Improvements to Emergy evaluations by using Life Cycle Assessment

Complementing emergy evaluation and life cycle assessment for enlightening the environmental benefits of using engineered timber in the building sector

Engineered timber can represent a great opportunity to mitigate the large impacts due to the global building sector. However, the most applied environmental assessment methodologies such a life cycle assessment (LCA) might show limited advantages when comparing the impact on climate change of buildings made of traditional materials, such as concrete and steel, and building based on engineered timber. This work proposes emergy evaluation (EME) as a complementary environmental assessment methodology. By expanding the boundaries of the assessment, EME captures input flows and related features, especially in terms of renewability, that are overlooked in LCA. LCA and EME were applied to two identically modeled buildings composed of either only traditional materials or engineered timber as their replacement. EME reveals the higher sustainability level of engineered timber compared to traditional materials in the building sector, capturing larger environmental benefits compared to LCA. Ultimately, the robustness of the results is tested through a comparative sensitivity analysis performed for three geographic scenarios, different energy use scenarios, and different transport distances.

Evaluation of resources and environmental carrying capacity of marine ranching in China: An integrated life cycle assessment-emergy analysis

Resources and environmental carrying capacity (RECC) describes the ability of a system to achieve healthy and sustainable development. Various marine ranching enterprises have emerged in China in recent years, which have aroused concern and debate about the RECC of marine ranching systems. By taking the environmental impact calculated by life cycle assessment (LCA) into consideration in emergy analysis (EA), this study evaluated the comprehensive RECC performance of the whole system and each stage of a marine ranching system in China. The resource use efficiency (RUE) and system carrying ratio (SCR) of the system were reasonably good. However, its environmental loading ratio (ELR), emergy yield ratio (EYR), and emergy sustainability index (ESI) were unsatisfactory. First, the nonrenewable resources dominated the emergy input. Second, the emergy input from the purchased resources was much greater than that of local resources. Third, the potential environmental impact mainly came from the construction stage. Fourth, serious overload of RECC was observed in the maintenance stage. The results indicate that the system is efficient, and its RECC is in a safe state, but the system has deficiencies in environmental protection and the exploitation and utilization of local resources. The proposed analysis framework helps us comprehensively understand the marine ranching RECC performance and provides a research paradigm reference for the sustainability analysis of other complex eco-economic systems.

Environmental, energy, and economic impact assessment of sludge management alternatives based on incineration

In this study, different management strategies for sewage sludge disposal were evaluated associated with environmental, energy, and economic impact, using life cycle assessment (LCA), cumulative energy demand (CED) and life cycle costing (LCC) approaches. Four scenarios, including mono-incineration, co-incineration in municipal solid wastes (MSW) incineration plant, co-incineration in coal-fired power plant and co-incineration in cement kiln, were assessed. The environmental burdens generated from the sludge incineration contributed primarily to the global warming, followed by eutrophication, marine aquatic ecotoxicity, and human toxicity potential across the four scenarios. Furthermore, mono-incineration scenario appeared to be the most environmentally unfriendly, energy and economy intensive alternative, with the LCA, CED and LCC value of 5.41E-09, 1736 MJ and 1.84 million CNY, respectively. By contrast, co-incineration in cement kiln exhibited the lowest CED (368 MJ), LCC (0.59 million CNY), and environmental burdens (1.02E-09). In addition, the sensitivity analysis indicated that four scenarios were sensitive to the changes in the electricity efficiency and the moisture content contained in sewage sludge, suggesting that it was of great significance to enhance the efficiency of sludge dewatering and thermal drying The findings of this study can provide scientific reference for selecting the optimal strategies for the most environmentally and economically friendly sewage sludge management with optimum energy efficiency.

Evaluating the Technical and Environmental Capabilities of Geothermal Systems through Life Cycle Assessment

In these days of heightened environmental consciousness, many countries are shifting their focus towards renewable energy sources for both large-scale uses (such as power plants that generate electricity) and smaller-scale applications (e.g., building heating and cooling). In this light, it is not surprising that there is a growing interest in technologies that are reliant on non-conventional sources of power, such as geothermal energy. This study is making an effort to provide a comprehensive understanding of the possible advantages and multiple uses of geothermal energy systems, in the context of their technical and environmental evaluation through Life Cycle Assessment. A brief description of the analyzing methods and the tools used to study a particular system or application is presented. The geothermal technologies and the applications of specific systems are discussed in detail, providing their environmental advantages and their technical barriers as well. District and domestic heating systems cover a significant fraction of the geothermal energy potential. The majority of the discussed studies cover the electricity production as the most important application of geothermal energy. The overall conclusion of the current work is that geothermal energy is an extremely viable alternative that, combined with other renewable energy systems, may mitigate the negative effects of the existing energy mix worldwide.

Prioritizing Cleaner Production Actions towards Circularity: Combining LCA and Emergy in the PET Production Chain

Petrochemicals, which convert oil and gas into products such as plastics, are fundamental to modern societies. Chemists recognize their role in designing materials and the adverse effects that these may have on the environment, preventing sustainable development. Several methodological frameworks and sustainability assessment approaches have been developed to evaluate the resources used in the petrochemical sector in terms of environmental costs. Still, there is a need to evaluate these systems in terms of environmental costs deeply. A combination of life cycle assessment and emergy accounting—to assess the environmental support for resource use—is applied in this study of the PET production chain in Europe. The unit emergy values of several intermediates are calculated or updated to facilitate the discernment of the quality of energy used and the processes’ efficiency. Several routes for synthesizing renewable para-xylene and ethylene glycol from biomass are discussed and confronted with the efforts focused on recycling and recovering the final product, providing concurrently a procedure and a valuable data set for future CP actions. The results show that understanding the efficiencies changing across the production chain may help stakeholders decide where and when interventions to promote a circular economy are most effective along a petrochemical production chain.

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.

Energy, Exergy, Exergoeconomic and Emergy-Based Exergoeconomic (Emergoeconomic) Analyses of a Biomass Combustion Waste Heat Recovery Organic Rankine Cycle

In recent decades, there has been an increasing trend toward the technical development of efficient energy system assessment tools owing to the growing energy demand and subsequent greenhouse gas emissions. Accordingly, in this paper, a comprehensive emergy-based exergoeconomic (emergoeconomic) method has been developed to study the biomass combustion waste heat recovery organic Rankine cycle (BCWHR-ORC), taking into account thermodynamics, economics, and sustainability aspects. To this end, the system was formulated in Engineering Equation Solver (EES) software, and then the exergy, exergoeconomic, and emergoeconomic analyses were conducted accordingly. The exergy analysis results revealed that the evaporator unit with 55.05 kilowatts and the turbine with 89.57% had the highest exergy destruction rate and exergy efficiency, respectively. Based on the exergoeconomic analysis, the cost per exergy unit (c), and the cost rate (C˙) of the output power of the system were calculated to be 24.13 USD/GJ and 14.19 USD/h, respectively. Next, by applying the emergoeconomic approach, the monetary emergy content of the system components and the flows were calculated to evaluate the system’s sustainability. Accordingly, the turbine was found to have the highest monetary emergy rate of capital investment, equal to 5.43×1012 sej/h, and an output power monetary emergy of 4.77×104 sej/J. Finally, a sensitivity analysis was performed to investigate the system’s overall performance characteristics from an exergoeconomic perspective, regarding the changes in the transformation coefficients (specific monetary emergy).

Emergy as a Tool to Evaluate Ecosystem Services: A Systematic Review of the Literature

The objective of this paper is to present a review of current research on the valuation of ecosystem services, using emergy evaluation methodology (EME). A bibliometric analysis and a systematic review were carried out between 2000 and 2020, using all of Web of Science database subfields that collected 187 papers, selected through the keywords “emergy” and “ecosystem services”. In the second part of the research, we carried out a new search on Web of Science of the 187 initial articles produced, with the words “valuation” and “economic”, in order to analyze those directly related to the evaluation of ecosystem services. The results showed that the EME method is an effective tool to evaluate ecosystem services, since it relates economic and ecological aspects in the evaluations. The research also indicated that the use of isolated methods does not appear to be the most appropriate solution, and that emergy used in combination with other methodologies can be used to obtain more accurate and comprehensive results to evaluate natural resources.

The critical role of advanced sustainability assessment tools in enhancing the real-world application of biofuels

Sustainability has become of paramount importance in the biofuel industry. Accordingly, various ‎sustainability assessment schemes such as emergy analysis, techno-economic analysis, life ‎cycle ‎assessment, energy accounting, and exergy analysis and its extensions (exergoeconomic, ‎exergoenvironmental, and ‎exergoeconoenvironmental analyses) are being employed increasingly for decision-‎making on biofuel production and consumption systems. In this opinion paper, after classifying ‎and describing biofuel generations, the developed sustainability assessment tools are critically ‎explained, and their pros and cons are discussed. Overall, among the various sustainability assessment approaches introduced so far, exergy-based methods appear to be ‎the most promising tools for developing ‎sustainable biofuel systems. This can be attributed to the fact that the exergy ‎concept is deeply ‎rooted in the well-defined principles of thermodynamics.‎

Measuring the environmental performance of a circular system: Emergy and LCA approach on a recycle polystyrene system

The search for sustainability has pointed to the need to transition from a linear to a circular model. However, such a transition is not trivial. Modifying production chains with the focus on reducing virgin raw materials consumption, cut emissions, and prevent waste generation implies implementing new processes and services, which can add considerable environmental impacts to the supply chain. This paper analyzes a real case from a production system aligned with circular economy principles. The production system consists of the manufacturing of baseboards made of recycled Expanded Polystyrene (EPS), obtained from an extensive reverse logistics system composed of different recycling processes. The system's potential environmental impacts were assessed by two widely used methodologies, Life Cycle Assessment (LCA) and Emergy Analysis (EMA). For comparison purposes, the analysis was carried out for a fictional linear production system, in which the baseboard would be made of virgin EPS. EMA attributed a lower emergy load to the circular scenario compared to the linear scenario (8.62E+15 seJ to recycled EPS versus 1.26E+16 seJ to virgin EPS). LCA results indicate both scenarios as environmental preferable depending on the impact category under analysis (e.g. circular system has better performance regarding global warming, while the linear scenario demonstrated better results under water consumption). For the circular scenario, EMA identified the main impact drivers, such as transportation and electricity consumption. From LCA perspective impacts are also driven by electricity consumption. However, differently from EMA, logistics were only significant for Land Use impact category whereas Liquefied Petroleum Gas consumption and, landfill air emissions were identified as impact hotspots. These convergences and differences between the findings of LCA and EMA have demonstrated potentially complementation to broaden available information related to systems, enabling decision makers to act effectively in improving the environmental performance of their production processes, especially when implementing circular practices.

Review of Emergy Analysis and Life Cycle Assessment: Coupling Development Perspective

Two methods of natural ecosystem assessment—emergy analysis (EMA) and life cycle assessment (LCA)—are reviewed in this paper. Their advantages, disadvantages, and application areas are summarized, and the similarities and differences between these two evaluation methods are analyzed respectively. Their research progress is also sorted out. The study finds that EMA and LCA share common attributes in evaluation processes and research fields, but they focus on different aspects of macrocosms and microcosms. The assessment of system sustainability is valued by both EMA and LCA, but the former has unique advantages in natural system input analysis, and the latter is more convincing in assessing environmental loading capacity. If the system boundaries of the two methods are expanded, in other words, factors such as ecosystem services, labor, and infrastructure construction are integrated into the upstream of the target system, and environmental impact is further analyzed using LCA in the downstream of the system, the two approaches would complete each other. The quantified results would be more objective. Therefore, these two theories have the necessity of coupling development. After reviewing recent coupling application cases, the results show that LCA and EMA have commonality in the upstream of the target system (mainly in inventory database construction), while the environmental impact assessment methods are different in the downstream. So the overall coupling analysis method is not formed. The current paper gives rational suggestions on the coupling development of the two systems in terms of the aggregate emergy flow table, the indicator system construction and indicator evaluation methods. In addition, it is necessary to introduce sensitivity analysis and uncertainty analysis in order to improve the reliability of assessment results. At present, the research on the coupling development of the two theories is in rapid development stage, but there are still many problems that need further exploration.

Environmental and economic consequences analysis of cropping systems from fragmented to concentrated farmland in the North China Plain based on a joint use of life cycle assessment, emergy and economic analysis

The policy of land rental activity from fragmented to concentrated farmland has been overwhelming encouraged by the Chinese government. The land management policy has paid more attention on the investigation of its economic and social performances of land rental activity, while information on its environmental consequence is still lacking. This study, therefore, compared the environmental and economic performances of small (SF) and large scale (LF) farms based on emergy evaluation (EME), life cycle assessment (LCA) methods, and economic analysis (EA), which reflected a land rental activity from fragmented to concentrated farmland in the North China Plain (NCP). The EME results showed that the environmental loading ratio of the LF was 5.0% lower, while the emergy yield ratio and emergy sustainability index of the LF were 1.48% and 8.0% higher, respectively, than that of the SFs. The LCA results demonstrated that the area-based and yield-based environmental impact indices of the LF were 28.8% and 18.3% lower than that of the SF, respectively. These results indicate that the environmental consequences of the cropping system were improved when the farmland was managed in a concentrated model instead of a fragmented model. In addition, the EA results showed that the income to cost ratio of the LF was reduced by 47.46% compared to that of the SF, due to high land rental costs in the LF. Nevertheless, the total profit of the LF was 1719.3% higher than that of the SF due to its lager farm scale. Also, the owner's total profit of the SF was increased by 195.5% compared to the farming by themselves in their own farmland instead of renting them out. These results showed that scale management can promote both managers who rented out and into the farmland to increase their annual total incomes. In conclusion, the concentrated farmland would be a platform for the improvement of environmental consequences of cropping systems in the NCP.

Holistic Analysis of Urban Water Systems in the Greater Cincinnati Region: (2) Resource Use Profiles by Emergy Accounting Approach

With increasing populations, mounting environmental pressures and aging infrastructure, urban water and wastewater utilities have to make investment decisions limited by both economic and environmental constraints. The challenges facing urban water systems can no longer be sustainably solved by traditional siloed water management approaches. A central premise of contemporary urban water management paradigms is that in order for urban water systems to be more sustainable and economical, an improvement in resource use efficiency at system level must be achieved. This study provides a quantification of the total resource use of a typical urban water system exemplified in Greater Cincinnati region from raw water extraction for drinking water to wastewater treatment and discharge, providing a better understanding of resource expenditure distributions within the system and a necessary benchmark to which future system improvements can be compared. The emergy methodology was used so that the total environmental work required to produce disparate system inputs could be expressed using a common unit. The results were compared to the concurring life cycle assessment (LCA) and life cycle costing (LCC) results of the same system. Emergy results highlight drinking water treatment and drinking water distribution as two resource-intensive stages, with energy for pumping and chemicals for conditioning representing the greatest inputs to the former and energy for pumping and metals for piping representing the greatest inputs to the latter. For wastewater collection and treatment stages, aeration and sludge handling were identified as the highest emergy unit processes, mostly due to energy use. Comparison with LCA results substantiate the environmental concerns associated with energy use in the drinking water treatment and distribution stages but indicate that environmental burdens associated with infrastructure are more dependent upon upstream resource use rather than downstream environmental impact. Results from emergy, LCA and LCC point towards aeration and sludge handling as two unit processes on the wastewater side that are particularly costly and environmentally impactful. Results in total are used to suggest alternative strategies that can alleviate identified environmental burdens and economic costs.

Assessment of Life Cycle Impacts on Ecosystem Services: Promise, Problems, and Prospects

The analysis of ecosystem services (ES) is becoming a key-factor to implement policies on sustainable technologies. Accordingly, life cycle impact assessment (LCIA) methods are more and more oriented toward the development of harmonized characterization models to address impacts on ES. However, such efforts are relatively recent and have not reached full consensus yet. We investigate here on the transdisciplinary pillars related to the modeling of LCIA on ES by conducting a critical review and comparison of the state-of-the-art in both LCIA and ES domains. We observe that current LCIA practices to assess impacts on "ES provision" suffer from incompleteness in modeling the cause-effect chains; the multifunctionality of ecosystems is omitted; and the "flow" nature of ES is not considered. Furthermore, ES modeling in LCIA is limited by its static calculation framework, and the valuation of ES also experiences some limitations. The conceptualization of land use (changes) as the main impact driver on ES, and the corresponding approaches to retrieve characterization factors, eventually embody several methodological shortcomings, such as the lack of time-dependency and interrelationships between elements in the cause-effect chains. We conclude that future LCIA modeling of ES could benefit from the harmonization with existing integrated multiscale dynamic integrated approaches.

Emergy-based assessment on industrial symbiosis: a case of Shenyang Economic and Technological Development Zone

Industrial symbiosis is the sharing of services, utility, and by-product resources among industries. This is usually made in order to add value, reduce costs, and improve the environment, and therefore has been taken as an effective approach for developing an eco-industrial park, improving resource efficiency, and reducing pollutant emission. Most conventional evaluation approaches ignored the contribution of natural ecosystem to the development of industrial symbiosis and cannot reveal the interrelations between economic development and environmental protection, leading to a need of an innovative evaluation method. Under such a circumstance, we present an emergy analysis-based evaluation method by employing a case study at Shenyang Economic and Technological Development Zone (SETDZ). Specific emergy indicators on industrial symbiosis, including emergy savings and emdollar value of total emergy savings, were developed so that the holistic picture of industrial symbiosis can be presented. Research results show that nonrenewable inputs, imported resource inputs, and associated services could be saved by 89.3, 32.51, and 15.7 %, and the ratio of emergy savings to emergy of the total energy used would be about 25.58 %, and the ratio of the emdollar value of total emergy savings to the total gross regional product (GRP) of SETDZ would be 34.38 % through the implementation of industrial symbiosis. In general, research results indicate that industrial symbiosis could effectively reduce material and energy consumption and improve the overall eco-efficiency. Such a method can provide policy insights to industrial park managers so that they can raise appropriate strategies on developing eco-industrial parks. Useful strategies include identifying more potential industrial symbiosis opportunities, optimizing energy structure, increasing industrial efficiency, recovering local ecosystems, and improving public and industrial awareness of eco-industrial park policies.

Emergy evaluation using the calculation software SCALE: case study, added value and potential improvements

This paper reports the emergy-based evaluation (EME) of the ecological performance of four water treatment plants (WTPs) using three different approaches. The results obtained using the emergy calculation software SCALE (EMESCALE) are compared with those achieved through a conventional emergy evaluation procedure (EMECONV), as well as through the application of the Solar Energy Demand (SED) method. SCALE's results are based on a detailed representation of the chain of technological processes provided by the lifecycle inventory database ecoinvent®. They benefit from a higher level of details in the description of the technological network as compared to the ones calculated with a conventional EME and, unlike the SED results, are computed according to the emergy algebra rules. The analysis delves into the quantitative comparison of unit emergy values (UEVs) for individual technospheric inputs provided by each method, demonstrating the added value of SCALE to enhance reproducibility, accurateness and completeness of an EME. However, SCALE cannot presently include non-technospheric inputs in emergy accounting, like e.g. human labor and ecosystem services. Moreover, SCALE is limited by the approach used to build the dataset of UEVs for natural resources. Recommendations on the scope and accuracy of SCALE-based emergy accounting are suggested for further steps in software development, as well as preliminary quantitative methods to account for ecosystem services and human labor.

Quantifying the environmental impact of an integrated human/industrial-natural system using life cycle assessment; a case study on a forest and wood processing chain

Life Cycle Assessment (LCA) is a tool to assess the environmental sustainability of a product; it quantifies the environmental impact of a product's life cycle. In conventional LCAs, the boundaries of a product's life cycle are limited to the human/industrial system, the technosphere. Ecosystems, which provide resources to and take up emissions from the technosphere, are not included in those boundaries. However, similar to the technosphere, ecosystems also have an impact on their (surrounding) environment through their resource usage (e.g., nutrients) and emissions (e.g., CH4). We therefore propose a LCA framework to assess the impact of integrated Techno-Ecological Systems (TES), comprising relevant ecosystems and the technosphere. In our framework, ecosystems are accounted for in the same manner as technosphere compartments. Also, the remediating effect of uptake of pollutants, an ecosystem service, is considered. A case study was performed on a TES of sawn timber production encompassing wood growth in an intensively managed forest ecosystem and further industrial processing. Results show that the managed forest accounted for almost all resource usage and biodiversity loss through land occupation but also for a remediating effect on human health, mostly via capture of airborne fine particles. These findings illustrate the potential relevance of including ecosystems in the product's life cycle of a LCA, though further research is needed to better quantify the environmental impact of TES.

Measuring environmental sustainability of water in watersheds

Environmental sustainability assessment is a rapidly growing field where measures of sustainability are used within an assessment framework to evaluate and compare alternative actions. Here we argue for the importance of evaluating environmental sustainability of water at the watershed scale. We review existing frameworks in brief before reviewing watershed-relevant measures in more detail. While existing measures are diverse, overlapping, and interdependent, certain attributes that are important for watersheds are poorly represented, including spatial explicitness and the effect of natural watershed components, such as rivers. Most studies focus on one or a few measures, but a complete assessment will require use of many existing measures, as well as, perhaps, new ones. Increased awareness of the broad dimensions of environmental sustainability as applied to water management should encourage integration of existing approaches into a unified assessment framework appropriate for watersheds.

Ore grade decrease as life cycle impact indicator for metal scarcity: the case of copper

In the life cycle assessment (LCA) of products, the increasing scarcity of metal resources is currently addressed in a preliminary way. Here, we propose a new method on the basis of global ore grade information to assess the importance of the extraction of metal resources in the life cycle of products. It is shown how characterization factors, reflecting the decrease in ore grade due to an increase in metal extraction, can be derived from cumulative ore grade-tonnage relationships. CFs were derived for three different types of copper deposits (porphyry, sediment-hosted, and volcanogenic massive sulfide). We tested the influence of the CF model (marginal vs average), mathematical distribution (loglogistic vs loglinear), and reserve estimate (ultimate reserve vs reserve base). For the marginal CFs, the statistical distribution choice and the estimate of the copper reserves introduce a difference of a factor of 1.0-5.0 and a factor of 1.2-1.7, respectively. For the average CFs, the differences are larger for these two choices, i.e. respectively a factor of 5.7-43 and a factor of 2.1-3.8. Comparing the marginal CFs with the average CFs, the differences are higher (a factor 1.7-94). This paper demonstrates that cumulative grade-tonnage relationships for metal extraction can be used in LCA to assess the relative importance of metal extractions.