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ZEH Info!

Wind Mills 

Today we are seeing wind gaining tremendous popularity in generating significant amounts of power both off-grid and as a source of energy for large utilities. European countries are leading the way in wind generation while Canada generally lags behind. Alberta has an established base of large-scale wind generators. Downtown Toronto now has a commercial scale turbine.

How it works
Wind turns the blades of the turbine which spins a shaft within the turbine structure. The shaft drives a generator to produce electricity. The electricity is either used directly or stored in batteries.

Types of Wind Generators
There are many different types and styles of wind generators. Many of the older, multi-blade units as seen on farms across the nation generate mechanical energy, often used to pump water.

  • Small-scale units (under 3 kW): used to charge batteries or direct use (such as pumping water or grid inertia).
  • Medium sized units (up to 50 kW): used in a grid-inertia environment to generate power and feed it to the utility grid. Energy Alternatives designs and installs medium scale units. Due to the nature of these projects, each system requires a detailed assessment prior to quotation or ordering products. Investment is typically $40,000+.
  • Large-scale units (megawatts): large, towering units that cost millions of dollars and generate power to run hundreds or thousands of homes or businesses. Generally suited to large utilities and power co-operatives.

Wind and PV
In many Canadian locations, a wind turbine is an excellent supplement to a solar electric system. Small wind systems are often combined with photovoltaic because seasonal variations in wind and solar resources are complementary. Most places in Canada do not have adequate wind to use as a primary power source. Locations such as the prairies that have constant prevailing winds are most suited to wind power. Contrary to popular belief, coastal areas do not always provide the best source of wind power - the winds are not as constant and predictable as those on the prairies.

Battery Size
Wind is a variable resource. The winds may be calm for a week or more, but when it does become windy it often blows very hard, most notably in the winter. For this reason wind energy systems usually require a larger battery to take advantage of the energy

when it is available and to store it for extended calm periods.

Maintenance
Unlike photovoltaic modules, wind turbines have moving parts. Periodic maintenance of bearings, brushes and shafts is required. It is important when installing a wind generator to consider how easy it will be to access the generator and conduct maintenance.

Towers are a critical component of wind power systems. Proper location and height of your tower is necessary to get maximum energy from a wind turbine. Improper tower design or installation may result in personal injury, property damage or a damaged generator. It will also likely result in less-than-satisfactory performance from your wind turbine.

You should be completely familiar with the installation procedures before you begin. Safety equipment should be used at all times. Check your local building department for bylaw or zoning restrictions for towers.

Tower Height
Wind generator operation is dependent on the quantity and quality of the wind hitting the blades. Turbulent wind will reduce the power output as the turbine swings back and forth hunting for the wind. The unequal stresses caused by turbulence and the variation in wind speed between the upper and lower blades of a wind turbine installed too close to the ground will reduce power output and wind turbine life.

Wind speed increases rapidly with tower height. Doubling tower height increases the available wind power by about 40%. It is often more economical to install a higher tower rather than purchasing a larger generator. A wind generator should be installed a minimum of 33 feet (10 meters) above any obstruction within 330 feet (100 meters).

What you need for a wind system

Wind
Wind generation is dependent on the quality and quantity of the wind hitting the blades. The better the wind you have the more power you will generate.
The power available in wind increases by the cube of the wind speed - if wind speed doubles, power output increases by eight.
Turbulent wind (from obstructions, geographical features, etc.) will reduce the power output as the turbine swings back and forth hunting for the wind.

A Good Site
The higher a turbine, the more power is generated, the better quality the wind.
A wind turbine should be at least 40 ft above any object within a 400 ft radius. Note there are often exceptions to this rule depending on your site.
It is often more economical to install a higher tower than purchasing a larger turbine.
Space. Generally locations with an acre or more will be suitable. Most urban locations will not permit you to install a wind generator in your yard. A guyed tower requires 1/2 the height of the tower as a radius at a minimum for location of anchor points. Space is also required for ground assembly and erection of the tower. Lattice towers require less surface area, but are more complex and expensive to install