System Boundaries Research Articles

A Critical Review of Life Cycle Assessments on Bioenergy Technologies: Methodological Choices, Limitations, and Suggestions for Future Studies

Bioenergy is one of the renewable energy sources with high expectations in terms of its potential for greenhouse gas (GHG) emissions mitigation, and thus has been included in most global warming limiting strategies and pathways. However, within this context, a state-of-the-art and comprehensive understanding of the environmental performance of currently available bioenergy technologies is still missing. Hence, we conduct this critical review on life cycle assessment (LCA) studies regarding a wide portfolio of bioenergy technologies to deal with this lack of knowledge. Our critical review of exhaustively searched literature identified commonly existing limitations and difficulties in the selected LCAs in terms of essential aspects of LCA, i.e., system boundaries, functional unit (FU), multifunctionality, and impact categories. Key findings of our review are as follows: inconsistency of system boundary definitions, incomparability of LCA results due to various FU definitions, incomprehensiveness of impact categories, as well as a lack of uncertainty and sensitivity analysis. Finally, in view of the above findings, we present a generic guideline for future studies with the purpose of overcoming the identified shortcomings.

Transforming towards what? A review of futures-thinking applied in the quest for navigating sustainability transformations

Abstract There is a growing call for transformations to remain within safe and just Earth system boundaries. Coherent visions of desired futures can help motivate and orient such transformations towards Sustainability, but the nature of these transformed futures is not well understood. This gap has inspired a growing body of research on ‘preferable’ or ‘desirable’ futures, which can help to unpack what endpoints such transformations to sustainability could entail and what is needed to get there. In this paper, we adopt a mixed methods approach to review the research literature focused on transformative futures so as to gain a general overview of the field and then undertake two qualitative analyses: i) unpacking the methods, terms and types of outputs produced; and ii) capturing emergent themes, commonalities and divergences in what is deemed to be a sustainable transformation in the future based on normative visions from either North, South or Global perspectives. Our findings show that the literature landscape on explorative scenarios has significantly increased in the past ten years with most publications led by authors in the Global North. From the fraction of studies that describe desirable futures, visions highlight social, environmental and equity dimensions, but nuances were found between North and South. The visions that suggest the most transformative potential seek a more harmonious human-nature relationship and consider outcomes holistically, but only a fraction offer actual ‘alternatives’ to the status quo. We find that several gaps remain at the interface of biodiversity/ecosystems and justice, or the integration and impact of diverse knowledges and cultures. Addressing these in participatory, just and creative ways seems of utmost urgency. We hope this review can offer a glimpse of how futures-thinking can contribute to research and action on sustainability transformations, and the insights can inform and inspire future research.

Analyzing the Environmental Burden of Electric Vehicle Batteries: A Life Cycle Assessment Synthesis

Introduction: The rapid growth of the EV market and the associated surge in battery demand raise environmental concerns regarding battery production and disposal. While EVs have zero tailpipe emissions, battery production contributes significantly to their overall environmental burden. Life Cycle Assessment (LCA) is a crucial tool for evaluating this impact, but inconsistencies in methodologies across different LCA studies hinder effective comparison and progress towards cleaner battery technologies. Objectives: The research aims to analyze numerous existing LCA studies on electric vehicle batteries using a standardized approach based on ISO 14040 guidelines. The goal is to ensure consistent comparisons and identify areas for environmental improvement throughout the battery life cycle. Methods: This review examines 20 relevant LCA studies on single battery models published between 2018 and 2023. It critically appraises these studies based on the ISO 14040 framework, focusing on the four key stages of LCA: defining objectives and scope, conducting inventory analysis, performing impact assessment, and interpreting the results. Results: The review found significant variability in methodologies, system boundaries (cradle-to-gate vs. cradle-to-grave), functional units, data sources (primary vs. secondary), and impact assessment methods used in the analyzed LCA studies. The production phase and the product use phase were identified as having the most significant environmental impacts. Global warming was the most frequently studied impact category. Conclusions: The inconsistency in LCA studies on EV batteries necessitates a more standardized approach. The author recommends using a cradle-to-grave system boundary, a consistent functional unit (like "kilometer traveled" or "kilowatt-hour of energy delivered over the battery's lifetime"), and a core set of nine relevant impact categories. Transparency in methodology, assumptions, and data quality is crucial for ensuring reliable and comparable results, ultimately informing efforts to improve the environmental performance of EV batteries.

Research on Wireless Sensor Network Technology

A wireless sensor network is a network system that connects numerous sensor nodes scattered within a certain area through wireless connection technology. As a cutting edge field of interdisciplinary integration, wireless sensor networks inherit sensor technology, communication technology, etc., and possess huge development potential. However, due to its large and complex technical system and unclear application scenario boundaries, further research and implementation of this technology are restricted. This paper mainly expounds on the principles, components, key technologies, and applications of wireless sensor networks, analyzes their current advantages and disadvantages, and looks ahead to future development trends.

Journey of a pill.

To estimate the global journey of a generic clonazepam pill to map steps of production, distribution, and disposal. PubMed; Google Scholar; industry and market reports; gray literature; pharmaceutical databases (eg, PharmaCompass); export records; pharmacies in Hamilton, Ont; industry professionals and leaders such as pharmaceutical company vice presidents, professors, a supply chain insurance company, and sustainable procurement consulting companies; and an international not-for-profit company. Data related to clonazepam's standard pharmaceutical production process, life cycle system boundaries, and most probable production locations were included in this review. This study depicts the estimated journey of a clonazepam pill's production and distribution, with the prescription being filled in Vancouver, BC. It begins with the extraction of salts to produce the active pharmaceutical ingredient. The main centres for clonazepam's active pharmaceutical ingredient and excipient salt extraction and production are in India and China. Quality testing and stocking occur elsewhere, such as within the European Union. The product is then shipped back to India for the next manufacturing stages. Excipients are shipped from China to India and are incorporated into formulation and tableting. The product is then sent to global markets for the final stages of pill formation and regional distribution. After shipment through Europe and Asia, the journey continues through several locations within the United States, specifically New Jersey, for the final stages of manufacturing. Once manufacturing is finalized in New Jersey, the pill is shipped to and repackaged in Tennessee for distribution and then sent to Canadian industry clusters, typically within the greater Toronto area in Ontario. Pills are then shipped to pharmacies and hospitals in Vancouver, BC, for consumer use. The total distance travelled in this scenario is approximately 63,162 km, not including the entire process of producing and shipping excipients or local retailer shipments. Health care prescribing practices have tangible environmental impacts and manufacturers should continue to invest in operational streamlining to reduce greenhouse gas emissions.

Sustainable Heat Production for Fossil Fuel Replacement—Life Cycle Assessment for Plant Biomass Renewable Energy Sources

This study aims to assess the environmental impact of using wood-based biomass as a high-efficiency fuel alternative to fossil fuels for heat production. To achieve this, the life cycle of biomass transformation, utilization, and disposal was analyzed using the life cycle assessment (LCA) methodology with SimaPro 9.5.0.2 PhD software. The system boundaries included extraction, processing, transportation, combustion, and waste management, following a cradle-to-gate approach. A comparative analysis was conducted between natural gas, the most widely used conventional heating fuel, and two biomass-based fuels: wood pellets and wood chips. The results indicate that biomass utilization reduces greenhouse gas emissions (−19%) and fossil resource depletion (−16%) while providing environmental benefits across all assessed impact categories analyzed, except for land use (+96%). Biomass is also to be preferred for forest waste management, ease of supply, and energy independence. However, critical life cycle phases, such as raw material processing and transportation, were found to contribute significantly to human health and ecosystem well-being. To mitigate these effects, optimizing combustion efficiency, improving supply chain logistics, and promoting sustainable forestry practices are recommended. These findings highlight the potential of biomass as a viable renewable energy source and provide insights into strategies for minimizing its environmental footprint.

Life cycle approach as a tool for assessing municipal biowaste treatment units: A systematic review.

Biowaste is an increasingly relevant environmental issue worldwide, causing significant environmental, economic and social impacts. Effective strategies are crucial to mitigate impacts, maximising biowaste's valorisation. This article presents a systematic literature review on using life cycle assessment (LCA) to evaluate municipal biowaste treatment facilities. The primary objective was to analyse how LCA is applied to assess the environmental efficiency of mechanical and biological treatment involving composting and anaerobic digestion (AD)-based systems. The article addressed the methodological heterogeneity across previous LCA studies, identifying critical gaps and challenges regarding standardisation and result comparability. It underscores the importance of accurately considering environmental indicators and emission factors, as these significantly affect overall LCA outcomes. Results show that most publications focus on Europe and Asia, highlighting a research gap in regions like Africa. The organic fraction municipal solid waste is the predominant feedstock, and 1 tonne of biowaste was the frequently used functional unit, reflecting the upstream impacts of waste. The most recurrent system boundary was the cradle-to-grave, offering a comprehensive analysis as it covers all stages of biowaste treatment from collection to disposal. The studies highlight the environmental benefits of AD-based systems through energy production compensations, particularly in reducing global warming potential, compared with other treatment operations such as landfills. While replacing mineral fertilisers with digestate and compost is very well discussed, it raises concerns about heavy metal content and nutrient availability. Therefore, selective collection of organic waste is crucial to improve compost quality and AD efficiency, though it increases transportation costs.

Understanding multiple resilience dividends and system boundaries in disaster- and climate-risk management: a systems approach for enhanced decision-making

Understanding multiple resilience dividends and system boundaries in disaster- and climate-risk management: a systems approach for enhanced decision-making

Sustainability building materials and circularity score of residential buildings

Building materials used, approaches and technologies related to the operation of residential buildings influence the environment and climate change. For this purpose, an assessment of environmental impacts and circularity of 11 residential buildings (marked as A) was carried out using the life cycle assessment (LCA) methodology. LCA analysis consisted of four parts. First, the goal and scope were defined. Then, inventory analysis (LCI) entered the assessment using input data. They were needed to quantify inputs and outputs, resource and energy flows, emissions, and other leakages. Life cycle impact assessment (LCIA) quantified the pollutants into impact categories. The last part was the interpretation of the results. Investigated buildings were assessed within a moderate climate zone and "Cradle to Cradle" system boundaries over a lifetime of 60 years. The product and energy consumption phases generally contributed to the highest GHG emissions. In terms of materials, aerated concrete (up to 89.4%), concrete (20-51%) and clay brick (38-47%) caused the highest values for the GWP indicator. The end-of-life phase, including incineration, landfilling and reuse of materials, was quantified in the 0.1-74% range. Quantified global indicators are Global warming potential (GWP), Depletion potential of the stratospheric ozone layer (ODP), and Abiotic depletion potential for non-fossil resources (ADP-E). In this study, regional indicators are Acidification potential (AP), Eutrophication potential (EP) and Formation potential of tropospheric ozone (POCP). A building that achieves higher circularity is the building that makes the most use of renewable or reused resources, so it uses less raw materials. The circularity score representing materials recovery was 23% to 48%. The best circularity score of building E (48%) was due to downcycling (45.8%) and use as energy (32.1%) of applied materials. The lowest circularity score was found for building I, with a value of 23%. The most suitable building in terms of environmental impact and circularity was identified using multicriteria analysis.

Prioritising the purpose: a Water System Justice framework for water utilities

ABSTRACT Water utilities provide water, sewerage and sanitation services. Yet, they have failed worldwide to provide safely managed water services to at least 2.2 billion people and safely managed sanitation services to between 3.5 and 4.4 billion. Following 70 years of experience in different modes of water services provision, this paper addresses the question: What lessons can be learnt from the scholarship on the policy and practice of water service provision, and how can these inform and be integrated into a justice framework? This paper examines the literature through the lens of Water System Justice, charting how an early stage of state water and sanitation provision gave way to an increase in private sector participation and eventually hybrid services provision. Neither the state, private nor hybrid models have been able to provide water and sanitation services to all. Combining a Water System Justice approach with a purpose-led market-shaping approach, we argue that the state must take responsibility for a purpose-based approach that puts the furthest behind first – in line with the Agenda 2030. This includes using water within water system boundaries (quantity) and standards (quality), through collaboration with other actors, using patient and local finance, contextual modular systems and ensuring accountability.

Topological chiral edge states in a synthetic dimension of atomic trap states

A key hallmark of quantum Hall physics is the existence of topological chiral states at the system boundary. Signatures of these edge states have been experimentally observed in cold atoms by using different approaches, including notably that of “synthetic dimensions” in which internal states are coupled together and reinterpreted as sites along an artificial spatial dimension. However, previous atomic synthetic dimension implementations have been limited to relatively small system sizes with inflexible boundaries. In this paper, we propose instead how to use a synthetic dimension of atomic trap states to observe chiral edge states in a large quantum Hall system with a tunable edge. We present numerical simulations for relevant experimental parameters, showing how this scheme may be used to probe the properties and robustness of the edge states to defects. Our work opens the way for future experiments in topological physics with synthetic dimensions, while also providing new ways to manipulate and control highly excited trap states. Published by the American Physical Society 2025

A life cycle assessment of broiler chicken meat and egg production in Iceland.

A life cycle assessment of broiler chicken meat and egg production in Iceland.

Environmental impact of rabbit production systems: a farm-based cradle-to-gate analysis.

Environmental impact of rabbit production systems: a farm-based cradle-to-gate analysis.

Vibration suppression boundary control and stability analysis of axial conveyors

The vibration control problem of axial conveyors becomes complex due to the possibility of vibration being caused by multiple factors. This article focuses on vibration problems, designs boundary controllers, and analyzes the stability of the system. The external disturbances of the axial conveyor are time-varying, which is more in line with reality. However, this brings difficulties to the design of controllers. The dynamic equations of the system under consideration are established using the Hamiltonian principle. The active control procedure is adopted in the system boundary to solve the vibration suppression problem. Active control can improve the tracking performance of the axial moving belt by actively adjusting the pulley to better follow the movement of the belt. Disturbance observers are used to estimate and compensate for system disturbances. The proposed boundary control law can reduce the vibration deviation of the system, avoid control overflow effects, and prove that the state of the axial motion belt system converges near the equilibrium point, ensuring the stability of the axial conveyor. The effectiveness of the controller was verified by comparing it with simulation results.

Corporate Biodiversity and Water Impact and Risk: Seven Key Principles for Leveraging Insights From Satellite Remote Sensing

AbstractAmid unprecedented biodiversity loss and water scarcity, calls for corporate responsibility are becoming louder and have led to emerging non‐financial disclosure frameworks with demanding data needs. While the role of satellite remote sensing (RS) is highly anticipated to address data needs and boost transparency, critical thought on what is feasible and how to strategically integrate its insights for ambitious corporate biodiversity and water disclosure is lagging behind. To address this, we propose applying a systems perspective to represent the complex, multi‐scale interactions between biodiversity, water systems, and corporate operations, and to guide how to integrate RS contributions to analyze the full spectrum of impacts and risks—ranging from direct and concurrent to cascading, cumulative, and emergent. We highlight seven guiding (non‐exhaustive) principles for leveraging satellite RS data to assess corporate biodiversity and water impacts and risks. This process requires an effective system boundary (1) set spatially, temporally, and process‐wise. Within which, biodiversity and water's multi‐dimensionality (2) needs to be addressed to monitor the spatio‐temporal dynamics (3) that characterize ecosystem responses. To attribute risk and impact of detected changes, interactions need to be defined by causality (4) and directionality (5), and ultimately consider compound impacts (6) across commodities, supply chains and portfolios, as well as cross‐system interactions (7), for example, between climate change, water and biodiversity. We review each of these principles and related challenges individually, providing a system theory definition, relevant RS capabilities, and research directions. Addressing these seven principles will be crucial to harness satellite RS's potential for comprehensive biodiversity and water disclosure for strong corporate accountability.

Generating regenerative agriculture

Despite its being still a somewhat vague concept, regenerative agriculture has progressively been gaining momentum and popularity in recent years. While discussing the meaning of the term regenerative agriculture, we propose to link regenerative agriculture with the safe and just Earth system boundaries framework, as the basis for the generation of a paradigm that could robustly ground an appealing regenerative narrative that could nourish the vocation of a new generation of farmers and agronomists. The evaluation of the safe and just Earth system boundaries accounts for Earth system resilience and human well-being in an integrated framework, which is precisely what sustainable agriculture is all about. Our proposal connects the small (the farm) with the colossal (the Earth) in an attempt to confront one of the main sources of criticism for agriculture, i.e., its global environmental impact. The idea is to define the performance of regenerative agriculture in terms of its positive influence on the eight safe and just Earth system boundaries through its sustainable contribution to a highly-productive, environmentally-sound, nature- and biodiversity-respectful, socially-responsible, and ethically-committed agriculture. Finally, we propose a definition of regenerative agriculture that incorporates the abovementioned proposal.

Observation of non-Hermitian topological synchronization

Non-Hermitian topology plays a pivotal role in physical science and technology, exerting a profound impact across various scientific disciplines. Recently, the interplay between topological physics and nonlinear synchronization has aroused a great interest, leading to the emergence of an intriguing phenomenon known as topological synchronization, wherein nonlinear oscillators at boundaries synchronize through topological boundary states. To the best of our knowledge, however, this phenomenon has yet to be experimentally validated, and the study of non-Hermitian topological synchronization remains in its infancy. Here, we investigate non-Hermitian topological synchronization, uncovering the influence of system size and boundary site geometry on synchronization effects. We demonstrate that simply varying the lattice size allows transitions between three distinct types of non-Hermitian topological synchronization. Furthermore, we reveal that the geometry of the boundary sites introduces a degree of freedom, enabling the control over the configuration of non-Hermitian topological synchronization. These findings are experimentally validated using non-Hermitian nonlinear topological circuits. This work significantly broadens the scope of nonlinear non-Hermitian topological physics and opens new avenues for the application of synchronization phenomena in future technologies.

Analytical review of visualization methods for launch and landing of spacecraft with consideration of 64-bit system boundary value issues

The subject matter of this article is the contemporary software solutions used for modeling and visualizing spacecraft missions, specifically during the stages of launch, flight, and landing. The goal of this article is to critically evaluate popular game engines like Unity and Unreal Engine 5, along with specialized flight simulation software such as OpenRocket and Orbiter, focusing on their application in space simulations. The tasks are as follows: to investigate and assess the capabilities of the Unity and Unreal Engine 5 game engines in the context of space missions; to identify the limitations of 64-bit floating-point precision for large-scale space simulations and propose the potential for transitioning to 128-bit systems; to evaluate specialized tools like OpenRocket and Orbiter regarding their use for simulating spacecraft behavior; to analyze the existing limitations in integrating real-time data and suggest directions for further research and development. The obtained results of the article: It was established that Unity and Unreal Engine 5, although primarily developed for the gaming industry, can be adapted for aerospace simulations. However, due to the limitations of 64-bit precision, they are prone to visualization artifacts and computational errors that compromise the accuracy of the simulations. The transition to 128-bit systems was identified as a promising approach for enhancing the precision and flexibility of space mission modeling. This shift would allow better handling of the extensive scales and detailed aspects of space simulations. Specialized tools like OpenRocket and Orbiter demonstrated high capabilities in modeling aerodynamic characteristics and space missions. Nevertheless, they also face limitations in handling large-scale phenomena or integrating real-time data. The need for further research and development of new algorithms and data structures to ensure high precision and support for large datasets was identified. Additionally, improving the integration of real-time data and user interfaces is necessary to make these tools more accessible. Conclusions. The development of 128-bit systems for space simulations is critically important for enhancing the accuracy and realism of the modeling. The Unity and Unreal Engine 5 game engines although having the potential for adaptation to aerospace simulations, require significant improvements in handling large scales and detailed aspects. The tools OpenRocket and Orbiter have significant potential in specialized areas but also need enhancement to expand their capabilities. Further research and development are necessary to create new solutions that will increase the accuracy and functionality of the software for simulating space missions, as well as to develop new hardware such as more powerful processors and increased memory.

Carbon-Negative Organic Beef Production: Upcycling Food Processing By-Products and Food Leftovers

A substantial amount of food processing by-products and food leftovers are managed as waste, while conventional beef production in Japan relies heavily on imported concentrate feed, leading to considerable environmental impacts. Hanzawa Ranch in Kushiro, Hokkaido, Japan, is a pioneering organic beef farm that utilizes only food processing by-products and food leftovers alongside farm-grown organic forage. This study conducted a life cycle assessment to evaluate the environmental impacts of organic beef production at Hanzawa Ranch (Hanzawa system) compared to the conventional Japanese beef production method. The objective was to determine the extent to which environmental load was reduced by using upcycled feed from food processing by-products and food leftovers. The system boundaries included feed production, transportation, processing, animal management, enteric fermentation, excreta, and its management. Additionally, the analysis for the Hanzawa system included the impacts of landfill avoidance by upcycling food processing by-products and food leftovers into feed. The functional unit was 1 kg of cold beef steer carcass. The assessment focused on contributions to climate change, acidification, eutrophication, and energy consumption. The environmental impacts of the Hanzawa system were 174%, 45%, 20%, and 80% lower for climate change, acidification, eutrophication, and energy consumption, respectively, compared to the conventional Japanese beef production system. The greenhouse gas emissions of the Hanzawa system were negative, attributed to the substantial benefits of diverting food processing by-products and food leftovers from landfill management by upcycling them into feed. Moreover, as no additional processing was required for upcycling in the Hanzawa system, this approach further reduced the environmental impacts of feed production across all assessed categories. Consequently, we conclude that carbon-negative beef can be produced using upcycled feed. Our findings suggest that livestock production plays a crucial role in advancing a circular bioeconomy and contributing to sustainable development.

Rethinking Sustainable Procurement: Investigating the Impact of System Boundary on Building Proposal Selection

The development of sustainable, healthy, and resilient buildings can position Canada as a global leader in the future of construction. Reforming the building procurement process will help achieve this goal, driving innovation in construction practices. Sustainable procurement has been gaining traction in the construction sector for the past two decades. Incorporating human health impact, durability, and resiliency into the framework ensures a more holistic approach to sustainability, addressing long-term well-being, structural longevity, and adaptability to changing environmental conditions. Yet there is a need to redefine sustainable procurement guidelines for buildings by incorporating human health impact and resiliency with the triple bottom line of sustainability. The objective of this research is to develop updated framework for the sustainable procurement of institutional buildings to enhance the construction procurement process by incorporating sustainability considerations and integrating resilience, durability and long-term human health. First, a comparative evaluation of system boundaries will be performed by comparing traditional procurement (cradle-to-gate) vs. the sustainable procurement framework (cradle-to-grave) for a selected institutional building. The outcomes of the case studies highlight that the cradle-to-grave system boundary offers a clear basis for decision-making in building construction. Second, a framework will be proposed for the sustainable procurement of institutional buildings based on the published literature and ISO 20400 standard, which will support the green procurement guidelines. The outcomes of this research will help assist Canada in achieving United Nations Sustainable Development Goals.