WIND ENERGY: THE NEW ALTERNATIVEBy James WashechekDepartment of Chemical Engineering, The University of Texas at Austin

DESCRIPTION OF WIND TURBINESConverts 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.

HISTORY OF WIND POWERED TURBINES200 B.C. Wind powered machines utilized by Persians.

1888 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.

FUTURE WIND ENERGY CAPACITYIncreasing exponentially

3 to 5 times larger energy capacity over next 6 years

20% of electrical energy supplied by wind energy by 2030World Wind Energy Capacity Approximation (Wiki, 2008)

TURBINE POWERDirectly 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 efficiencywhere,P = power (W) = design efficiency factor = density of air (kg/m)r = radius of wind turbine (m)v = velocity of wind (m/s)

COMPARISONS TO OTHER ENERGY SOURCESEnvironmentally friendly

Large resource supply

Cheap operating costs, 1cent/kWhr

Wind $55.80/MWh Coal $53.10/MWh Natural Gas $52.50/MWh

vs.WindCoalNatural Gas

HORIZONTAL AXIS WIND TURBINE (HAWT)Most common industrial design today

Wind sensors to rotate tower in yaw direction

Many found in West Texas where wind velocities are highHorizontal Axis Wind Turbine Design

HAWT ADVANTAGES AND DISADVANTAGESVariable 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 turbulenceMust be large scale making expensive construction costsMust be comprised of strong materials (carbon fiber and steel) to deal with high windsAdvantagesDisadvantages

VERTICAL AXIS WIND TURBINE (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 ADVANTAGES AND DISADVANTAGESCheaper 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 shaftLittle chance of structural failureCreate 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

CONCLUSIONSHorizontal 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

REFERENCESHansen, Martin O.L. Aerodynamics of Wind Turbines, 2nd Ed. Earthscan Publications Ltd, January 2008.Hau, Erich and H. von Renouard. Wind Turbines: Fundamentals, Technologies, Application, Economics, 2nd Ed. Springer, October 1, 2005.McCabe, W.L. and J.C. Smith. Unit Operations of Chemical Engineering, 7th Ed. McGraw-Hill, New York.Ragheb, M. Theory of Wind Machines, Betz Equation. 16 Nov. 2008 ."Wind Power." Wikipedia: The Free Encyclopedia. 10 Nov. 2008 ."Wind Turbine." Wikipedia: The Free Encyclopedia. 17 Nov. 2008 .