Stages Of Life Cycle Assessment Research Articles

Bridging LCA data gaps by use of process simulation for energy generation

Life Cycle Assessment (LCA) is now a mature environmental management strategy that is internationally standardized. A cornerstone of LCA involves Life Cycle Inventory (LCI) databases, which are largely implemented in several types of research. Finding consistent and transparent LCI data for LCAs still remains difficult. Setting up inventory data can be one of the most labour- and time-intensive stages of LCA. It is often challenging due to the lack of appropriate data for the product system under study (e.g. for production of chemicals). With the aim of bridging this gap, this paper proposes the combined use of a process simulation tool, experimental process data and LCA for the computation of energy-related emissions in connection with a given process. The case studies address the environmental impact assessment associated with steam production from a gas turbine. The practical application of the methodological framework is that different operating conditions and technologies can be modelled and evaluated systematically by an energy production simulator, in order to mitigate the effect of lack of data on environmental impact assessments. The combination of LCA and process modelling enables various alternatives for the energy production process to be assessed and can thus be used as a support for decision-making in a system-based approach.

Life cycle assessment of hydrogen energy systems: a review of methodological choices

As a first step towards a consistent framework for both individual and comparative life cycle assessment (LCA) of hydrogen energy systems, this work performs a thorough literature review on the methodological choices made in LCA studies of these energy systems. Choices affecting the LCA stages “goal and scope definition”, “life cycle inventory analysis” (LCI) and “life cycle impact assessment” (LCIA) are targeted. This review considers 97 scientific papers published until December 2015, in which 509 original case studies of hydrogen energy systems are found. Based on the hydrogen production process, these case studies are classified into three technological categories: thermochemical, electrochemical and biological. A subdivision based on the scope of the studies is also applied, thus distinguishing case studies addressing hydrogen production only, hydrogen production and use in mobility and hydrogen production and use for power generation. Most of the hydrogen energy systems apply cradle/gate-to-gate boundaries, while cradle/gate-to-grave boundaries are found mainly for hydrogen use in mobility. The functional unit is usually mass- or energy-based for cradle/gate-to-gate studies and travelled distance for cradle/gate-to-grave studies. Multifunctionality is addressed mainly through system expansion and, to a lesser extent, physical allocation. Regarding LCI, scientific literature and life cycle databases are the main data sources for both background and foreground processes. Regarding LCIA, the most common impact categories evaluated are global warming and energy consumption through the IPCC and VDI methods, respectively. The remaining indicators are often evaluated using the CML family methods. The level of agreement of these trends with the available FC-HyGuide guidelines for LCA of hydrogen energy systems depends on the specific methodological aspect considered. This review on LCA of hydrogen energy systems succeeded in finding relevant trends in methodological choices, especially regarding the frequent use of system expansion and secondary data under production-oriented attributional approaches. These trends are expected to facilitate methodological decision making in future LCA studies of hydrogen energy systems. Furthermore, this review may provide a basis for the definition of a methodological framework to harmonise the LCA results of hydrogen available so far in the literature.

Life-cycle GHG assessment of carbon capture, use and geological storage (CCUS) for linked primary energy and electricity production

Carbon capture, use and geological storage (CCUS) could be feasible when fossil fuel-power plants are close to oil and gas reservoirs where CO2-enhanced oil recovery (EOR) technologies are applicable. In this research, we used a novel “well-to-well” approach that included the operations from natural gas production at oil field to CO2 injection for EOR operations at depleted oil fields. This paper includes estimates for greenhouse gas (GHG) emissions arising from a hypothetical CCUS case with a natural gas combined cycle power plant (NGCC) and Global Warming Potential (GWP) impact, by using Life-Cycle Assessment (LCA) methodology. Our research comprises a comparison with other electricity-generation technologies, including super critical pulverized carbon (SCPC), NGCC without CO2 capture, geothermal, mini-hydro, wind and nuclear. The LCA stages that were undertaken in this study were natural gas supply system, electricity generation, CO2capture, CO2transport, EOR operations and environmental monitoring. Three different functional units were used in this study: MJ, kWh and produced oil barrel (bbl). Results indicate that the energy produced by the described CCUS system had an environmental impact on climate change (global warming potential) of 0.044kg CO2e/MJ. The NGCC power plant with carbon capture unit would produce 0.177kg CO2e/kWh, representing about 21% and 36% of the estimated values for the SCPC and NGCC (without CCS) cases respectively, and about 24% less greenhouse gas emissions than the geothermal scenario. The oil produced in the EOR stage had a greenhouse gas emission rate of 38kg CO2e per oil barrel and 251kg CO2e per oil barrel in the whole CCUS system.

Life-cycle assessment framework for indoor emissions of synthetic nanoparticles

Life-Cycle Assessment (LCA) is a well- established method to evaluate impacts of chemicals on the environment and human health along the lifespan of products. However, the increasingly produced and applied nanomaterials (defined as one dimension \100 nm) show particular characteristics which are different from conventional chemicals orlarger particles. As a consequence, LCA does not provide sufficient guidance on how to deal with synthetic nanomaterials, neither in the exposure, nor in the effect assessment. This is particularly true for the workplace, where significant exposure can be expected via the lung, the route of major concern. Therefore, we developed a concise method which allows the inclusion of indoor nanoparticle exposure into LCA. New nanospecific properties are included along the LCA stages with a particular focus on theworkplace environment. We builtupon existing LCA methods and nanoparticle fate and exposure studies. The impact assessment requires new approaches for nanopar- ticles,suchasguidanceonrelevantendpoints,nanospeci- fic properties that are relevant for the toxicity, and guidance on the chemical identity of nanomaterials, i.e., categorization and distinction of different forms of nanomaterials. We present a framework which goes beyond traditional approaches of LCA and includes nanospecific fate parameters in the indoor exposure assessment as well as guidance on the development of effect and characterization factors for inhaled nanopar- ticles.Specifically,theindoorone-boxmodelisamended with new particle-specific parameters developed in the exposure literature. A concentration conversion and parameter estimation tool are presented. Finally, the modification of the traditional intake fraction to capture size-specific deposition and retention rate are discussed along with a strategy for a more robust effect assessment. The paper is a further step toward a fair comparison between conventional and nano-enabled products by integrating occupational exposure to synthetic nanoma- terials into LCA.

Approximate Life Cycle Assessment via Case-Based Reasoning for Eco-Design

Life cycle assessment (LCA) is a fundamental tool used in eco-design. However, it can be costly and resource intensive. We take steps toward the automation of the inventory and impact analyses stages of LCA via the proposal and development of a case-based reasoning (CBR) procedure to estimate the ecological effects of a product. The case memory in CBR, which contains representations and ecological effects of known products, is organized using an extension of the function-behavior-structure (FBS) representation for products. The extension includes ecological characteristics and values. We develop similarity metrics to measure the distance between cases in the case memory and the new product. The $k$ -medoids algorithm is used to cluster the case memory, our metrics enable cluster retrieval and case selection, and multiple linear regression analysis is employed for adaptation. Using a database of 100 fans, we test the accuracy of the proposed approach on a cross flow fan not in the database. The method gives ecological effect estimates within 3% of the true values when there are similar fans in the retrieved cluster and about 7% when the retrieved cluster does not contain similar fans.

IMPROVEMENTS IN THE LIFE CYCLE APPROACH AS AN ENVIRONMENTAL EVALUATION TOOL IN ORGANIC FARMING

Very few studies objectively quantify environmental impact of organic farming practices. The Life Cycle Assessment (LCA) tool has proved to be an accurate, objective, and transparent tool to quantify many environmental impacts. The purpose of this paper is to disseminate the LCA methodology, demonstrate its usefulness as an environmental assessment tool for organic farming, and determine which aspects of LCA need further development to improve their relevance in organic systems. Following the stages of LCA, we discuss the main drawback for each stage: a) Goal stage: discussion of the actual function for organic agriculture; b) Inventory stage: lack of specific databases for organic agriculture c) Impact Assessment: importance of local impact categories for agriculture. We briefly summarise recent work that has been conducted addressing local impacts, but there remain some aspects that should be improved. Our recommendation is that further research should focus on: 1) better knowledge of the nutritional quality of organic food; 2) providing homogenised datasets and 3) development of characterisation factors to evaluate intensities of agricultural activity practices.

An introduction to life cycle assessment with hands-on experiments for biodiesel production and use

This paper describes a hands-on project that introduces first year engineering students to life cycle assessment (LCA) through the comparison of the environmental impact of the production and use of three diesel fuels: petroleum diesel, biodiesel from new vegetable oil, and biodiesel from waste vegetable oil. The purpose of this LCA project was to incorporate life cycle thinking into the engineering design process, to apply the four main steps of LCA (definition and scope, inventory analysis, impact assessment and improvement assessment), and to explore some of the challenges associated with each step. The inventory for biodiesel production (from both new and waste vegetable oils) was based on measurements obtained by the students in laboratory experiments. The fossil diesel production inventory was obtained from the SimaPro® database. The inventory for the use of all three fuels was obtained from measurements taken during combustion of the fuels in a generator. A cradle-to-grave life cycle analysis was then conducted using SimaPro® for each fuel. The assessment of learning outcomes indicates a significant increase in conceptual understanding of the four stages of life cycle assessment, and an average gain of over 55% in overall knowledge of life cycle assessment.

Life cycle assessment of engineered nanomaterials: State of the art and strategies to overcome existing gaps

The use of engineered nanomaterials offers advantages as well as disadvantages from a sustainability perspective. It is important to identify such points as early as possible in order to be able to build on existing strengths, while counteracting disadvantages. Life Cycle Assessment (LCA) is a suitable method to assess the environmental performance of a product or process. But so far studies applying LCA to the area of nanotechnology have been scarce. One reason might be that the LCA framework has a whole list of issues that need further precision in order to be applicable to nanotechnologies: system boundaries and a functional unit have to be chosen in a way that allows one to do a comparison of equal functionalities; adequate and comprehensive life cycle inventory data for engineered nanomaterials are the key on the level of inventory analysis; and the impact assessment step requires a clear definition of the degree of detail on the level of nanoparticle emissions. The LCA studies existing thus far in the area of nanotechnology have barely begun to cover all these aspects. Thus, in order to improve the current situation, the authors propose to go ahead in each of the LCA stages as far as scientific advances allow. For the inventory modelling this means e.g. that comprehensive, transparently documented and quality ensured data of the most important engineered nanomaterials should be collected and made available in a widely-accepted format. Concerning nanoparticle emissions, as many parameters as possible have to be collected pertaining to the production, use, and the disposal phase of these engineered nanomaterials. Furthermore, on the level of impact assessment, relevant physical characteristics have to be identified for a toxicity assessment of nanoparticles and a consensus has to be found for a limited but sufficient number of independent parameters influencing toxicity to be collected.

Environmental Assessment Framework for Policy Applications: Life Cycle Assessment, External Costs and Multi-criteria Analysis

The paper presents a framework for the analysis of external costs of environmental burdens, namely an impact pathway analysis, often coupled with the inventory stage of life cycle assessment (LCA). The ground rule is: quantify as much as possible in terms of burdens (pollutant emissions, etc.), impacts, and their monetary equivalent, then use multi-criteria analysis (MCA) for any remaining impacts that are considered to be too uncertain or defy quantification through to monetization. Although MCA could be used directly on estimates of burdens or impacts, monetary valuation provides a mechanism for consistent weighting of impacts categories based on assessment of public preference. Further advantages of extending LCA through detailed impact assessment combined with monetary valuation are that it greatly simplifies MCA by combining a large number of different environmental impact categories, thereby avoiding an unmanageably large number of criteria, and also facilitates cost benefit analysis (CBA). The risks are noted of inappropriate use of the tools or interpretation/use of the results, and recommendations are made for improved practice. These points are illustrated with examples. The key messages are: (1) that policies should be targeted correctly to give a clear signal which source of a burden should be reduced by how much; (2) that analysts should take into account the needs of policy makers and the link between the analysis and possible policy applications; and (3) that current LCA practice gives limited guidance in both areas, largely through a lack of consideration of the relative and absolute importance of different types of impact. However, this is precisely the strength of external costs analysis, particularly when used with MCA.

Influence of functional unit on the life cycle assessment of traction batteries

This paper describes the influence of the choice of the functional unit on the results of an environmental assessment of different battery technologies for electric and hybrid vehicles. Battery, hybrid and fuel cell electric vehicles are considered as being environmentally friendly. However, the batteries they use are sometimes said to be environmentally unfriendly. At the current state of technology different battery types can be envisaged: lead-acid, nickel-cadmium, nickel-metal hydride, lithium-ion and sodium-nickel chloride. The environmental impacts described in this paper are based on a life cycle assessment (LCA) approach. One of the first critical stages of LCA is the definition of an appropriate and specific functional unit for electric and hybrid vehicle application. Most of the known LCA studies concerning batteries were performed while choosing different functional units, although this choice can influence the final results. An adequate functional unit, allowing to compare battery technologies in their real life vehicle application should be chosen. The results of the LCA are important as they will be used as a decision support for the end-of-life vehicles directive 2000/53/EC (Official Journal of the European Communities L269/24 2000). As a consequence, a thorough analysis is required to define an appropriate functional unit for the assessment of batteries for electric vehicles. This paper discusses this issue and will mainly focus on traction batteries for electric vehicles. An overview of the different parameters to be considered in the definition of a functional unit to compare battery technologies for battery electric vehicle application is described and discussed. An LCA study is performed for the most relevant potential functional units. SimaPro 6 is used as a software tool and Eco-indicator 99 as an impact assessment method. The influence of the different selected functional units on the results (Eco-indicator Points) is discussed. The environmental impact of the different electric vehicle battery technologies is described. A sensitivity analysis illustrates the robustness of the obtained results. Five main parameters are considered in each investigated functional unit: an equal depth of discharge is assumed, a relative number of batteries required during the life of the vehicle is calculated, the energy losses in the battery and the additional vehicle consumption due to the battery mass is included and the same lifetime distance target is taken into account. On the basis of the energy content, battery mass, number of cycles and vehicle autonomy three suitable functional units are defined: ‘battery packs with an identical mass’, ‘battery packs with an identical energy content’ and ‘battery packs with an identical one-charge range’. The results show that the differences in the results between these three functional units are small and imply less variation on the results than the other uncertainties inherent to LCA studies. On the other hand, the results obtained using other, less adequate, functional units can be quite different. When performing an LCA study, it’s important to choose an appropriate functional unit. Most of the time, this choice is unambiguous. However, sometimes this choice is more complicated when different correlated parameters have to be considered, as it is the case for traction batteries. When using a realistic functional unit, the result is not influenced significantly by the choice of one out of the three suitable functional units. Additionally, the life cycle assessment allowed concluding that three electric vehicle battery technologies have a comparable environmental impact: lead-acid, nickel-cadmium and nickel-metal hydride. Lithium-ion and sodium-nickel chloride have lower environmental impacts than the three previously cited technologies when used in a typical battery electric vehicle application. The article describes the need to consider all relevant parameters for the choice of a functional unit for an electric vehicle battery, as this choice can influence the conclusions. A more standardised method to define the functional unit could avoid these differences and could make it possible to compare the results of different traction battery LCA studies more easily.

Integration of Functional and Environmental Performance Design Decisions: A Mechanical Component Case Study

SummaryProduct design‐for‐environment (DfE) has traditionally relied on life‐cycle assessment (LCA) as a primary means of assessing environmental performance. To date, LCA has focused on static inventory and impacts of material streams during the stages of resource extraction, component manufacture, product use, and end of life at a high level of aggregation. Improvement analysis, though theoretically an important stage of LCA, is practically very challenging to implement using LCA alone. One reason for this is that the focus on detailed characterization of material streams does not facilitate a development of an understanding of the mechanistic relationship between design intent and material, manufacturing, and use‐phase potential impacts. As the product development community transitions from sequential design to more streamlined concurrent design, interactive design tools are needed as a supplement to assessment tools in order to facilitate tradeoffs among environmental and other factors. This article presents an environmental analysis approach based on detailed process modeling which evaluates components from a functional design point of view. From a manufacturer's perspective, local potential effects in aggregate are often as important as global potential impacts. Furthermore, impacts often relate to explicit trade‐offs between different life‐cycle stages, such as production and use. In this article, the influence of functional design and manufacturing specifications (surface tolerance and finish) on localized potential impacts is illustrated through two different mechanical component (steel roller bearing and rotating shaft) case studies. Detailed analytical tools are key in enabling optimization and trade‐offs by designers and process planners. The functional modeling approach is an important complement to LCA in providing a well‐defined view of environmental performance.