Life Cycle Assessment (LCA) is a "cradle-to-grave" approach for evaluating products, materials, processes, services, and industrial systems with respect to their environmental impacts. Cradle-to-grave process begins with the extracting of raw materials from the earth to manufacture a product and ends at the point when all materials are returned to the earth in some form. LCA looks at all the stages of the product’s life one by one, estimates various environmental impacts at each stage and, as a result, allows selecting the path or processes that are least impactful based on chosen metrics.
LCA studies help decision-makers select the product, process, or technology that would be "least evil" in terms of its environment footprint, however the final judgment and interpretation of the results always depends on the key metrics and criteria that are most important to specific stakeholders. In that sense, LCA objectives should be set early in the analysis to answer the questions relevant to a particular project or application. Classic LCA deals primarily with environmental impacts, but further can be used with other pieces of information, such as cost and performance data, to find optimal solutions.
Support informed decision making for government, industry, and businesses
Provide basis for fair comparison between products and alternatives
Support recommendations for improving design and lowering impacts
The diagram below illustrates the main lifecycle stages to be considered in LCA:
This diagram is based around a box-shaped system that includes four processes and is surrounded by a System Boundary. The four highlighted stages are:
System Inputs are shown as arrows on the left of the system, outside the System Boundary. Inputs are represented by Raw Materials and Energy that flow into the system.
System Outputs shown as arrows on the right and at the bottom of the system, outside the System Boundary. Outputs are represented by Main Product and Co-Products (shown at the bottom), and Atmospheric Emissions, Waterborne Waste, and Solid Wastes (shown on the right).
As you can see in the diagram above, any product or technology would require input of some raw materials and energy at all stages: from acquisition to manufacturing, operation, and finally disposal. All of the mentioned lifecycle stages may produce atmospheric emissions, waterborne and solid wastes, simply because the efficiency of material use and energy conversion is always below 100% - there are losses and by-products, which sometimes can be highly undesirable. LCA helps to keep track of all useful and harmful outcomes, and the diagram in Figure 2.3 provides a guideline to LCA mapping.
A standard LCA study would consist of several key steps outlined below:
The standardized procedure for the LCA recommended for product and technology assessment in the U.S. is documented in the EPA guidelines referred below. Study this document carefully – some parts of this framework will be used as a basis for technology evaluation repeatedly in this course's assignments.
US EPA Document: Life Cycle Assessment: Principles and Practice, EPA/600/R-06/060 [1], 2006.
This document provides a detailed guideline on how lifecycle assessment should be performed. This is a long document and contains a significant amount of information. While I would like you to look through the entire file, here are a few things that you may want to focus on:
In this Lesson, we are going to do an exercise on LCA scoping for a simple product. That would only cover Stage 1 of the entire process. Still, it is a very important step that sets the ground for the entire analysis and provides directions for collecting data and developing metrics during the Inventory Analysis and Impact Assessment stages of the LCA. Please refer to the Canvas Module 2 for specific directions on this assignment.
Website: Design Life-Cycle, University of California, Davis, Department of Design, URL: http://www.designlife-cycle.com/ [2] Accessed: May 2020.
This website presents a very versatile collection of LCA studies of consumer products, fashion, architecture, electronics, and other technologies. Studies are presented in the "nutshell" form and enhanced by infographics. Very fun resource to explore!
Even for relatively small systems, LCA is a comprehensive task that requires interdisciplinary knowledge in the technical and economic areas. Hence, LCA projects are typically assigned to teams of experts and can rarely be performed by a single person with sufficient accuracy.
LCA approach has developed over decades, coming from a product-oriented model used to evaluate environmental impact to a bigger framework that elaborates on a wider environmental, economic, and social scale. At the current stage, LCA is being transformed into Life Cycle Sustainability Analysis (LCSA), which links the sustainability questions with the knowledge and research needed to address them. Check out the following article to learn more about the LCA history and background:
Journal article: J.B. Guinee et al., Life Cycle Assessment: Past, Present, and Future, Environ. Sci. Technol., 2011, 45, 90-96.
This article reviews the history and the most recent advances and trends in the life cycle assessment. It provides some good illustrations of method diversity, which can be both beneficial and challenging in terms of data interpretation and application. The article also exemplifies LCA being linked to policy development and decision making.
This reading is optional, but highly recommended in the context of this lesson. This article can be accessed online through the Penn State Library system database or via link in Canvas.