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Life cycle assessment

Life cycle assessment

Published: April 22, 2010, 6:07 pm
Updated: April 22, 2010, 6:07 pm
Lead Author: Goran Finnveden
Topics: Business & The Environment Bioremediation Complex Systems Environmental & Resource Management Environmental Assessment Environmental Impact Assessment Ecological Risk Assessment Environmental Monitoring Natural Resource Management & Policy Anthropogenic Ecosystems
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This article has been reviewed by the following Topic Editor: Leszek Bledzki

Description

A Life Cycle Assessment is one of many tools used to determine the environmental impacts of a particular good or service, just by its existence. In order to meet current environmental challenges, information on the environmental aspects of different systems is needed by businesses, individuals, public administrations, and policy makers [1]. Many tools and indicators for assessing environmental impacts of different systems have been developed, including; the Strategic Environmental Assessment (SEA), the Environmental Impact Assessment (EIA), the Environmental Risk Assessment (ERA), the Cost-Benefit Analysis (CBA), the Material Flow Analysis (MFA), the Ecological Footprint, and last but not least, the Life Cycle Assesment (LCA) [2], [3]. For broader sustainability assessments, a Life Cycle Assessment can be combined with a Life Cycle Costing study or any of the other systems mentioned for greater breadth and depth in understanding [4], [5]. Additionally, various types of Life Cycle Assessments can be combined to explore complexities within the environment (e.g. an environmental LCA with a social LCA).

An LCA assesses the environmental impacts of a product and the resources used throughout a product’s life cycle; from raw material acquisition, via production and use phases, to waste management (the term ‘product’ referring to both goods and services) [6]. It is this focus on the life cycle of a product that makes an LCA so unique. Consequently, an LCA offers a comprehensive view that considers impacts on the natural environment, human health, and resources, among other things [7]. This comprehensive scope is useful in order to avoid problem-shifting, i.e.: problems beginning in one phase of the life cycle and then appearing in another, or problems arising in one region and then becoming apparent in another [8]. LCA applications include product development and improvement, strategic planning, public policy making and marketing [9]. There are two basic types of LCA, an accounting or attributional LCA, and a consequential or effect-oriented LCA (see [10], [11], {[ref|12}}). In an accounting or attributional LCA, a system is described as it is. In a consequential or effect-oriented LCA, the consequences of a particular choice are modeled and considered. These two types of LCA use different types of data, one that is specific to basic processes, and one that allows for a reflection of change between the various end results of a choice.

The goal of LCA is to compare the full range of environmental and social damages assignable to products and services, to be able to choose the least harmful one.

Phases of Life Cycle Assessment

There are four phases in an LCA study: Goal and Scope Definition, Life Cycle Inventory Analysis (LCI), Life Cycle Impact Assessment (LCIA), and Interpretation. 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. The sum of all those steps - or phases - is the life cycle of the product.

  • In the Goal and Scope Definition phase the reasons behind the study, the intended application of the study, and the intended audience of the study are explained [12]. This is also the phase in which the system boundaries of the study are described and the functional unit is defined (the functional unit being a quantitative measure of the functions that the product in question provides) [13].
  • In the Life Cycle Inventory Analysis phase of the study, a list is compiled of the inputs (resources) and outputs (emissions) from the product in question. This list considers the inputs and outputs of the product over its life cycle in relation to the functional unit.
  • In the Life Cycle Impact Assessment phase of the study, the goal is to understand and evaluate the magnitude and significance of the potential environmental impacts of the studied system [14].
  • In the Interpretation phase, results from the previous phases are evaluated in order to reach conclusions and recommendations [15].

 

Of all the phases of an LCA study, the LCIA phase may be the most complex. This phase may consist of many different elements, including a selection of impact categories portion and a characterization portion [16]. The selection of impact categories portion of the LCIA phase involves choosing aspects of the environment that are potentially affected by the product being studied. Often a selection can be made based on pre-defined lists or recommendations [[17], [18], [19], [20], [21], [22]. Examples of often-used impact categories include climate change, acidification, human toxicity, abiotic resources, or biotic resources. In the characterization portion of the LCIA, the contributions to the selected impact categories are modeled quantitatively and then expressed as an impact score in a unit common to all contributions within the selected impact categories. For example, an often-used characterization factor for climate change is the global warming potential for time horizon 100 years (GWP100), or kg CO2-equivalents for greenhouse gases [23]. The characterization portion of the LCIA phase allows for the contributions from all emissions and resource extractions within each impact category to be totaled. It additionally allows for a translation of the inventory data into a profile of environmental impact scores [24]. An optional element in the LCIA phase of an LCA study is a weighting portion, where the results from the different impact categories are weighted against each other [25]. This can be useful in order to reach an overall ranking in comparative assessments.

LCA uses

An LCA study is one example of many environmental systems analysis tools [26]. As in all types of systems analysis, the question of system boundaries is essential in order to ensure accurate and reliable results. There are three major types of system boundaries to consider in an LCA, including boundaries between: the technical system and the environment, significant and insignificant processes, and the technical system under study and other technical systems [27]. In relation to the first system boundary, a distinction exists between the natural environment and the technical system. As an LCA should cover the entire life cycle, inputs should be traced all the way back to raw materials found in the natural environment. For example, crude oil can be considered an input, but not diesel oil. The distinction exists because crude oil is produced within the environment, while diesel oil is produced within the technical system. In parallel, the outputs should be distinct as well. In relation to the second type of system boundary, distinctions should be made between processes that are significant to the study and those that are not. In relation to the third system boundary, distinctions exist between various types of technical systems. It is imperative that the effects of one system be properly attributed to that system, or allocation problems will arise. For example, in a waste incineration plant three products are produced: heat, electricity, and waste treatment. If an LCA study is done on one of these products, then all of the inputs, outputs, emissions, and environmental effects must be properly attributed to the correct product. This is one of the most discussed methodological aspects of an LCA, and some recommended procedures have been developed [28], [29], [30], [31].


References

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Citation

Goran Finnveden (Lead Author);Leszek Bledzki (Topic Editor) "Life cycle assessment". In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth April 22, 2010; Last revised Date April 22, 2010; Retrieved February 10, 2012 <http://www.eoearth.org/article/Life_cycle_assessment>

The Author

Goran Finnveden Göran Finnveden is a Professor in Environmental Strategic Analysis, Head of the division for Environmental Strategies Research – fms at KTH (the Royal Institute of Technology), Stockholm, Sweden and vice head of the Department of Urban Planning and Environment. He has a MSc in Chemical Engineering, a PhD in Natural Resources Management and is an Associate Professor in Industrial Ecology. Göran Finnveden has specialised in environmental systems analysis tools with particular emphasis on Lif ... (Full Bio)

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