W IND E NERGY : T HE N EW A LTERNATIVE By James Washechek Department of Chemical Engineering, The University of Texas at Austin

D ESCRIPTION OF W IND T URBINES Converts wind kinetic energy into electrical power Numerous industrial turbine designs, for example horizontal and vertical axis wind turbines Clean energy alternative, with little to no environmental impact Affects environmental aesthetic integrity, some migratory bird patterns, and downwind wind velocity.

H ISTORY OF W IND P OWERED T URBINES 200 B.C. – Wind powered machines utilized by Persians – Charles F. Brush developed first energy producing windmill in Cleveland, Ohio. 1980s - First modern wind turbines were constructed. Past 20 years – Newer, better designed wind turbines have been developed.

F UTURE W IND E NERGY C APACITY Increasing exponentially 3 to 5 times larger energy capacity over next 6 years 20% of electrical energy supplied by wind energy by 2030 World Wind Energy Capacity Approximation (Wiki, 2008)

T URBINE P OWER Directly proportional to density of air, area of rotor blades, and cube of velocity Efficiency of internal parts affects maximum power available Limited to 59% maximum efficiency where,P = power (W) α = design efficiency factor ρ = density of air (kg/m³) r = radius of wind turbine (m) v = velocity of wind (m/s)

C OMPARISONS TO O THER E NERGY S OURCES Environmentally friendly Large resource supply Cheap operating costs, 1cent/kW·hr Wind – $55.80/MWh Coal – $53.10/MWh Natural Gas – $52.50/MWh vs. Wind CoalNatural Gas

H ORIZONTAL A XIS W IND T URBINE (HAWT) Most common industrial design today Wind sensors to rotate tower in yaw direction Many found in West Texas where wind velocities are high Horizontal Axis Wind Turbine Design

HAWT A DVANTAGES AND D ISADVANTAGES Variable wind pitch to optimize amount of wind absorbed. Able to increase height of tower to harness higher wind velocities at higher altitudes. Already the major design for industrial wind power generation. Inefficient close to ground level due to turbulence Must be large scale making expensive construction costs Must be comprised of strong materials (carbon fiber and steel) to deal with high winds AdvantagesDisadvantages

V ERTICAL A XIS W IND T URBINE (VAWT) Gearbox and generator at base of vertical rotor shaft. Utilizes wind flow in all directions (360°). Constructed on buildings to avoid ground level turbulence. Vertical Axis Wind Turbine Design

VAWT A DVANTAGES AND D ISADVANTAGES Cheaper due to less height needed for effective operation. No motor is needed to turn rotor blades. Routine maintenance easy due to components being situated under vertical rotor shaft Little chance of structural failure Create only half the amount of energy of a comparable HAWT Cannot harness higher winds at higher altitudes due to smaller height. Complete deconstruction for maintenance. AdvantagesDisadvantages

C ONCLUSIONS Horizontal axis wind turbine the preferred design for future industrial use. Future efforts in wind energy technology. Combination of wind energy with current energy infrastructure. Airborne Wind Generator

R EFERENCES Hansen, Martin O.L. Aerodynamics of Wind Turbines, 2 nd Ed. Earthscan Publications Ltd, January Hau, Erich and H. von Renouard. Wind Turbines: Fundamentals, Technologies, Application, Economics, 2 nd Ed. Springer, October 1, McCabe, W.L. and J.C. Smith. Unit Operations of Chemical Engineering, 7 th Ed. McGraw-Hill, New York. Ragheb, M. “Theory of Wind Machines, Betz Equation.” 16 Nov "Wind Power." Wikipedia: The Free Encyclopedia. 10 Nov "Wind Turbine." Wikipedia: The Free Encyclopedia. 17 Nov