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ID:
092789
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2009.
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| Summary/Abstract |
District heating is a technology for distributing centrally produced heat for space heating and sanitary hot-water generation for residential and commercial uses. The objectives are to identify which subsystems and components of a district heating grid are the main contributors to the overall impact of the infrastructure; and provide environmentally oriented design strategies for the future eco-redesign of these kinds of infrastructures. This paper performs a life-cycle assessment (LCA) to determine the environmental impacts of a district heating infrastructure in an urban neighbourhood context. The analysis covers seven subsystems (power plant, main grid, auxiliary components of the main grid, trench works, service pipes, buildings and dwellings) and twelve standard components. The results for the subsystems show that the sources of impact are not particularly located in the main grid (less than 7.1% contribution in all impact categories), which is the focus of attention in the literature, but in the power plants and dwelling components. These two subsystems together contribute from 40% to 92% to the overall impact depending on the impact categories. Concerning the components, only a reduced number are responsible for the majority of the environmental impact. This facilitates identifying effective strategies for the redesign of the infrastructure.
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| 2 |
ID:
125847
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2013.
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| Summary/Abstract |
Like cities, many large national parks in the United States often include "urban" visitor and residential areas that mostly demand (rather than produce) energy and key urban materials. The U.S. National Park Service has committed to quantifying and reducing scopes 1 and 2 emissions by 35% and scope 3 emissions by 10% by 2020 for all parks. Current inventories however do not provide the specificity or granularity to evaluate solutions that address fundamental inefficiencies in these inventories. By quantifying and comparing the importance of different inventory sectors as well as upstream and downstream emissions in Yosemite National Park (YNP), this carbon footprint provides a case study and potential template for quantifying future emissions reductions, and for evaluating tradeoffs between them. Results indicate that visitor-related emissions comprise the largest fraction of the Yosemite carbon footprint, and that increases in annual visitation (3.43-3.90 million) coincide with and likely drive interannual increases in the magnitude of Yosemite's extended inventory (126,000-130,000 t CO2e). Given this, it is recommended that "per visitor" efficiency be used as a metric to track progress. In this respect, YNP has annually decreased kilograms of GHG emissions per visitor from 36.58 (2008) to 32.90 (2011). We discuss opportunities for reducing this measure further.
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