In this lesson, students will extend their knowledge of matter and energy cycles in an organism to engineering life cycle assessment of a product. Students will learn about product life cycle assessment and the flow of energy through the cycle, comparing it to the flow of nutrients and energy in the life cycle of an organism.

Engineers can use life cycle assessment, often called cradle-to-grave assessment, when designing and creating products. This type of analysis looks at a product from raw materials through production, manufacture, packaging, distribution, use, end-of-life treatment and disposal. Life cycle assessment of a product allows engineers to determine the environmental impacts of a design over the various stages of development — allowing for improvements in recycling and reducing waste. One example of a product that easily illustrates the use of life cycle assessment is plastic versus paper packaging. Steps that need to be considered in this analysis for both plastic and paper include the raw materials taken from the Earth, creation of the plastic or paper material, creation of the packaging, use of the packaging, distribution of the packaged product, and disposal of the packaging, as well as emissions for the process to the air, water or noise. All these issues are assessed to determine the environmental impact of the development of paper or plastic packaging. life cycles waste recycle life cycle assessment nature butterfly energy The students should be familiar with the basic life cycle of an organism found in nature, such as a butterfly. After this lesson, students should be able to: Describe several basic steps in the life cycle assessment of a product. Compare and contrast the life cycle of an organism and an engineered product. Describe the flow of energy through a product's life cycle. Today we are going to talk about the life cycles of creatures found in nature as well as how engineers model nature's life cycles as inspiration to improve the efficiency and environmental impact of their own designs. Let's start with an example from nature. Many organisms have an observable life cycle. Think about a butterfly. Does anyone know what a butterfly is before it actually becomes a butterfly? Right, it starts out as an egg that its mother lays on leaves or tree branches. Once the egg hatches, what does it look like? It has become a caterpillar. The caterpillar spends all of its time eating the leaves and branches around it. Once it has had enough to eat, the caterpillar creates a chrysalis. What does the caterpillar do in the chrysalis? It changes from a caterpillar into a butterfly. How do butterflies and caterpillars look different? One has legs and crawls/hops, and the other has wings and flies. They eat different things as well. However, they are the same organism the whole time. As you can see, there is energy flow through the butterfly's life cycle as well, energy that butterfly takes in as food and gives back to the Earth as nutrients when it is decomposed. Can anyone name another organism that has a distinct life cycle? (Possible answers: ants, beetles, flies, etc.) Engineers also think about life cycles when developing a new product — implementing what is called the product's life cycle assessment. A product's life cycle is similar to the butterfly's life cycle, as it follows the product from creation to decomposition. The steps of an engineering life cycle assessment might include: materials acquisition, materials processing, manufacturing, packaging, transportation, use, and disposal of the product. Engineers think about the energy that flows through a product's life cycle as well. There is energy required to develop the product, package the product, deliver the product to market (transportation), use the product and dispose of the product. The energy that is used throughout a product's life cycle is combined with analyzing the physical steps of the cycle in order to determine the overall environmental impact of the product. Engineers use a product life cycle assessment to improve the environmental impacts of the product, creating the best products that use the smallest amount of non-renewable natural resources and energy pollution possible. Life cycle assessment helps engineers understand waste. Nature is not as wasteful as humans; she has developed many ways to reuse and recycle nutrients in the environment. Engineers think about the different ways that they can recycle energy and materials through every step of the product's life cycle. By analyzing the different steps of a product's life cycle, engineers can determine which steps are the most harmful to the air, water, land, or humans, and develop ways to decrease the impact of these steps. Let's think about the life cycle of something with which we are familiar. How about a shopping bag? When you go to the grocery store, you often take your groceries home in a bag. It could be plastic, paper or fabric, but for our purposes today, let's think about the product life cycle of a plastic grocery bag. The bag is made from fossil fuels that are taken out of the Earth and transformed into plastic. The plastic is shaped and formed into a set of plastic bags, which is then packaged for sale and, stored in a warehouse, and eventually delivered to the grocery store. The plastic bag is used to hold your groceries after checkout, as you travel to your house. Oftentimes, the bag is discarded after the groceries are brought home. Like the butterfly, the plastic grocery bag changes shape from nutrients in the Earth (fossil fuels) to a solid (plastic bag) that we use to carry home our groceries. Eventually the bag will break down over time, just as the adult butterfly does after decomposers break it down after its death. However, the butterfly is decomposed into organic nutrients, seeping into the soil that plants then use to grow. In time, the plant is eaten by the young caterpillars and the cycle begins again. Unfortunately, the plastic bag will never turn back into fossil fuels that can then be used to make a new bag. There is more recycling of nutrients in the butterfly life cycle than the plastic bag. Engineers might analyze the life cycle of the plastic bag and consider where the life cycle actually ends. Does it end with a pile of plastic bags in a landfill? Or, can the plastic bags be re-used as something else? Engineers are developing products that can be created from used plastics, such as playground equipment and furniture. Butterflies pass through four stages during their life cycle: egg, caterpillar, chrysalis and butterfly. The butterfly is an excellent and simple example to use when describing natural life cycles to students. The picture below illustrates the life cycle of a butterfly. A life cycle assessment is used to measure how much a product impacts the environment, from its creation to final disposal. There are several general steps to determining the overall environmental impact of a manufactured product. The first step is called an inventory analysis. In this phase, the inputs and outputs of a product's energy and materials are calculated, including the environmental emissions that result from raw materials extraction, product manufacture, distribution, use and disposal. The next step is an impact analysis, where the environmental impacts found in step one are calculated, looking at the impacts of generating electricity for each step in the product's life as well as any hazardous wastes that are a by-product of manufacturing. This step results in a number that represents the impact on the environment. Lastly, an improvement analysis is performed to determine if there is any way to reduce the impact on the environment. For example, conserving energy or water during any of the phases of the life cycle or exchanging materials for less hazardous waste producing ones. Then the changes are inserted back into the inventory analysis to determine if the total environmental impact has been reduced. There are several types of life cycle assessment for engineered products. Some of them include: Cradle-to-Grave: The full life cycle of a product from raw materials (cradle) to the disposal phase (grave). Cradle-to-Gate: A partial product life cycle assessment that investigates a product from raw materials (cradle) to the gate of the manufacturing facility (gate) before transportation to the consumer. Cradle-to-Cradle: A product life cycle assessment, where the end phase includes recycling of the product into a new product. The recycled product can be identical or different to the original product. The various stages through which something passes during its lifetime To reuse or adapt for a new use. Damaged, defective, or unusable material. Product Development and the Environment Today we discussed life cycles. What are some steps of the life cycle of a butterfly? (Answer: birth, caterpillar, chrysalis, butterfly, decompose.) What are some steps in the life cycle of a product? (Answer: materials acquisition, materials processing, manufacturing, packaging, transportation, use and disposal.) How is the life cycle of an organism similar to the life cycle of an engineered product? (Possible answers: Both life cycles follow the object from birth to death, beginning to end. Both cycles involve the flow of energy through the lifetime of the object.) How do the two cycles differ? (Answer: Often the life cycle of a product ends with disposal, where the life cycle of a natural organism is recycled into nutrient in the Earth.) Engineers are working to develop products that more closely resemble the life cycles in nature, where all materials, energy, and nutrients are recycled into the same or different new objects. Until then, we can reduce the impacts of manufacturing products on our environment by making the choice to use recyclable products over non-recyclable product when possible. Know / Want to Know / Learn (KWL) Chart: Before the lesson, ask students to write down in the top left corner of a piece of paper (or as a group on the board) under the title, Know, all the things they know about product life cycles. Next, in the top right corner under the title, Want to Know, ask students to write down anything they want to know about product life cycles. Diagramming: Ask the students to illustrate a product life cycle through drawing. After reading the introduction, have them make a drawing of the life cycle of a common product that includes the materials acquisition, materials processing, manufacturing, packaging, transportation, use, and disposal of the product. For a more detailed diagram, have the students label the energy flow in the cycle as well as any ideas for recycling of the materials. Concept Reflections / Environmental Impacts: Have the students reflect on the product life cycle assessment and write a journal entry on their thoughts. In thinking about the product life cycle assessment of a product they know, ask students the following questions: What types of steps might be involved in the life cycle of that product? During what steps are there harmful impacts to the environment (including pollution, waste and energy loss)? Are there some steps that are more harmful than others? Is there any step where recycling could be used? What do you recommend for improving the environmental impacts of the entire life cycle of the product? Know / Want to Know / Learn (KWL) Chart (continued): Finish the remaining section of the KWL Chart as described in the Pre-Lesson Assessment section. After the lesson, ask students to list in the bottom half of the page under the title, Learned, all of the things that they have learned about product life cycles. Ask students to name a few items and write them on the board. There are many types of life cycle analyses used by engineers for the development of different products. A few of these are mentioned in the background information for this lesson. Have students investigate the different types of life cycle assessment and what types of product are developed with each type. The EPA (Environmental Protection Agency) has a great poster for students that illustrates the product life cycle of a CD or DVD. http://www.epa.gov/epaoswer/osw/students/finalposter.pdf. This lesson can be expanded with a more thorough discussion of the life cycles of living organisms. Only one type of lifecycle (a butterfly) was discussed in this lesson, but there are other types, such mayflies that live part of their life in the water and another in the air. An interesting discussion could include the life cycles of organisms in different environments and compare them to products developed for those same environments (water, air, etc). Town of Shrewsbury, Massachusetts, Schools, "Beal," © 1992, The National Academy of Science, accessed February 14, 2008. http://www.shrewsbury-ma.gov/schools/beal/curriculum/butterfly/cycle/nsrccycle.html U.S. Environmental Protection Agency, Systems Analysis Research, Office of Research & Development, National Risk Management Research Laboratory, Program Brief, "Life Cycle Assessment Framework," January 29, 2007, accessed February 14, 2007. http://www.epa.gov/nrmrl/std/sab/lca/lca_brief.htm U.S. Environmental Protection Agency, Wastes, February 13, 2008, accessed February 21, 2008. http://www.epa.gov/epaoswer/osw/students/finalposter.pdf