Design Of Sustainable Systems Research Articles

Towards a complex investment evaluation framework for renewable energy systems: A 2-level heuristic approach

Renewable energy technologies still endure critical technical and financial challenges. These challenges demand for specially tailored decision support tools for planning the (renewable-based) strategical expansion of power systems. However, existing tools not always adequately integrate the tactical and operational dimensions of power systems into the evaluation process; hence, the designed investment strategies might fail to foresee how new infrastructure integrates with the existing power system and also fail to capture the volatile energy market dynamics. In this paper, this methodological gap is addressed by presenting a decision aid framework, based on mixed integer programming, for supporting long-term decision-making when planning (the expansion of existing) energy systems. The proposed framework relies on heuristically solving an optimization problem coined as the Generation, transmission and storage location and sizing of operation-aware sustainable power system design problem, which encodes two nested problems: a novel strategic renewable power system expansion problem, and a Unit Commitment problem. Using a case study from the Chilean power system, it is shown that the proposed tool ensures a more realistic and accurate economic evaluation, as it takes into account the influence of the evaluated project on the grid where it will be installed. In the considered case study, the devised framework designs a sustainable power system expansion investment strategy ensuring an investment rate of return of at least 7% and an annualized profit of more than 277 MM USD considering a 30 years evaluation horizon; furthermore, this is accomplished along with an equalization of the spot price resulting in a 13% reduction with respect to the current spot price of the system. This shows the impact of renewable sources and energy storage systems on the market operation. Furthermore, the proposed approach is used to investigate how high (public) subsidies on renewable technologies should be in order to increase the penetration of these technologies.

Copper Oxide Microtufts on Natural Fractals for Efficient Water Harvesting.

Hierarchical surfaces that aid in the droplet nucleation, growth, and removal is highly desirable for fog and moisture harvesting applications. Taking inspiration from the unique architecture of leaf skeletons, we present a multiscale surface capable of rapidly nucleating, growing, and directional transport of the water droplets. Copper oxide microtufts were fabricated onto the Ficus religiosa leaf skeletons via electroplating and chemical oxidation techniques. The fabricated surfaces with microtufts had high wettability and very good fog harvesting ability. CuO surfaces tend to become hydrophobic over time because of the adsorption of the airborne species. The surfaces were efficient in fog harvesting even when the hydrophobic coating is present. The overall water collection efficiencies were determined, and the role of the microtufts, fractal structures, and the orientation of leaf veins was investigated. Compared to the planar control surfaces, the noncoated and hydrophobic layer-coated copper oxide microtufts on the leaf skeletons displayed a significant increase in the fog harvesting efficiency. For superhydrophilic skeleton surfaces, the water collection rate was also observed to slightly vary with the vein orientation. The CuO microtufts along with high surface area fractals allowed an effective and sustainable way to capture and transport water. The study is expected to provide valuable insights into the design and fabrication of sustainable and efficient fog harvesting systems.

A self-sustainable wearable multi-modular E-textile bioenergy microgrid system

Despite the fast development of various energy harvesting and storage devices, their judicious integration into efficient, autonomous, and sustainable wearable systems has not been widely explored. Here, we introduce the concept and design principles of e-textile microgrids by demonstrating a multi-module bioenergy microgrid system. Unlike earlier hybrid wearable systems, the presented e-textile microgrid relies solely on human activity to work synergistically, harvesting biochemical and biomechanical energy using sweat-based biofuel cells and triboelectric generators, and regulating the harvested energy via supercapacitors for high-power output. Through energy budgeting, the e-textile system can efficiently power liquid crystal displays continuously or a sweat sensor-electrochromic display system in pulsed sessions, with half the booting time and triple the runtime in a 10-min exercise session. Implementing “compatible form factors, commensurate performance, and complementary functionality” design principles, the flexible, textile-based bioenergy microgrid offers attractive prospects for the design and operation of efficient, sustainable, and autonomous wearable systems.

Sustainability analysis for the design of distributed energy systems: A multi-objective optimization approach

The design of sustainable energy systems requires to enlarge the analysis beyond the traditional boundaries for including the economic, environmental, and societal needs and constraints in the decision-making process. In this regard, this work investigates the conceptual design of distributed energy systems by means of a multi-objective optimization strategy to simultaneously address the economic, environmental, and social aspects in the energy system design. Initially, the water consumption and the inherent safety indicators were introduced and evaluated through two single-objective optimization problems to enhance the analysis of the environmental and social dimensions of sustainability. Then, a framework including the total annualized cost, CO2 emissions, water consumption, grid dependence, and inherent safety index was used to perform the multi-objective analysis. To carry out a thorough and comprehensive analysis, four optimization problems including different combinations of the sustainability indicators were proposed and solved. The compromise among the objective functions was identified, and the obtained Pareto sets were explored for elucidating the changes in the design and operating conditions across the non-dominated solutions. According to results, the cost of energy can range between 0.37 and 0.63 €/kWh, the CO2 emissions can vary between 10.6 and 68.5 kgCO2/MWh, and the water consumption can be between 27.8 and 70.2 m3H2O/GWh depending on the evaluated objective. Moreover, it was determined that the safety of the energy system can be improved by increasing the use of the water electrolysis pathway to produce hydrogen and by reducing the capacity of the hydrogen storage unit.

A Stochastic Procedure for Temporal Disaggregation of Daily Rainfall Data in SuDS Design

Hydrological design of Sustainable urban Drainage Systems (SuDS) is commonly achieved by estimating rainfall volumetric percentiles from daily rainfall series. Nevertheless, urban watersheds demand rainfall data at sub-hourly time step. Temporal disaggregation of daily rainfall records using stochastic methodologies can be applied to improve SuDS design parameters. This paper is aimed to analyze the ability of the synthetic rainfall generation process to reproduce the main characteristics of the observed rainfall and the estimation of the hydrologic parameters often used for SuDS design and by using the generally available daily rainfall data. Other specifics objectives are to analyze the effect of Minimum Inter-event Time (MIT) and storm volume threshold on rainfall volumetric percentiles commonly used in SuDS design. The reliability of the stochastic spatial-temporal model RainSim V.3 to reproduce observed key characteristics of rainfall pattern and volumetric percentiles, was also investigated. Observed and simulated continuous rainfall series with sub-hourly time-step were used to calculate four key characteristics of rainfall and two types of rainfall volumetric percentiles. To separate independent rainstorm events, MIT values of 3, 6, 12, 24, 48 and 72 h and storm volume thresholds of 0.2, 0.5, 1 and 2 mm were considered. Results show that the proposed methodology improves the estimation of the key characteristics of the rainfall events as well as the hydrologic parameters for SuDS design, compared with values directly deduced from the observed rainfall series with daily time-step. Moreover, MITs rainfall volumetric percentiles of total number of rainfall events are very sensitive to MIT and threshold values, while percentiles of total volume of accumulated rainfall series are sensitive only to MIT values.

Radical α–alkylation of ketones with unactivated alkenes under catalytic and sustainable industrial conditions

The industrially–viable aerobic α–alkylation of cyclic and acyclic ketones with allyl and alkyl alkenes in the presence of catalytic amounts of Mn2+, under homo– and heterogeneous conditions, is achieved here. The substitution of organic peroxides by Mn2+ either as a simple soluble salt or supported in zeolites, in air, generates in–situ peracid radicals and circumvents the aggressiveness of current industrial protocols, to pave the way for the design of sustainable aerobic catalytic systems. Combined reactivity and mechanistic studies show that large cyclic ketones stabilize a radical in the α–position due to a higher polarizability, steric hindrance and no proximity effects. As a proof of concept, the gram–scale synthesis of the industrial fragrance exaltolide is carried out with the Mn2+ catalysts in air, which clearly improves any other previously reported method not only in safety and environmental terms but also in number of synthetic steps and overall yield.

Cognitive Maps Across Multiple Social Sectors: Shared and Unique Perceptions on the Quality of Agricultural Soils in Mexico

Incorporating the views and perceptions of local farmers and other actors with stakes in agricultural production is critical for better-informed decision making and tackling pressing issues, such as soil degradation. We conducted a study that sought to integrate and analyze perceptions regarding the quality and degradation of agricultural soils across different social sectors in Mexico, including producers of two annual crops (maize and beans) and two perennial crops (coffee and avocado), members of civil society organizations and members of the Federal Government. We analyzed the community perception using Cognitive Maps and network metrics. Our fully documented method to formally gather and analyze local and regional perceptions can be used in future efforts toward the collective design of sustainable food systems. Our results highlighted common and potentially conflicting aspects among the different perceptions and allowed us to identify and discuss drivers and processes of special interest in different regions in Mexico. This study also contributes to a deeper understanding of the current situation of agricultural soils in Mexico and seeks to inform the decision-making process regarding agricultural management in the country.

Assessing impacts of environmental peacebuilding in Caquetá, Colombia: a multistakeholder perspective

Abstract A major challenge in the field of environmental peacebuilding is showing the impact of its initiatives. Questions emerge, such as what kind of postwar peacebuilding dimensions are more likely to be affected by natural resource management projects? Although quantitative studies assess the relation between natural resource management programmes and conflict, the question remains: what are the mechanisms involved in implementing projects designed for environmental peacebuilding? To answer these questions, a mixed methods research approach is chosen, combining four qualitative and quantitative methods to triangulate results. First, we identify a set of peacebuilding dimensions and mechanisms based in the literature that facilitate assessing the impact of sustainable land-use systems (SLUS) design in the post-peace agreement region of Caquetá, Colombia. Second, not only do we interview experts and practitioners at global, national (Colombia) and local (Department of Caquetá) levels in the fields of peacebuilding, natural resource management and environmental peacebuilding, we also conduct three workshops and a survey in Caquetá to prioritize dimensions and discover explanatory mechanisms. The case of Caquetá, Colombia, shows that peacebuilding dimensions, such as socio-economic inclusion (e.g. sustainable livelihoods), creation of governance scenarios, and building capacities for dialogue and a peace culture, should be addressed to take account of the impacts of SLUS projects in post-conflict peacebuilding.

Design and Development of Sustainable Product Service Systems Based on Design-Centric Complexity

Product-service system (PSS) complexity is rapidly increasing in order to meet complex user requirements. Increased complexity leads to PSSs failing to meet sustainability requirements in their initial design. To enhance PSS sustainability and support social benefits, this paper proposes a sustainable PSS development framework based on design-centric complexity (DCC) theory. In the early design stage of a PSS, DCC theory is used to analyze the complexity of the system. Determination of the types of complexity in the system and the corresponding problems is then performed. By combining the sub-field model of TRIZ, the problems can be converted and solved, and the functional periodicity may be established to reduce system complexity. By using this development framework, the conflicts and potential problems of design attributes can be reduced and the possibility of achieving PSSs functional requirements (FRs) can be enhanced. This will maintain the long-term operation stability for the system and enhance the sustainability of the PSS. Finally, the feasibility of the development framework is verified here through the case analysis of a bicycle sharing service and management system.

Multi-objective Chaotic Butterfly Optimization with Deep Neural Network based Sustainable Healthcare Management Systems

Sustainable healthcare systems are developed to priorities healthcare services involving difficult decision-making processes. Besides, wearables, internet of things (IoT), and cloud computing (CC) concepts are involved in the design of sustainable healthcare systems. In this study, a new Multi-objective Chaotic Butterfly Optimization with Deep Neural Network (MOCBOA-DNN) is presented for sustainable healthcare management systems. The goal of the MOCBOA-DNN technique aims to cluster the healthcare IoT devices and diagnose the disease using the collected healthcare data. The MOCBOA technique is derived to perform clustering process and also to tune the hyperparameters of the DNN model. Primarily, the clustering of IoT healthcare devices takes place using a fitness function to select an optimal set of cluster heads (CHs) and organize clusters. Followed by, the collected healthcare data are sent to the cloud server for further processing. Furthermore, the DNN model is used to investigate the healthcare data and thereby determine the presence of disease or not. In order to ensure the betterment of the MOCBOA-DNN technique, an extensive simulation analysis take place. The experimental results portrayed the supremacy of the MOCBOA-DNN technique over the other existing techniques interms of diverse evaluation parameters.

Transdisciplinarity in agroecology: practices and perspectives in Europe

ABSTRACT Agroecology, as a science for the study, design and management of sustainable food systems, retakes epistemic, methodological and practical approaches of transdisciplinarity. However, there is not a unanimous understanding of these approaches and few studies investigate its implementation. Transdisciplinarity is defined lato sensu as the practices of collaboration and knowledge integration between non-academic actors and scientists. This approach is at stake in Europe, especially in the field of food systems. Our aim is to analyze the magnitude, conceptions and praxis of works from European agroecologists claiming transdisciplinarity. Based upon a content analysis of publications and interviews with some of their authors, our results show that, although there is a growing literature on transdisciplinarity in Europe, the proportion of publications is low compared to the overall publications in agroecology. Despite the global aspiration of using it as an approach to achieve cognitive justice and horizontal knowledge construction, our typology of transdisciplinarity in practice shows a diversity of patterns. Four clusters were identified, ranging from genuine co-creation of knowledge to uneven collaborations between scientists and stakeholders, thus questioning scholars’ responsibility As a nascent and promising domain, transdisciplinarity in agroecology should be encouraged in European research and experiences capitalized.

Analysis and optimization of the closed-adsorption heat storage bed performance

Sorption heat storage attracts considerable attention because its relatively high theoretical energy density compared to other heat storage methods offers various opportunities in the design of renewable and sustainable energy systems. However, limited heat transfer in the material bed remains one of the main limitations of a successful introduction to the market. In the present study, a mathematical model of the heat and mass transfer processes inside an adsorption bed of silica gel embedded with cylindrical and rectangular fins has been developed. A systematic analysis has been conducted to augment thermal transport in the adsorption bed with rectangular and pin fin configurations. A parametric study has been conducted for both fin configurations at different bed heights (δb), fin diameters/thicknesses (ϕfin/δfin) and fin spacings (δs). Further, a design-of-experiments study is conducted to relate the energy discharge (Edis) and peak power (Wpeak) to the various governing parameters, as such identifying which parameters maximize energy discharge (Edis) and peak power (Wpeak). The design-of-experiment study reveals that the rectangular fin configuration shows better performance compared to the cylindrical fin configuration.

Management strategies, silvopastoral practices and socioecological drivers in traditional livestock systems in tropical dry forests: An integrated analysis

Understanding traditional livestock management is essential in the design of more sustainable systems, given the forest loss associated to the growing demand for meat. In Latin America, where extensive livestock production is increasing, along with tropical dry forest (TDF) transformation, the role of small holders is critical for designing more sustainable management practices. This study is an integrated socioecological analysis of traditional livestock systems in a region with TDF in Mexico. The objectives were to: a) characterise the historical development and current state of livestock systems and silvopastoral practices, b) define the management strategies and their impacts on forests, and c) identify the regional and local socioecological drivers that influence decision-making processes in livestock and forest management. In-depth interviews were carried out to 32 cattle farmers and analysed using a qualitative-interpretative approach which included multivariate and narrative analyses. Three historical stages (colonization, promotion of livestock and forest conservation) had a strong impact in the development and current state of livestock systems. Access to natural and economic resources and proportion of plant cover (grassland/forest) were essential in defining four groups of management strategies. The main regional drivers favouring or restricting production include climate, native vegetation, markets and public policies; at the local scale, socioecological factors, such as water availability, native vegetation, economic assets, local knowledge and their interactions determine heterogeneity in management strategies, decision-making processes and their impacts on forests. Adaptive management of livestock and forests in a context of limited economic resources has allowed the conservation of forest areas and the use of silvopastoral practices with local tree species. The integrated socio-ecological approach and the use of mixed methods allowed a better understanding of drivers and their interrelationships, the local knowledge, objectives and perceptions of farmers in the decision-making processes regarding livestock and forest management. Perspectives of farmers on resource use can contribute to the design of more effective and inclusive policies for sustainable livestock systems in the dry tropics.

Integrating emerging and existing renewable energy technologies into a community-scale microgrid in an energy-water nexus for resilience improvement

Rapid urbanization around the world, especially in developing countries, has resulted in a dramatic increase in the need for energy and water resources. This global trend calls for a sustainable shift in energy supplies for urban areas that can deliver robust, economic, environmental, and social benefits. This paper presents a novel planning strategy, along with an integrated system design of microgrids (MGs), to help realize sustainable energy supply patterns in a decentralized manner for improving community resilience and environmental sustainability. The exploration started with the screening of emerging and existing renewable energy technologies that can be integrated and deployed in a community-scale MG. Seamless integration of energy and water technology hubs was examined to develop a sustainable system design of MG in an energy-water nexus within the community under study. Then, a multi-objective programming model was formulated for decision analysis by systematically considering the cost, greenhouse gas (GHG) emissions, and water consumption of the MG. In comparison with existing utility grids, the multi-objective decision analysis helps find a suite of tradeoffs among three economic and environmental indicators, i.e., cost, GHG emissions, and water consumption. Case studies show that the proposed system design of the MG for the urban community can cut more than 75.5% GHG and 75.6% water consumption, compared to the benchmark in a centralized utility system. Case studies also show that this planning strategy can harmonize environmental, economic, and social benefits, making the traditional wide-area synchronous grid greener, cheaper, and more reliable. It is indicative that the system design of MG in an energy-water nexus will improve the reliability of energy supplies and strengthen community resilience, thereby increasing overall economic benefits in the long run.

Design and optimization of sustainable passive treatment systems for phosphogypsum leachates in an orphan disposal site

The optimization of the dispersed alkaline substrate (DAS) technology was investigated to achieve the treatment of highly acidic and polluted effluents from a phosphogypsum pile in an orphan site of SW Spain. This phosphogypsum disposal area is located on the Tinto river marsh soils, where it acts as a source of pollution for the estuarine environment, releasing high concentrations of metal(loid)s and radionuclides, which degrade the surrounding waters. The methodology consists of flowing the leachates through columns loaded with a combination of a fine-grained alkaline reagent scattered in a non-reactive matrix to raise the water pH while decreasing the solubility of dissolved contaminants. Seven columns were built, one for each of the alkaline reagent used: limestone, barium carbonate, biomass ash, fly ash, MgO, Mg(OH)2, and Ca(OH)2. The Ca(OH)2-DAS and MgO-DAS treatment systems showed the highest effectiveness, reaching near-total removal for PO4, F, Fe, Zn, Cu, Al, Cr, and U with initial reagent mass:treated volume ratios of 36.3 g/L and 7.57 g/L, respectively. Total As removal was only achieved in the Ca(OH)2-DAS treatment. Phosphate precipitation was the main mechanism responsible for pollutants removal. Geochemical modeling using PHREEQC code and mineralogical evidence confirmed the precipitation of these minerals. This study forms the basis of an effective and environmentally sustainable treatment system for phosphogypsum leachates to reduce the impact of the fertilizer industry worldwide.

Tracing the Scientific History of Fe0-Based Environmental Remediation Prior to the Advent of Permeable Reactive Barriers

The technology of using metallic iron (Fe0) for in situ generation of iron oxides for water treatment is a very old one. The Fe0 remediation technology has been re-discovered in the framework of groundwater remediation using permeable reactive barriers (PRBs). Despite its simplicity, the improvement of Fe0 PRBs is fraught with difficulties regarding their operating modes. The literature dealing with Fe0 remediation contains ambiguities regarding its invention and its development. The present paper examines the sequence of contributions prior to the advent of Fe0 PRBs in order to clarify the seemingly complex picture. To achieve this, the current paper addresses the following questions: (i) What were the motivations of various authors in developing their respective innovations over the years?, (ii) what are the ancient achievements which can accelerate progress in knowledge for the development of Fe0 PRBs?, and (iii) was Fe0 really used for the removal of organic species for the first time in the 1970s? A careful examination of ancient works reveals that: (i) The wrong questions were asked during the past three decades, as Fe0 was premised as a reducing agent, (ii) credit for using Fe0 for water treatment belongs to no individual scientist, and (iii) credit for the use of Fe0 in filtration systems for safe drinking water provision belongs to scientists from the 1850s, while credit for the use of Fe0 for the removal of aqueous organic species does not belong to the pioneers of the Fe0 PRB technology. However, it was these pioneers who exploited Fe0 for groundwater remediation, thereby extending its potential. Complementing recent achievements with the chemistry of the Fe0/H2O system would facilitate the design of more sustainable Fe0-remediation systems.

Emerging Tools for Energy System Design Increasing Economic and Environmental Sustainability

Energy is a fundamental element supporting societal development, particularly with the increasing dependency on the Internet of Things. It is also the main contributor to environmental impacts and subsequently, a potential sector for mitigation. Sustainable energy system design considers energy savings and energy efficiency, waste and consumption reduction, process efficiency enhancement, waste heat recovery, and integration of renewable energy. Emerging tools range from advanced Process Integration, modelling, simulation, and optimisation, to system analysis and assessment. This review covers selected emerging studies promoting sustainable system design, including the recent developments reported in the Special Issue (SI) of the 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (PRES’19). The primary emphasis was to enhance the economic and environmental performance. However, social factors were also highlighted as essential for future sustainable development. The discussion and analysis in this review focus on the most recent developments of (a) heat integration and heat transfer; (b) integrated and newly developed heat exchangers, (c) integration of renewables, and (d) roles in economic and environmental sustainability. The key results are highlighted, and future research ideas are suggested according to their links to a broader context.

Assessing the Performance of Different Time of Concentration Equations in Urban Ungauged Watersheds: Case Study of Cartagena de Indias, Colombia

In ungauged watersheds, the estimation of the time of concentration (Tc) is always a challenging task due to the intrinsic uncertainty involved when making assumptions. Given that Tc is one of the main inputs in a hydrological analysis for the design of hydraulic structures for stormwater management, ten equations (including one proposed in several local studies) and two Tc methodologies (overland flow time plus channel flow time) were used to compute the Tc in fifteen urban ungauged watersheds, located in Cartagena de Indias (Colombia), with different area sizes and slopes to statistically assess their performance against the value obtained via the Natural Resources Conservation Service (NRCS) velocity method (assumed to be the true value). According to the Nash–Sutcliffe efficiency index, none of the equations proved to be reliable in all watersheds as only four equations predicted the Tc value in 53% of the cases. In addition, based on the percent bias, all equations tended to significantly over- or underestimate the Tc, which affects the quantification of the runoff volume necessary for, among others, the implementation of best management practices for watershed management (e.g., conventional and/or sustainable drainage system design), flood-prone area delineation and flood risk analyses, urban planning, and stream restoration.

Induction of uniaxial anisotropy by controlled phase separation in Y-Co thin films

In this study, molecular beam epitaxy is utilized to stabilize a nanostructured thin-film magnet consisting of a soft magnetic ${\mathrm{Y}}_{2}{\mathrm{Co}}_{17}$ exchange coupled to hard magnetic ${\mathrm{YCo}}_{5}$. While, typically, a phase decomposition can be obtained in rare-earth cobalt systems only by the addition of further elements like Cu, Fe, and Zr and complex heat treatments, here we directly induce phase separation by growth kinetics. The resulting nanoscale architecture, as revealed by cross-sectional transmission electron microscopy, is composed of a network of coherently interlinked and aligned ${\mathrm{Y}}_{2}{\mathrm{Co}}_{17}$ and ${\mathrm{YCo}}_{5}$ building blocks. The formation of coherent precipitations is facilitated by the perfectly matching lattice constants, atomic species, and crystal symmetry of the two phases with vastly different magnetocrystalline anisotropies. The hard magnetic phase induces an aligned uniaxial anisotropy in ${\mathrm{Y}}_{2}{\mathrm{Co}}_{17}$, resulting in substantial coercivity associated with enhanced energy products. This work highlights the importance of thin-film epitaxy in understanding magnetic hardening mechanisms and suggests strategies for a rational design of future sustainable magnetic systems.

An Actor-Oriented Multi-Criteria Assessment Framework to Support a Transition towards Sustainable Agricultural Systems Based on Crop Diversification

Crop diversification represents a key lever to support the development of sustainable agri-food systems. Knowledge on trade-offs and carry over effects from different crop diversification strategies is essential to inform agricultural stakeholders of potential costs and benefits. This knowledge is limited by existing data and performance measures predominantly focused on single crops, rather than complete rotations. Moreover, sustainability performance indicators are often used for assessment purposes, rather than supporting stakeholder learning and actions. A new set of 32 indicators was developed to address these needs, and used to evaluate the environmental, economic and social sustainability of the diversified agricultural systems highlighted in the case studies, which are often characterized by data availability constraints. This approach was tested in France, Germany and Italy to determine a critical ex-post diagnosis of the existing systems, and for the assessment of ex-ante innovative scenarios. The results will be used to support these case studies in the identification and design of more sustainable agricultural systems. Although the framework is based on feasible and proxy indicators, the assessment outcomes have allowed local actors to reflect on the effects generated by the implemented crop diversification strategies. Key issues include trade-offs occurring between optimizing economic and environmental performance.