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Unit 6: Life C ycle Assessment (LCA)
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Lecture 6
Life Cycle Assessment (LCA)
STRUCTURE
Overview Learning Objectives 6.1 Life cycle assessment and its purpose
- 2 Evolution of Life Cycle Assessment
- 3 Stages in LCA of a Product
- 4 A Code of Good Conduct for LCA
- 5 Procedures for LCA
- 5 .1 Defining the goal and scope
- 5 .2 Analysing the inventory
- 5 .3 Assessing environmental impact
- 5 .4 Evaluating environmental profiles
- 6 Different Applications of LCA
- 6 .1 Private sector applications
- 6 .2 Governmental application Summary Suggested Readings Case 6.1: Software for Performance of LCA Case 6.2: Environmental Effects to be considered in LCA Case 6.3: Life Cycle Analysis: Substitutes for PVC Case 6.4: LCA Case Study: Steel Sector in India Model Answers to Learning Activities
OVERVIEW
In Unit 5, we discussed, among others, how audits help improve the environmental performance of an industry. In Unit 6, we will discuss yet another tool for environmental management, i.e., life cycle assessment (LCA). We will first trace the evolution of LCA and describe the stages of a product life cycle. We will then identify the elements that contribute to the code of good conduct for an LCA. We will also explain the main steps involved in the LCA process, i.e., goal setting, inventory analysis, impact
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assessment and profile evaluation. We will close the Unit by explaining the application of LCA in private and public sectors.
LEARNING OBJECTIVES
After completing this Unit, you should be able to:
explain the concept of life cycle assessment (LCA) as an environmental management tool and its potential for identifying all the environmental impacts throughout the entire life cycle of a product; describe what a code of good conduct for LCA entails; discuss the basic steps involved in an LCA process; conduct/co-ordinate an LCA and critically evaluate its outcomes.
6.1 Life cycle assessment and its purpose
Life cycle assessment (LCA) is a tool to evaluate the environmental effects of a product or process throughout its entire life cycle. An LCA entails examining the product from the extraction of raw materials for the manufacturing process, through the production and use of the item, to its final disposal, and thus encompassing the entire product system. A schematic representation of a product life cycle is given in Figure 6.1:
Figure 6. Product Life Cycle
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operations occurring within a facility can also cause impacts outside the facility's gates that need to be considered when evaluating project alternatives.
Purpose of LCA: Government and customers who purchase products from different sectored companies are keen on environmental properties of all the products. EMAS and ISO 14000 are demanding continual improvement in the process of production and in the environmental management system. At this stage there is a need for a tool like LCA that helps organisations meet the demand to improvise process/product.
6.2 EVOLUTION OF LIFE CYCLE ASSESSMENT
The principles underlying an LCA were developed in the late 1960s. In the 1970’s, the US Environmental protection agency refined the methodology for evaluation of environmental impacts of products and were popularly known as resource and environmental profile analysis (REPA). Initially, it was used mainly on the consumption of energy and other resources. Knowledge of environmentally damaging releases and actions and the estimation of their effects, was too rudimentary at that time to allow a quantitative treatment of the environmental impacts of the product life cycle. Assessments of product life cycle experienced a renaissance through studies of the environmental loadings and potential impacts of beverage containers (e.g., beer cans, milk containers) performed in various European countries in the early 1980s. These studies involved further elaborations of the principles underlying the assessment of product life cycle and entailed a series of life cycle assessments of materials used in packaging containers (i.e., polyethylene, cardboard, aluminium, etc.). A
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common feature of the items analysed was their homogenous character and their widespread use in many different contexts.
The late 1980s and early 1990s have seen international attempts to standardise the principles underlying life cycle assessments and to develop codes of good conduct in this field. The list of products that have been subjected to LCA has grown quickly and now includes more complex products such as paints, insulation materials, window frames, refrigerators, hotplates, television sets, etc., as well as the entire service systems or technologies such as electricity production.
As a part of ISO 14000 series of standards ISO in 2000 has come out with the following standards:
ISO 14040: Environmental Management – LCA – Principles and Framework. ISO 14041: Environmental Management – LCA – Inventory Analysis. ISO 14042: Environmental Management – LCA – Impact Assessment. ISO 14043: Environmental Management – LCA – Interpretation.
Since the last decade or so, LCA is gaining importance as an environmental management tool. It has now emerged as a decision support tool in such areas as business, regulation and policy and to structure technology development in a coherent way. Many potential applications of LCA are envisaged including product improvement and design, environmental management, eco-labelling, green accounting, environmental auditing and reporting, resource management, definition of best available technology (BAT), product policy, strategic industrial planning, strategic environmental policy development, etc. As a general
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- Evaluation: Includes classification of inventory table into impact categories, aggregation within category, normalisation and weighting of different categories
- Improvement assessment: Includes sensitivity analysis and improvement priority and feasibility assessment
It is generally recognized that the first stage is extremely important. The result of the LCA is heavily dependent on the decisions taken in this phase.
The screening LCA is a useful step to check the goal-definition phase. After screening it is much easier to plan the rest of the project.
Figure 6.3 gives a diagrammatic representation of the stages in the life cycle of a product:
Figure 6. Product Life Cycle Stages
Note that Figure 6.3 complements Figures 6.1 and 6.2. As depicted in these figures, each stage of the life cycle receives materials and energy as inputs and produces:
outputs of material or products to subsequent life cycle stages; emissions to the environment.
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There are a number of issues associated with the life cycle stages, and we will touch upon some of these, next.
Extraction of raw materials
This stage in the life cycle includes the extraction of all materials involved in the entire life cycle of the product. Typical examples of activities included in this stage are forest logging and crop harvesting, fishing and mining of ores and minerals. The inventory for the extraction of raw materials should include raw materials for the production of the machinery (i.e., capital equipment) involved in manufacturing the product and other stages of the product life cycle. Raw materials used in the production of electricity and energy used in the different life stages of the product should also be considered. Collecting data for the raw materials extraction stage may prove to be a complex task. It may also lead into iterative processes such as assessing the inputs and outputs related to extraction of the raw materials that is used in the production of end products. Often, the most serious environmental problems of the product life cycle associated with this first stage. It is a common error to leave out parts of the raw materials stage from the LCA. Essentially, the decision of what to include or exclude in the LCA should be based on a sensitivity analysis.
Manufacture of a product
The manufacturing stage encompasses all the processes involved in the conversion of raw materials into the products considered in the LCA. Apart from the manufacturing processes at the plant where the product is made, this stage takes into account production of ancillary materials, chemicals and specific or general components at other plants, no matter where they are.
Transportation
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(iii) Incineration: This refers to the combustion of the product, generating heat that may be used for electricity production or heating.
(iv) Composting: This refers to the microbial degradation of biological materials yielding compost for improvement of agricultural soils.
(v) Waste water treatment: This refers to the organic matter degradation and nutrients removal from sewage water, creating sludge that is deposited on agricultural land.
(vi) Land filling: This means the deposition of the product in landfills.
Each form of waste treatment mentioned above may be considered a processing of waste associated with a certain consumption of resources. This results in various releases into the environment, and the possible generation of energy or materials that will be an input to the manufacturing process of this product or of other products. Before you read any further, it is a good idea to look at the Course Municipal Solid Waste Management in which we discussed the different waste management processes in detail.
As implied, the LCA of products is an important environmental management tool. However, as with every tool, difficulties do arise with LCA too. In Section 6.3, we will discuss the problems and the questions that have to be taken into consideration, while analysing the life cycle of a product.
6.4 A CODE OF GOOD CONDUCT FOR LCA
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As mentioned earlier, LCA emerged during the last decade as a tool to provide an objective assessment of the total environmental impact associated with a product through its entire life cycle. In several countries, LCA is considered the primary tool by which environmental impacts of products should be regulated by government authorities. However, problems do exist. Let us look at some of the major LCA limitations below, as revealed in various studies:
(i) Data quality: In a manufacturer-sponsored study to compare a product with its alternatives, the consultants performing the LCA were able to get a very detailed and current data from the manufacturer for the processes involved in the production of that product. However, they had to depend on secondary data from the literature or earlier studies with regard to the production processes concerning the alternative products. Obviously, comparative studies on the basis of the secondary data tend to lack credibility.
(ii) Life cycle boundaries: A Dutch study excluded the production of several raw materials, including crude oil, for the polycarbonate production. The German study did not include emissions from the energy production associated with the life cycle of the milk containers. Most studies did not consider the working environment.
(iii) Country-specific technology types: An example is the LCA conducted on the production of electricity used in the product life cycle. In a Swedish study, the electricity production was based on nuclear power and hydroelectricity, while a Swiss study, based on a US energy scenario since 1972, used coal as the energy source. This should explain the difference in the emissions found in the two studies. In
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(vi) Delimitation of syste m under study: This involves finding answers to such questions as: Is there an explicit and clear delimitation of the system under study? Is the life cycle described in detail, stage by stage? Are the life cycle description and process tree plausible? Do they describe the real world system in a realistic way? Does the study include the extraction of raw materials? Does the study include the production of electricity? What production scenario is used? Is it appropriate? Does the study include the manufacture of real capital for all life cycle stages? If the study has precluded capital, is this omission substantiated? Do you find the omission reasonable? Is the disposal stage covered by the study?, etc.
(vii) Inventory: This involves finding answers to such questions
as: Does the inventory cover all processes of the process tree? Is there a reference to the source of every piece of data in the inventory? Is the data quality appropriate, i.e., primary and recent data for all the important processes of the life cycle? Do the data describe a relevant technological level of the processes? Is the use of data of lower quality or omission of processes from the inventory based on sensitivity analyses? Is the quality of the data used for the compared alternatives similar? Are data on impacts to the working environment present in the inventory? Is it acceptable that they be left out in the considered study?, etc.
(viii) Impact assessment: This involves finding answers to such
questions as: Has any impact assessment been performed? Does it consider all the important environmental effect types? Does it consider resource and working environment issues?, etc.
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(ix) Evaluation: This involves finding answers to such questions as: Are the subjective steps of the evaluation separated from the objective ones? If not, is the evaluation transparent? Are the priorities clear? Are the conclusions of the assessment clear? Are the assumptions underlying the weighting explained, and do you agree with them?, etc.
6.5 PROCEDURE FOR LCA
Four steps are involved in carrying out an LCA, and these are:
LEARNING ACTIVITY 6.
Which of the materials described in Case 6.2 would you consider to be the least harmful to the external environment and the working environment? Note : a) Write your answer in the space given below. b) Check your answer with the one given at the end of this Unit.
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choice of reporting method. The goal can be redefined as a result of the findings throughout the study.
While the goal definition determines the level of sophistication of the study and the requirements to reporting, the definition of the scope of an LCA sets the borders of the assessment, i.e., what may be included in the system and what detailed assessment methods are to be used.
In defining the scope of an LCA study, the following elements must be considered and clearly described:
The functions of the system, or in the case of comparative studies, systems. The functional unit. The system to be studied. The system boundaries. The allocation procedures. The types of impact and the methodology of impact assessment and subsequent interpretation to be used. Data requirements. Assumptions. Limitations. The initial data quality requirements. The type of critical review, if any. The type and format of the report required for the study.
The scope should be sufficiently well defined to ensure that the breadth, the depth and the detail of the study are compatible and sufficient to address the stated goal. LCA is an iterative technique.
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Therefore, the scope of the study may need to be modified while the study is being conducted as additional information is collected.
Let us now describe some of the elements mentioned above to define the scope of an LCA.
Functional unit
Definition of the functional unit or performance characteristics is the foundation of an LCA because the functional unit sets the scale for comparison of two or more products including improvement to one product (system). All data collected in the inventory phase will be related to the functional unit. When comparing different products fulfilling the same function, definition of the functional unit is of particular importance. The three aspects that have to be taken into account when defining a functional unit are the efficiency of the product, the durability of the product and the performance quality standard (Lindfors et al., 1995c).
When performing an assessment of more complicated systems, e.g., multi-functional systems, special attention has to be paid to by-products. Waste treatment systems are an example of processes with different outputs (e.g., energy, a fertiliser). When comparing different systems, inclusion of the produced amount of energy and fertiliser is an example of handling of different by- products in the definition of the functional unit.
System boundaries
The system boundaries define the processes/operation (e.g., manufacturing, transport and waste management processes) and the inputs and outputs to be taken into account in the LCA. The input can be the overall input to a production as well as input to a single process, and the same is true for the output. The definition
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Reproducibility: This means the qualitative assessment of the extent to which formation about the methodology and data values allows an independent practitioner to reproduce the results reported in the study. Consistency: This means the qualitative assessment of how uniformly the study methodology is applied to the various components of the analysis.
Critical review process
The purpose of the critical review process is to ensure the quality of the life cycle assessment. The review can be either internal or external. This may also involve the interested parties as defined within the goal and scoping definition. The critical review process ensures that:
the methods used to carry out the LCA are consistent with the international standard and are scientifically and technically valid; the data used are appropriate and reasonable in relation to the goal of the study; the interpretations reflect the limitations identified and the goal of the study; the study report is transparent and consistent.
6.5.2 Analysing the inventory
Inventory analysis is the second phase in an LCA, consisting of issues such as data collection, refining system boundaries, calculation, verification of data, relating data to the specific system and allocation.
We will describe each of these issues, next.
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Data collection
The inventory analysis includes collection and treatment of data to be used in preparation of a material consumption, waste and emission profile for the phases in each life cycle. The data can be both site-specific (e.g., from specific companies, specific areas and specific countries) and general sources (e.g., trade organisations, public surveys, etc.) The data have to be collected from all single processes in the life cycle. The quantitative data are important in comparisons of processes or materials, but often the quantitative data are missing or the quality is poor (too old or not technically representative, etc.). However, a more descriptive qualitative data can be used for environmental aspects or single steps in the life cycle that cannot be quantified. This can be used when the goal and scope definitions allow a non-quantitative description of the conditions.
Data collection is often the most work intensive part of a life cycle assessment, especially if site-specific data are required for all the single processes in the life cycle. In many cases, average data from the literature (often previous investigations of the same or similar products or materials) or data from trade organisations are used. The average data can be used in the conception or simplified LCA to get a first impression of the potential inputs and outputs from producing specific materials. When doing a detailed LCA, site-specific data is preferred. Note that since average data are often some years old, they may not represent the latest in technological development.
Refining system boundaries
The system boundaries are defined as part of the scope definition procedure. After the initial data collection, the system boundaries can be refined, i.e., as a result of decisions of exclusion of life
