Wind Power - Sustainability Engineering and Practice | EE 80, Exams of Electrical and Electronics Engineering

Download Wind Power - Sustainability Engineering and Practice | EE 80 and more Exams Electrical and Electronics Engineering in PDF only on Docsity!

Wind Power

EE80j: Summer 2009

OUTLINE

History of wind power (do not memorize)

Types of wind turbines

Environmental impact

Economy

Commercial development and potential

Off shore

A. Shakouri

9/18/

Wind Energy

Captures the kinetic energy of wind

Electricity production

Wind turbines generate mechanicalpower, which is then used to generateelectricity

R&D Focus

Improvements in turbine designs,structural dynamics, lower cost

Green Mountain Power Wind Plant

NREL’s turbine test

field

Fastest growing renewable in the U.S. andworldwide

6,300 MW of capacity in U.S.

Almost 11 billion kWh/year of electricity

Power System Size Range

50 kW to several MW

Electricity Generation Cost

One of the most cost-competitive renewableenergy technologies

< 5¢/kWh at good wind sites

Sources: EIA Renewable Energy Annual 2002, DOE Wind and Hydropower Program Website, andEERE State Energy Alternatives Website

Palm Springs, CA, wind farm

Power Wind Plant

History

Panemone: First windmill to automategrain-grinding and water pumping(Persia 500-900 A.D)

First documented Chinese windmill

First documented Chinese windmill 1219 A.D.

Windmills in the Western World (1270A.D.) Horizontal axis

Ref 3

First wind turbine to incorporate the

aerodynamic design

1891 , Dane Poul La Cour (Denmark)

low-solidity, four-bladed rotorsincorporating primitive airfoil shapes) used in the best Europeanshapes) used in the best European tower mills.

The higher speed of the La Courrotor made these mills quitepractical for electricity generation.By the close of World War I, the useof 10-35 kW electrical output

Ref 3

Three-blade propeller

The Jacobs brothers developed a three-bladepropeller with an approximate diameter of 4metres and a directly driven DC generator. Tensof thousands of these Jacobs wind-loaders, with output between 1.8 and 3 kW, were builtwith output between 1.8 and 3 kW, were built between 1920 and 1960.

(USA)

Smaller applications, lightening farms, chargebatteries used to power crystal radios

Ref 3

A. Shakouri

9/18/

There is also a need for lower speed wind technology(x20 resources)

A. Shakouri

9/18/

Turbine Sizes

Source: AWEA/GEC ProjectDatabase, Sandia

Trend toward bigger

turbine size

Size limit

Square-Cube law

As a wind turbine rotor increases in size

Its energy output increases as the rotor-swept area(d

2

)

While the volume of material, and therefore its mass

While the volume of material, and therefore its mass and cost increases as the cube of the diameter (d

3

)

By smart engineering (removing material or byusing material more efficiently), in recent yearsblade mass has been scaling at roughly anexponent of 2.3 instead of 3

Ref 2

Examples of traditional vertical axis

windmills

Ref 1

High solidity vs. Low solidity

More blades, more interaction with wind, less required tipspeed ratio

Modern low solid turbine need high tip speed ratio to coverthe space virtually

Too high speed ratio will cause too much resistance to the wind so some of the wind goes around ( optimum tip speedwind so some of the wind goes around ( optimum tip speed ratio for modern turbines is between 6 to 20)

large number of blades can interfere with each-other andreduce the efficiency

Three- blade modern turbines are the most efficient ones

Generally turbines with more blades expect to generateless aerodynamic noise

Ref 1

Horizontal Axis Wind Turbine (HAWT)

Operate with their rotation axes in line withthe direction of the wind, rotation axis ismaintained in line with wind direction by ayawing mechanism which constantly realigns the wind turbine rotor (axial flew)the wind turbine rotor (axial flew)

most common form of wind turbines now,clean streamlined appearance, derived largelyfrom development in aircraft wing andpropeller design, usually 2 or 3 blades

Ref 1

Direction of the wind flow isperpendicular to the rotation axis(cross flow)

Less common, can harness wind fromany direction without the need toreposition the rotor,

M

odern VAWT are all evolved from

Vertical axis wind turbines (VAWT)

M

odern VAWT are all evolved from

the idea of a French engineer,Georges Darrieus (1925)

Several hundreds are installed in CA.

Hard to manufacture and installbecause of the unusual shape

Currently these are not economicallycompetitive with HAWT for largescale power generations

Darrieus VAWT

unable to self start

Giromill

Cheaper and easier design

$ 4,000500W