Chapter 3: Life Cycle Assessment (LCA) 

Learning Objectives:

After completing this section, you should be able to:

• Define life cycle assessment (LCA).
• Describe the four stages of an LCA.
• Explain the difference between a product’s life cycle and its environmental impacts.
• Identify the benefits and limitations of life cycle assessments.
• Apply life cycle thinking to everyday consumer products.

Introduction to Life Cycle Assessment:

Every product we use has an environmental story that begins long before it reaches a store and continues long after we throw it away. From the extraction of raw materials and manufacturing to transportation, use, and disposal, products require energy and natural resources while generating waste and pollution at each stage of their existence. Understanding these impacts is the purpose of Life Cycle Assessment (LCA).

Life cycle assessment recognizes that environmental impacts are interconnected. A product that appears environmentally friendly during one stage of its life may have significant impacts during another. For example, a reusable shopping bag may require more energy and raw materials to manufacture than a disposable plastic bag, but its overall environmental impact may be much lower if it is used repeatedly over many years. Similarly, recycling a product may reduce waste, but transportation and processing also require energy and resources. LCA helps account for these trade-offs.

Scientists, engineers, businesses, and governments use life cycle assessments to compare products, improve manufacturing processes, reduce pollution, conserve natural resources, and support more sustainable decision-making. Companies use LCA to design environmentally responsible products, while policymakers rely on life cycle information when developing environmental regulations and sustainability initiatives.

Life cycle assessments generally evaluate several categories of environmental impacts, including energy consumption, greenhouse gas emissions, water use, air and water pollution, resource depletion, and waste generation. By identifying where the greatest environmental impacts occur, organizations can focus their efforts on improving efficiency and reducing environmental harm.

As consumers, we also benefit from life cycle thinking. Understanding the environmental consequences of our purchasing decisions encourages us to consider not only the price or convenience of a product but also its long-term environmental footprint. Whether choosing reusable products, recycling materials, conserving energy, or supporting sustainably produced goods, life cycle thinking empowers individuals to make more informed and responsible choices.

Problem Solving for Sustainability

It should be clear by now that making decisions and solving problems in support of greater sustainability of human-created systems and their impact on the natural environment is a complex undertaking. Often in modern life our decisions and designs are driven by a single goal or objective (e.g. greater monetary profitability, use of less energy, design for shorter travel times, generation of less waste, or reduction of risk), but in most cases solving problems sustainably requires a more holistic approach in which the functioning of many parts of the system must be assessed simultaneously, and multiple objectives must be integrated when possible. Furthermore, often our decisions require the recognition of tradeoffs — there are many kinds of impacts on the environment and most decisions that we make create more than one impact at the same time. Of course choices must be made, but it is better if they are made with fuller knowledge of the array of impacts that will occur. The history of environmental degradation is littered with decisions and solutions that resulted in unintended consequences.

An illustrative example of the role of sustainability in solving problems is the issue of biofuels — turning plant matter into usable energy (mostly liquid hydrocarbon-based fuels). When viewed from afar and with a single goal, “energy independence,” using our considerable agricultural resources to turn solar energy, via photosynthesis, into usable fuels so that we can reduce our dependence on imported petroleum appears to be quite attractive. The United States is the largest producer of grain and forest products in the world. It has pioneered new technologies to maintain and even increase agricultural productivity, and it has vast processing capabilities to create artificial fertilizer and to convert biomass into agricultural products. And, after all, such a venture is both “domestic” and “natural” — attributes that incline many, initially at least, to be favorably disposed. However upon closer examination this direction is not quite as unequivocally positive as we might have thought. Yes it is possible to convert grain into ethanol and plant oils into diesel fuel, but the great majority of these resources have historically been used to feed Americans and the animals that they consume (and not just Americans; the United States is the world’s largest exporter of agricultural products). As demand has increased, the prices for many agricultural products have risen, meaning that some fraction of the world’s poor can no longer afford as much food. More marginal lands (which are better used for other crops, grazing, or other uses) have been brought under cultivation for fermentable grains, and there have been parallel “indirect” consequences globally — as the world price of agricultural commodities has risen, other countries have begun diverting land from existing uses to crops as well. Furthermore, agricultural runoff from artificial fertilizers has contributed to over 400 regional episodes of hypoxia in estuaries around the world, including the U.S. Gulf Coast and Chesapeake Bay.

In response to such problems, U.S. Congress passed the Energy Independence and Security Act in 2007, which limits the amount of grain that can be converted into biofuels in favor of using agriculturally-derived cellulose, the chief constituent of the cell walls of plants. This has given rise to a large scientific and technological research and development program to devise economical ways to process cellulosic materials into ethanol, and parallel efforts to investigate new cellulosic cropping systems that include, for example, native grasses. Thus, the seemingly simple decision to grow our biofuels industry in response to a political objective has had unintended political, financial, dietary, social, land use, environmental quality, and technological consequences. With hindsight, the multiple impacts of biofuels have become clear, and there is always the hope that we can learn from examples like this. But we might also ask if there is a way to foresee all or at least some of these impacts in advance, and adjust our designs, processes, and policies to take them into account and make more informed decisions, not just for biofuels but also for complex societal problems of a similar nature. This approach is the realm of the field of industrial ecology, and the basis for the tool of life cycle assessment (LCA), a methodology that has been designed to perform holistic analyses of complex systems.

Life Cycle Assessment Basics

LCA is a systems methodology for compiling and evaluating information on materials and energy as they flow through a product or service manufacturing chain. It grew out of the needs of industry, in the early 1960s, to understand manufacturing systems, supply chains, and market behavior, and make choices among competing designs, processes, and products. It was also applied to the evaluation of the generation and emission of wastes from manufacturing activities. During the 1970s and 1980s general interest in LCA for environmental evaluation declined as the nation focused on the control of toxic substances and remediation of hazardous waste sites but increasing concern about global impacts, particularly those associated with greenhouse gas emissions, saw renewed interest in the development of the LCA methodology and more widespread applications.

This LCA approach is often called “cradle-to-grave” analysis because it follows a product from the extraction of natural resources (the cradle) to its disposal (the grave). When products are designed so that materials are continuously reused or recycled, the approach is sometimes called “cradle-to-cradle.”

The figure above shows the main stages and typical inflows and outflows considered in lifecycle assessment.

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:

• Raw Materials Acquisition
• Manufacturing
• Operation/Use/Maintenance
• Recycle/Waste Management

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).

Credit: Mark Fedkin

US EPA Document Life Cycle Assessment: Principles and Practices, EPA/600/R-06/060, 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

Examples of LCA Projects

Website: Design Life-Cycle, University of California, Davis, Department of Design,

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!

Cradle to Cradle Design with William McDonough: Circularity

This video will assist you in understanding of Cradle to Cradle Design

The Importance of an LCA

Many products have hidden environmental impacts that consumers rarely see. For example, a paper coffee cup may seem environmentally friendly because it is made from paper, but producing the paper requires trees, water, energy, transportation, and manufacturing. Similarly, a reusable metal water bottle requires more energy and materials to produce than a disposable plastic bottle, but it may have a much lower overall environmental impact if used repeatedly. A Life Cycle Assessment helps us answer the following questions:

1. Which product has the lowest environmental impact?
2. Where in a product’s life cycle are the greatest environmental impacts occurring?
3. How can manufacturers reduce waste, energy use, or pollution?
4. How can consumers make more informed purchasing decisions?

LCA can facilitate communication of risks and benefits to stakeholders and consumers (e.g. the “carbon footprint” of individual activities and life styles). Perhaps most importantly of all, LCA can help to prevent unintended consequences, such as creating solutions to problems that result in the transferal of environmental burdens from one area to another, or from one type of impact to another.

A complete LCA assessment defines a system as consisting of five general stages of the product or service chain, each of which can be further broken down into substages:

• Acquisition of materials (through resource extraction or recycled sources)
• Manufacturing, refining, and fabrication
• Packaging
• Use by consumers
• End-of-life disposition (incineration, landfilling, composting, recycling/reuse)

Each of these involves the transport of materials within or between stages, and transportation has its own set of impacts.

In most cases, the impacts contributed from each stage of the LCA are uneven, i.e. one or two of the stages may dominate the assessment. For example, in the manufacture of aluminum products it is acquisition of materials (mining), purification of the ore, and chemical reduction of the aluminum into metal that create environmental impacts. Subsequent usage of aluminum products by consumers contributes very few impacts, although the facilitation of recycling of aluminum is an important step in avoiding the consumption of primary materials and energy. In contrast, for internal combustion-powered automobiles, usage by consumers creates 70-80% of the life cycle impacts. Thus, it is not always necessary that the LCA include all stages of analysis; in many cases it is only a portion of the product/service chain that is of interest, and often there is not enough information to include all stages anyway. For this reason there are certain characteristic terminologies for various “scopes” of LCAs that have emerged:

Industrial Ecology

Many systems designed by humans focus on maximizing profitability for the firm, business or corporation. In most cases this means increasing production to meet demand for the products or services being delivered. An unfortunate byproduct of this is the creation of large amounts of waste, many of which have significant impacts if they enter the environment. Figure Human-Designed Industry is a general-purpose diagram of a typical manufacturing process, showing the inputs of materials and energy, the manufacturing of products, and the generation of wastes (the contents of the “manufacturing box” are generic and not meant to depict any particular industry—it could be a mine, a factory, a power plant, a city, or even a university). What many find surprising is the large disparity between the amounts of waste produced and the quantity of product delivered.

Human-Designed Industry Generic representation of a human-designed industry. Source: Theis, T.

The life cycle of a t-shirt

Trace the life cycle of a classic white t-shirt to find out how they’re made and what is their ultimate environmental impact. — Consider the classic white t-shirt. Annually, we sell and buy 2 billion t-shirts globally, making it one of the most common garments in the world. But how and where is the average t-shirt made, and what’s its environmental impact? Angel Chang traces the life cycle of a t-shirt. Lesson by Angel Chang, directed by TED-Ed.

Additional Readings:

Journal article: J.B. Guinee et al., Life Cycle Assessment: Past, Present, and Future, Environ. Sci. Technol., 2011, 45, 90-96.

https://pubs.acs.org/doi/10.1021/es101316v

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.

Conclusions

The life cycle approach is a useful way to come to an understanding of the material and energy needed to make a product or deliver a service, see where wastes are generated, and estimate the subsequent impacts that these wastes may have on the environment. It is a good way to improve a product chain, articulate tradeoffs, and make comparisons among alternative processes and products. In these contexts LCA facilitates decision making by managers, designers, and other stakeholders. Most importantly, LCA is a way of framing policy options in a comprehensive and systematic way.

Review Questions:

• What is a life cycle assessment, and why is it useful?
• What are the four stages of an LCA?
• What is the difference between “cradle-to-grave” and “cradle-to-cradle”?
• Why are system boundaries important in an LCA?
• Identify two benefits and two limitations of life cycle assessments

Critical Thinking:

Choose two products that serve the same purpose—for example, paper versus reusable shopping bags or disposable versus rechargeable batteries. Using life cycle thinking, compare their environmental impacts during raw material extraction, manufacturing, transportation, use, and end-of-life disposal. Based on your analysis, which product is likely to be the more sustainable choice, and under what conditions?

Attributes

This chapter is composed of text taken from  the following sources:

Sustainability: A Comprehensive Foundation by Tom Theis, University of Illinois, Chicago and Jonathan Tomkin, University of Illinois, Urbana-Champaign.  Copyright Year: 2015. Publisher: OpenStax CNX  and is under CC BY license.    Sustainability A Comprehensive Foundation

Life Cycle of a t-shirt video. Lesson by Angel Chang, directed by TED-Ed.  –Life cycle of a T shirt

Life Cycle Assessment: Past, Present, and Future^†