IRANIAN STUDY ON BETTER WIND

How To Get Wind Turbines To Work Harder
June 17, 2009 (ScienceDaily)

"…Abolfazl Ahmadi and Mehdi Ali Ehyaei of the Department of Mechanical Engineering, at Iran University of Science and Technology-Arak Branch, in Arak, have investigated the "exergy" of wind power. Exergy is a term from thermodynamics that measures that the energy a system that is available to do work…

"Ahmadi and Ehyaei point out that wind turbines have to compete with many other energy sources, primarily fossil fuels but also other renewable energy sources such as solar and biomass technology. As such, a wind turbine has to be cost effective in order to be environmentally effective."

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"Turbine design must meet load requirements and produce energy at a minimal per dollar cost…[P]erformance characteristics such as power output versus wind speed or versus rotor angular velocity must be optimized. Exergy analysis looks at the "quality" of the energy produced by a system. To be viable, there is little point in producing intermittent power at wildly varying levels, as this feeds only low-quality energy into the power supply system.

"Usually, wind speeds of above 9 meters per second are considered irrelevant in exergy calculations of wind turbines and previous research has not taken all factors that are required for a holistic analysis into account…"

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"…[The Iranian team has] developed a [more detailed] exergy analysis for wind turbines…Their approach gives them a model of how the turbine's potential for work can be lost…[and] a way to optimize a wind turbine's three main parameters, cut-in, rated, and furling wind speeds, so that usable energy is maximized at any given wind speed from the gentlest breeze to a roaring gale; within the safe working parameters of the turbine.

"They have carried out an exergy analysis of turbines sited in two cities in Iran, Tehran and Manjil, where wind speeds are very different. Tehran has low average wind, whereas Manjil is a windy city. Their formula offers optimized values for wind turbine rotation speed, which can be altered depending on wind speed. The results are a theoretical boost of 20% efficiency at both sites and a decrease in "wasted" energy of 80%."