Wind Power Explained

In general, wind is a direct result of a difference in air pressure from one area to the next.  Air tends to move from high pressure cells to low pressure cells in an attempt to achieve a balance of air pressure.   These imbalances are frequently due to varying air temperatures.

As the sun heats the ground, heat from the surface is absorbed by the surrounding air.  As the near-surface air heats, it rises creating a low pressure area at ground level and a higher pressure area above the land.   These vertical winds are locally known as thermals.  On a global scale, much larger pressure cells are created due to unequal heating of the earth between the equator and the poles.

As the earth rotates, the sun heats the equatorial region causing cooler air from the hemispheres to rush in and replace the rising warmer air.  It is these larger pressure cells that cause surface winds.

 When exploring for good wind sites, factors like wind speed, elevation, topography, surface roughness, temperature and location are important factors because they all affect the quality and cost of energy that can be extracted from the wind.  For example, higher elevations have lower air pressures (lower air density) resulting in less energy than lower elevations that are rated at the same wind speed.

Large amounts of energy can be extracted from the wind through the use wind turbines.  These turbines capture the kinetic energy in surface winds and convert it to rotational (mechanical) energy which in turn is converted to electrical energy.

Benefits

There are many good reasons for developing wind energy.  These are:

• Zero fuel cost. Wind energy is fuelled by the sun and differential heating, so it is renewable, will never ‘run out’ and has zero cost.  In contrast, power plants that rely on fossil fuels (e.g. coal, oil and natural gas) to produce electricity are subject to fuel price volatility, putting cost forecasting and economic viability in doubt.  Thus, wind energy represents a good hedge against the price volatility of fossil fuels.
• Zero GHG emissions. Wind is a clean fuel source, meaning that wind energy production creates no green house gas (GHG) emissions.  Conversely, power plants that rely on the combustion of fossil fuels to produce electricity create GHG emissions that pollute the air and cause acid rain.[1]
• Green As a clean and renewable resource, wind energy carries green credit certificates (based on each MWh produced) or renewable energy credits (REC) that support renewable resource investment and encourage large industrial emitters (of GHG emissions) to reduce their dependency on fossil fuels.
• World class wind resources. Canada is regarded as having world class wind resources that are largely untapped.
• Wind energy costs decreasing. Wind energy has recently become one of the lowest-priced renewable forms of energy available today, costing between 6 and 12 ¢/kWh, depending upon the wind resource and the economic viability of a particular project.
• Federal and provincial incentives. Despite the fact that green energy has a cost premium today, no federal and provincial incentives are currently in place.
• Rural economic benefits. Wind turbines can be built on farms, ranches or ridges, thus benefiting the economy of rural areas as opposed to urban centers.
• Increased employment. Wind energy projects create new jobs in rural communities in manufacturing, transportation, and project construction.
• Increased local tax base. Property tax payments from a commercial-scale wind project will provide much needed revenue to rural communities for building new schools, roads, bridges, and other community infrastructure.
• Compatible land uses. The footprint of wind turbine towers is sufficiently small such that concurrent and compatible land use with agriculture, forestry and recreation is possible.
• Adding wind energy enhances the diversity and thus the security of electricity supply.

As one of the fastest growing sources of electricity in the world, wind energy offers a remarkably balanced economic and environmentally responsible opportunity.

[1] If the complete fuel cycle for implementing a wind project (i.e. the manufacture of equipment, plant construction and production) is evaluated for emissions, a wind energy facility’s CO2 emissions are 1% of those produced by a coal fired electricity plant, or 2% of a natural gas fired plant, per unit of electricity generated.  Using wind instead of coal to produce a unit of electricity therefore reduces CO2 emissions by 99%, and using wind instead of gas reduces CO2 emissions by 98% (American Wind Energy Association, 2004).

Concerns