Sensitivity analysis of temporal parameters in a dynamic LCA framework

Optimization of depth of filler media in horizontal flow constructed wetlands for maximizing removal rate coefficients of targeted pollutant(s)

Varying the depth of HFCW media causes differences in the redox status within the system, and hence the community structure and diversity of bacteria, affecting removal rates of different pollutants. The key functional microorganisms of CWs that remove contaminants belong to the phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. Secondary data of 111 HFCWs (1232 datasets) were analyzed to deduce the relationship between volumetric removal rate coefficients (K_BOD, K_TN, K_TKN, and K_TP) and depth. Equations of depth were derived in terms of rate coefficients using machine learning approach (MLR and SVR) (R² = 0.85, 0.87 respectively). These equations were then used to find the optimum depth for pollutant(s) removal using Grey wolf optimization (GWO). The computed optimum depths were 1.48, 1.71, 1.91, 2.09, and 2.14 m for the removal of BOD, TKN, TN, TP, and combined nutrients, respectively, which were validated through primary data. This study would be helpful for optimal design of HFCWs.

From hemp grown on carbon-vulnerable lands to long-lasting bio-based products: Uncovering trade-offs between overall environmental impacts, sequestration in soil, and dynamic influences on global temperature

In this study, the potential of carbon storage in soil combined with mitigation via bio-based products is investigated for the case of 100 years of hemp cultivation on carbon-vulnerable land (CV-lands) in France. The originality of this study lies in the coupling of soil organic carbon (SOC) simulations (over 100 years of hemp cultivation) with consequential life cycle assessment (LCA) to investigate the mitigation potential of different environmental impacts, and the coupling with dynamic LCA to investigate the long-term effects on global warming. When hemp stems (straw) are left on the ground, SOC increases of 25.8 t ha^-1 are observed over 100 years. However, the greenhouse gas (GHG) emissions that result from diverting the initial land use to hemp cultivation cannot be compensated for and, therefore, this scenario cannot mitigate global warming or most other impacts. Two long-lasting product scenarios were studied: insulation boards in buildings and car panels, both involving the production of hemp concrete as co-product. Our study shows that, even though no additional long-term carbon sequestration in soil could be achieved, both scenarios ensured a long-term climate benefit well beyond 2100, mostly because of carbon sequestered in the hemp-based products but also as a result of avoided fossil-based products. Uncertainty analyses reveal that the yield is the most influential parameter, inducing significant uncertainties in all scenarios and most impact categories. According to the overall results obtained, the car panel scenario is the most promising pathway with the lowest environmental impacts and the highest potential for long-term global warming mitigation; this is in part due to the reduction of fuel consumption during the use phase.

Systematic Literature Review on Dynamic Life Cycle Inventory: Towards Industry 4.0 Applications

Life cycle assessment (LCA) is a well-established methodology to quantify the environmental impacts of products, processes, and services. An advanced branch of this methodology, dynamic LCA, is increasingly used to reflect the variation in such potential impacts over time. The most common form of dynamic LCA focuses on the dynamism of the life cycle inventory (LCI) phase, which can be enabled by digital models or sensors for a continuous data collection. We adopt a systematic literature review with the aim to support practitioners looking to apply dynamic LCI, particularly in Industry 4.0 applications. We select 67 publications related to dynamic LCI studies to analyze their goal and scope phase and how the dynamic element is integrated in the studies. We describe and discuss methods and applications for dynamic LCI, particularly those involving continuous data collection. Electricity consumption and/or electricity technology mixes are the most used dynamic components in the LCI, with 39 publications in total. This interest can be explained by variability over time and the relevance of electricity consumption as a driver of environmental impacts. Finally, we highlight eight research gaps that, when successfully addressed, could benefit the diffusion and development of sound dynamic LCI studies.

Towards a LCA Database for the Planning and Design of Zero-Emissions Neighborhoods

The integration of science-based knowledge on greenhouse gas (GHG) emissions into practice-based neighborhood design and planning is key to inform and implement climate mitigation strategies. LCA is a method that is commonly used to provide objective and science-based information on the environmental impacts of specified systems or products. To use a LCA methodology at neighborhood scale is in turn dependent on the development of a common structure for life cycle inventory data. Such a LCA database does not operate on its own, but functions as a structured source of relevant high-quality data inputs linked to other different analytical tools. The aim of this study is to analyze the needs and requirements and provide a foundation for a LCA database at neighborhood scale that can provide users with an interface to find and access life cycle data in the users’ preferred format. The result of this study is the outline of the foundations of a user-centric LCA database for neighborhoods, including several sub-systems (buildings, infrastructure, mobility, and energy supply). Recommendations are given in the Conclusions Section to provide harmonized decision support on reducing GHG emissions at local levels in the planning and design of urban development projects at the neighborhood scale.

Model-based assessment of cardiopulmonary autonomic regulation in paced deep breathing

Autonomic dysfunction can lead to many physical and psychological diseases. The assessment of autonomic regulation plays an important role in the prevention, diagnosis, and treatment of these diseases. A physiopathological mathematical model for cardiopulmonary autonomic regulation, namely Respiratory-Autonomic-Sinus (RSA) regulation Model, is proposed in this study. A series of differential equations are used to simulate the whole process of RSA phenomenon. Based on this model, with respiration signal and ECG signal simultaneously acquired in paced deep breathing scenario, we manage to obtain the cardiopulmonary autonomic regulation parameters (CARP), including the sensitivity of respiratory-sympathetic nerves and respiratory-parasympathetic nerves, the time delay of sympathetic, the sensitivity of norepinephrine and acetylcholine receptor, as well as cardiac remodeling factor by optimization algorithm. An experimental study has been conducted in healthy subjects, along with subjects with hypertension and coronary heart disease. CARP obtained in the experiment have shown their clinical significance.

Designing a Framework for Materials Flow by Integrating Circular Economy Principles with End-of-life Management Strategies

Circular economy is an upward trending notion that has drawn worldwide attention of policymakers, industry administrators, environmentalist as well as academic researchers. Though there are several tools developed for monitoring the material recovery, a very few number of research have been conducted to integrate circular economy principles with end-of-life (EOL) management strategies. This paper proposes an EOL-driven circular economy framework for the management of materials flow so as to extend the lifetime of materials through improved durability as well as to provide more social, economic and environmental benefits through less material waste. A case study from the agricultural waste industry is presented in order to test the model and validate its performance. The results show that the proposed framework has a good potential for small and medium enterprises (SME) advances.

LCA Practices of Plastics and Their Recycling: A Critical Review

In a bid to help address the environmental footprints associated with products and services, life cycle assessment (LCA) applications have become increasingly popular throughout the years. This review summarizes some important methodological developments in recent years, such as the advent of dynamic LCA, as well as highlighting recent LCA applications in the context of plastics/recycling with a focus on their methodological choices. Furthermore, this review aims to offer a set of possible research lines to improve the gap between LCA and decision-making (policy). It was found that the majority of reviewed papers are mostly conservative in their methodological practice, employing mostly static analyses and making little use of other methods. In order to bridge the gap between LCA and policy, it is suggested to broaden system boundaries through the integration of dynamic modelling methods, incorporating interactions between fore- and background systems, and including behavioral components where relevant. In addition, advanced sampling routines to further explore and assess the policy space are recommended. This is of paramount importance when dealing with recycling processes as the molecules/polymers constituting the output of those processes have to be benchmarked in terms of costs and, crucially, their sustainability character against virgin ones.

Evaluation of Life-Cycle Assessment Analysis: Application to Restoration Projects and New Construction in Alpine Climate, Japan

The present paper discusses the applications of life-cycle assessment (LCA) to construction works in Japan. LCA has been frequently used to assess the environmental impacts of new construction. Nonetheless, the applications of LCA to restoration have not been fully confirmed to date. It is said that historical buildings may contribute to sustainable development. Nonetheless, as for heritage buildings, since the protection of cultural value is usually prioritised, their environmental impacts may not be sufficiently explored. To this aim, this paper evaluated the environmental impacts of the restoration of heritage buildings. This paper consisted of two tasks. First, the restoration projects of heritage buildings in Japan were introduced. The restoration of two heritage houses was discussed, referring to heritage protection legislation in Japan. Second, LCA was performed on the restoration of heritage houses and the construction of contemporary houses. Environmental impacts were compared between the restoration and new construction with regard to greenhouse gas emissions and operational energy use. A focus was given to the amount of materials used. Restoration consumes a limited amount of materials compared to new construction, although the energy use of heritage buildings is considerable. The environmental impacts of restoration were quantified so that they were compared with those of new construction. The comparison indicated issues applying LCA to heritage buildings.

Addressing temporal considerations in life cycle assessment

In life cycle assessment (LCA), temporal considerations are usually lost during the life cycle inventory calculation, resulting in an aggregated "snapshot" of potential impacts. Disregarding such temporal considerations has previously been underlined as an important source of uncertainty, but a growing number of approaches have been developed to tackle this issue. Nevertheless, their adoption by LCA practitioners is still uncommon, which raises concerns about the representativeness of current LCA results. Furthermore, a lack of consistency can be observed in the used terms for discussions on temporal considerations. The purpose of this review is thus to search for common ground and to identify the current implementation challenges while also proposing development pathways. This paper introduces a glossary of the most frequently used terms related to temporal considerations in LCA to build a common understanding of key concepts and to facilitate discussions. A review is also performed on current solutions for temporal considerations in different LCA phases (goal and scope definition, life cycle inventory analysis and life cycle impact assessment), analysing each temporal consideration for its relevant conceptual developments in LCA and its level of operationalisation. We then present a potential stepwise approach and development pathways to address the current challenges of implementation for dynamic LCA (DLCA). Three key focal areas for integrating temporal considerations within the LCA framework are discussed: i) define the temporal scope over which temporal distributions of emissions are occurring, ii) use calendar-specific information to model systems and associated impacts, and iii) select the appropriate level of temporal resolution to describe the variations of flows and characterisation factors. Addressing more temporal considerations within a DLCA framework is expected to reduce uncertainties and increase the representativeness of results, but possible trade-offs between additional data collection efforts and the increased value of results from DLCAs should be kept in mind.

Temporal Aspects in Emission Accounting—Case Study of Agriculture Sector

Complex relations link climate change and agriculture. The vast majority of the studies that are looking into the quantification of the climate impacts use the Global Warming Potential (GWP) for a 100-year time horizon (GWP100) as the default metrics. The GWP, including the Bern Carbon Cycle Model (BCCM), was proposed as an alternative method to take into consideration the amount and time of emission, and the fraction of emissions that remained in the atmosphere from previous emission periods. Thus, this study aims to compare two methods for GHG emission accounting from the agriculture sector: the constant GWP100 and the time dynamic GWP100 horizon obtained by using the BCCM to find whether the obtained results will lead to similar or contradicting conclusions. Also, the effect of global temperature potential (GTP) of the studied system is summarized. The results show that the application of the BCCM would facilitate finding more efficient mitigation options for various pollutants and analyze various parts of the climate response system at a specific time in the future (amount of particular pollutants, temperature change potential). Moreover, analyze different solutions for reaching the emission mitigation targets at regional, national, or global levels.

Bringing value to the chemical industry from capture, storage and use of CO2: A dynamic LCA of formic acid production

Low carbon options for the chemical industry include switching from fossil to renewable energy, adopting new low-carbon production processes, along with retrofitting current plants with carbon capture for ulterior use (CCU technologies) or storage (CCS). In this paper, we combine a dynamic Life Cycle Assessment (d-LCA) with economic analysis to explore a potential transition to low-carbon manufacture of formic acid. We propose new methods to enable early technical, environmental and economic assessment of formic acid manufacture by electrochemical reduction of CO₂ (CCU), and compare this production route to the conventional synthesis pathways and to storing CO₂ in geological storage (CCS). Both CCU and CCS reduce carbon emissions in particular scenarios, although the uncertainty in results suggests that further research and scale-up validation are needed to clarify the relative emission reduction compared to conventional process pathways. There are trade-offs between resource security, cost and emissions between CCU and CCS systems. As expected, the CCS technology yields greater reductions in CO₂ emissions than the CCU scenarios and the conventional processes. However, compared to CCS systems, CCU has better economic potential and lower fossil consumption, especially when powered by renewable electricity. The integration of renewable energy in the chemical industry has an important climate mitigation role, especially for processes with high electrical and thermal energy demands.

Peru's road to climate action: Are we on the right path? The role of life cycle methods to improve Peruvian national contributions

Most developing nations have had to perform a swift transition from the voluntary greenhouse gas (GHG) emissions mitigation actions engaged in the Copenhagen Accord, to the relatively ambitious mitigations signed in the frame of the Paris Agreement. Consequently, Peru is currently creating its national structure to combat climate change through mitigation and adaptation actions. Nationally-determined contributions (NDCs) are the planned interventions that nations report for intended reductions in GHG emissions. In fact, Peru has now committed to reduce its annual GHG emissions by 30% in 2030 with respect to a business-as-usual estimation for that same year. The 76 NDCs have been divided into six main sectors: energy, transport, industrial processes, agriculture, forestry and waste. In this context, the main goal of this study is to provide a critical review of the validity and effectiveness of current mitigation NDCs proposed by the Peruvian government to comply with the Paris Agreement. Moreover, the analysis is accompanied by a discussion on how the use of life-cycle methods, namely Life Cycle Assessment, can be of utility in terms of policy support to evaluate the mitigation potential of these NDCs, as well as in the identification of additional contributions in sectors where the mitigation potential has been obviated. The expansion of system boundaries beyond the national context to account for the globalized nature of current market flows or the modelling of indirect impacts of a particular policy appear as relevant advantages of including life-cycle methods in public climate policy. The analysis, which is intended to be of utility to policy-makers in Peru and in other developing and emerging economies across the world, suggests that life-cycle methods arise as adequate tools to monitor the environmental appropriateness of adopting or adapting low-carbon technology to the local context.

Removing Shadows from Consequential LCA through a Time-Dependent Modeling Approach: Policy-Making in the Road Pavement Sector

Lack of dynamic accounting in consequential life cycle assessment (CLCA) can keep policy-makers from having an accurate analysis of emission flows over time. In this study, we propose a dynamic CLCA framework to assess the environmental consequences of pavements. Dynamic changes in the demand vector and technosphere matrices were computed using relevant time horizons of affected supply technologies and incorporating time-dependent parameters. A Monte Carlo simulation was then conducted to propagate the variability, model uncertainty, and parameter uncertainty sources of LCI to the damage results. The results show that simplifying pavement CLCA framework through neglecting real-time changes results in notable diversions in the damage results. The environmental benefits of substituting asphalt with concrete are underestimated by 7, 17, and 77% for climate change, human health and resources categories, respectively. A divergence of 114% was also observed in ecosystem quality when using the static framework. Moreover, the lack of accounting for a temporal profile for GHG emissions using static characterization factors leads to a divergence of the GWP benefits of substituting asphalt with concrete of 473 t CO_2eq (105%). The uncertainty results show 41-71% contribution of the variance in the damage categories is caused by the variability sources and is primarily attributed to monthly temperature accounting and service life.

Exploring the Current Challenges and Opportunities of Life Cycle Sustainability Assessment

Sustainability decision making is a complex task for policy makers, considering the possible unseen consequences it may entail. With a broader scope covering environmental, economic, and social aspects, Life Cycle Sustainability Assessment (LCSA) is a promising holistic method to deal with that complexity. However, to date, this method is limited to the hotspot analysis of a product, service, or system, and hence only assesses direct impacts and overlooks the indirect ones (or consequences). This critical literature review aims to explore the challenges and the research gaps related to the integration of three methods in LCSA representing three pillars of sustainability: (Environmental) Life Cycle Assessment (LCA), Life Cycle Costing (LCC), and Social Life Cycle Assessment (S-LCA). The challenges and the research gaps that appear when pairing two of these tools with each other are identified and discussed, i.e., the temporal issues, different perspectives, the indirect consequences, etc. Although this study does not aim to remove the shadows in LCSA methods, critical research gaps are identified in order to be addressed in future works. More case studies are also recommended for a deeper understanding of methodological trade-offs that might happen, especially when dealing with the consequential perspective.