Review
Recent developments in Life Cycle Assessment

https://doi.org/10.1016/j.jenvman.2009.06.018Get rights and content

Abstract

Life Cycle Assessment is a tool to assess the environmental impacts and resources used throughout a product's life cycle, i.e., from raw material acquisition, via production and use phases, to waste management. The methodological development in LCA has been strong, and LCA is broadly applied in practice. The aim of this paper is to provide a review of recent developments of LCA methods. The focus is on some areas where there has been an intense methodological development during the last years. We also highlight some of the emerging issues. In relation to the Goal and Scope definition we especially discuss the distinction between attributional and consequential LCA. For the Inventory Analysis, this distinction is relevant when discussing system boundaries, data collection, and allocation. Also highlighted are developments concerning databases and Input–Output and hybrid LCA. In the sections on Life Cycle Impact Assessment we discuss the characteristics of the modelling as well as some recent developments for specific impact categories and weighting. In relation to the Interpretation the focus is on uncertainty analysis. Finally, we discuss recent developments in relation to some of the strengths and weaknesses of LCA.

Introduction

Climate change and other environmental threats have come more into focus during the last years. In order to meet these challenges, environmental considerations have to be integrated into a number of different types of decisions made both by business, individuals, and public administrations and policymakers (Nilsson and Eckerberg, 2007). Information on environmental aspects of different systems is thus needed, and many tools and indicators for assessing and benchmarking environmental impacts of different systems have been developed (e.g., Finnveden and Moberg, 2005, Ness et al., 2007). Examples include Life Cycle Assessment (LCA), Strategic Environmental Assessment (SEA), Environmental Impact Assessment (EIA), Environmental Risk Assessment (ERA), Cost-Benefit Analysis (CBA), Material Flow Analysis (MFA), and Ecological Footprint. In this paper, the emphasis is on LCA, but we will also address its influences from ERA, ecological footprint, etc. and vice-versa.

Life Cycle Assessment is a tool to assess the potential environmental impacts and resources used throughout a product's life-cycle, i.e., from raw material acquisition, via production and use phases, to waste management (ISO, 2006a). The waste management phase includes disposal as well as recycling. The term ‘product’ includes both goods and services (ISO, 2006a). LCA is a comprehensive assessment and considers all attributes or aspects of natural environment, human health, and resources (ISO, 2006a). The unique feature of LCA is the focus on products in a life-cycle perspective. The comprehensive scope of LCA is useful in order to avoid problem-shifting, for example, from one phase of the life-cycle to another, from one region to another, or from one environmental problem to another.

The interest in LCA grew rapidly during the 1990s, also when the first scientific publications emerged (e.g., Guinée et al., 1993a, Guinée et al., 1993b). At that time LCA was regarded with high expectations but its results were also often criticized (e.g., Udo de Udo de Haes, 1993, Ayres, 1995, Ehrenfeld, 1998, Krozer and Viz, 1998, Finnveden, 2000). Since then a strong development and harmonization has occurred resulting in an international standard (ISO, 2006a, ISO, 2006b), complemented by a number of guidelines (e.g., Guinée et al., 2002) and textbooks (Wenzel et al., 1997, Baumann and Tillman, 2004). This has increased the maturity and methodological robustness of LCA. The method is still under development, however. There are also several ongoing international initiatives to help build consensus and provide recommendations, including the Life Cycle Initiative of the United Nations Environment Program (UNEP) and the Society of Environmental Toxicology and Chemistry (SETAC; UNEP, 2002), the European Platform for LCA of the European Commission (2008b), and the emerging International Reference Life Cycle Data System (ILCD).

Sustainability assessment of products or technologies is normally seen as encompassing impacts in three dimensions – the social, the environmental, and the economic (Elkington, 1998). On all the three a life cycle perspective is relevant to avoid problem shifting in the product system. With inspiration from environmental LCA, work has started on the development of methods for social LCA, and under the UNEP/SETAC Life Cycle Initiative, a project group is working on this topic (Grießhammer et al., 2006). Jørgensen and co-workers give a review of the state-of-the-art for social LCA (Jørgensen et al., 2008). Also Life Cycle Costing (LCC) is being developed as a method on its own. A recent overview was provided by SETAC (Hunkeler et al., 2008). The integration of the three sustainability dimensions is analysed and discussed in, for example, the EU 6th Framework Co-ordination Action for innovation in Life-Cycle Analysis for Sustainability (CALCAS, 2009) and the EU 7th Framework project Development and application of a standardized methodology for the PROspective SUstaInability assessment of TEchnologies (PROSUITE; Patel, 2009). This paper, however, focuses on environmental LCA.

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 Goal and Scope Definition includes the reasons for carrying out the study, the intended application, and the intended audience (ISO, 2006a). It is also the place where the system boundaries of the study are described and the functional unit is defined. The functional unit is a quantitative measure of the functions that the goods (or service) provide. The result from the LCI is a compilation of the inputs (resources) and the outputs (emissions) from the product over its life-cycle in relation to the functional unit. The LCIA is aimed at understanding and evaluating the magnitude and significance of the potential environmental impacts of the studied system (ISO, 2006a). In the Interpretation, the results from the previous phases are evaluated in relation to the goal and scope in order to reach conclusions and recommendations (ISO, 2006a).

The aim of this paper is to provide a review of recent developments in LCA methodology. We build upon previous reviews (e.g., Rebitzer et al., 2004, Pennington et al., 2004). Our focus is on areas with significant methodological development during the last years. We also highlight some of the emerging issues. In relation to the Goal and Scope Definition, we especially discuss the distinction between attributional and consequential LCA (Section 3). This distinction is relevant, for example, when defining system boundaries in the LCI which is further discussed in Section 5. The use of scenarios in LCA is discussed in Section 4. We also highlight developments concerning databases and input–output and hybrid LCA in Section 6. In the sections on LCIA (Sections 7 Impact assessment; general structure, 8 Current developments in Life Cycle Impact Assessment) we discuss the characteristics of the modelling as well as some recent developments for specific impact categories (including spatial differentiation, toxicity, indoor air pollution, and impacts from use of land, resources, and water) and weighting. In relation to the interpretation we focus on uncertainty analysis (Section 9). Finally, we discuss these developments in relation to some of the strengths and weaknesses of LCA. First, however, some characteristics of LCA are elaborated in Section 2.

Section snippets

Some characteristics of Life Cycle Assessment vis-à-vis other environmental assessment tools

The focus on a product system in Life Cycle Assessment has some important implications for the nature of the impacts, which can be modelled in LCA:

  • The product system is extended in time and space, and the emission inventory is often aggregated in a form which restricts knowledge about the geographical location of the individual emissions (this is further discussed in Section 8.3).

  • The LCI results are also typically unaccompanied by information about the temporal course of the emission or the

Attributional and consequential LCA

In the Goal and Scope Definition, questions or hypotheses should be formulated. This is an important phase since the appropriate LCA method depends on the purpose of the individual study (Consoli et al., 1993). Many attempts have been made to describe when different types of LCA are appropriate. We distinguish between two types of methods for LCA: attributional and consequential LCA. Attributional LCA is defined by its focus on describing the environmentally relevant physical flows to and from

Scenarios

In many applications, it is relevant to model future systems. This may, for example, be the case for consequential LCA where the impacts of a future possible decision are assessed, or in attributional LCAs aiming at assessing future technologies or systems. Whenever the systems that are modelled are future systems, a decision must be made on how to model the future. An easy way is of course to assume that the future is like the present and then model the present system. Sometimes this may be a

System boundaries and allocation

There are three major types of system boundaries in the LCI (Guinée et al., 2002):

  • between the technical system and the environment,

  • between significant and insignificant processes, and

  • between the technological system under study and other technological systems.

Sometimes time and geographical limits are mentioned as system boundaries. However, these can be seen as special cases of boundaries towards the environment or towards other technological systems (see below).

In relation to the system

Database development

An LCI requires a lot of data. Setting up inventory data can be one of the most labour- and time-intensive stages of an LCA. This is often challenging due to the lack of appropriate data for the product system under study (e.g., for chemicals production). In order to facilitate the LCI and avoid duplication in data compilation, many databases have therefore been developed in the last decades. These include public national or regional databases, industry databases, and consultants' databases

Impact assessment; general structure

The purpose of the Life Cycle Impact Assessment (LCIA) is to provide additional information to help assess the results from the Inventory Analysis so as to better understand their environmental significance (ISO, 2006a). Thus, the LCIA should interpret the inventory results into their potential impacts on what is referred to as the “areas of protection” of the LCIA (Consoli et al., 1993), i.e., the entities that we want to protect by using the LCA. Today, there is acceptance in the LCA

Towards a recommended practice for LCIA

Life Cycle Assessment is still a young discipline, mainly developed from the mid-1980s until now. Throughout the 1990s, a number of consecutive international working groups in SETAC took the method development and consensus building a good step forwards (Consoli et al., 1993, Fava et al., 1993, Udo de Haes, 1996, Udo de Haes et al., 2002), but LCIA is still a discipline in vivid development.

Today, several LCIA methods are available, and there is not always an obvious choice between them. In

Uncertainties in LCA

As with many decision support tools, uncertainties are often not considered in LCA studies although they can be high. But, there is arguably a necessity for an analysis of the uncertainties involved in carrying out an LCA study to help focus research efforts and also to provide support in the interpretation of LCA study results. In this section, we build on and extend several review papers that concentrate on uncertainty in LCA, notably Huijbregts et al., 2001, Björklund, 2002, Heijungs and

Discussion

The LCA methodological development has been strong over the last decades. Several of the limitations that have been mentioned in critical reviews have also been addressed. Several of them can never be fully solved and are common to other tools, but better data and better methods are developed. For example:

  • LCA is very data intensive, and lack of data can restrict the conclusions that can be drawn from a specific study. However, as discussed above, better databases are developed, and growing

Conclusions

Environmental considerations need to be integrated in many types of decisions. This includes decisions related to goods and services. In order to do that, knowledge must be available. When studying environmental impacts of products and services it is vital to study these in a life cycle perspective, in order to avoid problem-shifting from one part of the life-cycle to another, from one geographical area to another. It is also important to make a comprehensive assessment in terms of

Disclaimer

The views presented in this manuscript are those of the authors and do not necessarily reflect the opinions of the associated organisations.

Acknowledgements

The work presented here is financially supported by several organisations including the European Commission (through the CALCAS project), the Foundation for Strategic Environmental Research (MISTRA), and the Swedish Environmental Protection Agency (through the research programme Towards Sustainable Waste Management). All are gratefully acknowledged.

References (261)

  • O. Eriksson et al.

    ORWARE – a simulation tool for waste management

    Resour. Conserv. Recycling

    (2002)
  • O. Eriksson et al.

    Life Cycle Assessment of fuels for district heating: a comparison of waste incineration, biomass- and natural gas combustion

    Energy Policy

    (2007)
  • G. Finnveden et al.

    Environmental systems analysis tools – an overview

    J. Cleaner Prod.

    (2005)
  • G. Finnveden et al.

    Exergies of natural resources in life cycle assessment and other applications

    Energy

    (1997)
  • G. Finnveden et al.

    Solid waste treatment within the framework of life-cycle assessment

    J. Cleaner Prod.

    (1995)
  • K. Gäbel et al.

    The design and building of a lifecycle based process model for simulating environmental performance, product performance and cost in cement manufacturing

    J. Clean. Prod.

    (2004)
  • J.B. Guinée et al.

    A proposal for the classification of toxic substances within the framework of Life Cycle Assessment of products

    Chemosphere

    (1993)
  • J.B. Guinée et al.

    Quantitative life cycle assessment of products: 1. Goal definition and inventory

    J. Clean. Prod.

    (1993)
  • J.B. Guinée et al.

    Quantitative life cycle assessment of products: 2. Classification, valuation and improvement analysis

    J. Clean. Prod.

    (1993)
  • R. Heijungs

    A generic method for the identification of options for cleaner products. Ecol

    Economics

    (1994)
  • R. Heijungs

    Identification of key issues for further investigation in improving the reliability of life-cycle assessments

    J. Cleaner Prod.

    (1996)
  • R. Heijungs et al.

    Allocation and “what-if” scenarios in life cycle assessment of waste management systems

    Waste Manage.

    (2007)
  • Anon

    Guide to the Expression of Uncertainty in Measurement

    (1993)
  • APME

    Plastics Europe. Association of Plastics Manufacturers (APME). Life Cycle and Eco-profiles

  • Åström, S., 2004. Marginal Production of Pulpwood to the Pulp and Paper Industry. Master's Thesis T2004-283, Department...
  • Audsley, E., Alber, S., Clift, R., Cowell, S., Crettaz, P., Gaillard, G., Hausheer, J., Jolliet, O., Kleijn, R.,...
  • J.C. Bare et al.

    Midpoints versus endpoints: the sacrifices and benefits

    Int. J. LCA

    (2000)
  • J.C. Bare et al.

    TRACI, the tool for the reduction and assessment of chemical and other environmental impacts

    J. Ind. Ecol

    (2003)
  • J.C. Bare et al.

    Development of the method and US normalization database for life cycle impact assessment and sustainability metrics

    Environ. Sci. Technol

    (2006)
  • H. Baumann et al.

    A Hitchhiker's Guide to Life Cycle Assessment

    (2004)
  • Bayart, J.B., Bulle, C., Deschênes, L., Margni, M., Pfister, S., Vince, F., Koehler, A., submitted for publication. A...
  • E. Benetto et al.

    Possibility theory: a new approach to uncertainty analysis?

    Int. J. LCA

    (2006)
  • Björklund, A., Carlsson, A., Finnveden, G., Palm, V., Wadeskog, A., 2007. IPP-indicators for private and public...
  • A.E. Björklund

    Survey of approaches to improve reliability in LCA

    Int. J. LCA

    (2002)
  • M.E. Bösch et al.

    Applying cumulative exergy demand (CExD) indicators to the ecoinvent database

    Int. J. LCA

    (2007)
  • A. Braunschweig et al.

    Ökobilanzen für Unternehmungen; eine Wegleitung für die Praxis

    (1993)
  • K.H. Bruch et al.

    Sachbilanz einer Ökobilanz der Kupfererzeugung und -verarbeitung, Part 1

    Metall

    (1995)
  • CALCAS, 2009. Co-ordination action for innovation in life-cycle analysis for sustainability....
  • C. Capello et al.

    Life-cycle inventory of waste solvent distillation: statistical analysis of empirical data

    Environ. Sci. Technol.

    (2005)
  • T.H. Christensen et al.

    Experience with the use of LCA-modelling (EASEWASTE) in waste management

    Waste Manage. Res.

    (2007)
  • A. Ciroth

    ICT for environment in Life Cycle Applications: open LCA − a new open source software for Life Cycle Assessment

    Int. J. LCA

    (2007)
  • A. Ciroth et al.

    Validation. The missing link in life cycle assessment. Towards pragmatic LCAs

    Int. J. LCA

    (2006)
  • U. Claeson

    Analyzing Technological Change Using Experience Curves – A Study of the Combined Cycle Gas Turbine Technology

    (2000)
  • CPM, 2007. SPINE@CPM database. Competence Center in Environmental Assessment of Product and Material Systems (CPM),...
  • P. Crettaz et al.

    Assessing human health response in life cycle assessment using ED10s and DALYs: Part 1 – Cancer effects

    Risk. Anal.

    (2002)
  • M.A. Curran

    Co-product and input allocation approaches for creating life-cycle inventory data: a literature review

    Int. J. LCA 1/07

    (2007)
  • Deutsches Kupferinstitut, 1995. Sachbilanz einer Ökobilanz der Kupfererzeugung und – verarbeitung. Deutsches...
  • J. Dewulf et al.

    Cumulative Exergy Extraction from the Natural Environment (CEENE): a comprehensive Life Cycle Impact Assessment method for resource accounting

    Environ. Sci. Technol.

    (2007)
  • Doka, G., 2003. Life Cycle Inventories of Waste Treatment Services. Ecoinvent Report No. 13 (Parts I–IV), Swiss Centre...
  • Cited by (2326)

    View all citing articles on Scopus
    View full text