⚡ Models Of Life Cycle Assessment (LCA)

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Models Of Life Cycle Assessment (LCA)

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Life cycle assessment (LCA) of paper

For instance, in the case of a manufactured product, environmental impacts are assessed from raw material extraction and processing cradle , through the product's manufacture, distribution and use, to the recycling or final disposal of the materials composing it grave. An LCA study involves a thorough inventory of the energy and materials that are required across the industry value chain of the product, process or service, and calculates the corresponding emissions to the environment.

The aim is to document and improve the overall environmental profile of the product. ISO provides the 'principles and framework' of the Standard, while ISO provides an outline of the 'requirements and guidelines'. LCA studies the environmental aspects and potential impacts throughout a product's life cycle i. The general categories of environmental impacts needing consideration include resource use, human health, and ecological consequences. Criticisms have been leveled against the LCA approach, both in general and with regard to specific cases e.

Without a formal set of requirements and guidelines, an LCA can be completed based on a practitioner's views and believed methodologies. In turn, an LCA completed by 10 different parties could yield 10 different results. The ISO LCA Standard aims to normalize this; however, the guidelines are not overly restrictive and 10 different answers may still be generated. Life cycle assessment LCA is sometimes referred to synonymously as life cycle analysis in the scholarly and agency report literatures. As stated by the National Risk Management Research Laboratory of the EPA , "LCA is a technique to assess the environmental aspects and potential impacts associated with a product, process, or service, by:. Hence, it is a technique to assess environmental impacts associated with all the stages of a product's life from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance , and disposal or recycling.

The results are used to help decision-makers select products or processes that result in the least impact to the environment by considering an entire product system and avoiding sub-optimization that could occur if only a single process were used. Therefore, the goal of LCA is to compare the full range of environmental effects assignable to products and services by quantifying all inputs and outputs of material flows and assessing how these material flows affect the environment.

The term life cycle refers to the notion that a fair, holistic assessment requires the assessment of raw-material production, manufacture, distribution , use and disposal including all intervening transportation steps necessary or caused by the product's existence. Consequently, it should not be considered a single, unique method, but rather a family of methods attempting to quantify results through a different point-of-view. A third type of LCA, termed "social LCA", is also under development and is a distinct approach to that is intended to assess potential social and socio-economic implications and impacts. The limitations of LCA to focus solely on the ecological aspects of sustainability, and not the economical or social aspects, distinguishes it from product line analysis PLA and similar methods.

This limitation was made deliberately to avoid method overload, but recognizes these factors should not be ignored when making product decisions. According to standards in the ISO and , an LCA is carried out in four distinct phases, [4] [15] [ page needed ] [16] [ page needed ] as illustrated in the figure shown at the above right at opening of the article. The phases are often interdependent, in that the results of one phase will inform how other phases are completed. Therefore, none of the stages should be considered finalized until the entire study is complete. It is recommended that a study uses the keywords represented in the Standard when documenting these details e. Generally, an LCA study begins with an explicit statement of the goal, which sets out the context of the study and explains how and to whom the results are to be communicated.

Per ISO guidelines, the goal must unambiguously state the following items:. The goal should also be defined with the commissioner for the study, and it is recommended a detailed description for why the study is being carried out is acquired from the commissioner. Following the goal, the scope must be defined by outlining the qualitative and quantitative information included in the study. Unlike the goal, which may only include a few sentences, the scope often requires multiple pages. Life Cycle Inventory LCI analysis involves creating an inventory of flows from and to nature ecosphere for a product system. It is the process of quantifying raw material and energy requirements, atmospheric emissions, land emissions, water emissions, resource uses, and other releases over the life cycle of a product or process.

To develop the inventory, it is often recommended to start with a flow model of the technical system using data on inputs and outputs of the product system. Generally, the more detailed and complex the flow diagram, the more accurate the study and results. As referenced in the ISO standard, the data must be related to the functional unit, as well as the goal and scope. However, since the LCA stages are iterative in nature, the data collection phase my cause the goal or scope to change.

Conversely, a change in the goal or scope during the course of the study may cause additional collection of data or removal or previously collected data in the LCI. The output of an LCI is a compiled inventory of elementary flows from all of the processes in the studied product system s. The data is typically detailed in charts and requires a structured approach due to its complex nature.

When collecting the data for each process within the system boundary, the ISO LCA standard requires the study to measure or estimate the data in order to quantitatively represent each process in the product system. Ideally, when collecting data, a practitioner should aim to collect data from primary sources e. Items on the questionnaire to be recorded may include:.

Often times, the collection of primary data may be difficult and deemed proprietary or confidential by the owner. An alternative to primary data is secondary data, which is data that comes from LCA databases, literature sources, and other past studies. With secondary sources, it is often you find data that is similar to a process but not exact e. As such, it is important to explicitly document the differences in such data. However, secondary data is not always inferior to primary data. For example, referencing another work's data in which the author used very accurate primary data.

When identifying the inputs and outputs to document for each unit process within the product system of an LCI, a practitioner may come across the instance where a process has multiple input streams or generate multiple output streams. In such case, the practitioner should allocate the flows based on the "Allocation Procedure" [26] [28] [29] outlined in the previous "Goal and Scope" section of this article. One area where data access is likely to be difficult is flows from the technosphere. The technosphere is more simply defined as the human-made world. Typically, they will not have access to data concerning inputs and outputs for previous production processes of the product. The entity undertaking the LCA must then turn to secondary sources if it does not already have that data from its own previous studies.

National databases or data sets that come with LCA-practitioner tools, or that can be readily accessed, are the usual sources for that information. Care must then be taken to ensure that the secondary data source properly reflects regional or national conditions. This information is typically pulled from government agency national statistics tracking trade and services between sectors. This phase of LCA is aimed at evaluating the potential environmental and human health impacts resulting from the elementary flows determined in the LCI.

Life cycle impacts can also be categorized under the several phases of the development, production, use, and disposal of a product. Broadly speaking, these impacts can be divided into first impacts, use impacts, and end of life impacts. The results from the inventory analysis and impact assessment are summarized during the interpretation phase. The outcome of the interpretation phase is a set of conclusions and recommendations for the study. According to ISO , [15] [37] the interpretation should include the following:. A key purpose of performing life cycle interpretation is to determine the level of confidence in the final results and communicate them in a fair, complete, and accurate manner.

Interpreting the results of an LCA is not as simple as "3 is better than 2, therefore Alternative A is the best choice". This is accomplished by identifying the data elements that contribute significantly to each impact category, evaluating the sensitivity of these significant data elements, assessing the completeness and consistency of the study, and drawing conclusions and recommendations based on a clear understanding of how the LCA was conducted and the results were developed. Specifically, as voiced by M. Curran, the goal of the LCA interpretation phase is to identify the alternative that has the least cradle-to-grave environmental negative impact on land, sea, and air resources.

It has been suggested [ by whom? Major corporations all over the world [ peacock term ] are either undertaking LCA in house or commissioning studies, while governments support the development of national databases to support LCA. LCA also has major roles in environmental impact assessment , integrated waste management and pollution studies. A life cycle analysis is only as accurate and valid as is its basis set of data. Data validity is an ongoing concern for life cycle analyses.

If one of the pair, e. With regard to the timeliness of data, it has been noted that data validity can be at odds with the time that data-gathering takes. As noted above, the inventory in the LCA usually considers a number of stages including: materials extraction, processing and manufacturing, product use, and product disposal. Data sources used in LCAs are typically large databases. Common data sources include: [ according to whom?

Calculations for impact can then be done by hand, but it is more usual to streamline the process by using software. This can range from a simple spreadsheet, where the user enters the data manually to a fully automated program, where the user is not aware of the source data. Cradle-to-grave is the full Life Cycle Assessment from resource extraction 'cradle' to use phase and disposal phase 'grave'. For example, trees produce paper, which can be recycled into low-energy production cellulose fiberised paper insulation , then used as an energy-saving device in the ceiling of a home for 40 years, saving 2, times the fossil-fuel energy used in its production.

After 40 years the cellulose fibers are replaced and the old fibers are disposed of, possibly incinerated. All inputs and outputs are considered for all the phases of the life cycle. Cradle-to-gate is an assessment of a partial product life cycle from resource extraction cradle to the factory gate i. The use phase and disposal phase of the product are omitted in this case. Cradle-to-gate assessments are sometimes the basis for environmental product declarations EPD termed business-to-business EPDs.

This allows the LCA to collect all of the impacts leading up to resources being purchased by the facility. They can then add the steps involved in their transport to plant and manufacture process to more easily produce their own cradle-to-gate values for their products. Cradle-to-cradle is a specific kind of cradle-to-grave assessment, where the end-of-life disposal step for the product is a recycling process. It is a method used to minimize the environmental impact of products by employing sustainable production, operation, and disposal practices and aims to incorporate social responsibility into product development.

Allocation of burden for products in open loop production systems presents considerable challenges for LCA. Various methods, such as the avoided burden approach have been proposed to deal with the issues involved. Gate-to-gate is a partial LCA looking at only one value-added process in the entire production chain. Gate-to-gate modules may also later be linked in their appropriate production chain to form a complete cradle-to-gate evaluation.

Well-to-wheel is the specific LCA used for transport fuels and vehicles. The analysis is often broken down into stages entitled "well-to-station", or "well-to-tank", and "station-to-wheel" or "tank-to-wheel", or "plug-to-wheel". The first stage, which incorporates the feedstock or fuel production and processing and fuel delivery or energy transmission, and is called the "upstream" stage, while the stage that deals with vehicle operation itself is sometimes called the "downstream" stage. The well-to-wheel analysis is commonly used to assess total energy consumption, or the energy conversion efficiency and emissions impact of marine vessels , aircraft and motor vehicles , including their carbon footprint , and the fuels used in each of these transport modes.

The well-to-wheel variant has a significant input on a model developed by the Argonne National Laboratory. The model evaluates the impacts of fuel use using a well-to-wheel evaluation while a traditional cradle-to-grave approach is used to determine the impacts from the vehicle itself. The model reports energy use, greenhouse gas emissions , and six additional pollutants: volatile organic compounds VOCs , carbon monoxide CO , nitrogen oxide NOx , particulate matter with size smaller than 10 micrometre PM10 , particulate matter with size smaller than 2. Economic input—output LCA EIOLCA involves use of aggregate sector-level data on how much environmental impact can be attributed to each sector of the economy and how much each sector purchases from other sectors.

Additionally the translation of economic quantities into environmental impacts is not validated. While a conventional LCA uses many of the same approaches and strategies as an Eco-LCA, the latter considers a much broader range of ecological impacts. It was designed to provide a guide to wise management of human activities by understanding the direct and indirect impacts on ecological resources and surrounding ecosystems.

Developed by Ohio State University Center for resilience, Eco-LCA is a methodology that quantitatively takes into account regulating and supporting services during the life cycle of economic goods and products. In this approach services are categorized in four main groups: supporting, regulating, provisioning and cultural services. Exergy of a system is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir.

This exergetic material input per unit of service EMIPS has been elaborated for transport technology. The service not only takes into account the total mass to be transported and the total distance, but also the mass per single transport and the delivery time. Life cycle energy analysis LCEA is an approach in which all energy inputs to a product are accounted for, not only direct energy inputs during manufacture, but also all energy inputs needed to produce components, materials and services needed for the manufacturing process.

It is recognized that much energy is lost in the production of energy commodities themselves, such as nuclear energy , photovoltaic electricity or high-quality petroleum products. Net energy content is the energy content of the product minus energy input used during extraction and conversion , directly or indirectly. A controversial early result of LCEA claimed that manufacturing solar cells requires more energy than can be recovered in using the solar cell [ citation needed ].

The result was refuted. Energy cannibalism refers to an effect where rapid growth of an entire energy-intensive industry creates a need for energy that uses or cannibalizes the energy of existing power plants. Thus during rapid growth the industry as a whole produces no energy because new energy is used to fuel the embodied energy of future power plants. Work has been undertaken in the UK to determine the life cycle energy alongside full LCA impacts of a number of renewable technologies.

If materials are incinerated during the disposal process, the energy released during burning can be harnessed and used for electricity production. This provides a low-impact energy source, especially when compared with coal and natural gas [89] While incineration produces more greenhouse gas emissions than landfills , the waste plants are well-fitted with regulated pollution control equipment to minimize this negative impact. A study comparing energy consumption and greenhouse gas emissions from landfills without energy recovery against incineration with energy recovery found incineration to be superior in all cases except for when landfill gas is recovered for electricity production.

Energy efficiency is arguably only one consideration in deciding which alternative process to employ, and should not be elevated as the only criterion for determining environmental acceptability. In recent years, the literature on life cycle assessment of energy technology has begun to reflect the interactions between the current electrical grid and future energy technology. Some papers have focused on energy life cycle, [94] [95] [96] while others have focused on carbon dioxide CO 2 and other greenhouse gases. If this is not done, a given class energy technology may emit more CO 2 over its lifetime than it initially thought it would mitigate, with this most well documented in wind energy's case.

A problem that energy analysis method cannot resolve is that different energy forms— heat , electricity , chemical energy etc. Life cycle assessment is a powerful tool for analyzing commensurable aspects of quantifiable systems. Rigid system boundaries make accounting for changes in the system difficult. This is sometimes referred to as the boundary critique to systems thinking.

The accuracy and availability of data can also contribute to inaccuracy. For instance, data from generic processes may be based on averages , unrepresentative sampling , or outdated results. Comparative life cycle analysis is often used to determine a better process or product to use. However, because of aspects like differing system boundaries, different statistical information, different product uses, etc. An in-depth review of 13 LCA studies of wood and paper products [] found a lack of consistency in the methods and assumptions used to track carbon during the product lifecycle.

Media related to Life-cycle assessment at Wikimedia Commons. From Wikipedia, the free encyclopedia. Methodology for assessing environmental impacts. For other uses, see Cradle to the grave disambiguation. This article is about the environment impacts of products. For the ultimate cost of business decisions, see Life cycle cost analysis. This article has multiple issues. Please help to improve it or discuss these issues on the talk page. Learn how and when to remove these template messages. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources.

Unsourced material may be challenged and removed. This article possibly contains original research. LCA is based on 4 main phases as in figure : 1 goal and scope 2 inventory analysis, 3 impact assessment, 4 interpretation. Figure: Life Cycle Assessment steps: goal and scope definition, life cycle inventory, life cycle impact assessment and interpretation Sala et al. In the goal and scope phase, the aims of the study are defined, namely the intended application, the reasons for carrying out the study and the intended audience. Main methodological choices are made in this step, in particular the exact definition of the functional unit, the identification of the system boundaries, the identification of the allocation procedures, the studied impact categories and the Life Cycle Impact Assessment LCIA models used, and the identification of data quality requirements.

The Life Cycle Inventory LCI phase involves the data collection and the calculation procedure for the quantification of inputs and outputs of the studied system. Data collected concern foreground processes e. Data are validated and put in relationship to the process units and functional unit. This is done through LCIA methods which firstly classify emissions into impact categories and secondly characterize them to common units so as to allow comparison details on the LCIA are presented in the section below. This step includes completeness, sensitivity and consistency checks. Uncertainty and accuracy of obtained results are also addressed in this step. Once the inventory data on the life cycle of product are compiled, the environmental performance of the product shall be evaluated by means of the Life Cycle Impact Assessment LCIA phase.

It includes four additional sub-steps classification, characterisation, normalisation and weighting as following detailed. Life Cycle Assessment LCA LCA is defined by the ISO as the compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life cycle. LCA methodology phases LCA is based on 4 main phases as in figure : 1 goal and scope 2 inventory analysis, 3 impact assessment, 4 interpretation. CO 2 , methane, etc. Characterisation Characterisation refers to the calculation of the magnitude of the contribution of each classified input and output to their respective impact categories, and aggregation of the contributions within each category. This is carried out by multiplying the inventoried values by the relevant characterisation factor for each impact category considered.

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