Today’s post introduces the topic of wind energy, a renewable energy source. While researching some information on solar energy, I discovered that wind energy is a form of solar energy. Initially, this concept seemed odd, however, after giving it more thought, it makes a lot of sense.
Perhaps my desire for cooler temperatures in Phoenix’s summer heat directed my mind and research towards wind energy. A cool summer breeze is highly desirable right about now as we have been dealing with 100+ degree Fahrenheit temperatures for almost two months. This is wishful thinking seeing that we are only half-way through what my friends and I refer to as our journey through hell’s kitchen.
Ever wonder where wind comes from? Winds develop from the uneven heating of the atmosphere by the sun, the irregularities of the earth’s surface, and the rotation of the earth. Wind flow patterns are modified by the earth’s terrain, bodies of water, and vegetative cover. And similar to solar, wind can be “harvested” using a wind turbine to generate electricity.
The wind resource map provided here in Figure 1 show areas or regions of wind power across the United States.
Wind resources are characterized by wind-power density classes, ranging from Class 1 (the lowest) to Class 7 (the highest). Good wind resources (e.g., Class 3 and above) have an average annual wind speed of at least 13 miles per hour). [Ref 1] As show in Figure 1 above, the U.S. has good wind resources in a number of locations.
The term wind energy or wind power describes the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. [Ref 1]
Like electricity or solar energy, mechanical power is needed to convert the wind power to electricity. The tool that can make that happen is a wind turbine. Wind turbines, like aircraft propeller blades, turn in the moving air and power an electric generator that supplies an electric current. Like steam turbines or other power generating equipment, the electricity that is generated can be used for many things including powering homes and businesses.
If it takes more than a few minute to wrap your head around how wind power works, think of it as a fan in reverse. A fan uses electricity to make wind or air currents. Wind turbines use wind to make electricity. Similar to water and steam turbines, the wind turns the blades that spin a shaft. The shaft connects to a generator to make electricity.
Most wind turbines found in operation today are either horizontal-axis or vertical-axis in design. Most large modern wind turbines are horizontal-axis turbines. Standard equipment found on a typical horizontal wind turbine includes blades or rotors, a drive train, and a tower.
The rotors (blades) convert the energy in the wind to rotational shaft energy. The drive train usually includes a gearbox and a generator, while the tower provides support and stability for the equipment. Wind turbines are often grouped together to make up a wind power plant or wind farm. Wind farms generate bulk electricity that can be fed to a utility grid like other power sources.
When someone mentions wind farms, my mind conjures up the image of wind turbines near Altamont Pass in northern California (east of San Francisco and near the City of Livermore), and the San Gorgonio Wind Resource Area near southern California (east of Los Angeles and near the City of Palm Springs).
From January thru April 2014, the U.S. generated a total of 1,329,042 thousand megawatt-hours (mWh) of energy from all sources. This amount includes 68,516 thousand mWh. [Ref 2] Simple math shows that wind energy accounts for about 5% of the electricity generated during this period…not a lot, but every little bit helps.
One of the questions to answer in the next post is why wind energy has not gained in popularity as solar energy?
Between now and then, stay cool!
1) Wind Energy Basics, http://windeis.anl.gov/guide/basics/index.cfm
2) Electric Power Monthly, Table 1.17.A – Net Generation from Wind by State, by Sector, April 2014 and 2013, http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_1_17_a