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High-altitude wind power (HAWP) is the harnessing of the power of winds high in the sky by use of tether and cable technology. An atlas of the high-altitude wind power resource has been prepared for all points on Earth.〔(Global Assessment of High-Altitude Wind Power )〕 A similar atlas of global assessment〔(High Altitude Wind Resource Modeling & Analyses, Archan Padmanabhan )〕 was developed at Joby Energy. The results were presented at the first annual Airborne Wind Energy Conference held at Stanford University by Airborne Wind Energy Consortium.〔(http://www.aweconsortium.org/ )〕 Various mechanisms are proposed for capturing the kinetic energy of winds such as kites, kytoons, aerostats, gliders, gliders with turbines for regenerative soaring,〔(Flight Without Fuel - Regenerative Soaring Feasibility Study )〕 sailplanes with turbines, or other airfoils, including multiple-point building- or terrain-enabled holdings.〔(Wind Turbines on Mounts )〕 Once the mechanical energy is derived from the wind's kinetic energy, then many options are available for using that mechanical energy: direct traction,〔(SkySails )〕〔(Anne Quéméré, the Oceankite and Extreme Weather )〕 conversion to electricity aloft or at ground station, conversion to laser or microwave for power beaming to other aircraft or ground receivers. Energy generated by a high-altitude system may be used aloft or sent to the ground surface by conducting cables, mechanical force through a tether, rotation of endless line loop, movement of changed chemicals, flow of high-pressure gases, flow of low-pressure gases, or laser or microwave power beams. There are two major scientific articles about jet stream power. Archer & Caldeira〔Archer, C. L. and Caldeira, K. (Global assessment of high-altitude wind power, IEEE T. Energy Conver., 2, 307–319, 2009. ) Retrieved on January 16, 201208.〕 calculated that, if the world's entire electrical energy demand were supplied by HAWP, the climatic impact would be negligible. Miller, Gans, & Kleidon〔L.M. Miller, F. Gans, & A. Kleidon (Jet stream wind power as a renewable energy resource: little power, big impacts. Earth Syst. Dynam. Discuss. 2. 201-212. 2011. ) Retrieved on January 16, 201208.〕 claim that the jet streams can generate the total power of only 7.5 TW, and that the climatic impact will be catastrophic. ==High-altitude wind for power purposes== Winds at higher altitudes become steadier, more persistent, and of higher velocity. Because power available in wind increases as the cube of velocity (the velocity-cubed law),〔(Wind Power Curves )〕〔(The Power of the Wind: Cube of Wind Speed by the Danish Wind Industry Association )〕 assuming other parameters remaining the same, doubling a wind's velocity gives 23=8 times the power; tripling the velocity gives 33=27 times the available power. With steadier and more predictable winds, high-altitude wind has an advantage over wind near the ground. Being able to locate HAWP to effective altitudes and using the vertical dimension of airspace for wind farming brings further advantage using high-altitude winds for generating energy. High-altitude wind generators can be adjusted in height and position to maximize energy return, which is impractical with fixed tower-mounted wind generators. In each range of altitudes there are altitude-specific concerns being addressed by researchers and developers. As altitude increases, tethers increase in length, the temperature of the air changes, and vulnerability to atmospheric lightning changes. With increasing altitude, exposure to liabilities increase, costs increase, turbulence exposure changes, likelihood of having the system fly in more than one directional strata of winds increases, and the costs of operation changes. HAWP systems that are flown must climb through all intermediate altitudes up to final working altitudes—being at first a low- and then a high- altitude device. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「High-altitude wind power」の詳細全文を読む スポンサード リンク
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