This lecture will focus on life-cycle assessment. This is also called life-cycle analysis or cradle-to-grave analysis. It's a cradle-to-grave approach for assessing industrial systems, that evaluates all stages of a product's life. The life-cycle assessment provides a comprehensive view of the environmental aspects of the product or the process being studied.
We study life-cycle assessment because it helps us make environmental decisions. It's used by policy makers, businesses, and individual citizens. It's used for comparing, on an environmental basis, the various types of similar products, processes or services, production methods, and product and process choices. It evaluates multiple stages of the life of the product including the preproduction stage, the production stage, the distribution and packaging stage, the utilization stage, and the disposal stage. Water, air, and soil conditions are evaluated from the time the raw materials are grown, mined, or produced through the disposal of the product. We may look at the consumption of natural resources, at pollution that may occur as a result of this product being produced and used and then disposed, and we would also look at the overall affects on the ecosystem in which it's produced and used. So it's a very comprehensive way of looking at a product. In this slide we see two life-cycle assessments, one of a t-shirt and another of a motorbike. These are simple examples and presented to give you an idea of what goes into a life-cycle assessment.
Many companies have gone through life-cycle assessments of their products. For the most part, these assessments have been conducted in Europe. Here's a partial list of products and services on which life-cycle assessment has been conducted.
As we conduct life-cycle assessments on the preproduction, the production, the distributions, and utilization of biofuels; we're most interested in the production of greenhouse gases. In this slide, we see a biofuel for which we're interested in the production of greenhouse gases from the time the feedstock begins growth, through harvesting and then to transporting it to the bio-refinery. At the bio-refinery it's converted into ethanol or to biodiesel. From there it's distributed to where the end-user can use it. At each one of these stages, we are interested in the greenhouse gases that are produced.
In the next few slides we're going to look at the life-cycle assessment conducted by Levi Strauss on a pair of 501 jeans. Levi Strauss used a quantitative method to evaluate the environmental impacts of this product. They looked at the life-cycle prospective from the time the cotton was cultivated until the jeans had gone through their useful life and were disposed or recycled. A life-cycle assessment, typically does not include the social impacts of the products being assessed, nor does it include the economic impacts of the product being assessed. In this lecture we're going to only look at a partial number of the slides in the slide set. I would encourage you to go to the website that's listed on this slide and view the entire slide set on your own.
Here we see the life-cycle assessment for that pair of Levi's, starting with cotton production, going to fabric production, garment manufacture, transportation, distribution of the product, the consumer using the product, and then the recycling or disposal of the product, depending on what the consumer does with it. Again, for more information about each of these steps, go to the Levi Strauss website that's posted on the bottom of this slide.
Here we see a graphic depiction of the life-cycle assessment of a pair of 501 Levi's jeans. It begins with the cotton being grown in West Texas or the Mississippi Delta or in Brazil and it concludes with the disposal in a landfill or disposal via incineration. What's striking to me, throughout this whole process, is the number of times the product is moved, the number of steps it takes to produce a pair of Levi's, and then finally, the distances traveled in the production of these pants. Evaluating the environmental inputs at each step goes into the life-cycle assessment.
During the life-cycle of a pair of Levi's 501 jeans, we see the major source of greenhouse gas production, that likely impacts climate change, occurs as the product is being used. The majority of this is used when washing and drying the jeans. For example, more greenhouse gases are produced if the product is washed in warm versus cold water, if it's dried in a dryer versus hung on a clothes line for drying, or if the jeans are washed after every wearing or after three or four wearings .
As in climate change, we see that it's the user that consumes the most energy during the lifespan of a pair of Levi's 501 jeans. The production of the fabric does use a significant amount of energy, but overall, washing and drying uses the greatest amount of energy is during the blue jeans' lifespan.
Users consume a large amount of water in the care of their Levi's, but the greatest amount of water is used in cotton production. As a result of the large amount of water used to grow the cotton. Levi Strauss is looking at methods of growing cotton more sustainabley to reduce water use. Levi Strauss is also looking at changing the care label on the garments in order to encourage washing in cold water and washing less frequently than some users may have washed them, in order to conserve energy, reduce greenhouse gas emissions, and conserve water.
On this slide we see what Levi Strauss learned from conducting a product life-cycle assessment on that pair of 501 Levi's and how they may change what they're doing to reduce the water use during the life-cycle of the pair of Levi's.
Similar to the last slide, here we see the actions Levi Strauss are taking as a result of the life-cycle assessment conducted on the 501 jeans.
As we started, here's a life-cycle assessment for a t-shirt. So what are the results of life-cycle assessment? Well, it allows us to identify all of the environmental aspects of the entire life-cycle of the product or process we're working with and it allows us to focus on what really matters in the manufacture of the product or the process. Life-cycle assessment also allows us to study the flow in the production of a product or of a process. It allows us to define what's acceptable as we're looking at the stages in the product life-cycle. Finally, it allows use to compare between products or processes with similar functions.
