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Course Title
100 Home
101 Introduction
102 FAQ Page
103 Course Catalog
104 Green World
105 Demand & Supply
106 Conservation Careers
107 Solar Careers
108 Wind Turbine Careers
109 Entrepreneurs
110 Employee or Employer?
200 Demand Management
201 Summary
202 Residential Energy Profile
203 Ten Conservation Rules
204 HVAC System
205 Kitchen Appliances
206 Water Heater
207 Lighting
208 Laundry Appliances
209 Calculating Savings
300 Renewable Technology
301 Solar Energy
302 Solar Collectors
303 Solar Water Heating
304 Stirling Engines
305 Basic AC-DC Electronics
306 Silicon Solar Panels
307 Thin Film Solar Panels
308 Wind Turbines
309 Inverters
310 Grid Tied and Off Grid
311 Solar Site Survey
312 Solar Site Diagram
313 Sun Path Chart
314 Site Survey Worksheet
315 Wind Turbine Site Survey
316 Wind Turbine Worksheet
400 Solar Thermal Design
401 Solar Heat Overview
402 System Configuration
403 Site Survey
404 SRCC Compliance
405 System Specification
406 Bill of Materials
407 System Installation
408 Solar Heat Incentives
409 Document Package
410 Future Products
500 Solar PV Design
501 Solar PV Overview
502 System Configuration
503 Site Survey
504 Grid Tied & Off Grid
505 System Specification
506 Bill of Materials
507 System Installation
508 Solar PV Incentives
509 Document Package
510 Future Products
600 Wind Turbine Design
601 Wind Turbine Overview
602 System Configuration
603 Site Survey
604 Grid Tied and Off Grid
605 System Specification
Green Collar Links
Green Collar Sponsors

 

Green Collar Careers - Wind Turbines

In regions with steady wind conditions wind turbines can be very cost effective for electricity production.  Commercially wind has been by far the largest investment in renewable energy generation.  From 2007 to 2008 the volume of commercial wind generated power in America nearly doubles to 1.3%, and is expected to reach 10% before 2015.  Spain currently generates over 1/3 of their electricity from the wind with Germany in excess of 10%.

Cost effective wind energy is an economy of scale; airflow close to the surface of the earth, around 100 feet is often obscured by objects including trees and natural land formations.  While it may feel windy on the ground, above 100 feet there is almost always a stronger more steady wind current.  Therefore the more efficient systems rely on a taller tower for the wind turbine, and that comes at a higher cost.

Windmills are mechanical devices that are more susceptible to failure then solar PV based systems.  Commercial generation companies can plan on having a staff in place to service and repair systems, however home owners are generally on their own when a failure occurs, and they generally don't have access to wholesale service/repair component pricing.

Windmills consist of at least 3 component groups; Turbine, Generator, Pedestal (or tower).

Turbines are the "sails" that catch the wind and convert that energy to rotating energy.  Most conventional designs are the 3-bladed propellers however there are several other designs.  On large scale commercial wind turbines the angle of the blades to the wind (pitch) may be altered to maintain some level of rotating speed control over varying wind speeds.

Generators are coupled to the rotating turbine shaft usually via a gearbox and generate either direct current or alternating current.  On large scale commercial wind turbines the generator/gearboxes are also known as "nacelles".  As high wind conditions prevail these systems may require a mechanical braking systems.

Pedestals provide the mounting for the wind turbine and generator system.  Most conventional designs (horizontal shaft) require the blades be pointed into the wind (Yaw direction) and the pedestal is equipped with a system to steer the blade facing to the desired direction.  Simple smaller systems may just rely on a tail fin where larger commercial systems are motor driven Yaw control.  Commercial systems and most horizontal shaft systems are mounted high so the Tower is included as a Pedestal component.

There are two classes of wind turbine designs;  Horizontal Axis and Vertical Axis.

 
Horizontal Axis are those with the turbines mounted on a horizontal shaft.  Horizontal Axis wind systems typically provides the most cost effective design particularly for large scale commercial applications.


 
Vertical Axis have turbines mounted on a vertical shaft.  Two key designs of vertical shaft turbines include the Darrieus and Savonius styles.  Small scale vertical axis turbines (under 25kWh) have been making some great progress with cost, reliability and low speed wind operation.  One of the newer technologies has been the use of magnetic levitation (maglev) eliminating bearing wear and friction.

 

  • Highest efficiency - Horizontal Axis
  • Lowest cost per kWh - Horizontal Axis
  • Lowest wind speed required to operate - Vertical Axis
  • Most reliable - Vertical Axis