BKCHAP02-2011 - Chapter 2 LIFE CYCLE ASSESSMENT 2.1...

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2-1 Chapter 2 LIFE CYCLE ASSESSMENT 2.1 Introduction Life-cylce assessment (LCA) is a process that allows an evaluation of the technology, process and the end-of-pipeline treatment that are necessary to compare all energy systems in an even footing. A primary goal of a system designer or an energy analyst is to ensure that energy supply systems are designed to minimize the impacts to the wider world during their entire life-span from origin to disposal. For example, if one attempts to compare nuclear power with solar photovoltaic electricity, it is necessary to look at nuclear power from the mining of uranium to the treatment of nuclear waste on one hand, and the extraction of solar cell materials to the recycling of used solar cell modules on the other. The Society of Environmental Toxicology and Chemistry defines the LCA process as follows (SETAC 1991): The life-cycle assessment is an objective process to evaluate the environmental burdens associated with a product, process, or activity by identifying and quantifying energy and material usage and environmental releases, to assess the impact of those energy and material uses and releases on the environment, and to evaluate and implement opportunities to effect environmental improvements. The assessment includes the entire life cycle of the product, process or activity, encompassing, extracting and processing raw materials; manufacturing, transportation, and distribution; use/re-use/maintenance; recycling; and final disposal. Such an analysis involves many players and is a large and complex effort. There is, nevertheless, a preliminary agreement on the formal structure of LCA. This contains three stages: inventory analysis, impact analysis and improvement analysis (Graedel and Allenby 1995). Inventory analysis uses quantitative data to establish the levels and types of energy and material inputs necessary for establishing the system and the environmental releases that result in the process. The assessment is done over the entire life cycle - materials extraction, processing, distribution, use and disposal. For example, if our system is a coal-fired power plant, we will look at the inputs necessary for, and environmental releases due to, mining and transport of coal and the construction of the power plant including the land-use impacts. The impact analysis involves relating the outputs of the system to the impacts on the external world where those outputs flow. In the case of the coal-fired power plant this will include plant emissions that cause acid rain, smog, loss of visibility, global warming, etc. The third stage, the improvement analysis , includes analyzing the needs and opportunities for reducing impacts as a result of the industrial activity. Again, in terms of our power plant example, one can look into high-BTU and low-sulfur coal, atmospheric fluidized bed combustion, high efficiency boilers, etc. to minimize the environmental impacts of coal burning. There are costs associated with each of these stages that comprise the life-cycle assessment.
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This note was uploaded on 03/16/2012 for the course ECE 5374G taught by Professor Srahman during the Spring '12 term at Virginia Tech.

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BKCHAP02-2011 - Chapter 2 LIFE CYCLE ASSESSMENT 2.1...

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