Green Collar Job Training - Free

#

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 Turbine Design

Over the last 5 years Wind Turbines has seen a phenomenal growth in commercial AC production.  Several European countries have taken a strong leadership role including Germany, Great Britain and Spain.  From a commercial standpoint wind energy makes a strong economic case;  it has a higher production cost then natural gas or coal although it is less expensive then nuclear when all operational costs are considered.

Commercial AC systems are quite different from the systems you'll see on farms and private homes due to the scale of production.  Two reasons account for the differences:
 
First, commercial AC generation uses a much larger scale system measured in megawatts rather then kilowatts.  The towers are very tall, typically 300' high.  Wind flow closer to the ground below about 100' tend to be interrupted by objects and a condition known as laminar flow - the lower boundary layer of air between the ground and the undisturbed natural layer of flowing air.

The image at right depicts the difference in wind speed for a 75 and 300 foot tall tower.  Different terrain has different effects on the lower boundary layer but you get the idea.

Wind turbine production is not a linear relationship to wind speed;  most wind turbines need at least 8MPH wind to turn at all, and generally the power produced at 20 mph wind speed is 3-4 times that at 10 MPH wind speed.

Second, the mechanical nature of a wind turbine tends to make the system significantly more maintenance intensive then a solar PV cell system.  For someone with only one or two wind turbines the occasional service required may not be a problem.  Full scale commercial AC wind farms hire a staff to climb the towers and perform maintenance.

Wind speed is the crucial factor in design.  No matter how tall the tower is, if you don't have a sufficient average sustained wind speed a wind turbine will be nothing more then an expensive yard ornament.  Wind speeds are generally very unpredictable from one location to another mostly due to surface features of the earth.  For example locations with hills, mountains, and passes may offer a spectacular application site while sites less the a mile away won't produce enough juice to run a light bulb.  San Gorgonio Pass near Palm Springs California is an example of the perfect location for wind turbines; wind speeds in San Gorgonio Pass average about 18 MPH year round while the Palm Springs airport has an annual average wind speed of 7.3 MPH - less then 10 miles away.

With over half the population living in a coastal community, and as wind tends to be more powerful along the coast there are some good an bad points to consider.  The good point is there will almost always be a enough wind to produce power.  The bad points are that occasional storms and very high winds are likely to pose a risk to a long term installation and salt spray carried inland 1-2 miles may tend to accelerate maintenance requirements.

If you find a site that has a steady supply of wind that exceeds an annual average wind speed of 8 MPH it may be an excellent candidate for a wind turbine.  The Solar Site Survey Regional Wind Speed worksheet has the average annual wind speeds reported for 275 locations across America.  The site specific may vary for local terrain reasons.

The design technology varies among the dozens of manufacturers, but there are the key system design elements to look for:

  • Brushless Alternator design
  • Gearless technology - newer rare earth magnets allow the alternator to produce sufficient power at shaft speeds equal to the turbine speed.
  • Low wind start up speed
  • Output Graph performance - kWh/Wind Speed - compare systems
  • Survivable wind speed
  • Manufacturer Warrantee