Wind Turbines: A Revolution-ary Energy Technology
According to the U.S. Bureau of Labor Statistics, the second fastest-growing job in the United States is “wind turbine service technician”, which has a median annual wage of $54,370. And while Mississippi does not have an abundance of wind to utilize as a renewable energy source, ABB Inc. is a leading manufacturer of wind turbine power transmission parts, among other products, with facilities in Senatobia and Crystal Springs, MS. Indeed, there are currently 114,000 U.S. workers with jobs associated with wind energy.
Wind is caused by uneven heating of the earth’s surface. Wind flow patterns and speeds are affected by factors such as differences in terrain and bodies of water, and vary considerably across the United States. One way to harness this energy is with wind turbines. In these devices, three propeller-like blades catch the kinetic energy of the wind to begin spinning; this causes a shaft to rotate, which is connected to a generator that converts the mechanical energy into clean electricity.
Over the last decade, renewable energy, largely driven by wind, has more than tripled its capacity. Nearly 7% of the total electrical energy produced in the United States last year was generated by wind power, equivalent to powering 32 million average American homes annually. The Department of Energy predicts that as much as 20% of U.S. electricity could be supplied by wind energy in 2030 and up to 35% by 2050. An estimated 200 million tons of carbon dioxide (CO2) emissions, equivalent to the CO2 emissions of ~43 million cars, were avoided in 2018 by wind-derived electricity. Wind energy also reduced water consumption by the U.S. power sector by roughly 95 billion gallons. To put this into perspective, more water is used by the U.S. power sector than any other sector, including agriculture, according to a recent report by the U.S. Geological Survey. Thermal power plants based on coal, natural gas, and nuclear energy use large amounts of water while wind turbines operate water-free.
The cost of electricity generated from wind has dropped steadily during recent years due, in part, to the increase in size of wind turbines. A common wind turbine has blades around 50 meters long on towers about 80 meters high! Although there are many that are much bigger. Larger turbines can capture more wind energy in a given area for two reasons. First, at higher altitudes the wind is stronger and more consistent. Second, the circular area formed by rotation of the blades, also called the “swept area”, is directly related to a wind turbine’s power output. The relationship between blade length and power output is not linear; four times as much power can be produced by doubling the length of the wind turbine blades. Larger systems, perhaps counterintuitively, are also able to start generating electricity at lower wind speeds relative to smaller models.
The drive to build larger and larger turbines does present challenges. Longer blades and tall, skinny towers must be engineered to withstand the stress of heavy winds. With advances in wind turbine technology, including new materials and designs, the average lifespan of these devices is over 25 years. Indeed, decades of zero-emission electricity can be generated by wind turbines as the carbon footprint associated with their construction is repaid in about 6 months, according to the American Wind Energy Association.
Are there any drawbacks to this technology? In comparison to other forms of energy, wind farms actually kill birds at a lower rate (0.27 bird deaths per gigawatt-hour of electricity) relative to nuclear power plants and fossil fuel-based power plants when taking into account mining, climate change, acid rain, and mercury pollution, according to a 2013 report by Benjamin Sovacool. Wind energy is a better alternative in this regard. The variability of wind energy has also been overcome with energy storage and by using real-time data to manage the supply and demand of electricity in conjunction with conventional power plants and other renewable sources (solar and hydroelectric). Noise pollution and aesthetics are additional concerns. However, wind turbines are typically constructed at least 300 meters away from residential areas, and often on land that continues to be farmed for various crops such as corn or soybeans, which gives farmers another source of much needed income. Their decibel level at this distance (300 m) falls somewhere between that of a refrigerator and a mid-size air conditioner window unit. At longer distances, the noise is comparable to usual background noise levels and is therefore indistinguishable.
In summary, wind turbines are an environmentally friendly energy technology with minimal drawbacks that generate clean electricity. Thousands of good-paying jobs have been created as a result of wind energy, which is a tremendous resource and accounts for a growing share of renewable electricity worldwide.
Jonah W. Jurss, Ph.D. is a chemistry professor at the University of Mississippi who does research in the field of renewable energy. He joined the Department of Chemistry and Biochemistry in 2014.