Life Cycle Assessment Essay ⋆ Environment Essay Examples ⋆ EssayEmpire

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Is it best to use cups made of paper, polymer foam, or ceramic? Which ones cause the least environmental damage? Paper, of course, comes from wood, and wood is a natural renewable resource. On the other hand, foam cups are made of polystyrene, which is obtained from crude oil, a nonrenewable resource. Does this mean a paper cup is more environmentally friendly than a foam cup? However, even though paper is from a renewable source, many harmful chemicals are emitted during its manufacture. Do the advantages of renewability outweigh the harm from emissions? Life Cycle Assessment (LCA) aims to answer questions such as these and can be useful for making technological choices.

LCA evaluates the environmental impact of a product throughout its life cycle starting from raw material extraction, going through product manufacture, use, recycle, and disposal. The life cycle of a paper cup would thus include cutting down the trees to obtain wood chips, transporting them to paper mills where they are converted to paper cups, transportation of cups to the market, sale of cups to consumers, and use by consumers. The cycle would end when the cups are reused, recycled, or discarded.

A typical LCA of a product consists of four steps: goal and scope definition, inventory analysis, impact assessment, and improvement analysis. The first step consists of specifying the purpose of the life cycle study and in simple cases means comparing the environmental burden of two products with similar uses. Scope definition implies identifying and specifying the important processes to be included in the life cycle of a product.

For the second step, inventory data are collected for each of the processes in the life cycle. Input data typically includes material and energy consumption data, while output data includes the emissions of various substances. There can be a variety of emissions during the entire life cycle, such as carbon dioxide, sulfur dioxide, methane, or benzene. These have different impacts on human health and ecosystem quality.

Impact assessment, the third step, aims at understanding the quantitative magnitude and significance of the potential environmental effects of all these emissions in different impact categories. For example, carbon dioxide and methane can cause global warming; sulfur dioxide and benzene can affect human health. This is the step in life cycle assessment where the results are used to draw conclusions and make recommendations for improving the environmental performance of a product.

Returning to the example of the paper, plastic, and ceramic mugs, it turns out that each of these three cups has a dark side. A ceramic mug is made from clay, which is relatively clean; it can also be used multiple times, which reduces waste. These properties make it attractive. But is it better than a paper or plastic cup?

Wood, the original source material of paper, is supposedly green, but during the transformation of wood to paper, steam is needed to heat the wood, machines are used to grind the wood fiber, and vacuum pumps and dryers are essential to remove the water from the pulp. All of these consume energy. Additionally, many inorganic chemicals-chlorine, sodium hydroxide, sodium chlorate, sulfuric acid, sulfur dioxide, and calcium hydroxide-are used during the pulping and bleaching phases. Also, although paper is biodegradable, it releases methane during its degradation, which contributes to global warming.

A foam cup is made entirely from materials derived from crude oil, a nonrenewable resource. Impacts from extraction of crude oil and its subsequent refining are significant. Any accidental spill during drilling, production, or transportation of crude oil can pose an ecological disaster. In the manufacture of a foam cup, pentane, an organic compound that may cause smog, is employed as the blowing agent. Since polystyrene is relatively inert to decomposition, it will persist much longer than paper in a landfill.

The last example is that of a ceramic cup. Although it requires a lot of energy during its manufacture, a ceramic cup can be used many times, therefore it should probably be better than a paper or plastic cup. However, the cup needs to be cleaned after each use, and this requires a large amount of hot water and soap. Energy is necessary to get hot water. The soapy wastewater needs treatment. These requirements might offset the benefits obtained from reuse. A ceramic cup is not biodegradable either, and may stay in the landfill forever.

This simple example illustrates that significant use of materials and energy, and emission of pollution, can occur in any phase of the life cycle: In the resource extraction phase for a foam cup, in the manufacturing phase for a paper cup, in the use phase for a ceramic cup, and in the disposal phase for all three of them.

This suggests that LCA is crucial to evaluating and comparing the broader environmental burden of products that perform similar functions. In addition, it can help identify opportunities for improving the efficiency of existing processes.

Bibliography:

Chris T. Hendrickson, Lester Lave, and H. Scott Matthews, Environmental Life Cycle Assessment of Goods and Services: An Input-Output Approach (RFF Press, 2006);
Guido Sonnemann, Francesc Castells, and Marta Schuhmacher, Integrated Life-Cycle and Risk Assessment for Industrial Processes (CRC, 2003).