Expanding System Boundaries Research Articles

The circular bioeconomy: a driver for system integration

BackgroundHuman and earth system modeling, traditionally centered on the interplay between the energy system and the atmosphere, are facing a paradigm shift. The Intergovernmental Panel on Climate Change’s mandate for comprehensive, cross-sectoral climate action emphasizes avoiding the vulnerabilities of narrow sectoral approaches. Our study explores the circular bioeconomy, highlighting the intricate interconnections among agriculture, forestry, aquaculture, technological advancements, and ecological recycling. Collectively, these sectors play a pivotal role in supplying essential resources to meet the food, material, and energy needs of a growing global population. We pose the pertinent question of what it takes to integrate these multifaceted sectors into a new era of holistic systems thinking and planning.ResultsThe foundation for discussion is provided by a novel graphical representation encompassing statistical data on food, materials, energy flows, and circularity. This representation aids in constructing an inventory of technological advancements and climate actions that have the potential to significantly reshape the structure and scale of the economic metabolism in the coming decades. In this context, the three dominant mega-trends—population dynamics, economic developments, and the climate crisis—compel us to address the potential consequences of the identified actions, all of which fall under the four categories of substitution, efficiency, sufficiency, and reliability measures. Substitution and efficiency measures currently dominate systems modeling. Including novel bio-based processes and circularity aspects might require only expanded system boundaries. Conversely, paradigm shifts in systems engineering are expected to center on sufficiency and reliability actions. Effectively assessing the impact of sufficiency measures will necessitate substantial progress in inter- and transdisciplinary collaboration, primarily due to their non-technological nature. In addition, placing emphasis on modeling the reliability and resilience of transformation pathways represents a distinct and emerging frontier that highlights the significance of an integrated network of networks.ConclusionsExisting and emerging circular bioeconomy practices can serve as prime examples of system integration. These practices facilitate the interconnection of complex biomass supply chain networks with other networks encompassing feedstock-independent renewable power, hydrogen, CO2, water, and other biotic, abiotic, and intangible resources. Elevating the prominence of these connectors will empower policymakers to steer the amplification of synergies and mitigation of tradeoffs among systems, sectors, and goals.

Failing to Grasp our Failure to Grasp Automation Failure

This paper discusses three points inspired by Skraaning and Jamieson’s perspective on automation failure: (a) the limitations of the automation failure concept with expanding system boundaries; (b) parallels between the failure to grasp automation failure and the failure to grasp trust in automation; (c) benefits of taking a pluralistic approach to definitions in sociotechnical systems science. While a taxonomy of automation-involved failures may not directly improve our understanding of how to prevent those failures, it could be instrumental for identifying hazards during test and evaluation of operational systems.

The water, land and carbon footprint of conventional and organic dairy systems in the Netherlands and Spain. A case study into the consequences of ecological indicator selection and methodological choices

Dairy farming systems are multifunctional processes that provide milk but also beef, veal and manure. These outputs provided by dairy farms are important foods for humans but their production require natural resources like water and land, and release emissions to the water and air contributing to climate change. Many studies quantified the environmental performance of dairy farms by using a life cycle assessment (LCA) or environmental footprint calculation. This study provides a better understanding of how different methodological decisions (e.g., the choice of system boundary, GHG metric, allocation procedure for multifunctionality, and multi-environmental indicators) influence the environmental performance calculation. From a footprinting point of view, the water footprints (WFs) (i.e., green, blue and grey), land footprints (LFs) and carbon footprints (CFs) of milk, beef and veal produced in two conventional (Dutch and Spanish) and an organic Dutch dairy system are estimated. Here the system boundaries are expanded so calve systems are included. Next, the use of different indicators is discussed, e.g., green WFs and the GWP100 or GWP20. The Dutch conventional system has relatively small footprints due to high efficiency. Green, blue and grey WFs per kg of milk are 0.62, 0.09 and 0.14 m3. The Spanish system has green, blue and grey WFs per kg of milk of 0.67, 0.15 and 0.09 m3; the Dutch organic system of 0.84, 0.13 and 0.26 m3. The Spanish system has the largest LF and CF, caused by feed import from countries with relatively low yields and transport greenhouse gas emissions. Dutch systems use more locally produced feed. Due to lower efficiency, the organic system has larger footprints than the Dutch conventional system. Expanding system boundaries to include calves results in an 8 to 15% CF increase. Green water dominates total WFs, an aspect excluded in LCA studies. For grey WFs, earlier studies only included nitrogen. However, if also pesticides would be included, results might be less favourable for systems relying on feed crops instead of grasslands. Also, water quality standards influence grey WFs. The study emphasizes that indicator choice influences final results. Indicators like animal welfare, biodiversity or pesticide use give different outcomes which might be more favourable for organic production.

Comparative life cycle assessment of emergency disposal scenarios for medical waste during the COVID-19 pandemic in China

The COVID-19 pandemic attracts concerns globally and leads to an exponential increase in medical waste generation, and disposal of medical waste is an urgent need for preventing the epidemic spread. Emergency disposal scenarios of medical waste generated during the COVID-19 pandemic require a systematic assessment to quantify their potential environmental impacts. The environmental impacts and key factors of three movable disposal scenarios (i.e. incineration disposal vehicle, movable steam and microwave sterilization equipment both followed by co-incineration with municipal solid waste) were quantified via life cycle assessment approach. Furthermore, the environmental impacts of three movable disposal and two co-incineration scenarios were compared via life cycle assessment by expanding system boundaries. The results show that co-incineration with municipal solid waste has the lowest environmental impacts due to environmental benefits produced by power generation, while co-incineration with hazardous waste is the highest due to the high energy consumption. Energy consumption (i.e. kerosene, electricity and diesel) are the key factors for three movable disposal scenarios. For movable steam and microwave sterilization equipment followed by co-incineration with municipal solid waste, power generation from incinerating disinfected medical waste has significant beneficial environmental impacts due to avoided impacts of electricity consumption. The recommendations for improvement of the emergency disposal and management of medical waste during the COVID-19 pandemic globally and other serious epidemic in the future are provided.

The cost-effectiveness of energy savings through water conservation: a utility-scale assessment

It is well-established that water infrastructure systems require energy to treat and deliver water to end-users. This fundamental relationship presents an opportunity to secure energy savings through water conservation. In a previous study, the energy savings linked to a statewide water conservation mandate in California were found comparable in both resource savings as well as cost-effectiveness to the energy savings achieved directly through energy efficiency programs. This study pursues a similar line of inquiry, but at the scale of an individual city as opposed to a statewide assessment. Los Angeles, California, serves as the case study for estimating the energy savings secured through water conservation programs relative to energy efficiency (EE) programs enacted in the study region. We apply three different estimates of energy intensity (EI) for the conversion of water savings to energy savings. These applied EI scenarios are differentiated by scale and system boundary, including: a direct assessment of EI within the water utility service territory, an expanded boundary that includes imported water infrastructure systems, and a broader, top-down estimate for the regional hydrologic zone. Across all scenarios, the estimated energy savings secured through water conservation programs prove to be cost-competitive with the energy efficiency programs enacted by the utility. When using estimates of EI with expanded system boundaries that include the upstream energy embedded in imported water supplies, water conservation becomes a significantly more attractive pathway for saving energy. This outcome underlines the importance of clearly defining the water-energy system boundary of interest, both to determine an accurate EI value, and subsequently, to design and implement cost-effective programs that jointly conserve both water and energy resources.

Construction project productivity evaluation framework with expanded system boundaries

PurposeWhile the investment in construction projects has increased over the past few decades, low construction project productivity (CPP) appeared to be persistent, thereby reflecting an “investment-in-failure” paradox between the investment and CPP. Hence, this paper aims to develop a systematic and holistic CPP evaluation framework to explain the apparent paradox in the construction industry.Design/methodology/approachThe paper first reviews the literature about the theories of system, production, principal–agent and project success evaluation to re-conceptualise the CPP and proposes a two-stage CPP evaluation framework. The framework is subsequently explored through a sequential qualitative mixed-methods design within the context of the Hong Kong construction industry by combining 32 semi-structured interviews with senior industry experts and exploratory case studies, with three real-life construction projects.FindingsThe paper identifies three system boundaries for CPP evaluation, that is, parameter, timeframe and stakeholder, and develops a two-stage CPP evaluation framework to indicate site efficiency and utilisation effectiveness, thereby accessing the productivity of both the construction and post-construction stages. The “investment-in-failure” paradox associated with current CPP evaluation approaches is primarily attributed to the narrowly defined CPP boundaries.Research limitations/implicationsThe qualitative exploration of the evaluation framework only focusses on the Hong Kong construction industry. Further case studies within other urban contexts could be used to improve the generalisability of the findings. Quantitative research is also necessary to advance theoretical development of the two-stage CPP evaluation.Practical implicationsThe systemic CPP conceptualisation and the two-stage CPP evaluation framework support the systems thinking of industry stakeholders and enable them to formulate holistic strategies for long-term CPP enhancement.Originality/valueThe research demonstrates the needs to expand the system boundaries of CPP to reflect its systemic value and to shift the paradigm of CPP evaluation from being output-orientated and quantity-focussed to being outcome-orientated and value-focussed.

Systems Thinking and Green Chemistry: Powerful Levers for Curricular Change and Adoption

Curricular change within the chemistry curriculum is often difficult and slow, in part because there are numerous specific barriers to implementation. However, a larger issue is that the curriculum, and the institutions that it is connected with, are complex systems. In the implementation of a new green chemistry curriculum for the organic teaching laboratory, we employed a systems-thinking approach to develop and disseminate the new curriculum. We identified five key leverage points where targeted efforts could yield significant gains in the design and implementation of the curriculum. Two key strategies that emerged from these efforts were the importance of expanding system boundaries to garner support for our efforts and building capacity of faculty to participate in curricular change. The systems approach contributed significantly to the successful introduction of green organic chemistry into the curriculum. Systems-based strategies are likely to catalyze future curricular-change efforts throughout the curriculum.

Life Cycle Greenhouse Gas Emissions and Costs of Production of Diesel and Jet Fuel from Municipal Solid Waste.

This paper quantifies and compares the life cycle GHG emissions and costs of production of diesel and jet fuel derived from municipal solid waste (MSW) in the United States via three thermochemical conversion pathways: conventional gasification and Fischer-Tropsch (FT middle distillate, MD), plasma gasification and Fischer-Tropsch (Plasma FT MD), and conventional gasification, catalytic alcohol synthesis, and alcohol-to-jet upgrading (ATJ MD). We use expanded system boundaries to capture the change in existing MSW use and disposal, and account for parameter uncertainty with Monte Carlo simulations. We estimate median life cycle GHG emissions of 32.9, 62.3, and 52.7 gCO2e/MJ for FT, Plasma FT and ATJ MD fuels, respectively, compared to a baseline of 90 gCO2e/MJ for conventional MD fuels. Median minimum selling prices are estimated at 0.99, 1.78, and 1.20 $ per liter with the probability of achieving a positive net present value of fuel production at market prices of 14%, 0.1% and 7% for FT, Plasma FT and ATJ MD fuels, respectively. If the societal perspective rather than an investor's perspective is evaluated, then the probability of positive net present value of fuel production increases to 93%, 67%, and 92.5% for the FT, Plasma FT, and ATJ MD fuels, respectively.

Ecologically Inspired Water Network Optimization of Steel Manufacture Using Constructed Wetlands as a Wastewater Treatment Process

Abstract Traditional optimization models often lack a systems-level perspective at conception, which limits their effectiveness. Expanding system boundaries allow scientists and engineers to model complex interactions more accurately, leading to higher efficiency and profitability in industrial systems. Ecological systems have evolved for billions of years under conditions of material and energy shortage, and ecologists have defined analysis tools and metrics for identifying important principles. These principles may provide the framework to circumvent the limitations of traditional optimization techniques. More specifically, by recruiting functional roles that are often found in ecological systems, but are absent in industrial systems, industries can better mimic how natural systems organize themselves. The objective of this analysis is to traditionally optimize a manufacturing process by comparing the model with ecological and resource-based performance metrics in order to redesign the model with the addition of important functional roles that are found throughout nature. Industry partners provided data for this analysis, which involved building a water network for an existing steel manufacturing facility in China. The results of the traditional optimization model indicate a 23%, 29%, and 20% decline in freshwater consumption, wastewater discharge, and total annual cost, respectively. However, our ecologically inspired optimization model provides an additional 21% and 25% decline in freshwater consumption and total annual cost, respectively. Furthermore, no water is discharged. These results suggest that this unconventional approach to optimization could provide an effective technique not used by existing algorithms to solve the challenging problem of pursuing more sustainable industrial systems.

An environmental evaluation of food waste downstream management options: a hybrid LCA approach

PurposeFood waste treatment methods have been typically analysed using current energy generation conditions. To correctly evaluate treatment methods, they must be compared under existing and potential decarbonisation scenarios. This paper holistically quantifies the environmental impacts of three food waste downstream management options—incineration, composting, and anaerobic digestion (AD).MethodsThe assessment was carried out using a novel hybrid input–output-based life cycle assessment method (LCA), for 2014, and in a future decarbonised economy. The method introduces expanded system boundaries which reduced the level of incompleteness, a previous limitation of process-based LCA.ResultsUsing the 2014 UK energy mix, composting achieved the best score for seven of 14 environmental impacts, while AD scored second best for ten. Incineration had the highest environmental burdens in six impacts. Uncertainties in the LCA data made it difficult determine best treatment option. There was significant environmental impact from capital goods, meaning current treatment facilities should be used for their full lifespan. Hybrid IO LCA’s included additional processes and reduced truncation error increasing overall captured environmental impacts of composting, AD, and incineration by 26, 10 and 26%, respectively. Sensitivity and Monte Carlo analysis evaluate the methods robustness and illustrate the uncertainty of current LCA methods. Major implication: hybrid IO-LCA approaches must become the new norm for LCA.ConclusionThis study provided a deeper insight of the overall environmental performance of downstream food waste treatment options including ecological burdens associated with capital goods.

Carbon balances of bioenergy systems using biomass from forests managed with long rotations: bridging the gap between stand and landscape assessments

AbstractStudies report different findings concerning the climate benefits of bioenergy, in part due to varying scope and use of different approaches to define spatial and temporal system boundaries. We quantify carbon balances for bioenergy systems that use biomass from forests managed with long rotations, employing different approaches and boundary conditions. Two approaches to represent landscapes and quantify their carbon balances – expanding vs. constant spatial boundaries – are compared. We show that for a conceptual forest landscape, constructed by combining a series of time‐shifted forest stands, the two approaches sometimes yield different results. We argue that the approach that uses constant spatial boundaries is preferable because it captures all carbon flows in the landscape throughout the accounting period. The approach that uses expanding system boundaries fails to accurately describe the carbon fluxes in the landscape due to incomplete coverage of carbon flows and influence of the stand‐level dynamics, which in turn arise from the way temporal system boundaries are defined on the stand level. Modelling of profit‐driven forest management using location‐specific forest data shows that the implications for carbon balance of management changes across the landscape (which are partly neglected when expanding system boundaries are used) depend on many factors such as forest structure and forest owners’ expectations of market development for bioenergy and other wood products. Assessments should not consider forest‐based bioenergy in isolation but should ideally consider all forest products and how forest management planning as a whole is affected by bioenergy incentives – and how this in turn affects carbon balances in forest landscapes and forest product pools. Due to uncertainties, we modelled several alternative scenarios for forest products markets. We recommend that future work consider alternative scenarios for other critical factors, such as policy options and energy technology pathways.

A hybrid life-cycle inventory for multi-crystalline silicon PV module manufacturing in China

China is the world’s largest manufacturer of multi-crystalline silicon photovoltaic (mc-Si PV) modules, which is a key enabling technology in the global transition to renewable electric power systems. This study presents a hybrid life-cycle inventory (LCI) of Chinese mc-Si PV modules, which fills a critical knowledge gap on the environmental implications of mc-Si PV module manufacturing in China. The hybrid LCI approach combines process-based LCI data for module and poly-silicon manufacturing plants with a 2007 China IO-LCI model for production of raw material and fuel inputs to estimate ‘cradle to gate’ primary energy use, water consumption, and major air pollutant emissions (carbon dioxide, methane, sulfur dioxide, nitrous oxide, and nitrogen oxides). Results suggest that mc-Si PV modules from China may come with higher environmental burdens that one might estimate if one were using LCI results for mc-Si PV modules manufactured elsewhere. These higher burdens can be reasonably explained by the efficiency differences in China’s poly-silicon manufacturing processes, the country’s dependence on highly polluting coal-fired electricity, and the expanded system boundaries associated with the hybrid LCI modeling framework. The results should be useful for establishing more conservative ranges on the potential ‘cradle to gate’ impacts of mc-Si PV module manufacturing for more robust LCAs of PV deployment scenarios.

Expanding the boundaries of clinical informatics for interdisciplinary systems research

Health-care organizations and the information they exchange are increasingly complex and difficult to understand necessitating fresh methodological approaches on the part of clinical informatics researchers. Looking at the interplay between health-care information technology (HIT), clinical workflow, and the surrounding organization requires some notion of a system and an interdisciplinary orientation toward research. The paper offers practical advice grounded in the systems approach to researchers who wish to view HIT holistically and part of an integrated system. Examples from literature describe the importance of expanding system boundaries, looking for relationships within those boundaries, simplifying complexity, and accounting for social behavior.

Environmental impacts of combined milk and meat production in Norway according to a life cycle assessment with expanded system boundaries

The environmental burdens from combined milk and meat production in Norway have been studied. A model of three typical farms was constructed to represent the three most important regions for dairy production in Norway (central, central southeast and southwest). Processes from cradle to farm gate were covered in the assessment, including all activities on the farm, along with the production of machinery, equipment, buildings, diesel, oil, fertilizer, lime, seeds, pesticides, detergents, plastic, silage additive, medicines and related transport. The results were given for the impact categories global warming potential (GWP), fossil depletion, freshwater ecotoxicity, freshwater eutrophication, human toxicity, marine ecotoxicity, marine eutrophication, ozone depletion, agricultural land occupation, photochemical oxidant formation, terrestrial acidification and terrestrial ecotoxicity.To document the impact and to be able to compare the findings to results from previous studies, processes often excluded in literature were individually omitted from the assessment. The consequences of using alternative literature values for selected sub-processes were calculated and the sensitivity of the results to different parameter settings was evaluated by varying the parameter values ±50% of the default value.GWP impacts of 1.5–1.6kgCO2-eq per kg energy corrected milk (ECM) and 17.7–18.4kgCO2-eq per kg carcass were calculated. By excluding production of machinery, buildings, medicines, detergents, seeds, fence and pesticides, the GWP impacts were reduced by approximately 8% per kg carcass and 9% per kg ECM. Compared to results from other studies, the GWP related to production of milk and meat was high in the present investigation. The validity of comparisons with other studies is however low due to differences in allocation and system boundaries.

Life Cycle Greenhouse Gas Emissions of Trough and Tower Concentrating Solar Power Electricity Generation

SummaryIn reviewing life cycle assessment (LCA) literature of utility‐scale concentrating solar power (CSP) systems, this analysis focuses on reducing variability and clarifying the central tendency of published estimates of life cycle greenhouse gas (GHG) emissions through a meta‐analytical process called harmonization. From 125 references reviewed, 10 produced 36 independent GHG emissions estimates passing screens for quality and relevance: 19 for parabolic trough (trough) technology and 17 for power tower (tower) technology. The interquartile range (IQR) of published estimates for troughs and towers were 83 and 20 grams of carbon dioxide equivalent per kilowatt‐hour (g CO2‐eq/kWh),1 respectively; median estimates were 26 and 38 g CO2‐eq/kWh for trough and tower, respectively.Two levels of harmonization were applied. Light harmonization reduced variability in published estimates by using consistent values for key parameters pertaining to plant design and performance. The IQR and median were reduced by 87% and 17%, respectively, for troughs. For towers, the IQR and median decreased by 33% and 38%, respectively. Next, five trough LCAs reporting detailed life cycle inventories were identified. The variability and central tendency of their estimates are reduced by 91% and 81%, respectively, after light harmonization. By harmonizing these five estimates to consistent values for global warming intensities of materials and expanding system boundaries to consistently include electricity and auxiliary natural gas combustion, variability is reduced by an additional 32% while central tendency increases by 8%. These harmonized values provide useful starting points for policy makers in evaluating life cycle GHG emissions from CSP projects without the requirement to conduct a full LCA for each new project.

Comparison through a LCA evaluation analysis of food waste disposal options from the perspective of global warming and resource recovery

This study evaluated feed manufacturing including dry feeding and wet feeding, composting, and landfilling for food waste disposal options from the perspective of global warming and resource recovery. The method of the expanded system boundaries was employed in order to compare different by-products. The whole stages of disposal involved in the systems such as separate discharge, collection, transportation, treatment, and final disposal, were included in the system boundary and evaluated. The Global Warming Potential generated from 1 tonne of food wastes for each disposal system was analyzed by the life cycle assessment method. The results showed that 200 kg of CO 2-eq could be produced from dry feeding process, 61 kg of CO 2-eq from wet feeding process, 123 kg of CO 2-eq from composting process, and 1010 kg of CO 2-eq from landfilling. Feed manufacturing and composting, the common treatment methods currently employed, have been known to be environment friendlier than other methods. However, this study shows that they can negatively affect the environment if their by-products are not appropriately utilized as intended.

Using LCA to evaluate impacts and resources conservation potential of composting: A case study of the Asti District in Italy

Separate collection of municipal solid waste has overcome the 50% threshold in the Asti District in northern Italy, nearly one-third being composed of household and green organic waste. In order to address present and future solutions, it becomes therefore fundamental to assess the environmental performances of the current management of organic waste from separate collection. A from-gate-to-cradle life cycle assessment (LCA) model has been developed by expanding system boundaries, in order to carry out the assessment in the context of the whole waste management streamline. The environmental performances of an existing aerobic plant were made available, based on field measured data, by paying attention to the role and contribution of waste management subsystems. The need for actual and reliable data on materials and energy input, as well as gross and net gains from materials recovery, including benefits arising from use of compost in farming activities, was probably the major drawback that had to be faced. The study integrated the findings of different investigations from the literature with field measured data in order to obtain a more comprehensive framework representative of the area under study. The results may help public administrators to better understand the suitability of using LCA tools when dealing with solid waste management strategies.

Strategic electricity sector assessment methodology under sustainability conditions: a Swiss case study on CO<SUB align=right>2 emissions, competition and stranded costs

Designing and implementing a sustainable energy sector will be a key element of defining and creating a sustainable society. In the electricity industry, the question of strategic planning for sustainability seems to conflict with the shorter time horizons associated with market forces as deregulation replaces vertical integration. In order to address such questions, a project called SESAMS (Strategic Electricity Sector Assessment Methodology under Sustainability) has been established to develop electricity sector planning methods related to sustainability. This effort is part of the Alliance for Global Sustainability (AGS) formed by the Massachusetts Institute of Technology (MIT), the Swiss Federal Institutes of Technology (ETHZ and EPFL), and the University of Tokyo (UT). The initial phase of SESAMS in 1997 created a methodology integrating multi-scenario simulation, life-cycle analysis and multi-criteria decision analysis. This 1998 case study has expanded the methodology to study the transitional effects of deregulation associated with the issues of stranded cost. This analysis has studied the inclusion of different classes of stranded assets, different recovery periods, and recovery of costs on a fixed vs. variable (per kWh) basis. On a societal basis, stranded costs are a zero-sum transfer payment, but the ownership patterns of stranded assets mean that compensation for stranded assets will produce relative winners and losers. These winners and losers shift according to the stranded cost and other options present in different scenarios. The results of the stranded cost analysis are integrated with updated multi-criteria trade-off analysis and life-cycle analysis results, based on expanded system boundaries.

Net-waste-reduction analysis applied to zero-water discharge systems for chromic acid electroplating

Chromic acid recovery and treatment technologies were evaluated to determine total waste produced by alternatives that approach zero- or low-wastewater discharge systems. System boundaries were expanded to account for hidden waste produced by generation of energy required for operation of the recovery technologies. This type of analysis highlights the importance of expanding system boundaries when evaluating pollution prevention options, and demonstrates why zero-discharge electroplating processes may not be environmentally desirable.