Eco-efficiency Analysis Research Articles

Ranking of walling materials using eco-efficiency for tropical climatic conditions: A survey-based approach

All over the world, “Construction” is an important sector that consumes a significant amount of resources and produces a lot of waste. Buildings as a whole share nearly one-fourth of total electricity generation in tropical countries that results in adverse effects on the natural environment and their national economies. Enhancing the building energy efficiencies relies on material and technology selection that complement the local climatic conditions. Compressed Stabilized Earth Blocks are considered as an innovative and proven building envelope upgrade that enhances building efficiencies both economically and environmentally considering their cradle-to-gate phase. However, the cradle-to-grave life cycle impacts of Compressed Stabilized Earth Blocks compared to conventional walling materials are yet to be assessed in tropical climatic conditions for long-term decision making. Accordingly, the objective of this study is to compare compressed Stabilized Earth Blocks with conventional walling materials such as Burnt Clay Bricks and Cement Sand Blocks. The life cycle thinking approach was integrated with eco-efficiency analysis to compare and evaluate the above-mentioned materials considering their entire life span from cradle to grave. Accordingly, Compressed Stabilized Earth block has been selected as the more efficient material with environmental benefits. Moreover, since it can be used as a walling element even without the application of plaster, costs and environmental impacts could be further reduced when used without plastering. The findings of this research will encourage building developers, contractors, and practitioners in selecting the most desirable material for their projects considering costs and environmental impacts of the material life cycle.

Achieving waste recovery goals in the medium/long term: Eco-efficiency analysis in a Brazilian city by using the LCA approach

The aim of this study was to analyse how to ensure that medium- and long-term waste recovery goals can be achieved in Brazilian cities, based on the incorporation of viable and accessible technology. The identification of the strengths of the Brazilian cities with better (dry and wet) waste recovery rates allowed different strategies to be proposed for João Pessoa (the city selected as a case study). Those strategies were based on the improvement of (1) the selective collection of the recyclable dry waste fraction, (2) the material recovery facility to increase the recovery of recyclable dry waste fraction to be recycled and/or wet waste fraction to be composted, and finally (3) the working conditions of waste workers. A combination of these improvement strategies at two different levels of implementation (partial and total) allowed the definition of 14 alternative scenarios, which were analysed from an eco-efficiency perspective (environmental vs. economic). After analysing the evolution over time of the alternative scenarios proposed, the proposal that was finally selected was based on the initial implementation of a mechanical biological and composting facility capable of handling up to 50% of the mixed municipal solid waste collected by 2023 with a material recovery efficiency of 30%. From there, the efficiency of the mechanical biological and composting facility should increase up to 60% to achieve the waste recovery goals by 2034 (management of 60% of the mixed waste collected). This rate has not yet been reached in any of the Brazilian mechanical biological and composting facilities analysed, so the reduction in the amount of waste generated and the increase in the selective separation of waste at source are identified as key elements to be able to fulfil the long-term goals. The approach used in the case study provides guidelines for application in other geographical contexts.

PREMISES FOR ECO-EFFICIENCY ANALYSIS ON CONSTRUCTION AND DEMOLITION WASTE RECYCLING

The construction industry is associated with significative impacts such a consumption of natural resources and waste generation. Eco-efficiency is an instrument for sustainable analysis which indicates the relation between environmental costs and impacts. While the most environmental method used is the lifecycle assessment (LCA), standardized by ISO 14040, the economic indicator should be selected according to the stakeholder. Total cost, Unit Cost, Net Present Value (NPV) and Internal Rate of Return (IRR) are some of the economic indicators used in the economic analysis of Construction and Demolition Waste (CDW) recycling, however, the search for literature regarding the Eco-efficiency analysis shows a tendency to use the total cost regardless of its objective. In this sense, the objective of this paper is to propose the main premises to be considered in the selection of the economic indicator and in the normalization of the analysis of the CDW recycling Eco-efficiency index results. The search method adopted was comprised for three steps: Systematic review of literature; Analysis and comparison of Eco-efficiency indicators (including economic and environmental inputs); Discussion about the main assumptions in the CDW recycling Eco-efficiency analysis. 14 articles were identified in the Science Direct and Springer platforms. This paper provides information to propose premises to the Eco-efficiency analysis on CDW recycling. As a result, was defined a standard Eco-efficiency analysis according the objective: assessment of the cost to minimizing impacts, a simple comparison between scenarios or economic and environmental viability. The first two objectives refer to the input data variation and the scenarios evaluated, respectively. The third objective needs to compare the results with the current scenario, the final disposal and established market material that recycled aggregate can replace. Using the simplified flowchart proposed for each CDW recycling Eco-efficiency analysis objective will allow to standardize studies of this aspect, thus enabling more credible, replicable and comparable development.

Environmental performance of alkali-activated binders for ground improvement

The use of alkali-activated binders (AAB) with industrial waste materials such as fly ash (FA) and ground granulated blast-furnace slag (GGBFS) as precursors for ground improvement has recently gained popularity as an alternative to Portland cement. This study assesses the life cycle environmental impacts of AABs, after scaling up the process from laboratory to field application, compared to conventional cement-based binders. Several terrestrial, marine, and climatic impact categories were evaluated from cradle to construction, covering the extraction of resources, processing, and manufacturing of alkali activators and other materials, transportation, and construction. The study investigated different AAB mixes including two precursors, FA and GGBFS, and two alkali activators, sodium silicate (Na2SiO3) and sodium hydroxide (NaOH). The comparative analysis demonstrated that, under the tested conditions and methods, the production of both alkali activators is the key environmental hotspot throughout all life cycle impact categories. The soil treated with AABs with FA as precursor and NaOH as an activator outperformed cement in four out of the ten evaluated impact categories, namely global warming, tropospheric ozone formation, fine particulate-matter formation, and terrestrial acidification. Standard normalization and aggregation of all impact categories have confirmed the significant improvement of the soil treated with this AAB mix compared to cement. Moreover, the sensitivity analysis corroborated the superiority of this AAB mix over cement under varying transportation distances and compressive strengths. Furthermore, an eco-efficiency analysis was carried out, combining the incurred costs with the environmental footprint, and revealed that this AAB was the most eco-efficient binder out of the examined mixes. Overall, the findings suggest that, to improve the environmental performance of AABs in ground improvement applications, the manufacturing of activators must utilize sustainable sources of energy for electricity production. Moreover, the reduction of activators, or use of sustainable alternatives, in AABs is crucial, especially when low compressive strength is required.

An eco-efficiency analysis of refinery effluent pretreatments for water reuse under a Zero Liquid Discharge regime

This paper presents an eco-efficiency analysis of five scenarios for treating a petrochemical unit effluent defined sequentially to increase the water reuse rate to the limit condition of Zero Liquid Discharge perspective. The base process, consisting of reverse osmosis, an evaporator and crystallizer, displayed pretreatment alternatives the addition of antifouling agents, desupersaturation of barium ions and coprecipitation of low solubility salts to increase osmosis efficiency. The eco-efficiency analysis applied the life cycle approach to verify environmental and energy performances and determined the costs of the treatment unit installation and operation for a time horizon of 9.5 years. The pretreatment increased water recovery during osmosis from 84% to over 97%. The environmental-energetic analysis indicated a strong influence of electric energy, consumed mainly during the thermal stages of the treatment, and of the chlorine-derived compounds used in the pretreatment. Also due to pre-treatment, it was possible to reduce impacts in terms of Global Warming Potential by up to 59%, and in Primary Energy Demand by 64% for the best scenario. The economic analysis depicted a significant influence of operating costs, and the electricity consumed in the processes is responsible for the largest share of expenses. The reuse water presented a cost ranging between US$ 1.08/m3 and US$ 1.80/m3. The systems with pretreatment by coprecipitation with Ca(OH)2 and CaCO3 and monoacids to adjust the pH of the final effluent showed to be more eco-efficient than the other options under analysis.

Eco-Efficiency Analysis for the Russian Cities along the Northern Sea Route: A Data Envelopment Analysis Approach Using an Epsilon-Based Measure Model.

In this paper, an eco-efficiency analysis is conducted using the epsilon-based measure data envelopment analysis (EBM-DEA) model for Russian cities along the Northern Sea Route (NSR). The EBM-DEA model includes five input variables: population, capital, public investment, water supply, and energy supply and four output variables: gross regional product (GRP), greenhouse gas (GHG) emissions, solid waste, and water pollution. The pattern of eco-efficiency of 28 Russian cities along the NSR is empirically analyzed based on the associated real data across the years from 2010 to 2019. The empirical results obtained from the analysis show that St. Petersburg, Provideniya, Nadym, N. Urengoy, and Noyabrsk are eco-efficient throughout the 10 years. The results also indicate that the cities along the central section of the NSR are generally more eco-efficient than those along other sections, and the cities with higher level of GRPs per capita have relatively higher eco-efficiency with a few exceptions. The study provides deeper insights into the causes of disparity in eco-efficiency, and gives further implications on eco-efficiency improvement strategies. The contributions of this study lie in the fact that new variables are taken into account and new modeling techniques are employed for the assessment of the eco-efficiency of the Russian cities.

Eco-efficiency assessment of wave energy conversion in Western Australia

Western Australia is an ideal location for wave energy conversion with some of the highest energy density waves in the world. Renewable energy technologies have had an emerging presence in Australia, seen as a vehicle to decarbonise energy generation and provide a sustainable future. This paper examines the environmental and economic feasibility of energy generation from wave energy conversion in Western Australia by undertaking an Eco-Efficiency Analysis (EEA). The environmental impacts of wave energy converters (WEC) were assessed by application of a Life Cycle Analysis (LCA) while the economic performance considered the Life Cycle Costing (LCC). An eco-efficiency portfolio was developed to visualise the sustainability of coastal energy generation options – wave generation, offshore wind and diesel generation – finding that wave generation was the most eco-efficient option and could be deemed a sustainable energy generation technology. The LCA results were comparable to literature, validating the impact assessment. The proposed wave device was estimated to produce a global warming potential of 27.3 kg CO2 eq/MWh and have a levelised cost of energy at 134 $AUD/MWh. The environmental impact of the device was significantly lower than alternative coastal energy generation methods in Western Australia while the associated cost of energy remained competitive. This favourable assessment using the eco-efficiency framework confirmed that the application of WEC in Western Australia would be an eco-efficient option and that research should be undertaken to develop this technology as a key player in the transition to a sustainable energy industry.

Eco-efficiency analysis of integrated grey and black water management systems

Unconventional wastewater management systems have been developed to cope with the ever-increasing demand on the existing infrastructure. Grey water separation and treatment emerged to address the limitations of conventional sanitation systems. Towards achieving key sustainable development goals, this study aims to assess the performance of grey and black water separation alternatives with on-site treatment (SOT) or dual collection (SDC), compared to conventional collection and treatment (CCT). The on-site treated grey water in the SOT scenario was used for toilet flushing, leading to 25% reduction in domestic water demand. A novel manhole configuration was designed to suit the dual sewer collection network in the SDC scenario, where the sewer-collected grey water was conveyed directly to the tertiary treatment stage due to its low solids and organic load. A comprehensive, cost-integrated life cycle analysis was carried out to quantify the environmental impacts and assess the financial feasibility of the examined wastewater management systems. An eco-efficiency analysis was conducted to aggregate the results of life cycle costing (LCC) and life cycle assessment (LCA). The proposed collection and treatment alternatives were applied on a residential development in Dubai based on local design guidelines. Results of the environmental assessment indicated that SOT had the highest impacts in all midpoint impact categories with a single score of 1.27, followed by CCT (0.94) and SDC (0.89) systems. Over 50-year assessment period, the LCC findings revealed close net present values of CCT and SDC systems ($30 and 25 million, respectively), compared to SOT system ($8 million). The environmental impacts and financial burdens of the SOT system were reduced by 54 and 59%, respectively, when the treated grey water was reused instead of potable water for toilet flushing. The eco-efficiency analysis indicated that the SDC is the most sustainable system. Overall, this research emphasized the potential environmental and financial benefits of grey water separation, collection and treatment systems taking into consideration the entire urban water cycle.

Ecological Analysis of Selected Stages of the Food Packaging Production Process

Abstract Eco-efficiency is a new concept of environmental analysis seeking to improve products, processes and manufacturing materials. The eco-efficiency analysis gives the opportunity to find the most effective solution with the lowest environmental burden in the bottle forming process. For this purpose, the LCA (Life Cycle Assessment) technique of environmental management was used to evaluate selected stages of the bottle forming process. The analysis was carried out using the Eco Indicator 99 method using the SimaPro software.

Optimization and eco-efficiency analysis of extractive distillation processes with different solvents for separating the ternary mixture embedding two azeotropes

The selection of feasible solvent is of great significance for separating azeotropes via extractive distillation since various solvents can cause different product orders, flowsheet structures, and eco-efficiencies of extractive distillation processes. Limited efforts are focused on the effect of various solvents on the separation of ternary mixtures embedding two azeotropes, especially for the design of the extractive dividing-wall column separation configurations. To fill the research gap, the separation of azeotropic mixtures embedding two azeotropes is investigated using extractive distillation method with various solvents through taking the methyl acetate/ethyl acetate/methanol mixture as an example. First, the theoretical thermodynamic feasibility of four solvents including ethylene glycol, dimethyl sulfoxide, chlorobenzene, and aniline is explored. The individual light-heavy component orders are determined through the thermodynamic insights including the construction of the pseudo binary vapor–liquid phase equilibrium diagrams and overall phase diagrams with residue curves and iso-volatility curves after adding solvents, while are further verified using σ-profiles from microscopic mechanism. Second, the conceptual design of the extractive distillation flowsheets including conventional extractive distillation and extractive dividing-wall column separation configurations with individual solvents is performed. The effects of various solvents on the flowsheet structures and product orders are analyzed. Afterwards, the extractive distillation flowsheets are simulated and optimized economically to minimize the total annual costs through the genetic algorithm, except for the solvent ethylene glycol due to the unfeasibility of realistic simulation. The eco-efficiency analysis is performed via quantifying the Eco-Indicator 99 and thermodynamic performances as well as economic costs. The results indicate that the extractive distillation processes with dimethyl sulfoxide or chlorobenzene as solvent can show a certain degree of advantage compared with that using aniline as solvent in terms of eco-efficiency. The optimal separation configuration is the extractive dividing-wall column containing two dividing-walls with CB as solvent, and its Eco-efficiency Comparison Index increased to 80.54% compared to the worst scheme that is the extractive dividing-wall column containing one dividing-wall with AN as solvent.

A novel approach for developing composite eco-efficiency indicators: The case for US food consumption

Eco-efficiency analysis can provide useful information for sustainability benchmarking of products and sectors while assessing and monitoring their economic and environmental performances. The eco-efficiency is defined as a ratio between economic performance and environmental impact. With multiple environmental and economic metrics, the eco-efficiency assessment is computationally complex. One common aspect of this complexity is associated with the importance (a.k.a. Relative weights) of sustainability indicators in the presence of high multicollinearity. A novel weighting method integrating two well-established methods for reducing the multicollinearity consequence during the aggregation process is presented in the study. The proposed method’s mathematical and operational procedures, called Weighted Penalized Maximum Likelihood Estimation (W-PMLE), are demonstrated for the eco-efficiency analysis of U.S food consumption. The eco-efficiency analysis results revealed that the CO2 emissions, the level of consumption of the metallic mineral, and water were the most critical to the eco-efficiency performance of U.S. consumption.

Eco-efficiency of FAME production based on the requirements of ISO 14045:2012

The aim of the work was to present the issue of eco-efficiency, based on the PN-EN ISO 14045:2012 standard in relation to the production of fatty acid methyl esters (FAME). The ecoefficiency analysis takes into account economic and environmental aspects in the improvement of products and processes / technologies. Eco-efficiency considers the product and technology throughout the life cycle, from the construction phase, through use to decommissioning. The impact on the natural environment is assessed on the basis of: consumption of energy, materials, dust and gas emissions, waste and sewage. Total costs include: production costs, raw material costs, costs during the use phase including maintenance, repair and operating costs, product disposal or recycling. The eco-efficiency analysis is helpful in making decisions regarding the selection of a new product or designing a new technology, and enables the selection of the variant that is the most economical and has the least possible impact on the natural environment. These issues are particularly important in the case of biofuels. The rapid growth of their production and the European Union’s policy, which aims to increase the share of energy from renewable sources, cause concerns of many experts regarding the threats related to the production of biofuels, both for the environment and food security. In particular, efforts are made to minimize the amount of waste and residues by implementing the idea of a circular economy. This approach promotes the development of new technologies that are more environmentally friendly. Due to the regulations set out in the RED and RED II Directives, there is a chance that the biofuels will have a less negative impact on the environment. This results from the obligation to certify compliance with the sustainability criteria, which is carried out by voluntary systems recognized by the European Commission, such as the KZR INiG System.

Environmental impact assessment of agro-services symbiosis in semiarid urban frontier territories. Case study of Mendoza (Argentina)

In the next 10 years, cities will house 60% of the world's population, where in agro-urban frontier territories, mainly in semiarid regions, problems associated with land use and water distribution will arise. Therefore, a model of growth that contemplates the lowest use of resources must be proposed. The aim of this study is to determine the environmental impact of the use of resources in agro-services frontier territories of semiarid regions in three urban growth scenarios, linear and circular systems. The study is focused on Luján de Cuyo in Mendoza, Argentina. Through a life cycle assessment, environmental performance was evaluated for the current scenario and the three proposed ones. In addition, an ecoefficiency analysis was performed in relation to climate change and water consumption and the cost of surface uses, as well as an assessment according to the multifunctionality of surface use. Scenario 1 is a linear diffuse urban system, scenario 2 a circular water agro-urban system, and scenario 2 green plus energy a circular water and energy agro-urban system. The outcomes illustrate that scenario 2 green plus energy has the least environmental impacts. Compared to the linear scenario, both circular scenarios show a substantial reduction in water consumption (38–40%) and marine eutrophication (32–47%) and curtail freshwater eutrophication impacts. Furthermore, household energy impacts are reduced by 39% in scenario 2 green plus energy with photovoltaic panel implementation, and maximum ecoefficiency in response to climate change is reached. Additionally, the impacts of scenario 2 green plus energy are more than 42% less than those of scenario 1 in terms of the multifunctionality of surface use. This study shows that it is possible to achieve more sustainable semiarid urban frontier territories with local water and regional energy circularity.

Eco-Efficiency of Milk Production in Poland Using the Life Cycle Assessment Methodologies

Purpose: The main objective of the study was to perform an environmental and economic evaluation of milk production in the main production types pursued by Polish farms. The second objective was to analyze the eco-efficiency of milk production. Design/Methodology/Approach: The study was conducted in a group of 24 farms, among which 15 farms focused on milk production and 9 farms conducted mixed livestock production (milk production and pig fattening). The data for the study concerned the period 2017-2018. Cattle was raised in a closed breeding cycle. Fat stocks was supplied by calves born on the farms. Life cycle assessment (LCA) at the stage from cradle-to-farm gate and LCC were used for environmental impact assessment. The functional unit was 1 kg raw milk corrected for fat and protein (FPCM). The studied environmental profile was applied to five categories of impacts: climate change (GWP100), acidification (AP), eutrophication (EP), abiotic resource depletion potential for fossil fuels (ADP fuel), abiotic resource depletion potential for minerals (ADP min) and photochemical ozone creation potential (POCP). Findings: A farming type specializing in milk production showed a more favourable environmental profile compared to the mixed livestock type. The group of processes responsible for generating direct emissions in cattle raising (enteric fermentation and manure management) had the greatest impact on GWP100 and AP. Imported feed and home grown feed contributed much to ADP fuel, ADP min and EP. The higher eco-efficiency of milk production was recorded for the milk farming type. In the type of mixed livestock farming, both the reduction of total environmental impact and costs should be the primary factors in improving the eco-efficiency of milk production. Practical Implications: Attention should be paid to the practical importance of eco-efficiency analysis, which, so far, has been an insufficiently used measurement tool for achieving targets in sustainable milk production. Originality/value: In the article we propose the evaluation of eco-efficiency of milk production by considering both environmental and economic impacts from the life cycle perspective.

Pursuing the route to eco-efficiency in dairy production: The case of Galician area

The search for more efficient and sustainable processes has become the cornerstone of any production system. It is within this framework that it is highly relevant to propose improvement actions based on a detailed eco-efficiency analysis of different facilities so that roadmaps for more sustainable processes are considered. The joint use of Life Cycle Assessment (LCA) and Data Envelopment Analysis (DEA) appears to be an appropriate methodology to assess the eco-efficiency of multiple units, providing targets and benchmarks for inefficient ones. This work advances in this direction by integrating both analysis methodologies in the calculation of environmental indicators associated with milk production for a large group of farms, nearly 100 decision-making units. Twenty-one dairy farms were identified as efficient, and the average efficiency score of the inefficient farms was 0.58. Based on the comparison of current operation levels with target levels, it was possible to quantify average reductions of up to 53% for input consumption levels, resulting in average impact reductions of 49% in carbon footprint and 55% in water footprint. Comparing the outcomes of this study with those reported in 2011 for Galician farms (Northwest Spain), a slight decrease in eco-efficiency was noted in the dairy sector. This study shows how the Galician dairy sector must address sustainable development objectives, especially those established in Agenda 2030 to achieve constant improvement and sustainable and efficient production.

Eco-Efficiency Analysis of Environmental and Industrial Engineering

With the expanding weighty weight from condition and nature asset, individuals has taken creative measures to liberate themselves from the current unreasonable financial improvement design, and unequivocally advanced the improvement of round sort and ecotype economy. The fundamental undertakings of eco-mechanical building are to bring the thoughts of ecotype into the plan of modern framework dependent on the speculations of roundabout economy, and accomplish the agreement of financial advantage and natural advantage. So as to acquire viable use proportion of asset and lower condition contamination, eco-effectiveness consolidates economy with condition. This paper dependent on exploring eco-proficiency markers framework, calls attention to eco-mechanical designing assessment strategies because of the eco-effectiveness.

Land tenure, soil conservation, and farm performance: An eco-efficiency analysis of Austrian crop farms

We measure the eco-efficiency (EE) of agricultural production in regard to soil erosion and decompose it into technical efficiency (TE) and soil conservation efficiency (SCE). Data Envelopment Analysis is applied to a panel of 135 Austrian crop farms. As a proxy for soil conservation behavior, we estimate C- and P-factors, frequently applied in Revised Universal Soil Loss Equations, at the parcel-level and combine this with farm-level accountancy data. We investigate the impact of land tenure and other determinants on EE and its components using truncated regression and bootstrapping techniques. Results reveal that: i) the average EE, SCE, and TE is 0.16, 0.26, and 0.54, respectively, suggesting a substantial improvement potential in the soil conservation behavior of farms; ii) tenants have, on average, a significantly higher TE than landowners, but a significantly lower SCE; iii) the effect of tenancy on EE is significantly negative. Results point towards tenants maximizing short-term economic benefits leading to the overexploitation of soils. Results ask for regulations that increase the duration and security of rental contracts, and a shift in agricultural subsidies from direct payments based on area to compensations that provide public goods and internalize externalities.

A socio-eco-efficiency analysis of water and wastewater treatment processes for refugee communities in Jordan

As of 2017, the United Nations has estimated that there are 68.5 million displaced people in the world which live in refugee camps (RCs) in 125 host countries. RCs frequently encounter water scarcity issues which lead to a low daily limit of water consumption, as well as face management difficulties such as septic tank overflowing which contribute to the development of health problems. Considering the need for more sustainable water, sanitation, and hygiene system in RCs, a socio-eco-efficiency analysis (SEEA) framework is proposed for the analysis and comparison of different wastewater treatment methods. The SEEA framework consists of the integration of the economic and environmental aspects analysed by an eco-efficiency analysis (EEA) with the social aspects evaluated by a social life cycle assessment (S-LCA) using the analytic hierarchy process. The SEEA framework was applied to compare different wastewater treatment methods in Zaatari Refugee Camp in Jordan. The SEEA results show that, if adopted, an effluent water reuse-based treatment would increase economic efficiency by 75%, decrease environmental impacts by 57%, and increase social sustainability by 57% compared to the current operation of the camp, where a wastewater system connects groups of seven to nine households to communal septic tanks. A ternary diagram is used to represent the comparison of different wastewater treatment methods for an RC. The diagram shows the degree of socio-eco-efficiency of each wastewater treatment method, in terms of its social impacts, environmental impacts, and cost by normalising results of the EEA and S-LCA into one score.

Design and comparison of conventional and side-stream extractive distillation sequences for separating the methanol-toluene binary azeotrope with intermediate boiling entrainer

The side-stream extractive distillation (SSED) system is attracting widespread attention due to its high eco-efficiency. In the article, three double-column SSED (DC-SSED) sequences and two single-column SSED (SC-SSED) sequences with different side-stream extraction locations are proposed for separating the methanol-toluene azeotrope with intermediate boiling entrainer triethylamine, which are compared with two conventional extractive distillation (CED) processes including direct and indirect CED sequences. The genetic algorithm is employed to optimize seven extractive distillation sequences to minimize the total annual costs (TAC). CO2 emissions and thermodynamic efficiency of the optimized processes are quantified as well as TAC to calculate the Eco-efficiency Comparison (ECI) Index for eco-efficiency analysis. The results illustrate that two DC-SSED sequences demonstrate the eco-efficiency superiority compared to the optimal CED process (direct CED), and their side-streams are located in the rectifying section and extractive section of the side extractive distillation column, while their ECI indexes reach 97.38% and 97.60%.

Analysis of industrial eco-efficiency and its influencing factors in China

Industry is the largest sector for energy consumption and pollution emissions in China. Thus, improving industrial eco-efficiency is necessary for China to achieve sustainable development. Based on panel data from 31 industrial sectors from 2001 to 2015, a three-stage data envelopment analysis model was used to empirically explore industrial eco-efficiency and its influencing factors from the perspective of industrial heterogeneity. The results show that the overall level of industrial eco-efficiency in China is not high, first declining and then rising during the study period. Low eco-efficiency was mainly due to low scale efficiency. After removing the influences of external environmental factors and noise, industry profit rates, ownership structures, and foreign direct investments were all significantly and positively correlated with eco-efficiency. Environmental regulations were significantly and negatively correlated, while the intensity of research and development exhibited no linear relationship. Industrial heterogeneity significantly affects eco-efficiency. Capital-intensive industries had the highest eco-efficiencies, followed by resource-intensive industries and labor-intensive industries, respectively. Comparison of technical efficiency (TE) before and after adjustment on a panel of 31 industries in China from 2001 to 2015.