The first (believed to be) windmills were developed to assist in the task of grain-grinding and water-pumping and the earliest-known design is the vertical axis system developed in Persia about 500-900 A.D.
Until the invention of the steam engine, wind ranked second only to wood as a energy source. Wind energy, long used to pump water and grind grain and other crops, is experiencing a comeback in popularity and may soon become an important part of the electrical supply source. Modern technology can be utilized in many areas to produce mechanical and electrical energy systems, thereby reducing our use of fossil fuels.
USING WIND ENERGY;
Using the wind for our use is as old as mankind. It was utilized in ancient times to separate wheat from chaff, and to power sailing ships. The modern windmills are familiar fixtures across the American landscape as well as throughout Europe and Asia. Although the use of wind energy has declined since the development of electricy in the 1930s, windmills are still used today for pumping water for livestock, wildlife, and on farms where providing the electric cost is prohibitive.Wind is air in motion, also as some proclaim a form of “solar Energy” as heat from the sun does create wind currents This fact is well known to the American sportsman who uses wind direction in his pursuit of game in America. The heating of the earth’s atmosphere by radiant energy from the sun causes air to move and creates the earth’s winds and wind patterns. Wind is an appealing because it is clean, inexhaustible, and as long as the sun shines, wind will be available. For this reason wind has been labeled a “renewable energy resource”.
WIND ENERGY APPLICATIONS;
Historically the most common uses for wind has been of a mechanical nature. Examples include pumping water and running a grist mill to grind corn. “In 1887 Charles F. Brush designed and erected the world’s first wind-powered electric generator in Cleveland, Ohio. It operated for 12 years delivering 12 kilowatts of power to Brush’s home on 37th and Euclid Avenue. Average annual wind speeds as low as 8 mph (miles per hour) can be used for pumping water. Average annual wind speeds of at least 10 mph are usually required to generate electricity, however with new technologies and lighter materials these base speeds are changing. Wind energy has both large and small scale applications. For example instance, it can be used to pump water at a single source or it is also capable of generating utility-grade power on a large scale. In remote areas where electricity is not available from a power company or would cost too much to install, wind systems are used to power communications equipment, water pumps, desalination systems, and lighting. Wind is also being used by homeowners to reduce utility bills. Wind powered turbines can operate in parallel with the utility and can be connected to existing homes and farms.
TYPES OF WIND SYSTEMS;
The two main types of wind systems are windmills normally used for pumping water, and wind powered electric generators.Windmills; Windmills are usually a device with several fan type blades mounted horizontally to a shaft that drives a rod or water pump. This system is still in use today as is normally used for pumping water.Wind driven electric generators; Wind mills or systems that generate electricity are called wind generators,or wind turbines depending on the type of generator mounted to the blades of the system. Wind generators produce electricity either in alternating current (AC) the type of current in most homes, or direct current (DC) the type of power in a vehicle. Wind generators can be either vertical or horizontal in nature and most will produce power with wind speed about 8mph. Most all of the small units (example 400 watt) will produce power with as little as 3-4 mph.According to the industry the most efficient speed for medium and large systems is between 15-20 mph.Horizontal/-Axis generators wind usually have two or three blades, and are on towers. Horizontal axis wind generators are self-starting. When the wind blows, the blades turn.Vertical-axis wind generators are unusual looking. Their blades are horizontal, or level with the ground. These machines are named after the Frenchman, D.G.M. Darrieus, who designed them in the 1920s. They have two or three thin, curved blades that look like an eggbeater. The advantages of a vertical-axis system is that it can be located near the ground, it does not need to rotate toward the wind to function. Its shape is also part of the mounting tower system eliminating the need for a separate tower. The major drawback on this type of design is that it cannot start itself. A power unit must get it rotating before it can function. Vertical-axis wind generators were not generally available in small sizes but new types are now on the market and development is ongoing for smaller units. The best of these are spire units, currently manufactured in the U.S.
Sizes;
Wind generator systems blade and output ranges can be from 1 foot at 400 watts to over 100 feet and several hundred kilo-watts. DC current or Ac current depending on the manufacture.
Wind to Electrical Power Systems;
The Wind Energy system is made up of several components. These can include but are not limited to the following. 1.The rotor or blades to spin the “generator” 2.A transmission assembly (if required). This takes the speed of the blades and matches it to the generator end of the units. 3.A generator, this actually produces the electric power (AC or DC). 4.A power and speed control unit. This can be one piece of equipment or two depending on size and manufacture of the system. 5.A power distribution system. This gets the power generated to its end source, whether that be a power grid, your home or business, or a battery storage system. 6.A mounting system for the rotor and generator. The two main types are guyed and free standing towers. 7.Last but not least, if required is a energy storage system usually (batteries).NOTE: Depending on use, other equipment will be required for connection to a live power grid. This will depend on local and state requirements. These can be found at your local utility company that handles your area.
System Efficiency;
The current generating systems are most efficient with winds of between 15-20 mph. This varies greatly between manufactures and types of systems. All wind systems have some type of speed control so that the unit does not over-speed and cause damage to itself and surrounding equipment. As a rule of thumb about 25% or the winds energy is converted to electrical power. This number is getting greater as new types of rotors are being tested and built. As wind is not a constant source of energy,a wind power system must be well though out prior to buying and installing.
System Types;
1. A system that connects directly to a power grid. Commonly referred to as a utility interconnect system. 2. Stand alone. This system is not connected to storage, or to the power grid. You can use the power only while it is being generated. 3. Stand alone with power storage. This system allows you to store power via a battery system, for use at a later time. Most off grid locations use this to ensure a longer use time of the power generated.Utility interconnect systems are gaining popularity in most states as it is being mandated by the Federal government that utilities get a percentage of there power form “Renewable Energy Sources”. Most states allow this in some fashion. You must check with your local utility to see if you can “connect” to the grid. We recommend you do this during your site testing phase.
System Costs;
Using the wind for energy is a proven technology. However the systems can be expensive. The prices have a range form $350.00 for a small battery charger to several thousand for a whole house stand alone with storage system. Before investing in a system it pays to do your shopping and see what the real time pay back is on the system you choose. The one place were this type of system is reasonable and has the quickest pay back (roi) is in remote areas were getting power from the grid is more expensive that having your own power system.
EVALUATING WIND;
Wind resources vary across each location and state, this can and will vary the performance of a wind system. This evaluation is vital in deciding whether to purchase a wind system. Usually a minimum average annual wind speed is required to run a wind generator with any degree of economy (check with the manufacture to determine actual need wind speed). If the average wind speed is 12 mph or greater the site location will probably support a wind system. Again check with the manufacture of the system you plan on installing.
Conducting a Wind Survey;
A wind survey will determine the wind speed and direction at a particular location. This can be done by a consultant or a DYI project. As most people usually get the wind speed greater than it actually is the following steps should guide you in your decision.1. Check wind speed maps. Several are free to use. One of the basic information maps can be downloaded from The department of Energy is at http://www.windpoweringamerica.gov/wind_maps.asp, or go to our website home page. 2. This is a general guide to determining wind resources in your area. These maps will provide a rough estimate of wind conditions; but realize this is just a guide. Rolling or mountainous areas, the wind speed and direction is more site specific and requires a more detailed analysis. 3. Examine your location, if the wind has effected the areas vegetation especially trees, this may indicate a very stable wind direction and speed. As trees and vegetation growing in an area with constant wind, the trees, and shrubs will lean or grow normally in one direction. This effect is known as flagging. 4. Check with local owners of wind systems in your vicinity. Their experience will be extremely valuable, especially if they have current wind monitoring data. (Wind machine manufacturers, dealers, as well as utility companies, may be able to supply names of local, owners, or wind data from your local weather service. 5. (Optional) Measure existing wind conditions at the actual sit, especially if a map indicates a low level of wind resource and there are no other wind systems. Usually the more obstructions such as hills, bluffs, passes, tall trees or buildings, the more requirements are needed for an on a site survey. A variety of measurement devices are available from inexpensive, hand-held instruments to anemometers mounted on towers. Data gathered with hand-held devices are generally less reliable.
Measurement Techniques:
Two basic types of on-site, measurement are long term and short term. Long-term involves the collection of data over a period of usually at least 12 months. Although this is the most reliable, it is also the most costly and time consuming. For a short-term measurement a period of 3 months is suggested, preferably during the windiest months. In this method, site data should also be compared with data from the nearest weather station to establish the projecting wind speeds for the remaining 9 months. The sophistication of instruments will depend on your needs and budget. The cost can run form $350.00 to several thousand dollars, based on the accuracy and the analysis of the data you want.
SITE TIPS;
If a site survey indicate that a wind system would be feasible, the next step is placement. Choosing the proper site for a system is critical in the performance of your system. It takes very little in wind change to effect the operation of your system. A prime example is the difference in wind speed. If the wind increases 2 fold, say form 6 mph. To 12 mph. The power production is increased 8 times (8X) not twice as would be expected. Wind speeds are best over long stretches of unobstructed terrain. Generally, the best locations are open to the wind for some distance. Examples are hill tops, plains, and coast lines. Trees and man made structures, can significantly reduce wind speeds,and cause air currents that have the potential of damaging your system. If there are structures on the site, the system must be placed up or down wind to avoid turbulent air flow from the structure. In some cases a taller tower may solve the problem. As a rule of thumb the system should be placed up-wind of the problem a distance of (2X) two times the height of the structure. If located down wind the rate is (5X) 5 times. Added to this the mounting tower should be at least 30 to 40 feet taller than the height of the obstruction. Small wind machines are best located as close as possible to the end use to reduce the cost of connecting to your power system.
Environmental Impact;
Wind systems are clean, nonpolluting (once manufactured) and typically have little environmental impact. However, there are several factors to consider when looking in a wind system. Noise: This equipment produces some noise. This can be an important consideration, depending on location and zone requirements. Visual: Some people find wind machines a eyesore. Access: Wind systems that are remote in location and require access roads for maintenance may not be viaable on for a small system. Birds: Birds have been known to fly into wind systems and have been killed, however there number seems to be no greater than other structures that birds fly into.
