Wind power works: Doing small wind right

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On a recent trip through rural Australian countryside I saw quite a few small wind electric systems on the properties of rural homes and farms. The sight of wind systems dotting the landscape is incredibly heartening. These small wind systems represent energy independence, a hedge against increasing energy prices, decreased carbon emissions and, importantly, support for the local economy.

Seeing small wind systems in the countryside is also heartening because wind systems produce negligible, if any, energy in urban areas. I see five of these urban turbines in Sydney on my bike ride into work and it still makes me cringe to think about these poor investment decisions (and inherently bad marketing for renewable energy).

However, on my drive through rural Australia I also saw many poorly sited wind electric systems. The owners of poorly sited systems have the best of intentions, but unfortunately these good intentions may not come to fruition when the installer does not locate or design the system appropriately. It was the drive through the countryside that prompted me to revisit some of the small wind siting truths in order to provide some guidance for those interested in installing a small wind energy system.

Why is siting important?
Small wind energy has a significant role to play in helping countries meet their goals for distributed energy and carbon reduction. According to the World Wind Energy Association’s 2012 Small Wind Report, the market for small wind turbines has seen dynamic growth this year and the total capacity worldwide has reached 440 MW: about the same as the combined capacity of all Victoria’s wind farms at the start of 2012.

However, it is no use installing wind electric systems if they are not sited correctly. A wind system, like a solar PV system, needs access to the resource.

Truth #1: Installing a wind system on a tower that is too short is akin to installing a solar electric panel in your basement. Both would be interesting to observe up close, but totally useless in terms of energy production.

The wind turbine needs to be at a height where the wind blows at a sufficient speed for energy production. Wind turbines are rated with a ‘cut-in’ wind speed, but this is often much lower than what’s needed to provide useful amounts of energy. While the blades of a wind turbine might appear to spin rapidly, you need an average wind speed of at least 5 m/s to generate enough energy to make a wind system worthwhile. More useful amounts of energy will be generated at average wind speeds above about 6 m/s, although this occurs much less frequently.

If you do not have access to average wind speeds of 5 m/s or greater at your site—even with a tower height of 40 metres—install solar PV instead.

Read the full article in ReNew 122.

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