Winds worldwide have the potential to produce approximately 5,800 quads of energy per year. This is about 15 times the current world energy demand. Each quad could offset about 172 million barrels of oil or 45 million tons of coal per year. Clearly, there is enormous potential and benefits for harvesting wind as an energy source.
The United States ranks second in the world in wind power capacity, after Germany. Denmark generates 20% of its electricity from wind. In windy western Denmark, wind turbines supply 100% of electricity. In the US, there are currently wind farms operating in 28 states.
The states with the most wind production are Texas, California, Iowa, Minnesota, and Oklahoma. The states with the most wind energy potential are North Dakota, South Dakota, Montana, Texas, and Kansas. North Dakota alone has the potential to produce enough wind-generated power to meet more than one-fourth of U.S. demand.
Wind speed varies by and from season to season. Wind is strongest in cold-weather months when electricity demand is also at its peak, so variability tends to mirror demand.
Unfortunately, many of the best wind sites are in remote locations far from areas where power demand is highest. Good sites for wind farms are the tops of hills, open plains, shorelines, and mountain gaps that cause wind to be funneled through a ravine.
This means that transmission is a key issue in deploying wind power. Another issue is intermittency. This issue can be addressed by using batteries to store electricity or by deploying a large number of wind turbines spread over a wide geographic area to produce a consistent supply of electricity.
Proper placement means that a wind turbine can produce electricity about 70 percent of the time. The output of a wind turbine depends on size and wind speed. Wind speed is critical.
The amount of harvestable energy in wind is proportional to the cube of its speed. In other words, if a turbine’s rotor receives wind speeds of 12 mph it will generate approximately 33% more electricity than a turbine receiving 11-mph winds. A small difference in wind speed translates to a large difference in electricity produced. This affects not only availability but the cost of the electricity produced. Wind speed greater than 9 mph are needed for smaller turbines, while wind farms need minimum speeds of 13 mph.
Wind turbines can be deployed as singular turbines for a home, or as arrays called wind farms. Turbines come in many sizes and power ratings. Turbines consist of large blades mounted on tall towers attached to a horizontal shaft. Wind turns the shaft to generate electricity. Wind turbines are classified by the direction of the rotating shaft, whether horizontal'”axis or vertical-axis. The towers are usually steel. The blades are fiberglass-reinforced polyester or wood-epoxy. Electrical cables carry electrical current to transmission lines.
Wind farms produce no pollution, greenhouse gases or toxic wastes. Wind is renewable, reliable and efficient and now affordable. It is compatible with other land uses and can boost rural economic development for farmers who lease their land.
Wind energy offsets emissions from other energy sources. In 2006, US wind turbines offset 30 billion pounds of carbon dioxide, 76,000 tons of sulfur dioxide, and 36,000 tons of nitrogen oxides by generating clean electricity. Even if turbine production is included in assessing wind energy’s “footprint”, it still has 99% less CO2 emissions than coal and 98% than natural gas.
Unlike power plants, many wind farms are not owned by public utility companies but by business people. These Independent Power Producers sell the electricity produced on the wind farm to electric utilities.
The most economical deployment of wind turbines is in clusters called wind farms. These generally have a higher initial investment than fossil-fueled power plants. About 80% of this initial cost is the turbines; the rest is site assessment, preparation and installation.
Life-span costs for wind farms are lower than for fossil-fuel plants as there is no fuel to purchase and negligible operating expenses. In the past 20 years, the cost of electricity from wind farms has decreased by over 80% while the cost of oil and natural gas has soared.
Farmers who lease their land for wind farms can still raise cattle and grow crops near the turbines. Only about 2-3 acres of land need to be taken out of production in return for lease payments. This can help increase a farm’s income.
The only serious drawback to wind farms seems to be visual. There is some concern over the noise produced by the rotor blades and birds and bat collisions. There are questions about fragmenting habitat and erosion. Most of these problems have been resolved through better engineering or by site assessment prior to installing turbines.
Bat collisions at wind plants generally tend to be low in number and to involve common species which are quite numerous. Bird collision studies indicate that this is a site-specific issue that will not be a problem at most potential wind sites.
Collisions with turbines currently account for less than 1% of human-induced avian mortality. Proper site assessment and turbines that rotate more slowly can mitigate this problem.
With decreasing start-up costs and increasing revenue potential, investing in wind energy will be hugely beneficial for the US and other countries as we wean ourselves off the dead-end track of using fossil fuels to generate energy.