Environmental Life Cycle Assessment of Goods and Services

An Input-Output Approach

Chris T. Hendrickson, Lester B. Lave, H. Scott Matthews

• Verlag: Routledge
• Jahr: 2010
• ISBN:
  9781136525490
• Auflage: 1
• Thema: Diritto
• Thema: Diritto ambientale

Environmental life cycle assessment is often thought of as cradle to grave and therefore as the most complete accounting of the environmental costs and benefits of a product or service. However, as anyone who has done an environmental life cycle assessment knows, existing tools have many problems: data is difficult to assemble and life cycle studies take months of effort. A truly comprehensive analysis is prohibitive, so analysts are often forced to simply ignore many facets of life cycle impacts. But the focus on one aspect of a product or service can result in misleading indications if that aspect is benign while other aspects pollute or are otherwise unsustainable. This book summarizes the EIO-LCA method, explains its use in relation to other life cycle assessment models, and provides sample applications and extensions of the model into novel areas. A final chapter explains the free, easy-to-use software tool available on a companion website. (www.eiolca.net) The software tool provides a wealth of data, summarizing the current U.S. economy in 500 sectors with information on energy and materials use, pollution and greenhouse gas discharges, and other attributes like associated occupational deaths and injuries. The joint project of twelve faculty members and over 20 students working together over the past ten years at the Green Design Institute of Carnegie Mellon University, the EIO-LCA has been applied to a wide range of products and services. It will prove useful for research, industry, and in economics, engineering, or interdisciplinary classes in green design.

PART I

Introduction to the EIO-LCA Method

Part I introduces economic input–output environmental life cycle assessment (EIO-LCA). Chapter 1 describes the method and explains why it may be useful in informing decisions about activities, products, processes, and policies. Chapter 2 sets the EIO-LCA method in the context of other approaches to life cycle assessment; in many cases EIO-LCA can complement other methods. Chapter 3 discusses how monetary costs may be balanced against improved environmental impacts. Of course, we all wish to find new designs or technologies that are less expensive and more capable, and have lesser environmental impacts.However, sometimes we have to consider the tradeoffs between costs and environmental impact. Chapter 4 discusses uncertainty in the EIO-LCA results and suggests some ways to improve confidence in them. Finally,Chapter 5 provides a nuts-and-bolts overview of the method and some example problems for readers wishing to use the EIO-LCA software (www.eiolca.net) directly. This chapter is self-contained and may be safely skipped by readers who do not yet need to use the software.

1
Exploring Environmental Impacts and Sustainability through Life Cycle Assessment

Paper or plastic? This simple question at the grocery store checkout counter might seem to sort those who care about the quality of the environment and the sustainability of our economy from ignorant or apathetic shoppers. We know that the correct answer is “paper,” because it is a “natural” product rather than some chemical. We can feel self-satisfied, even if the bag gets wet and tears, spilling our purchases on the ground.

Consumers are confronted with other questions: Paper or foam cups? Cloth or paper (disposable) diapers? The last question causes a particular stir, as disposable diapers are more convenient and less time-consuming than cloth diapers.

A few scientists have seen that these questions can, and should, be answered by data and analysis, rather than a feeling that the natural product is better. The ensuing analysis has ignited a major controversy over how to decide which product is better for the environment, beginning with an analysis of paper versus polystyrene cups (Hocking 1991). The controversy and scientific analysis have created the field of life cycle assessment, or LCA (Matthews et al. 2002).

This book is about life cycle thinking and getting the information to make sound decisions to improve environmental quality and sustainability. How can we design products, choose materials and processes, and decide what to do at the end of a product’s life in ways that produce less environmental discharges and use less material and energy?

Defining Life Cycle Assessment

Life cycle assessment “studies the environmental aspects and potential impacts throughout a product’s life (i.e. cradle-to-grave) from raw material acquisition through production, use, and disposal” (ISO 1997). Figure 1-1 summarizes the components of a life cycle. The life cycle assessment consists of three complementary components—inventory, impact, and improvement—and an integrative procedure known as “scoping.” The LCA “process analysis” developed by the Society of Environmental Toxicology and Chemistry (SETAC) and the U.S. Environmental Protection Agency (EPA) uses engineering to create energy and materials balances for each relevant process: mining ore, making materials and subcomponents, making the product, and the end of product life. Each material and energy balance tabulates the energy and material inputs, the desired outputs, and the undesired outputs that become environmental discharges.

FIGURE 1-1 A Generic Supply Chain Life Cycle Model

LCA requires careful energy and materials balances for all the stages of the life cycle (for example, the production of a car):

1. the facilities extracting the ores, coal, and other energy sources;

2. the vehicles, ships, pipelines, and other infrastructure that transport the raw materials, processed materials, and subcomponents along the supply chain to manufacture the consumer product, and transport the products to the consumer: iron ore ships, trucks carrying steel, engines going to an automobile assembly plant, trucks carrying the cars to dealers, trucks transporting gasoline, lubricating oil, and tires to service stations;

3. the factories that make each of the components that go into a car, including replacement parts, and the car itself;

4. the refineries and electricity generation facilities that provide energy for making and using the car; and

5. the factories that handle the vehicle at the end of its life: battery recycling, shredding, landfills for shredder waste.

Each of these tasks requires energy and materials. Reducing requirements saves energy, as well as reducing the environmental discharges, along the entire supply chain. Often a new material requires more energy to produce, but promises energy savings or easier recycling later. Evaluating whether a new material helps improve environmental quality and sustainability requires an examination of the entire life cycle of the alternatives. To make informed decisions, consumers, companies, and government agencies must know the implications of their choices for environmental quality and sustainability. Having good intentions is not sufficient when a seemingly attractive choice, such as a battery-powered car, can wind up harming what the manufacturer and regulator were trying to protect. This book provides some of the tools that allow manufacturers and consumers to make the right choices.

Life Cycle Controversies

The initial life cycle assessments surprised many people, since they found that paper bags, paper cups (or even ceramic cups), and cloth diapers were not obviously superior in terms of using less energy and materials, producing less waste, or even disposal at the end of life. Paper requires cutting trees and transporting them to a paper mill, both of which use a good deal of energy. Paper-making results in air emissions (the sulfite process) and water discharges of chlorine and biological waste (UNEP 1996). After use, the bag goes to a landfill where it gradually decays, releasing methane. A paper hot-drink cup generally has a plastic coating to keep the hot liquid from dissolving the cup. The plastic coating introduces the same problems as the foam plastic cup. The plastic is made from petroleum with relatively small environmental discharges. Perhaps most surprising, washing a ceramic cup by hand uses a good deal of hot water and soap, resulting in discharges of waste water that has to be treated and the expenditure of a substantial amount of fuel to heat the water, although washing the cup in a fully loaded dish washer uses less soap and hot water per cup. In short, it is not obvious which product is more environmentally benign and more sustainable.

The amount of hot water and electricity required to wash and dry the cloth diapers is substantial. If water is scarce or sewage is not treated, washing cloth diapers is likely to cause more pollution than depositing disposable diapers in a landfill. The best option turns on the issue of water availability (washing uses much more water) and heating the water.

The analyses found that the environmental implications of choosing paper versus plastic were closer than people initially thought. Which is better depends on how bad one thinks water pollution is compared to air pollution compared to using a nonrenewable resource. Perhaps most revealing was the contrast between plants and processes to make paper versus plastic. The best plant-process for making paper cups was much better than the worst plant-process; the same was true for plastic cups. Similarly, the way in which the cups were disposed of made a great deal of difference. Perhaps the most important lesson for consumers was not whether to choose one material over another, but rather to insist that the material chosen be made in an environmentally friendly plant.

The original analyses showed that myriad processes are used to produce a material or product, and so the analyst has to specify the materials, design, and processes in great detail. This led to another problem: in a dynamic economy, materials, designs, and processes are continually changing in response to factor prices, innovation, regulations, and consumer preferences. For example, in a life cycle assessment of a U.S.-manufactured automobile, the design and materials had changed significantly by the time the analysis was completed. Still another problem is that performing a careful material and energy balance for a process is time-consuming and expensive. The number of processes that are practical to analyze is limited. Indeed, the rapid change in designs, materials, and processes together with the expense of analyzing each one means that it is impractical and inadvisable to attempt to characterize a product in great detail.

The use phase of a product raises still more controversy. For example, foam plastic cups are good insulators while paper cups are not. Thus it is common to use two paper cups instead of one foam plastic cup. If this is the assumed comparison, paper cups are worse for the environment. A highway paved with concrete lasts longer than one paved with asphalt, but making the steel reinforced concrete requires more energy and results in more discharges than making asphalt. How much longer must a concrete highway last than an asphalt roadway in order to pay back the additional energy and environmental discharges (see )?

Still another issue is the end of life of a product (Lave et al. 1999). Is the product reused, recycled, put into a modern landfill, burned to generate electricity, or discarded into the environment? Some products contain toxic materials, such as lead-acid automobile batteries. If the batteries are not recycled, a great deal of lead goes into the environment. Indeed, many small consumer batteries are thrown into the trash and some times burned in a municipal waste incinerator, putting appreciable quantities of toxins into the air. If aluminum is recycled, the energy premium declines each time the material is recycled. Thus recycled aluminum represents a much smaller energy use than does virgin aluminum.

Another lesson from the early comparisons is that the scope of the analysis has to be appropriately broad. For example, California environmental regulations required that 3% of the new cars sold in 1998 had to be “zero emissions” vehicles. From a life cycle perspective, there are no zero emissions vehicles, since all vehicles are made with energy and materials, all require energy for propulsion, and all involve some disposal at the end of their lives. That perspective encourages an analyst to consider the difference between vehicles in terms of the full life cycle, not just the use of the vehicle. The only technology that produced no emissions directly from the vehicle was a battery-...

Inhaltsverzeichnis

• Cover Page
• Half Title page
• Title Page
• Copyright Page
• Contents
• Preface
• I Introduction to the EIO-LCA Method
• II Example Applications
• III Further Developments in the EIO-LCA Method
• Appendix I Sectors and Outputs in the 1997 U.S. Benchmark EIO-LCA
• Appendix II Some Alternative Model Forms for EIO-LCA
• Appendix III Disaggregation Options for Conducting Hybrid Life Cycle Assessments
• Appendix IV Uncertainty in Leontief Input–Output Equations: Some Numerical Examples
• Appendix V Compliance of an LCA Study Conducted Using the EIO-LCA Model with the Requirements of ISO 14040, 14041, 14042, and 14043 Standards
• References
• Index