Environmental Life Cycle Assessment
As concern has increased over the relationship between the economy and the environment various techniques have been developed to assess the effect of human and industrial activities on the environment.
Life cycle assessment serves the function of taking the account of the environmental effects of a product or service through all of its life stages from raw material to final disposal of the product. It assesses all the relevant effects of the product from cradle-to-grave.
As concern over Climate change increased in the late 60’s and early 70’ several projects evolved to quantify industry use of raw materials and energy. These were initially called energy analysis but their focus broadened to consider use of resources and waste production.
The projects were now called resource analysis. One of the first resource analysis studies conducted for the Coca Cola Company to determine alternative container system with the lowest energy and natural resource consumption developed a process which analysed this from cradle to grave this process was called the Resource and Environmental Profile Analysis (REPA).
This and other studies formed the basis for the life cycle inventory phase of LCA. Analysis of pollution problems caused by industry as a result of smog in Los Angeles and Tokyo, acid rain in Scandinavia, global warming and ozone depletion resulted in the expansion of the use of methodology to calculate energy and resource consumption to analyse pollution to land water and air.
This expanded analysis was called eco-balance and evolved to be part of the LCA.
The Society for Environmental Toxicology and Chemistry (SETAC) played a leading role in developing terms and methodology of LCA. They have developed a methodological framework and a code of practice for LCA to ensure consistent approach practice and reporting of LCAs. SETAC also had an important role in integrating impact assessment into LCA.
In 1993 however, since LCA was becoming a standard tool for making environmental claims, there was a need for standardization. The International Organisation for Standardisation evolved some standards in order to achieve this.
ISO 14040 Life Cycle Assessment: Principles and Framework ISO 14041 Life Cycle Assessment: Life Cycle Inventory Analysis ISO 14042 Life Cycle Assessment: Impact Assessment
ISO 14043 Life Cycle Assessment Interpretation ISO 14048 Life Cycle data documentation format
ISO 14049 Life Cycle Assessment- Examples of application of ISO 1404 goal and scope definition and inventory analysis
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.
It has also been defined by the Society for Environmental Toxicology and Chemistry (SETAC) as a process to evaluate the environmental burdens associated with a process, product or activity by identifying and quantifying energy and materials used and wastes released to the environment; and to identify and evaluate opportunities to affect environmental improvements.
The assessment includes the entire life cycle of the product, process or activity, encompassing, extracting and processing raw materials; manufacturing, transportation and distribution; use, re-use, maintenance; recycling and final disposal.
LCAs attempt to quantify the environmental burdens caused by industrial or product systems since the system generates the waste and not the product.
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A product system is a collection of operations connected by flows of intermediate products which perform one or more detailed functions. When describing a product system it must be done such that another practitioner can duplicate the inventory analysis.
Thus the scope of the LCA must clearly specify the functions of the system being studied. The functional unit is a measure of the performance of the functional outputs of the product system. A functional unit must be measurable as it forms the basis of the LCA.
After identifying the industrial/product system, you must draw the system boundary differentiating it from the system environment which is the source of all inputs and the receiver of all outputs.
There are also usually sub-systems or unit processes which have the same characteristics as the industrial main system and should be enclosed within their own system boundary.
Methodology of LCA
There are four keys steps to the LCA as defined by ISO14000:
Define the goal and scope- decide what you want to achieve
Life cycle inventory analysis (LCI) –gather and process relevant data
Life cycle impact assessment- determine the main environmental impacts
Life cycle interpretation- evaluate their relative interpretation
Define the Goal and Scope
It is vital to identify exactly the purpose for carrying out the study i.e. goal definition. The goal of an LCA should unambiguously state the intended application, the reasons for carrying out the study and the intended audience.
The goal defines what is to be accomplished by the LCA, how results will be used, what decisions will be based on the LCA output and if results will be used externally or internally.
These answers affect the scope of the study. An example of a goal is the quantification of energy, raw materials, air emissions, effluents and solid wastes of a printing factory.
As resources are limited the researcher must decide the breadth and depth of the study based on the goal. The scope should be sufficiently well defined to ensure that the breadth and the details of the study are compatible and self-sufficient to address the stated goal.
Scoping will entail defining the function under study, the system which performs the function, the boundaries of this system, data categories needed to address the stated goal. Sometimes a detailed scoping pinpoints the main impacts of the system and based on the goal removes the need for a full LCA or leads to a reformulation of original decisions concerning the study.
While there is no correct system, it is necessary to specify the system in a clear and transparent manner i.e. system specification, in addition the LCA must cover the life cycle of the system from cradle to grave.
The starting boundary at which the system is considered must be clearly stated, as must the boundaries at the end points of the system .Then the unit operations in between should be defined.
This is represented using a process tree below;
Key steps in inventory analysis
This phase tries to gather the information relating to all the inputs to the extended system including energy and ancillary materials, and all the environmental outputs associated with the various parts of the system.
Prepare tocollect data – determine type of data required i.e. primary data collected on site to be entered in a worksheet and secondary data obtained from literature, references, government and industry sources, websites, databases.
Complete a data set ensuring data quality and proper allocation. Data quality is affected by age, whether it is aggregate, whether it is an estimate or actually measured and data completed.
Allocation refers to the procedure where environmental burdens are apportioned between multiple inputs or outputs i.e. in a production unit with multiple products.
Normalizing– this is the expression of inputs and outputs to relative standard unit of throughput.
This is because the quantity of input/output used /produced per unit process is a function of the mass going through the system at the point in time. The standard unit is called the functional unit.
Computation – Data is entered into a computer model to calculate the inventory of the overall system. This produces data sets known as inventory tables.
Once the inventory is generated, the results must be interpreted by assessing the environmental impact of the inputs/outputs identified by the inventory by following the steps below.
Selection & definition of impactcategories – categories selected of issues such as global climate change, acidification, and smog will depend on the goals and scope of the study.
Assignment or classification – allocates the inventory data to the relevant issue categories. Some data (stressors) will impact a number of categories.
Category Modelling – calculations are carried out to evaluate the relative significance of each stressor to the overall impact of the system being studied. e.g. using the Global Warming Potential GWP in CO2 equivalents.
Assessment – This stage involves assessing the import of the impact on the system. This stage may be omitted but when carried should be done carefully using databases.
Weighting – this is a subjective process and involves assigning relative weights or values to impacts. Weighting helps in decision making but is accused of being based on value judgments and politics not science.
Relative weights used for ranking is based on societal value and preferences (determined by decision theory techniques) or monetary values (external damage cost estimates).
Life cycle interpretation is determined by ISO to be a systematic procedure to identify, qualify, check, and evaluate information from the conclusions of the inventory analysis and/or impact assessment of a system, and to present them in order to meet the requirements of the application as described in the goal and scope of the study.
It is also a process of communication of the more technical phases of LCA…in a form which is both comprehensible and useful to the decision maker.’
ISO 14043 Interpretation involves a review to ensure a systematic and consistent process. In addition when comparing environmental impacts related to different options the checks must ensure the approach is consistent so comparison is meaningful.
The report produced must State the objectives clearly, explain the scope, explain the system boundary and the reason for its choice, show flow diagrams of important inputs, outputs and products, describe the method used stating the value judgements and assumptions, data showing source and quality, conclusions drawn from study.
Uses of LCA
Provides a comprehensive baseline of environmental information. These are determined during inventory and impact assessment components of LCA and are used in the EMS
Optimizes reduction of environmental impact by identifying areas of maximum improvements with least resources
Provides consumption and environmental loading data for product, process or activity comparisons
Improves eco-design by providing information that will enhance (re)design of products, processes or activities
Used as an EMS tool for analyzing environmental aspects since it identifies and quantifies energy and raw material usage, releases due to products, process or activities and assess environmental impact.
Used as an EMS tool for continuous improvement as actual opportunities are identified and evaluated in the interpretation stage of LCA.
Substantiation of environmental claims
Help in formulating environmentally benign purchasing- ensure purchases with less impact
Influence formulation of public policy
Provide information for public education
Encourage research and development by emphasizing gaps
In conclusion,life cycle assessment is a useful tool in EMS during the preliminary environmental review, when identifying and evaluating which aspects are significant and when setting objectives and targets since it helps to identify maximum improvements with minimum resources and product, process and activity comparisons.
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LCA assesses all the relevant effects of the product from cradle-to- grave. It developed in the 1960 and early 70’from fuel cycle studies like energy analysis and resource analysis.
The Society for Environmental Toxicology and Chemistry (SETAC) played a leading role in developing terms and methodology of LCA while the International Organisation for Standardisation evolved its standards.
There are four keys steps to the LCA:
Definition of the goal and scope
Life cycle inventory analysis (LCI)
Life cycle impact assessment
Life cycle interpretation
Life cycle assessment is a useful tool in EMS during the preliminary environmental review and for continuous improvement as actual opportunities are identified and evaluated in the interpretation stage of LCA.
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