Exponential Growth

Our energy dilemma can be analyzed in terms of fundamental principles. A corollary of the first law of thermodynamics is it is a physical impossibility to have continued exponential growth of any product or exponential consumption of any resource in a finite system. The present rate of consumption and the size of the system give a tendency for people to perceive the resource as either infinite or finite. The total energy output of the sun and the amount of mass in the solar system are infinite...

Measures Of Performance

Capacity factor Capacity factor is the average power, which is equivalent to an average efficiency factor. CF average power rated power (8.1) In general, capacity factors are calculated from the kilowatt-hour produced during a time period, since power energy time. The time periods vary however, the most representative time period would be 1 year, although capacity factors for a month and a quarter have been reported. Capacity factors of 0.3 would be good, 0.4 would be excellent, while those of...

Distributed Systems

Distributed systems are the installation of wind turbines on the retail side of the electric meter for farms, ranches, agribusiness, small industries, and small-scale community wind for schools, public lighting, government buildings, and municipal services. As an example, in Lubbock, Texas, the American Wind Power Center and Museum installed a 660 kW unit, a cottonseed oil plant installed ten 1 MW units, and three school districts in nearby towns have installed eight 60 kW units. By 2007, there...

World

The European Wind Atlas also has offshore winds (Figure 4.7). The Predicting Offshore Wind Energy Resources project 23 aimed to assess the offshore wind power potential in European Union waters, taking into account coastal effects and highlighting those sea areas where hazardous wind or wave conditions exist. These estimates can then be used to pinpoint areas, which are favorable for siting a wind farm. More detailed monitoring can then be undertaken to improve the initial wind power estimates...

Chapter

Important In physics the answer cannot be more accurate than the data that the calculation is based on. This is called significant figures or significant digits. Therefore, for handheld calculations, calculators, computers, and spreadsheets do not provide all the available numbers in the answer. Round off all answers to the correct significant digits. 1. Power in the wind increases with the cube of the wind speed. Power across a rotor increases by the square of the radius. Notice in the table...

Doubly Fed Induction Generator VariableRPM Operation

There is a gearbox connected to a standard (mostly 1,500 rpm) doubly fed induction generator. The stator is directly connected to the utility grid and the rotor of the generator is connected to a converter. An rpm range of 60 to 110 of the rated rpm is sufficient for good energy production. At wind speeds above the rated wind speed, the blades are pitched to reduce aerodynamic efficiency. Variable blade pitch is also used for start-up, shut down, and overspeed. FIGURE 7.10 Ring generator for...

Regulations On Installation And Operation

Permits are required in residential areas for construction, and even in rural areas in some states. The major zoning issues are tower height, setbacks, noise, aesthetics, environmental impact, and safety. The probability of failure, such as a thrown blade, is the most common objection. However, risks are accepted from other areas, such as cars, utility lines (electric and gas), etc. Signs, trees, and even utility poles have failed in high winds or under conditions of icing. Tower access needs...

Percent Component Costs for Wind Farm Installation

Is higher because the world demand for wind turbines is higher than production. A comparison of the estimated components of the cost of energy shows, as expected, that capital cost is the major component 15 , and the primary installed cost is for the wind turbine (Table 12.4). The installed cost for offshore wind farms is around 1.5 times that for wind farms on land.

Rating of Visual Impact of Small Wind Turbines

Negligible Minimal Moderate Significant viewpoint and 18 for the public viewpoint. If the score (Table 9.2) is below the significant range, the wind turbine is unlikely to have a visual impact unless it is close to and at the center of a scenic view. The score is only a general indicator for visual impact of small wind turbines. Wind turbines will be visible, at least from some viewpoints, as they will be above surrounding trees. In the Plains areas with few trees, small wind turbines will be...

Other Wind Farms in the United States

Wind farms generated an estimated 26.3 TWh in 2006, and some capacity factors were over 40 6 . The capacity factor (Figure 8.5) and specific output (Figure 8.6) were analyzed for four wind farms (Table 8.2) in the Southern High Plains, same wind turbine, but with smaller rotor diameter and hub height for White Deer and part of Fluvana. Capacity factors ranged from 33 to 45 , and the largest annual specific output was 1,350 kWh m2. The yearly variation is the same across the region however, the...

Siting for Wind Farms

The number of met stations and the time period for data collection to predict the energy production for a wind farm vary depending on the terrain and the availability of long-term base data in the vicinity. In general, numerical models of wind flow will predict wind speeds to within 5 for relatively flat terrain and 10 for complex terrain, which means an error in energy of 15-30 . Therefore, a wind measurement program is imperative before a wind farm is installed. However, if a number of wind...

Wind Project Development

The three most important considerations for development of wind farms are 1. Land with good to excellent wind resource 2. Contract to sell electricity produced 3. Access to transmission lines (proximity and carrying capacity) The American Wind Energy Association 11, 12 and Wind Powering America 13 also have information on project development. The project development list covers many areas however, it was placed in economics, as that is the final decision on a project. Much of the information...

Estimated Wind Power for Texas Alternative Energy Institute

The same procedures of terrain enhancement and GIS were used to estimate the capturable wind power for Texas 27 . The selection criteria were wind class 3 or higher from revised wind map using terrain exposure, slope of 0-3 , excluded lands (urban, highways, federal and state parks, lakes, wildlife refuges, and federal wetlands), and within 15 km of transmission lines (115 kV and above). The capturable annual power was calculated for the following conditions for the wind turbines 50 m hub...

Small Wind Turbines

There is an overlap of small wind turbines with village power systems, as most of these wind turbines are less than 100 kW, and it is also the same for some of the distributed and wind-diesel systems. In World Installed Wind Capacity (MW) by Region for 2006 and 2007 World Installed Wind Capacity (MW) by Region for 2006 and 2007 Estimation of Global Installed Number and Capacity and Production for 2007 by Manufacturers of Large Wind Turbines Estimation of Global Installed Number and Capacity and...

Wind Farm Performance

Capacity factors have improved with the newer and larger wind turbines, so it is expected that wind farms installed from 2000 on will have better capacity factors than the older installations The early wind farms in California had average capacity factors below 20 , while wind farms in good to excellent wind regimes with new wind turbines should have capacity factors from 35 to 40 . Availability and capacity factor are related, because if the wind turbines are having operational problems,...

Representative Lease for Wind Farm

Resource Flat fee acre year Contract Option Construction, road, etc. Flat fee Income year Royalty Per turbine (minimum) Escalation 1-4 30 year 2 (10 year) 3-4 month 4,000 MW For wind farms, the landowner may receive one or more offers, and the leases (Table 12.2) will differ by region, wind resource, and access to transmission. Some landowners are forming associations for dealing with wind farm developers. In the United States, wind turbines can be installed on land currently under the...

Wind Resource Screening

As an example, wind resource screening for the Texas Panhandle is presented 25, 26 . The DEM data (3 arc seconds resolution) along with DLG data were used. The original DEM data were in blocks of 1 by 1 . Data for utility transmission lines (69 kW and higher) were input by hand. Two GIS systems, IDRISI and PC ARC INFO, for personal computers were used. IDRISI has built-in functions that enhance its use for wind resource screening slope, hill shading, aspect, and orthographic projection. A data...

Wind Measurement For Small Wind Turbines

For a very small wind turbine of the order of 100 W to 3 kW, the expense of anemometers, data loggers, and the analysis is more than the price of the wind turbine. In one sense, the wind turbine is the anemometer, as the energy produced is the measurement. So you should depend on historical and regional data to determine feasibility of installing a small wind turbine. Two other indicators of feasibility are the past historical use of farm windmills in the area and a check with owners on...

References

Life cycle costing, a practical guide for energy managers. Atlanta, Georgia Fairmont Press. 2. J. M. Cohen et al. 1989. A methodology for computing wind turbine cost of electricity using utility economic assumptions. NREL TP-257-3628. Paper presented at Proceedings, Windpower '89. CD. 3. H. C. Wolfe, ed. 1975. Efficient use of energy, AIP Conference Proceedings, No. 25. New York American Institute of Physics. 4. W. R. Briggs. 1980. SWECS cost of energy based...

Village Power

Around 1.6 * 109 people do not have electric service because they are too far from transmission lines of conventional electric power plants. Extension of the grid is too expensive for most rural areas, and if extended, it has poor cost recovery. There is an effort to bring electricity to these villages using renewable energy (wind, PV, mini and micro hydro, biomass). Other components to supply reliable energy (limited) include controllers, batteries, and conventional diesel gas generators. In...

Surface Roughness

Performance will be reduced by the airfoil sensitivity to blade roughness. Just as for wings on airplanes, ice reduces performance drastically (Figure 8.17), to the point where the rotor will not turn. Also, falling chunks of ice from large blades present a safety hazard. If icing is a major problem, then it might be economic to have heated blades. Black blades have been used on some wind turbines to assist thawing when the sun comes out. FIGURE 8.17 Ice on Carter 25 blade. Blades did not...

Windstats

WindStats Newsletter 4 contains reports and wind energy production tables on thousands of wind turbines ID, manufacturer, kilowatt rating, swept area, tower height, estimated annual energy production, monthly and quarterly energy production, quarterly capacity factor, specific output (kWh m2 and kWh kW), annual production for the previous 1 or 2 years, and date installed. In addition for Denmark, there is information on reliability. The information for wind turbines in Denmark is available...

Estimated Wind Power for Texas Pacific Northwest Labs

Contour Line Wind Turbines

Pacific Northwest Labs (PNL) estimated the capturable wind power for Texas at 50 m height as 134,000 MW from class 3 and above winds, with 28,000 MW for class 4 winds. Class 4 winds are FIGURE 9.7 Digital elevation map (16 shades) of the Panhandle of Texas with county boundaries and major highways. Contour lines are 62 m apart. FIGURE 9.7 Digital elevation map (16 shades) of the Panhandle of Texas with county boundaries and major highways. Contour lines are 62 m apart. FIGURE 9.8 Terrain...

Permanent Magnet Alternator VariableRPM Operation

This is also a direct-drive system with no gearbox, and it is common on small wind turbines. The most common control for high winds is by furling using a tail. However, Southwest Wind Power has a downwind unit where electrodynamic braking is used for high winds and shutdown. Some larger permanent magnet alternators are available (500 kW), and General Electric has a 2.5 MW unit. The advantages of permanent magnet excitation are lower losses, lower weight, and lower cost. A disadvantage is that...

Comments

Wind turbine and wind farm performance (annual, quarterly, monthly, or by period of peak demand) will determine economic viability and will help in comparisons of wind turbines. The main performance factors are the amount of energy produced and the cost of that energy compared to other sources. Of course, electricity is the major application, with water pumping secondary. Capacity factors in good to excellent wind regimes should range from 30 to 40 , and annual specific outputs should be over...

Simple Payback

A simple payback calculation can provide a preliminary judgment of economic feasibility. The difference is usually around 3-7 between borrowing money for a system and lost interest if you have enough money to pay for the system. In 2003 and again in 2008, the lost interest rate was very low. The easiest calculation is cost of the system divided by cost displaced per year, and assuming that operation and maintenance is minimal and will be done by the owner. where SP simple payback, years IC...

General Comments

The general uncertainty regarding future energy costs, dependence on imported oil, reduction of pollution and emissions, and to some extent availability, has provided the driving force for the development of renewable sources. The prediction of energy costs escalation is a hazardous endeavor, as the cost of energy is driven primarily by the cost of oil. Oil was 15-25 barrel in the 1990s, and predictions in the late 1990s were for a gradual increase to 30 barrel by the year 2020. However, oil...

Numerical Models

Numerical models for predicting winds are becoming more accurate and useful, especially for those areas of the world where surface wind data are scarce or unreliable. Models were primarily derived from numerical models for weather prediction 32 . Remember that a small difference in wind speed can make a large difference in energy. Therefore, in the final analysis, surface wind data are still needed for wind farms. Texas, Intercepted and Capturable Wind Power and Annual Energy Potential from...

Applications and Wind Industry

The main applications are the generation of electricity and water pumping (Table 10.1). Except for the installed capacity for wind farms, the other numbers are best estimates, as data are difficult to acquire. Applications for generation of electricity are divided into the following categories utility-scale wind farms small wind turbines, which include remote and stand-alone systems distributed wind-diesel village power (generally hybrid systems) and telecommunications (high-reliability hybrid...

Summary

Continued exponential growth is a physical impossibility in a finite (closed) system. Previous calculations made about the future are just estimations, and possible solutions to our energy dilemma are 1. Reduce demand of fossil fuels to depletion rate. 2. Use renewable energy at sustainable rate and begin a steady-state society. 3. Redefine the size of the system colonize the planets and space. The problem is, this will not solve the energy dilemma on earth. From our present viewpoint, the...

Wind Resource

There are two aspects of wind resource assessment 1 determination of the general wind power potential and 2 determination of wind power potential and predicted energy production for wind farms. Wind resource assessment for wind farms will be covered in the chapter on siting. The general wind power potential was determined from the wind speed data available, and then wind maps were developed. In general, the wind speed data that were available were at heights of 6 to 20 m however, some...

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...

Phase Angle and Power Factor

Power Factor Phase Angle

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

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

Horizontal Double Wind Turbine

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

Average Size Windmill

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...

Rotor Area and Wind

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

Rotating Cylinder Electrode Photos

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...

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...

Boundary Layer Control

Earth Boundary Layer Windmill

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...

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...

Extractable Limits Of Wind Power

Synoptic Scale Mesoscale Wave

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...

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...

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

Suzlon Offshore Wind

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

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

Windmill Diagram Water

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

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...

Wind Turbine Blade Rpm And Length Of Blade500 Kw

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

Lift And Drag Forces Hawt

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

Von Der Hoven Spectrum

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...

Orientation Of The Rotor Axis

Mcdonnell Giromill

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

Vortice Generator 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

Windmill 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...

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...

Vertical Wind Turbine - 200kw Vawt

Sandia Test Bed Vawt

World energy production in 1995 was estimated at 5 million MWh year from over 22,000 wind turbines with an installed capacity of around 4,000 MW. The American Wind Energy Association set a very optimistic goal for the United States of 10,000 MW by the year 2000. This was not achieved, although there was a lot of activity in other states outside of California due to the new incentive of the production tax credit PTC for 1990-1995. The PTC was 0.015 kWh for 10 years, with an inflation factor for...

Preface Of Windenergy

The big question How do we use science and technology such that Spaceship Earth will be a place for all life to exist We are citizens of the planet Earth, and within your lifetime there will be major decisions over the following energy including food , water, minerals, space, and war which I can state will happen with 99.9 probability . The previous statements were written over 20 years ago when I first taught introductory courses on wind and solar energy. Since then the United States has been...

Enertech

A long-term performance test of an Enertech 44 14 provided monthly values of energy production, connect time, availability, and wind speed. The variation of power by month and year is shown in Figure 8.7. Connect time, which is the time the unit is connected to the grid, is around 60 Table 8.3 , or over 5,000 h per year. From 1989 to 1996, when the unit was rated at 40 kW, it averaged 78,000 kWh year. The prototype wind turbine induction generator, constant rpm, stall control was installed at...

Power Quality

Wind turbines and especially wind farms, which in reality are wind power plants, must provide the power quality 10, 11 to ensure the stability and reliability of the system, which include power quality for other customers on the grid. The four types Figure 7.12 of connection depend on the electrical conversion, generator, and connection direct or partial and full converter . Induction generators require reactive power from the grid, and capacitor compensation is often used, at the wind turbine...

Rest of the System

Lattice Tower Wind Turbine

For large wind turbines, the most common configuration is three blades made from FRPs, upwind, drive train, asynchronous generator, and tubular steel tower. The driver is the rotor, and these dynamic loads are transferred to the rest of the system drive train, generator, and tower. The difference between variable- and constant-rpm operation is that part of the wind loads can be absorbed by inertia of the rotor in variable-rpm operation. This reduces the severity of the loads for the drive train...

Measured Power And Power Coefficient

Pitch Angle Wind Turbine

A common specification is the power output of the wind turbine versus wind speed, a power curve. The power curve generally includes all efficiencies from wind to electrical output, not just the rotor efficiency. Since all wind turbines must control power output at high wind speeds, at some point the efficiency is lower. Control can be implemented by changing blade pitch or by operating fixed-pitch blades at constant angular speed. Operating at fixed pitch is also called stall control. Power...

Duration Curve

Velocity Duration Curve Wind

Wind data can also be represented by a speed-duration curve Figure 3.13 , which is a plot of cumulative frequency starting at the largest wind speed subtract 100 from percent frequencies of cumulative frequencies if starting at the lowest wind speed . The percent duration is usually converted multiplying by 8,760 to number of hours in a year. From wind speed-duration curves, estimates of the time the wind speed is above a given value can be obtained. The data in Table 3.5 and the curve in...

Construction Blades

Vawt Composite Blade Manufacturing

For years, small wind turbines blades were made of wood, carved from a single piece or from a wood block glued together from several pieces. The material properties of wood are good strength, flexibility, and resistance to fatigue. Machines could carve up to four blades from a master blade. However, for large blades, solid wood was not acceptable, as the weight became too large. For larger blades, one construction was similar to an airplane wing, a spar and ribs with a covering. The spar is the...

Aerodynamic Performance Prediction

Blade Twist Wind Turbine

The ratio of lift to drag for airfoils is around 100, so the two forces, which act at the quarter chord of the airfoil, are represented by a force that makes the blade rotate, tangential force, and a force trying to push the rotor over, perpendicular force. So if these lift and drag forces are calculated for a blade, then the tangential and perpendicular forces are calculated and the performance of the rotor can be predicted. If the angle between the blade path and the wind at the blade is O...

Energy Dilemma In Light Of The Laws Of Thermodynamics

There is not an energy crisis, as energy cannot be created or destroyed, only transformed to another form. We have an energy dilemma in the use of finite energy resources and their effect on the environment, primarily due to the burning of fossil fuels. The first and primary objective of any energy policy must be conservation and efficiency. It is the most economical form for alleviating our energy problems. Conservation means if you do not need it, do not turn it on or use it. Admonitions to...

Vegetation Indicators

Vegetation can indicate regions of high wind speed where there are no measurements available. Deformation or flagging of trees 17, p. 96 is the most common indicator Figure 4.13 . In some cases the flagging of trees is a more reliable indicator of the wind resource than the data available. For example, the Arenal region of Costa Rica has high winds, which have now been measured average for twelve stations at 11 m s 29 . There is a meteorological station near Fortuna in the region, which was...

Wilson R.e. Lissaman P.b.s. And Walker S.n. 1976 Aerodynamic Performance Of Wind Turbines. Energy Research And

Von Dolnhoff. 1959. Theory of wing sections, including a summary of airfoil data. Dover. 2. S. J. Miley. 1982. A catalog of low Reynolds number airfoil data for wind turbine applications. RFP-3387, Department of Aerospace Engineering, Texas A amp M University. 3. R. E. Wilson, P. B. S. Lissaman, and S. N. Walker. 1976. Aerodynamic performance of wind turbines. ERDA NSF 04014-76-1, UC-60. Available from NTIS. 4. D. M. Eggleston and F. S. Stoddard. 1987. Wind turbine...

Wake Effects

The wake is expanding and the wind speed is reduced downwind, so if there are multiple wind turbines, how far apart should they be placed Also, vortices are generated from the tips of blades, trailing edges of blades, and by the tower, and they increase the turbulence of the wake. So tips of airfoils and trailing edges are designed to reduce the vortices and to reduce the noise accompanying some vortices. The three primary methods of wake and array loss research have been numerical modeling,...

History

Albans Wind Turbine Andreau

The use of wind as an energy source begins in antiquity. Vertical-axis windmills for grinding grain were reported in Persia in the tenth century and in China in the thirteenth century 2 . At one time wind was a major source of energy for transportation sailboats , grinding grain, and pumping water. Windmills, along with water mills, were the largest power sources before the invention of the steam engine. Windmills, numbering in the thousands, for grinding grain and pumping drainage water were...

Wind Industry

Wind Turbines Nasa Mod Sweden

After the oil crisis in 1973, the first step was the development of small wind turbines defined as lt 100 kW . Most companies in the United States began by importing wind turbines, finding abandoned units to refurbish for personal use or to sell, and then designing and building systems similar to the wind chargers of the 1930s and 1940s direct current, 0.1-4 kW, up to 5 m diameter . A number of home builders turned to the Savonius type because of its simplicity and ease of construction. FIGURE...

Annual Energy Production Mwh Year Per Turbine

Rule of thumb, 5-10 m above the building. So tower should be around 25 m tall, which is 80 ft. Place it 10 m away from the building. 2. Rule of thumb, tower height should be 5-10 m above the trees or move tower farther away from trees. So tower should be 40 m tall. Need to look in a catalog for cost of towers guyed lattice tower would be the cheapest. Need to check manufacturer's brochure for recommended tower size strength of structure for that size wind turbine example, 10 kW from Bergey...

Specific Output kWhm for Wind Turbines Most but Not All Manufacturers in California

In the 1990s, the older wind turbines, primarily in the range of 50-100 kW 55 of the MW capacity installed , were being cannibalized for parts and uneconomic wind turbines were dismantled. The following trends are noted wind turbines became larger now megawatts , capacity factors were better, and reliability increased. Also, the drop in production in 1997 was due to older, smaller units being taken out of production and then replaced with bigger turbines in 1998. As the poor-performing units...

Wind Speed Histograms

A wind speed histogram shows the number of hours or whatever time period is used the wind blew at each wind speed class Table 3.5 . Wind speeds were sampled at 1 Hz and averaged for 1 h, and year wind speed histograms for 1996-1999 were averaged to obtain a representative annual value. An average density of 1.1 kg m3 was used to calculate the average wind power potential. The average wind speed was 8.2 m s, and the average wind power potential was 467 W m2 for a height of 50 m. The plots of the...

Evolution

200kw Wind Turbine

Since 1970 the design of modern wind turbines evolved from two different ends, utility-scale, large wind turbines and small wind turbines. The large wind turbines were primarily funded by governments, and only prototypes were built and tested, while the small wind turbines were built in large numbers by private manufacturers for the emerging commercial market. In the United States, NASA-Lewis began with the MOD-O design, a two-blade, downwind turbine, 100-200 kW, which progressed to the design...

Wind Speed Distributions

Rayleigh Distribution Wind

If data are not available, then the wind speeds can be predicted from one or two parameters. A number of different distributions have been tried, but only two are in general use, Rayleigh and Weibull distributions. These distributions give poor estimates of power for low mean wind speed situations. At higher wind speeds, both give adequate estimates for many locations however, for those regions with steady winds, such as the trade winds, the Weibull distribution is better. The Rayleigh...