Gjalt Huppes

Life Cycle Assessment: Past, Present, and Future†

Environmental life cycle assessment (LCA) has developed fast over the last three decades. Whereas LCA developed from merely energy analysis to a comprehensive environmental burden analysis in the 1970s, full-fledged life cycle impact assessment and life cycle costing models were introduced in the 1980s and 1990 s, and social-LCA and particularly consequential LCA gained ground in the first decade of the 21st century. Many of the more recent developments were initiated to broaden traditional environmental LCA to a more comprehensive Life Cycle Sustainability Analysis (LCSA). Recently, a framework for LCSA was suggested linking life cycle sustainability questions to knowledge needed for addressing them, identifying available knowledge and related models, knowledge gaps, and defining research programs to fill these gaps. LCA is evolving into LCSA, which is a transdisciplinary integration framework of models rather than a model in itself. LCSA works with a plethora of disciplinary models and guides selecting the proper ones, given a specific sustainability question. Structuring, selecting, and making the plethora of disciplinary models practically available in relation to different types of life cycle sustainability questions is the main challenge.

A Framework for Quantified Eco‐Efficiency Analysis

Eco‐efficiency is an instrument for sustainability analysis, indicating an empirical relation in economic activities between environmental cost or value and environmental impact. This empirical relation can be matched against normative considerations as to how much environmental quality or improvement society would like to offer in exchange for economic welfare, or what the trade‐off between the economy and the environment should be if society is to realize a certain level of environmental quality. Its relevance lies in the fact that relations between economy and environment are not self‐evident, not at a micro level and not at the macro level resulting from micro‐level decisions for society as a whole. Clarifying the why and what of eco‐efficiency is a first step toward decision support on these two aspects of sustainability. With the main analytic framework established, filling in the actual economic and environmental relations requires further choices in modeling. Also, the integration of different environmental effects into a single score requires a clear definition of approach, because several partly overlapping methods exist. Some scaling problems accompany the specification of numerator and denominator, which need a solution and some standardization before eco‐efficiency analysis can become more widely used. With a method established, the final decision is how to embed it in practical decision making. In getting the details of eco‐efficiency better specified, its strengths, but also its weaknesses and limitations, need to be indicated more clearly.

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

Abstract Quantitative environmental life cycle assessment of products can be a useful tool in product-oriented environmental management. With this methodology the environmental impacts of the product during its entire life cycle are attributed quantitatively to the functioning of the product as far as possible. Currently, the scientific basis of methods for assessing the environmental impacts of products is not yet adequate. Methods are divergent, yield conflicting results and contain considerable gaps. In two successive articles an overview of the similarities and differences between these methods, as developed in different countries, is given. To enable fruitful discussions on methods used, and to make life cycle assessment (LCA) an acceptable tool for product-oriented environmental management, a general methodological framework is proposed. In this first article a general introduction to LCA is given, a general methodological framework is proposed and two components of the methodological framework, the goal definition and the inventory, are discussed in more detail.

Three Strategies to Overcome the Limitations of Life‐Cycle Assessment

Summary Many research efforts aim at an extension of life-cycle assessment (LCA) in order to increase its spatial or temporal detail or to enlarge its scope. This is an important contribution to industrial ecology as a scientific discipline, but from the application viewpoint other options are available to obtain more detailed information, or to obtain information over a broader range of impacts in a life-cycle perspective. This article discusses three different strategies to reach these aims: (1) extension of LCA—one consistent model; (2) use of a toolbox—separate models used in combination; and (3) hybrid analysis—combination of models with data flows between them. Extension of LCA offers the most consistent solution. Developments in LCA are moving toward greater spatial detail and temporal resolution and the inclusion of social issues. Creating a supertool with too many data and resource requirements is, however, a risk. Moreover, a number of social issues are not easily modeled in relation to a functional unit. The development of a toolbox offers the most flexibility regarding spatial and temporal information and regarding the inclusion of other types of impacts. The rigid structure of LCA no longer sets limits; every aspect can be dealt with according to the logic of the relevant tool. The results lack consistency, however, preventing further formal integration. The third strategy, hybrid analysis, takes up an intermediate position between the other two. This strategy is more flexible than extension of LCA and more consistent than a toolbox. Hybrid analysis thus has the potential to combine the strong points of the other two strategies. It offers an interesting path for further discovery, broader than the already well-known combination of process-LCA and input-output-LCA. We present a number of examples of hybrid analysis to illustrate the potentials of this strategy. Developments in the field of a toolbox or of hybrid analysis may become fully consistent with LCA, and then in fact become part of the first solution, extension of LCA.

Life cycle assessment of municipal solid waste management with regard to greenhouse gas emissions : Case study of Tianjin, China

The environmental impacts of municipal solid waste (MSW) management have been highlighted in China, due to the continually increasing amount of MSW being generated and the limited capacity of waste treatment facilities. Of particular interest is greenhouse gas (GHG) mitigation, aided by the Kyoto Mechanisms. China is an important case study for this global issue; however, an analysis of the entire life cycle of MSW management on GHG emissions is not available for China. This study evaluates the current and possible patterns of MSW management with regard to GHG emissions, using life cycle assessment (LCA), based on the Tianjin case. We assess the baseline scenario, reflecting the existing MSW management system, as well as a set of alternative scenarios, five exploring waste treatment technology innovations and one exploring integrated MSW management, to quantitatively predict potentials of GHG mitigation for Tianjin. Additionally, a sensitivity analysis is used to investigate the influence of landfill gas (LFG) collection efficiency, recycling rate and methodological choice, especially allocation, on the outcomes. The results show GHG emissions from Tianjins MSW management system amount to 467.34 Mg CO2 eq. per year, based on the treatment of MSW collected in the central districts in 2006, and the key issue is LFG released. The integrated MSW management scenario, combining different improvement options, shows the highest GHG mitigation potential. Given the limited financial support and the current waste management practice in Tianjin, LFG utilization scenario would be the preferred choice. The sensitivity analysis of recycling rate shows an approximately linear relation of inverse proportion between recycling rate and total GHG emissions. Kitchen waste composting makes a considerable contribution to total GHG emissions reduction. Allocation choices result in differences in total quantitative outcomes, but preference orders and contributions analysis are found to be robust, suggesting LCA can support decision making.

Economic Allocation : Examples and Derived Decision Tree

Goal, Scope and BackgroundIn the recently published (Dutch) Handbook on LCA, economic allocation is advised as baseline method for most allocation situations in a detailed LCA. Although the Handbook on LCA aimed to provide a ‘cookbook’ with operational guidelines for conducting each step of an LCA, this was not completely achieved for the allocation step. The guidelines for allocation largely remained at the level of principles. This restricted elaboration of economic allocation may hamper application in practice. Therefore, this paper elaborates some examples applying economic allocation.MethodTwo concepts are of particular importance when applying economic allocation: functional flow and multi-functional process. The definitions of these concepts are presented and discussed. The basic principle of economic allocation is that having determined the various functional flows of a multi-functional process, all other flows need to be allocated to these functional flows according to their shares in the total proceeds. Proceeds are based on prices and these are not always easy to determine for a process. A summary of possible solutions for different problems when determining prices is given.Results and DiscussionThe examples presented focus on co-production and various recycling situations. All examples are hypothetical in order to avoid discussions on the data. The examples show that the prices of the functional flows determine the allocation results. It is of importance to have correct information on the relative prices of the functional flows at stake, especially whether they are negative or positive. Learning from these examples, we establish a decision tree for economic allocation. The decision tree is meant for identifying and handling multi-functionality situations starting from a defined (product) system. This decision tree is with minor adaptations also applicable to other allocation methods and has a more general value than for the economic allocation method only.Conclusions and perspectiveThe examples have helped us to establish a decision tree for handling the multi-functionality problem by economic allocation. The examples can be broadened to other materials and allocation situations. We would encourage others to provide other examples and experiences as we expect that these will help to further improve and refine the guidelines and decision tree for economic allocation in future.

Material flows and economic models: an analytical comparison of SFA, LCA and partial equilibrium models

Abstract The growing concern for environmental problems in the current economy has spurred the study of the way materials and substances flow through the economy, resulting in many different types of analysis. Since all of these have their merits and shortcomings, much of the present theoretical research seems to be focusing on combining the best aspects of each model type into an integrated model. The aim of this paper is to make a first step in bridging the gap between the various types of analysis of material flows in the economy, by discussing the main differences and similarities of three often employed model types: substance flow analysis, life cycle assessment and partial economic equilibrium analysis. Instead of submitting each model to a lengthy theoretical discussion, we apply them to a single, hypothetical example of a pollution problem. By doing so we are able to evaluate the differences and similarities of the methods and results of the model in a practical way. It appears that the results of the three models are complementary rather than contradictory. Each of them puts an emphasis on different aspects of ‘the real world’. A sequential application of a number of limited models may therefore be an approach that provides more useful information than the tedious construction and application of an encompassing model that integrates these models.

Missing inventory estimation tool using extended input-output analysis

Intention, Goal, Scope, BackgroundInput-Output Analysis (IOA) has recently been introduced to Life Cycle Assessment (LCA). In applying IOA to LCA studies, however, it is important to note that there are both advantages and disadvantages.ObjectivesThis paper aims to provide a better understanding of the advantages and disadvantages of adopting IOA in LCA, and introduces the methodology and principles of the Missing Inventory Estimation Tool (MIET) as one of the approaches to combine the strengths of process-specific LCA and IOA. Additionairy, we try to identify a number of possible errors in the use of IOA for LCA purposes, due to confusion between industry output and commodity, consumer’s price and producer’s price.MethodMIET utilises the 1996 US input-output table and various environmental statistics. It is based on an explicit distinction between commodity and industry output.Results and DiscussionMIET is a self-contained, publicly available database which can be applied directly in LCA studies to estimate missing processes.ConclusionBy adopting MILT results in existing, process-based, life-cycle inventory (LCI), LCA practitioners can fully utilise the process-specific information while expanding the system boundary.Recommendations and OutlookMIET will be continuously updated to reflect both methodological developments and newly available data sources. For supporting information sec http:// wwwJeidenuniv.nl/cml/ssp/softwarc/miet.

Biorefining of lignocellulosic feedstock - technical, economic and environmental considerations.

Biorefinery, an example of a multiple products system, integrates biomass conversion processes and equipment to produce fuels, power and chemicals from biomass. This study focuses on technical design, economic and environmental analysis of a lignocellulosic feedstock (LCF) biorefinery producing ethanol, succinic acid, acetic acid and electricity. As the potential worldwide demand of succinic acid and its derivatives can reach 30 million tons per year, succinic acid is a promising high-value product if production cost and market price are substantially lowered. The results of the economic analysis show that the designed refinery has great potentials compared to the single-output ethanol plant; even when the price of succinic acid is lowered or the capital investment doubled. In terms of eco-efficiency, the LCF biorefinery shows better environmental performances mainly in global warming potential due to CO(2) fixation during acid fermentation. The overall evaluation of the eco-efficiency depends on the importance attached to each impact category.

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

In a previous article about life cycle assessment (LCA), a methodological framework was proposed and two components of this framework were discussed in more detail: the goal definition and the inventory. In this second article, the other components of the framework are discussed in detail: the classification, the valuation and the improvement analysis. In the classification, resource extractions and emissions associated with the life cycle of a product are translated into contributions to a number of environmental problem types, such as resource depletion, global warming, ozone depletion, acidification, etc. For this, each extraction and emission is multiplied with a so-called classification factor and the multiplication results are aggregated per problem type. Classification factors are proposed for a number of environmental problem types. The valuation includes both a valuation of the different environmental problem types and an assessment of the reliability and validity of the results. For the valuation of the environmental problem types, qualitative or quantitative multicriterion analysis could be applied. Given a standard list of weighting factors the quantitative multicriterion analysis seems preferable, because of its low costs and its simplicity. The main problem, however, is to get a broadly supported standard list. In studies so far little attention is paid to the assessment of the reliability and the validity of the results. To improve this situation methods which could support this assessment are proposed. In the improvement analysis potential options to improve the product(s) studied are identified. Combined with expertise in other fields, such as costs and technological feasibility, the improvement analysis may yield a number of serious options for the redesign of a product. Two complementary techniques for the identification of the potential options are discussed. With these techniques and the active participation of process technologists and designers, LCA might become an analytic tool for eco-design supporting a continuous environmental improvement of products.