Cup and Propeller Anemometers
A widely used anemometer for wind resource measurements has a circular magnet four poles in the cup housing, and then one or two coils for pickup of the signal Figure 4.10 , which approximates FIGURE 4.8 Meteorological station in Jujuy, Argentina. FIGURE 4.8 Meteorological station in Jujuy, Argentina. a sine wave. The transducer counts zero crossings sampling time is generally 1 Hz , so wind speed is related to number of counts. The advantage is that signals can be transmitted 150 m without...
General
Tim Appenzeller. 2004. The end of cheap oil. National Geographic, June, 80. A. A. Bartlett. 2000. An analysis of U.S. and world oil production patterns using Hubbert-style curves. Mathematical Geology 12 1 Available as pdf, http jclahr.com bartlett 20000100, 20 Mathematical 20Geology.pdf. Lester R. Brown. 2006. Plan B 2.0. W.W. Norton New York, London. C. J. Campbell. 2005. Oil crisis. Multi-Science Publishing Essex, UK. Wilson Clark. 1974. Energy for survival The alternative to extinction....
Phase Angle and Power Factor
The instantaneous voltage and current are given by v Vp sin fflt , i Ip sin at 0 FIGURE 7.4 Current and voltage across a resistor, capacitor, and inductor, showing the phase relationship between the voltage and current. Voltage, dashed line current, solid line. FIGURE 7.4 Current and voltage across a resistor, capacitor, and inductor, showing the phase relationship between the voltage and current. Voltage, dashed line current, solid line. where Vp and Ip are the peak values a, rad s, is the...
Inverters
There are a number of inverters on the market however, there are only a few manufacturers of inverters for wind turbines. Inverters need to be designed for the much different inputs of wind turbines, as inverters for PV have less stringent operating requirements. There are inverters for hybrid systems where power is taken from the battery storage. For wind turbines with permanent magnet alternators, the output is rectified to DC and the inverter converts that to the constant voltage and...
Avoided Costs
Avoided costs were established by the public utility regulatory body in each state. The Federal Energy Regulatory Commission defines avoided cost as the incremental or marginal cost to an electric utility of energy or capacity, which the utility would have to generate or purchase from another source if it did not buy power from the qualifying facility. Avoided cost reflects the cost from new power plants, not the average cost from plants already installed. The avoided cost includes not only...
PROBLEMS Jmw
1. A building is 20 by 15 m and 15 m tall. You want to install a 10 kW wind turbine. How tall of a tower and how far away from the building would you place it 2. There are a number of trees 20 to 30 m in height close to a house. You want to install a 10 kW wind turbine. What is the minimum height of the tower What is the approximate cost of that tower 3. Refer to Figure 9.3. The building is 15 m tall. What is the power reduction at 15 m height at a distance of 60 m downwind At 150 m downwind...
Power In The Wind
The moving molecules of air have kinetic energy, so locally the amount of air molecules moving across some area during some time period determines the power Figure 3.3 . This area is not the surface area of the earth, which was referred to in the estimation of extractable power and energy, but the area perpendicular to the wind flow. The mass, m, in the volume of the cylinder that will pass across the area, A, in time, t, can be determined from the density of the air, p, and the volume of the...
Economics
The most critical factors in determining whether it is financially worthwhile to install wind turbines are the initial cost of the installation and the annual energy production. In determining economic feasibility, wind energy must compete with the energy available from competing technologies. If the system produces electrical energy for the grid, the price for which the electrical energy can be sold is also critical. Today, wind farms are essentially competitive with all new power plants, even...
Solar Energy Research Institute Innovative Wind Program
Innovative wind turbines VAWT Tornado type wind energy system Diffuser-augmented wind turbine Wind electric power-charged aerosol Electrofluid dynamic wind generator Energy from humid air Madras rotor power plant, phase I Vortex augmenters Yawing wind turbine, blade cyclic pitch Oscillating vane Dynamic inducer West Virginia University Grumman Aerospace Grumman Aerospace Marks Polarized University of Dayton South Dakota School, M amp T University of Dayton Polytechnic Institute, New York...
Wind Power Potential
The most comprehensive, long-term source of information on wind speeds, pressure, and temperature is data collected at National Weather Stations. Other sources in the United States on record at the National Climatic Center, Asheville, North Carolina, are from Federal Aviation Administration stations, U.S. air bases, Coast Guard, etc. In the early 1960s anemometers at National Weather Stations were changed from their previous locations 20-30 m heights on airport control towers, hangers, etc., to...
REFERENCES Wot
1. D. Bain. 1980. An introduction to PURPA, sections 201 and 210. In Proceedings, Windpower '80, ed. V. Nelson, p. 33. 2. U.S. Federal Energy Regulatory Commission. Order 69. Final rule regarding the implementation of section 210 of the Public Utility Regulatory Policies Act of 1978. Docket RM79-55. 3. A. J. Cavallo. 1994. High capacity factor wind turbine Transmission systems. Wind Energy 15 87. 4. J. E. Bryson. 1980. New directions for utilities. In Proceedings, Windpower '80, ed. V. Nelson,...
Rotor Area and Wind Map
The amount of energy produced by a wind turbine primarily depends on the rotor area, also referred to as cross-sectional area, swept area, or intercept area. The swept area for different types of wind turbines can be calculated from the dimensions of the rotor see Figure 1.7 . HAWT area n r2, where r radius. VAWT, where H height and D diameter of rotor Giromill area H D Savonius area H D Darrieus area 0.65 H D The annual average power area can be obtained from a wind map, and then the energy...
Innovative Wind Systems
Innovative or unusual wind systems Figure 5.17 have to be evaluated in the same way as other wind turbines. The important categories are system performance, structural requirements, and quantity and characteristics of materials. Innovative ideas include the tornado type, tethered units to reach the high winds of the jet stream, tall tower to use rising air, tall tower and humid air, torsion flutter, electrofluid, diffuser augmented, the Magnus effect, and others. Many of these have been...
European Union
The Europeans have a concentrated effort on wind resource assessment beginning with the publication of the European Wind Atlas 12 in 1989. Part 1 provides an overall view of the wind resources. Part 2 provides information for determining the wind resource and the local siting of wind turbines. It provides descriptions and statistics for the 220 met stations in the countries of the European Community EC and includes methods for calculating the influence on the wind due to landscape features such...
Vortex Generators
A vortex generator mixes the faster-moving laminar flow with the boundary layer, which delays flow separation from the blade and stall. Typically there are counterrotating pairs of vortex generators on the low-pressure side of the blade, with 20 angles of incidence at 10 chord on the inner portion of the blade Figure 8.23 , which is thicker and more prone to dynamic stall. Vortex generators were installed on the MOD 2 and the MOD 5 wind turbines, and the performance was improved 31 . A Carter...
Generator Size
This method gives a rough approximation because wind turbines with the same size rotors can have different size generators where AKWH annual energy production, kWh year CF capacity factor and 8,760 number of hours in a year. The effect of the wind regime and the rated power for the rated wind speed can be estimated by changing the capacity factor. The capacity factor is the average power divided by the rated power generator size . The capacity factor is estimated from energy production over a...
PROBLEMS Nca
1. Estimate the difference in the amount of material in the rotor for a giromill and a Savonius rotor with H 10 m, D 10 m. 2. A wind turbine is rated at 300 kW. Estimate annual energy production using the generator size method. 3. For a 1.5 MW wind turbine, estimate the annual energy production for a good site using the generator size method. 4. For a conventional HAWT, radius of 50 m, estimate annual energy output for a good wind region use class 4, 5, or 6 from U.S. wind power map. 5. For a...
Boundary Layer Control
Boundary layer control is all those methods that can be used to reduce the skin friction drag, by controlling the transition to turbulent flow, and reduce the development of turbulent flow and the separation of both laminar and turbulent flow. Boundary layer control tries to keep the flow attached further along the chord, thereby increasing lift and reducing drag, and by keeping dynamic stall from happening. Dynamic stall, which is seen as a hysteresis loop of lift caused by changing high...
Noise
Although zoning is an institutional issue, the regulations will affect the possibility of erecting a small wind turbine and, if possible, then the size of the wind turbine, tower height, how much space is needed around the tower, and the possibility of the effect of noise and even visual concerns of FIGURE 9.4 Three stacked wind turbines Darrieus , 4 kW each, next to building. Notice man on top. Photo by Coy Harris, American Wind Power Center and Museum. With permission. FIGURE 9.4 Three...
CHAPTER Ktr
3. Ancillary costs are additional costs the utility incurs because there are wind turbines on the grid. 4. Two main environmental issues are birds and possible impact on playa lakes. 5. Discussion question. Know the difference between the tax credits of the early 1980s based on units installed, kW and the production tax credit of the 1990s kWh . 6. R amp D, demonstration projects, guaranteed loans, commercialization projects, subsidies for village power are examples. Need to back up your...
California Wind Farms
The California Energy Commission CEC instituted a program in 1984 for Wind Performance Reporting System regulations 5 . All California wind projects greater than 100 kW that sell electricity to a power purchaser have to report quarterly performance. The quarterly reports contain the following information turbine manufacturers, model numbers, rotor diameters and kilowatter ratings, number of cumulative and new turbines installed, the projected output per turbine, the output for each turbine...
PROBLEMS Xzw
1. From Table 8.1 calculate annual specific output, kWh kW, for two different wind turbines. 2. From Table 8.1, calculate capacity factor for Fayette, Vestas 23, Bonus 120. 3. From Table 8.3, what is the average capacity factor for 1989 through 1996 4. Calculate the specific output, kWh m2 in a 1985 for Enertech 44 60 and b 1990 for Enertech 44 40. 5. From Table 8.4 calculate for 7 months for Enertech 44 25 a kWh m2 and b capacity factor. 6. From Table 8.4 calculate for 1985 a kWh m2 and b...
CHAPTER Rjq
1. See Figure 1.7. Solidity is a ratio of area of blades to area of rotor. Notice that the solidity of the Savonius is 1 or greater. Assume 1. The giromill has a low solidity, around 0.2. Therefore, the difference in blade material is around 5 1. Another way, use rotor swept area, 10 10 100 m2. Blade area of Savonius is 100 m2 or greater. Giromill has three blades assume blades are 10 m long, 0.5 m wide. Blade area 3 10 0.5 15 m2. Therefore, the ratio of Savonius to giromill is 100 15. 2....
Extractable Limits Of Wind Power
Solar energy drives the wind, which is then dissipated due to turbulence and friction at the earth's surface. The earth's atmosphere can be considered a giant duct, and if energy is taken out at one location, it is not available elsewhere. Therefore, it is important to distinguish between the kinetic energy in the wind and the rate and limits of the extraction of that energy, the power in the wind, and the maximum power extractable. A comparison can be made on the basis of the kinetic energy of...
REFERENCES Uau
1. E. F. Lindsey. 1974. Windpower. Popular Science, July, 54. 2. B. Kocivar. 1977. Tornado turbine. Popular Science, January, 78. 3. V. Chase. 1978. 13 wind machines. Popular Science, September, 70. 4. J. Schefter. 1983. 5 wild windmills. Popular Science, June, 76. 5. B. Juchau. 1983. 650-foot power tower. Popular Science, July, 68. 6. J. Schefter. 1983. Barrel-bladed windmill Power from the Magnus effect. Popular Science, August, 70. 7. G. Lorente. 1982. Nuevo concepto de generador...
Bergey Xcel
A Bergey Xcel wind turbine was installed at the AEI Wind Test Center in August 1991 and is still operating in 2008. The specifications are three-phase, 240 V, permanent magnet alternator, rated at 10 kW. The variable voltage, variable frequency is converted to DC, which is then inverted to 60 Hz for connection to the utility line. Power and wind speed were sampled at 1 Hz and then averaged over 15 min. This time sequence data were then averaged over 1 month for each 15 min period to give an...
Small Wind Turbines
Generally small horizontal-axis wind turbines are kept facing into the wind by a tail. The control mechanism to reduce power in high winds is that the rotor axis is offset from the pivot point, axis of connection to the tower Figure 6.24 . Therefore, there is more force on one side of the rotor than the other, which tries to move the rotor parallel to the wind however, the wind force on the tail keeps the rotor perpendicular to the wind. For high winds the unequal force on the rotor is greater...
Faradays Law of Electromagnetic Induction
Another way of looking at electromotive forces is by Faraday's law of electromagnetic induction. The amount of magnetic flux, Om, is equal to the strength of the magnetic field times the area where 9 is the angle between B and A. The electromotive force is then equal to the negative change in magnetic flux with time In generators and motors, the magnetic field and area can be kept constant, and the angle between the two changed by rotating a loop of wire. This gives an alternating voltage and...
DESCRIPTION OF THE sYsTEM
The total system consists of the wind turbine and load. A typical wind turbine consists of the rotor blades and hub , speed increaser gearbox , conversion system, controls, and tower Figure 5.9 . The nacelle is the covering or enclosure. The output of the rotor, rotational kinetic energy, can be converted to electrical, mechanical, or thermal energy. Generally, it is electrical energy, so the conversion system is a generator. Blade configuration may include a nonuniform platform blade width and...
Case Study Wind Village Power System
Huaerci 34 is a village in the mountainous area of eastern Xinjiang Province with 90 households, 360 inhabitants, with the primary economic activity being animal husbandry. The income per capita is well below the national poverty level. The distance to the nearest electricity grid is 110 km, and the roads are very bad. Lighting at night was provided by candles, and for children to do their homework, most families used two candles per night. The renewable resources are wind annual mean wind...
Maximum Cp For Drag Device
1. Blade, r to center of mass 5 m, mass 500 kg, F 320 Nm. T r F 5 m 320 Nm 1,600 Nm2 J 2. Use Equation 6.9, P F v, and substitute force from Equation 6.8. Notice that power loss is proportional to velocity cubed. CD 1, and assume p 1 kg m3. Strut is 4 m x 0.025 m, rpm 180. ffl rpm 2 60 180 rc 30 18.8 rad s. Area for 1 m section length width 1 m 0.025 m 0.025 m2. Power loss for each section, P 0.5 v3 A 0.0125 v3, watt. Take r at the midpoint of the section. Have to find velocity at center of...
Series Preface
By 2050 the demand for energy could double or even triple as the global population grows and developing countries expand their economies. All life on Earth depends on energy and the cycling of carbon. Energy is essential for economic and social development and also poses an environmental challenge. We must explore all aspects of energy production and consumption, including energy efficiency, clean energy, the global carbon cycle, carbon sources, and sinks and biomass, as well as their...
Water Pumping 1
The pumping of water and sailboats are the oldest and longest-term uses of wind power. The two common examples of mechanical water pumping are the historical Dutch windmill for pumping large volumes of water from a low lift and the farm windmill for pumping small volumes of water from a high lift 35-37 . For mechanical windmills or wind turbines the important considerations are the power in the wind and how that power can be transferred by the system. This means that the characteristics of the...
Lift Device 1
A lift device can produce on the order of 100 times the power per unit surface area of blade versus a drag device. See Rohatgi and Nelson 14, chap. 6 for more details. Suppose we have a two-blade wind turbine, each blade is 5 m long, 0.1 m wide. As a drag device, the capture cross section is 1 m2. As a lift device in a HAWT, its capture cross-sectional area is 78.5 m2. If the difference in efficiencies is included, the ratio of the power out per blade area for the lift device over the drag...
Lift Device
Most lift devices use airfoils for blades similar to propellers or airplane wings however, other concepts have been used. Using lift, the blades can move faster than the wind and are more efficient in terms of aerodynamics and amount of material needed for the blades. The tip speed ratio is the speed of the tip of the blade divided by the wind speed. At the point of maximum efficiency for a rotor, the tip speed ratio is around 7 for a lift device and 0.3 for a drag device. For a lift device the...
PROBLEMS Prh
1. A blade is 12 m long, weight 500 kg, and the center of mass is at 5 m. What is the torque if the force is 320 Nm 2. Find the power loss for three struts on a HAWT. Struts are 4 m long, 2.5 cm in diameter. Rotor speed is 180 revolutions per minute. Use numerical approximation by dividing strut into 1 m sections and calculate at midpoint of section. Then add the values for each section. CD 1. 3. Calculate the power loss for the struts on a VAWT. Center tube, torque tube, diameter 0.5 m. Struts...
Aerodynamics
The moving blades of the wind turbine convert part of the power in the wind to rotational power. where T is the torque N-m and co rad s is the angular velocity. The same power can be transferred with a large Tand small co, or a small Tand large co. The torque- characteristics of the rotor should be matched to the torque- characteristics of the load. Note 0 is the angle, where units are degrees or radians. A radian is the angle where the arc of the circle equals the radius, so circumference 360...
Instrumentation
An anemometer is a device for measuring airflow. There are a number of measuring devices for wind speed pitot tube, cup, vane, propeller, hot wire, hot film, sonic, and laser Doppler anemometers. The common devices are the cup and propeller anemometers, since they are cheaper. However, their response times to changes in wind speed are slower. Wind turbines also have a response time to changes in wind speed, so cup anemometers are adequate for determining the wind energy potential. Sonic and hot...
Variations In Wind Power Potential
Since the motion of the atmosphere varies on a scale from seconds to years, wind power and wind energy will also vary on the same time scale. The annual average wind power 6 m height for Amarillo, Texas, was 220 watts m2 for the period 1962-1977 6 however, the variation from one year to the next can be quite large. A minimum of 2 years of data are needed to obtain an estimate for the annual wind power potential, and 5 years of data are needed to obtain a mean value within 6 of the long-term...
Problems 1
Use spreadsheet if applicable and available. 1. Calculate the power, in kilowatts, across the following areas for wind speeds of 5, 15, and 25 m s. Use diameters of 5, 10, 50, and 100 m for the area. Air density 1.0 kg m3. 2. Solar power potential is around 1 kW m2. What wind speed gives the same power potential 3. Calculate the factor for the increase in wind speed if the original wind speed was taken at a height of 10 m. New heights are at 20 and 50 m. Use the power law with an exponent a...
REFERENCES Dbb
1. R. N. Clark. 1983. Reliability of wind electric generation. ASAE Paper 83-3505. 2. W. Pinkerton. 1983. Long term test Carter 25. In Proceedings, Wind Energy Expo '83 and National Conference, ed. V. Nelson, p. 307. 3. F. S. Stoddard. 1990. Wind turbine blade technology A decade of lessons learned, 1980-1990, California windfarms. Report, Alternative Energy Institute, West Texas A amp M University. 4. WindStats Newsletter. www.windstats.com. 5. Wind Performance Reporting System, California...
Orientation Of The Rotor Axis
Wind turbines are further classified by the orientation of the axis of the rotor with respect to the ground horizontal-axis wind turbine HAWT and vertical-axis wind turbine VAWT Figures 1.7 and 5.6 . The rotors on HAWTs need to be kept perpendicular to the flow of the wind to capture the maximum energy. This rotation of the unit or rotor about the tower axis, yaw, is accomplished by a tail on upwind units small wind turbines, up to 10 kW, although there have been tails on some 50 kW units , by...
Flow Visualization
The performance of blades, rotors, and towers can be checked by flow visualization smoke, tuffs, stall flags, pressure-sensitive liquid crystals, and oil streak. Tuffs are driven by frictional drag, while FIGURE 8.24 Vortex generators on inner portion of blade of GE wind turbine 77 m diameter, 1.5 MW . FIGURE 8.24 Vortex generators on inner portion of blade of GE wind turbine 77 m diameter, 1.5 MW . stall flags are pressure driven. The stall flag responds to separated flow with an optical...
United States
A number of wind power and wind energy maps have been prepared for the United States however, the earlier maps did not take into account the height differences of the anemometers. As part of the overall evaluation of wind energy, two major contracts were awarded to General Electric and Lockheed in 1975. Their estimates of the wind energy potential for a height of 50 m indicated that most of the United States has a fairly large potential. The problem is that most of these values were estimated...
Lifetime Of A Finite Resource
If the magnitude of the resource is known, or can be estimated, then the end time, TE, when that resource is used up, can be calculated for different growth rates. The size of resource, S, is put in Equation 2.9, and the resulting equation is solved for TE If the demand is small enough or is reduced exponentially or reduced at the depletion rate, a resource can essentially last a very long time. However, with increased growth, TE can be calculated for different resources Table 2.4 , and the...
Philosophy
Scientists have been very successful in understanding and finding unifying principles. Many people take the resulting technology for granted and do not understand the limitations of humans as being part of the physical world. There are moral laws or principles , civil laws, and physical laws. Moral laws have been broken, such as murder and adultery, and everybody has broken some civil law, such as driving over the speed limit. However, nobody breaks a physical law. Therefore, we can only work...
Micrositing
Wind maps, meteorological data from met towers, models, and other criteria are used for selection of the wind farm locations. Other considerations for the wind farm developer are the type of terrain complex to plains wind shear wind direction spacing of the wind turbines, which then depends on predominant wind direction and availability and cost of the land and other items, such as roads, turbine, and substation. Terrain can be classified as complex, mesas, rolling, and plains. Passes may be...
PROBLEMS Cdi
1. What are the two most important factors in the cost of energy The factors that influence COE the most 2. Calculate the simple payback for a Bergey 1 kW wind turbine. Go to www.bergey.com to get price and place it on a 20 m or 60 ft tower. It produces 2,000 kWh year. Assume a value for O amp M and FCR 0. 3. Calculate the cost of energy use Equation 12.3 for a 400 W Air X wind turbine Southwest Windpower . Installed costs are 1,500, which includes 10 m tower and battery. Annual energy...
Drag Device
In a drag device, the wind pushes against blade or sail Figure 5.1 , and drag devices are inherently limited in efficiency since the speed of the device or blades cannot be greater than the wind speed. For a drag wind turbine, the wind pushes on the blades, forcing the rotor to turn on its axis. Examples of drag devices are cup anemometers, vanes, and paddles, which are shielded from the wind or change parallel to the wind on half the rotor cycle Figure 5.2 . Clams shells, which open on the...
Mathematics Of Exponential Growth
Values of future consumption, r, can be calculated from the present rate, r0, and the fractional growth per time period, k Present consumption is 100 units year and growth rate is 7 per year. r 100 ea07 100 100 e7 100 1,097 1 105 per year The consumption per year after 100 years is 1,000 times larger than the present rate of consumption. Note Exponents never have any units associated with them. The doubling time, T2 in years, for any growth rate can be calculated from Equation 2.8 Take the...