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A Climate-friendly Energy Future: Prospects for Wind

Posted on:2015-05-26Degree:Ph.DType:Thesis
University:Harvard UniversityCandidate:Huang, JunlingFull Text:PDF
GTID:2472390017497941Subject:Energy
Abstract/Summary:
The objective of this thesis is to evaluate the potential for wind as an alternative energy source to replace fossil fuels and reduce global CO 2 emissions. From 1995 to 2007, fossil fuels as the major energy source accounted for an addition of 89.3 Gt of carbon to the atmosphere over this period, 29 % of which was transferred to the ocean, 15 % to the global biosphere, with the balance (57 %) retained in the atmosphere. Building a low-carbon and climate-friendly energy system is becoming increasingly urgent to combat the threat of global warming.;Onshore wind resources in the contiguous US could readily accommodate present and anticipated future US demand for electricity. The problem with the output from a single wind farm located in any particular region is that it is variable on time scales ranging from minutes to days posing difficulties to incorporate relevant outputs into an integrated power system. The issue of interconnection of wind farms is studied with specific attention to the physical factors that determine the temporal variability of winds in the near surface region of the atmosphere.;From a global perspective, generation of electricity from wind is determined ultimately by the balance between the production and dissipation of kinetic energy in the atmosphere. The origin of wind energy from 1979 to 2010 is investigated. The atmosphere acts as a thermal engine to produce wind energy, absorbing heat at higher temperatures (approximately 256 K), releasing heat at lower temperatures (approximately 253 K), as a consequence producing wind energy at a rate of 2.45 W/m2, with a thermodynamic efficiency of 1.03 %.;The continuous blowing of wind is maintained by the thermodynamic instability of the atmospheric system. A framework is constructed to probe the relationship between the energy and entropy of the atmosphere, and to quantify two variables, the maximum work and the maximum increase in entropy which represent the thermodynamic instability. A large value for either variable corresponds to high thermodynamic instability and large potential for the atmosphere to produce wind energy. The results offer a fresh perspective on the energetics of the atmosphere.
Keywords/Search Tags:Energy, Wind, Atmosphere
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