than those of the ABR + A2/O process, and the emergy sustainability development index of the ABR + CASS process was higher than that of the ABR + A2/O process, showing better sustainability. The research methods and findings of this study play an important role for decision makers in selecting sustainable wastewater treatment processes.

Integrated Energy System Planning Based on Life Cycle and Emergy Theory

Integrated energy system (IES) is of great significance in the construction of the modern energy system. Reasonable planning is one of the important means to improve the economy of the IES and promote the consumption of renewable energy. However, the complex coupling characteristics between energy sources make it difficult to quantify the production efficiency of multi-energy heterogeneous resources uniformly in the economic benefit model during the planning cycle. Quantifying the production efficiency of the IES for planning is currently an urgent problem to be solved. This study proposes a planning method for the IES based on the life cycle and emergy theory. First, emergy theory is applied to quantify the production efficiency of the IES. A complete economic benefit model is established based on life cycle theory. Second, a bi-level planning model of the IES is established. The upper-level model aims at minimizing the whole life cycle cost of the IES to plan the capacity and location of the coupling equipment. The lower-level model aims at maximizing the emergy yield ratio of the IES to provide the operating data for the upper level. Finally, comparing experimental evaluations with traditional planning schemes considering annual average cost and energy quality coefficient, the method in this study reduces planning costs by 23.16% and increases the consumption rate of renewable energy by 4.26%. It can be seen that the planning method proposed in this study improves the planning economy and the level of renewable energy consumption of the IES.

The Environmental-Economic Performance of a Poblano Family Milpa System: An Emergy Evaluation

The family milpa system (FMS) is of great importance to food security and the livelihoods of rural families in Mexico. However, the performance of the system can be compromised due to inappropriate agricultural practices. Therefore, a suitable evaluation strategy is required to identify the best management of resources. Nonetheless, at present, there is no holistic understanding around the nature–society interface that allows us to predict the global behavior of the FMS. Thus, this study assesses the global performance of a Poblano FMS through emergy-based indices. The emergy evaluation was carried out by accounting for the available energy of different qualities used in the system, which were subsequently converted to one kind of energy (solar emjoules). The percentage of renewable emergy (%Ren) used in the system was 72.16%. The emergy self-support ratio (ESR) showed that 74% of the emergy used came from free local resources. The emergy investment ratio (EIR) of 0.36 indicated that the emergy use was efficient. The emergy yield ratio (EYR) was 3.78, which in terms of net emergy (NE), was equivalent to a gain of 1.35 × 1016 sej ha−1 y−1. The environmental loading ratio (ELR) was 0.39, which indicated a low potential environmental impact. The emergy sustainability index (ESI) was high (9.80) compared to other agricultural systems. The performance of the FMS is superior compared to other agricultural systems, including ecologic and recycling systems. However, the use of resources is not optimum and needs to be improved to reach maximum empower.

An integrated approach to analyzing the effect of biofloc and probiotic technologies on sustainability and food safety in shrimp farming systems

Aquaculture is essential to meet the demand for seafood due to the decrease in fish stocks caused by predatory fishing. Even though aquaculture is a sustainable seafood option, shrimp farming is often associated with eutrophication, mangrove destruction, disease propagation, and biodiversity reduction in coastal regions. These environmental problems generate financial losses, and to minimize the impacts on shrimp farms, producers use bioflocs technology and commercial probiotics to improve water quality and be more productive. This study uses emergy and microbiology analyses to estimate the improvement of microorganisms on the sustainability and food safety indicators of three commercial farms that use probiotic and bioflocs technology to produce shrimp. The first farm had 385 ha, a conventional system, stocked 10 shrimp/m2 and used probiotics. It had the best transformity (Tr = 10.6) and emergy yield ratio (EYR = 1.94) but the worst food safety indices for water and shrimp. The second farm also had a conventional system and used probiotics, but its area was 1.9 ha and with a stocking density of 56 shrimps/m2. It had the highest environmental load ratio (ELR = 28.17), but shrimp and water had better food safety indices than other farms. These two farms would have worse sustainability and food safety indices without the benefit of microorganisms. The third farm had 0.3 ha, a system with biofloc technology, and produced 400 shrimp/m2. It had the best renewability (R% = 14.79), environmental load ratio (ELR = 5.76), and emergy sustainability index (ESI = 0.20). Water and shrimp were within acceptable limits of microorganisms, and the type of biotechnology used contributed to different qualities of the final product. The microorganisms from biofloc technology and probiotics improve the sustainability and food safety indicators on aquaculture, but the absence of other sustainable practices limits these benefits.

Emergy-based method for evaluating and reducing the environmental impact of stamping systems

The stamping industry is critical in the automotive and aerospace industries, and the environmental impacts and sustainability of stamping systems have attracted considerable attention. To analyze the environmental impact and sustainability of stamping systems quantitatively, this paper presents an emergy-based evaluation method considering all the associated environmental impact factors of a pressing workshop including material and energy consumption, waste flows, time and mass losses, and processing costs. On the basis of analyzing the stamping processes and sustainability, this method comprises data collection, emergy based sustainability evaluation model and the development of sustainable evaluation indexes and systems. Based on the proposed method, the environmental impact of an industrial vehicle stamping workshop was evaluated. The results show that the net emergy yield ratio of the stamping system was greater than 2, and the waste emergy output ratio was very low, indicating that the system had high productivity levels, high yields, and low pollution discharge rates. However, its sustainability index was less than one owing to its high energy and material consumption during the production processes. To reduce the environmental impact of this stamping system and improve its sustainability, we investigated the potential improvements that could be achieved in energy consumption, productivity, and environmental impact by implementing energy-saving scheduling in the stamping workshop. The results show that the corresponding net emergy yield ratio and sustainability index of the system were both improved. The proposed emergy-based method could be used to quantitatively evaluate the environmental impacts and sustainability of stamping systems and facilitate efforts to reduce the environmental impacts of pressing workshops while improving their productivity and economic profitability.

Emergy-based environmental impact evaluation and modeling of selective laser melting

Additive manufacturing (AM) technologies, such as direct laser and selective laser melting (SLM) manufacturing, allow the fabrication of functional products with high added value. This paper proposes an emergy-based method for evaluating the environmental impact and economic cost of the SLM manufacturing process while considering the environmental flows (materials, energy, and wastes) and economic factors (time, costs, and quality). By analyzing the emergy flows in an SLM system, sustainable evaluation indexes are developed to estimate its sustainability level. Then, the method is applied to analyze the environmental impact and economic cost of the SLM of a part. The results show that the cost of the process for a single part is high, the net emergy yield ratio of the SLM system is low, and its environmental load rate is very high. The sustainability indexes of the system indicated a high environmental impact and low production efficiency. However, the waste emergy output ratio of the system was very low, which reflected the near-net-shape characteristics of SLM, indicating a high sustainability potential. The results of this study are expected to contribute to increased sustainability and optimization of SLM.

Rice-crayfish systems are not a panacea for sustaining cleaner food production.

Integrated rice-crayfish systems are expanding rapidly and are the most widely applied planting-breeding modes in Jianghan Plain in China. We conducted nutrient use efficiency, economic, and emergy analysis of three rice production modes, namely, rice monoculture (RM), rice-crayfish rotation (RCR), and rice-crayfish coculture (RCC), in Jingzhou City, which is located in the Jianghan Plain. Compared with RM mode, rice-crayfish systems using the RCR and RCC modes increased rice yield by 5-7%, showed more than 8% higher chemical nutrient use efficiency, and increased the value-to-cost ratio from 1.5-fold to 2.7-fold and the benefit-cost ratio from 2.5-fold to 3.8-fold, while decreasing irrigation water consumption and land occupation by 31% and 82-86%, respectively. RCC resulted in 10% higher crayfish yield, 12% higher phosphorus use efficiency, and 38% higher feed use efficiency than RCR. However, compared with RM, rice-crayfish systems decreased renewable fraction by 10-14%, emergy yield ratio by 9%, and emergy sustainability index by 23-26%, and they increased environmental loading ratio to 18-23%. Labor and service, fertilizer utilization, and machine and tools play important roles in these negative environmental effects. Scenario analysis showed that the rice-crayfish systems increased sustainability index by 38-45%. The technical training of new planting-breeding technology should be adopted by farmers for the efficient use of fertilizers and improvement of food yield. This study suggests that rice‑crayfish systems are not a panacea to sustain cleaner food production.

Co-Benefits Analysis of Buildings Based on Different Renewal Strategies: The Emergy-Lca Approach.

Many cities have encountered challenges associated with rapid urban development, population growth and aging, in which urban renewal has become a promising option. Different renewal strategies, such as redevelopment, refurbishment and conservation, not only contributes to quality improvement and energy consumption reduction of dilapidated urban area, but also to greenhouse gas (GHG) emissions mitigation. Such integrated benefits are often termed as co-benefits. However, choosing the most co-benefits strategy to adopt requires a holistic understanding of social-economic and environmental aspects, which has been less reported in the existing literature. Under such circumstance, this article aims to shed light on the co-benefits of different renewal strategies by adopting the Emergy-Life cycle assessment method. Then, the method is applied to one case study of the refurbishment of an educational building located in Chongqing, China. Resource allocation, CO2 emissions and emergy-based indicators are calculated to assess the co-benefits during a 60-year research period, to compare the impacts of the complete demolition followed by a new one (rebuilding strategy) and the refurbishing of the existing building (refurbishment strategy). The case study shows that the annual emergy in the O&M phase of rebuilding strategy and refurbishment strategy were lower than existing building. Rebuilding and refurbishment strategies released approximately 59.1% and 80.6%, respectively, of the total CO2 emissions that would be produced by the existing building. The results reveal that substantial environmental benefits can be obtained in both the refurbishment and rebuilding strategies. On the other hand, it can be concluded that the emergy yield ratio (EYR) for the rebuilding strategy is higher than refurbishment strategy, which demonstrate the better performance of refurbishment considering that less resources are required to generate greater benefits. In addition, the value of environmental loading ratio (ELR) and emergy sustainability index (ESI) also suggests that the refurbishment strategy performs better from the perspective of the environment. Thereby, the refurbishment strategy is more suitable than the rebuilding strategy. Findings from this study can be useful to urban planners and decision-makers in choosing the most suitable strategy to improve the quality of existing buildings.

A survey on the ecological sustainability of introducing new crops in the cropping pattern using emergy approach

The sustainability of production of four widely grown crops, including wheat and barley (as preceding crops in the cropping pattern) vs. sugar beet and saffron (as introduced crops in cropping pattern) were compared using emergy approach in Khoushab County, Khorasan Razavi province, Iran. The results showed that the total emergy consumption of the introduced crops was higher than that of preceding crops. The total supporting emergy for wheat, barley, sugar beet and saffron was respectively 2.32E+16, 1.91E+16, 4.95E+16, and 2.04E+16 sej ha−1. The greatest portion of renewable environmental resources were obtained in sugar beet production systems (4.1% of total emergy), and non-renewable environmental resources occurred in barley production systems (55.7% of total emergy). Saffron production systems showed the greatest portion of renewable purchased resources (40.8% of total emergy) and non-renewable purchased resources (36.48% of total emergy). Introduction of saffron and sugar beet as new crops in a given region, compared to wheat and barley as preceding crops in the cropping pattern, caused enhancement in renewable emergy ratio, environmental loading ratio, environmental sustainability index, and emergy input ratio, while decreased emergy yield ratio, environmental sustainability index, and sustainable development emergy index. Saffron and sugar beet production as new introduced crops to the region resulted in the highest environmental sustainability index. Although the environmental loading ratio index of saffron cultivation was higher than other production systems, modified environmental loading ratio was lower than the three other production systems. Therefore, saffron can be recommended as a sustainable crop that has put the lowest pressure on environmental resources. In this study, the results of emergy analysis and calculation of economic indicators, indicated the greater sustainability and economic benefit of the saffron production system compared to the other three systems.