Wind Energy
- Wind turbine credit: Grace Staed
Wind is an inexhaustible resource that is derived from the redistribution of solar energy in the atmosphere. It involves hot air which rises and cool air which sinks to take the warm air's place close to the earth. It is this convective motion that drives the winds around the globe, and this energy can be captured with a wind turbine.
Why Wind Power Matters to Local Governments
Wind power is a technology that is one of the most affordable of the renewable energy technologies. In terms of megawatt capacity it is the fastest growing renewable resource. As of 2008, there has been 121 GW of wind power installed worldwide, up from 74 GW in 2006 (REN21, 2009).Local governments can map the wind resources in their jurisdictions, remove barriers to wind projects (zoning laws, setback rules, streamline permitting, lower or remove application fees for permits), enable community ownership and cooperatives to participate, among other actions which encourage wind power usage in their area.
Community Power
Of particular interest and commonly within the bounds of action in a municipality is the facilitation of community power and cooperative groups seeking to implement renewable energy projects. Local renewables encourages local economic development and sustained local job creation by providing opportunities for local maintenance, management, and manufacturing. The inclusion of the public in the planning and ownership of wind projects is crucial for the broader acceptance of wind power, within the community and beyond, as these communities will have control, input, and benefit financially. If people can buy into and profit from a wind farm being developed in their locality, they are much more likely to support it. Community ownership and participation directly contributes to the increased awareness in the community about renewable energy. An excellent website for Community Power is www.cpfund.ca.
- Wind turbine credit: Grace Staed
The Technology
Most wind turbines today have 3 blades that are normally half as long as the tower, and these blades turn a shaft that is attached to a generator that sits atop a tall tower. The generator and shaft, among other equipment is housed within what is called the nacelle. Not all turbines are of this design (with a vertical axis) and wind turbines can vary in size from the small rooftop turbines (5 to 20 KW), smaller standing turbines (a few hundred KW up), to the most common and productive turbines that range from 1 MW up to 5-6 MW for some offshore turbines. Turbines have been increasing in size over time. The MW rating is derived from the combination of wind speed, blade length (or sweep range), and generator size. These turbines require large towers for support secured with a concrete foundation to reach the higher quality wind resources found at higher elevations.
The Wind Resource
Wind speed is normally measured in metres per second (m/s). For power production, the best sites for wind turbines are areas with high fetch, in other words, an unobstructed wind path. High fetch is important because it allows for higher, more consistent wind speeds. Wind resources over water are particularly good for this reason, making large lake and coastal shores ideal for wind turbine siting.Wind speeds vary daily, monthly and seasonally. This intermittency lowers wind’s capacity factor. Capacity factor refers to percentage of time the turbine or wind farm can deliver power. However, capacity factor can be increased through better management of the grid, having a diversity of renewable technologies feeding into the grid, dispersing wind turbines and farms geographically (the wind is always blowing somewhere), matching wind resources with hydro, and through the use of energy storage technologies.
Offshore Wind
Locating wind turbines off-shore requires higher installation costs but normally results in higher production levels of electricity, since wind moves faster over open water.
Read about Copenhagen's off-shore wind farm.
