Wind Energy Basics

Since wind is a converted form of solar energy, wind energy and solar energy go hand in hand. The radiation from the sun heats the various parts of the earth at differing rates. This occurs because the different surfaces of the earth, e.g. water and land, absorb or reflect the sun’s radiation at different rates. Consequently, sections of the atmosphere warm differently. As hot air rises, the atmospheric pressure at the earth’s surface is reduced, causing cooler air to be drawn in to replace it; the result of which is wind.

The energy that the wind then produces can be transformed by a wind energy system into mechanical or electrical energy, which can then be harnessed for functional use. Mechanical wind energy is most often used to pump water in the form of a farm windmill found in rural locations. The farm windmill is one example of a mechanical wind pumper which can be used for many other purposes as well, such as sawing, grinding grain, and pushing a sailboat. Electrical wind energy is generated through the use of electrical turbines, which create electricity for homes and businesses and to sell to utilities.

Electrical wind turbines come in two basic designs: vertical-axis, or “egg-beater” style, and horizontal-axis, or “propeller” style. The horizontal-axis wind turbines constitute almost all of the “utility-scale” turbines in the global market, which consequently makes them the most common type of wind turbine used today.

Utility-scale wind turbines used on land-based wind farms are available in a variety of sizes. The rotor diameters of these turbines range from 50 to 90 meters with towers of roughly the same size. A turbine that has a 90-meter rotor and a 90-meter tower for a total height of approximately 135 meters would definitely fall on the large end of the size spectrum for wind turbines. Offshore turbine designs, however, are currently under development to have even larger rotors.

Turbines that are intended to be used for homes or small business are much smaller. The rotor diameters of these turbines are typically 8 meters or less and are placed on towers measuring 40 meters or less in height.

The electrical output of a wind turbine depends on both the size of the turbine and the speed of the wind through the rotor. Wind turbines manufactured today have a range of power ratings from 250 watts to 5 megawatts. Not surprisingly, wind speed is a crucial factor in determining the efficiency of a turbine. For small turbines, an annual average wind speed that is greater than 9 miles per hour is required, while utility-scale turbines necessitate a minimum speed of 13 miles per hour.

Putting Solar Energy to Good Use

Humans have been using the energy of the sun for pretty much as long as humans have existed. Going as far back as 5,000 years ago, people of many different religions used to “worship” the sun. For example in ancient Egypt, the sun god, Ra, was considered to be the very first Egyptian king. The sun has been influential in many other religions as well, such as Hinduism, Buddhism, Zoroastrianism, Mithraism, Roman religion, and the Aztecs of Mexico.

In modern times, what science tells us about the sun is that it is the nearest star to our planet, and without it, life on earth would not be sustainable. From the utilization of the sun’s powers to dry wet clothes hanging on a line to plants using the light from the sun to make food, the sun’s energy is used in many different ways today. In fact, in one way or another, the sun and the other stars are responsible for all of the earth’s energy, including nuclear energy, whose uranium atoms were produced in the ferocity of a nova, or an exploding star. Three more specific ways that the energy from the sun is used today are: solar hot water, solar thermal electricity, and solar cells or photovoltaic energy.

Solar water heaters have been used in the United States since the 1890’s. When they were first introduced, solar water heaters proved to be a vast improvement over wood and coal-burning stoves. However, when large deposits of oil and natural gas were discovered in the U.S., solar water heaters started to be replaced with heaters that burned fossil fuels. Solar water heaters are making a comeback today though. In the state of California alone, there are now more than half a million solar water heaters, which heat water to be used in homes, business, and swimming pools. The way that solar water heaters function is that solar panels containing water pipes are placed on the roof of a building. Then, when the sun hits the panels and pipes, it heats them up.

The energy from the sun can also be used to create electricity. The way that this feat is accomplished is through the use of a highly curved mirror called a parabolic trough which concentrates the light from the sun onto a pipe that runs the length of a central point located above the mirror’s curve. As the mirror is concentrating the light onto the pipe, the pipe becomes so hot that it is able to boil water and make steam, which can then be used to move a turbine to create electricity. In the Mojave Desert of California rows of these solar mirrors are arranged together into what is called a solar thermal power plant. This type of plant has the capacity to generate enough electricity for more than 350,000 homes.

Solar cells or photovoltaic energy is a third way of using the sun’s energy. With this method, sunlight is directly changed into electricity through the use of solar cells, which are also called photovoltaic cells or PV cells for short. First developed in the 1950’s, solar cells are composed of silicon and a special kind of melted sand. Their original purpose was to be used on U.S. space satellites, but they can also be found on many household appliances, such as calculators. When sunlight hits a solar cell, it causes electrons to be knocked loose. The disentangled electrons then migrate towards the treated front surface of the solar cell, which consequently creates an imbalance between the electron count on the front and back surfaces of the solar cell. Electricity is generated when the front and back surfaces are joined together by a wire and the positive and negative sides are connected. The individual solar cells are organized together into PV modules, which are then arranged into groups of arrays. The electrical energy from the arrays of solar cell is then able to be used directly by homes and businesses for lights and appliances. It can also be stored in batteries for later use and some experimental automobiles also function through the use of solar cells. The most common use for solar cells, however, is in satellites in outer space.

Wind Energy in California

The wind is not only useful for kite flying and providing a cool breeze on a hot summer day. The energy of the wind can also be used to perform other kinds of work. The wind’s kinetic energy can be altered into either mechanical or electrical energy. Boats use wind energy as the wind presses against the boat’s sails and causes the boat to be pushed through the water. Wind energy is used by farmers to pump water from wells through the use of windmills. Plus, wind energy is used to rotate large grinding stones to mill wheat and corn similar to the way that a water wheel rotates because of water power.

These are all examples of how mechanical wind energy is used, but another example of how wind energy can be used is to generate electrical energy, electricity. The way that the wind is used to create electricity is through the use of devices called wind turbines. Wind turbines are exactly like large versions of toy pinwheels, using the blowing wind to cause the blades of the wind turbines to spin.

The blades of a wind turbine are connected to a center point that is attached to a turning shaft. The turning shaft runs through a gear transmission box which is where the turning speed of the blades is adjusted. The transmission box is affixed to a high-speed duct whose job is to turn a generator which then creates electricity. If wind speeds become too high and forceful, there is a brake in the turbine that will prevent the turbine’s blades from spinning to fast and getting damaged.

In the state of California, there are many windy areas that are perfect for wind turbines. A significant problem with wind turbines, however, is that the wind is an unreliable source of energy. It is not windy all of the time, which means that when there is no wind power, energy can’t be produced. In California, it is generally windier during the summer time when the wind streams inland from cooler locations, like the ocean, and then replaces the hot rising air from California’s central valleys and deserts.

In order for the blades of a wind turbine to be able to turn fast enough to generate electricity, wind speeds must be above 12 miles per hour. On average, each wind turbines produces between 50 and 300 kilowatts of electricity. To put this into perspective, this means that a wind turbine that creates 300 kilowatts of electricity has the capability of illuminating 3,000 light bulbs that use 100 watts of electricity.

In the year 1999, there were 11,368 wind turbines in California. These turbines are not spread out or located in isolation from one another. Rather, they are grouped together in what are referred to as wind farms. For the most part, these wind farms are located in the 3 windiest sections of the state. These sections are: Altamont Pass, east of San Francisco; San Gorgonio Pass, near to Palm Springs; and Tehachapi, south of Bakersfield.

If the forces of the wind farms in these 3 California locations are combined, they generate enough electricity to power a city the size of San Francisco. California’s wind farms produce 11 percent of the entire world’s wind-generated electricity. Denmark and Germany are two other locations that use a significant amount of wind energy.