Incentives for Renewables

A great deal of renewable energy development in the U.S.A. occurred in the 1980s, and the prime stimulus for it was the passage in 1978 of the Public Utility Regulatory Policies Act (PURPA). It created a class of nonutility power generators known as the qualified facilities (QFs). The QFs were defined to be small power generators utilizing renewable energy sources and or cogeneration systems utilizing waste energy. For the first time, PURPA required electric utilities to interconnect with QFs...

Industry Overview

The total annual primary energy consumption in 1997 was 390 quadrillion (1015) BTUs worldwide1 and over 90 quadrillion BTUs in the United States of America, distributed in segments shown in Figure 1-1. About 40 percent of the total primary energy is used in generating electricity. Nearly 70 percent of the energy used in our homes and offices is in the form of electricity. To meet this demand, 700 GW of electrical generating capacity is now installed in the U.S.A. For most of this century, the...

Pv Cell Technologies

In making comparisons between alternative power technologies, the most important measure is the energy cost per kWh delivered. In pv power, this cost primarily depends on two parameters, the photovoltaic energy conversion efficiency, and the capital cost per watt capacity. Together, these two parameters indicate the economic competitiveness of the pv electricity. The conversion efficiency of the photovoltaic cell is defined as follows _ electrical power output solar power impinging the cell The...

Wind Speed and Energy Distributions

The wind turbine captures the wind's kinetic energy in a rotor consisting of two or more blades mechanically coupled to an electrical generator. The turbine is mounted on a tall tower to enhance the energy capture. Numerous wind turbines are installed at one site to build a wind farm of the desired power production capacity. Obviously, sites with steady high wind produce more energy over the year. Two distinctly different configurations are available for the turbine design, the horizontal axis...

Wind Speed Distribution

Having the cubic relation with the power, the wind speed is the most critical data needed to appraise the power potential of a candidate site. The wind is never steady at any site. It is influenced by the weather system, the local land terrain, and the height above the ground surface. The wind speed varies by the minute, hour, day, season, and year. Therefore, the annual mean speed needs to be averaged over 10 or more years. Such a long term average raises the confidence in assessing the...

Power Systems

Merchant Marine Academy Kings Point, New York Principal Engineer, General Electric Company Fellow Engineer, Westinghouse Reasearch Center Boca Raton London New York Washington, D.C. Wind and solar power systems Mukund R. Patel. p. cm. Includes bibliographical references and index. ISBN 0-8493-1605-7 (alk. paper) 1. Wind power plants. 2. Solar power plants. 3. Photovoltaic power systems. I. Title. TK1541.P38 1999 This book contains information obtained from authentic and highly regarded...

Global Wind Patterns

Pictures Four Bladed Wind Turbine

The global wind patterns are created by uneven heating and the spinning of the earth. The warm air rises near the equator, and the surface air moves in to replace the rising air. As a result, two major belts of the global wind patterns are created. The wind between the equator and about 30 north and south latitudes move east to west. These are called the trade winds because of their use in sailing ships for trades. There is little wind near the equator, as the air slowly rises upward, rather...

Pv Energy Maps

Energy Map

The solar energy impinging the surface of the earth is depicted in Figure 3-15, where the white areas get more solar radiation per year. The yearly 24-hour average solar flux reaching the horizontal surface of the earth is shown in Figure 3-16, whereas Figure 3-17 depicts that in the month of December. Notice that the 24-hour average decreases in December. This is due to the shorter days and clouds, and not due to the cold temperature. As will be seen later, the pv cell actually converts more...

Solar Photovoltaic Power System

Photovoltaic Effect

The photovoltaic effect is the electrical potential developed between two dissimilar materials when their common junction is illuminated with radiation of photons. The photovoltaic cell, thus, converts light directly into electricity. The pv effect was discovered in 1839 by French physicist Becquerel. It remained in the laboratory until 1954, when Bell Laboratories produced the first silicon solar cell. It soon found application in the U.S. space programs for its high power capacity per unit...

Building Integrated pv Systems

Commercial Building Solar Power

In new markets, the near-term potentially large application of the pv technology is for cladding buildings to power air-conditioning and lighting loads. One of the attractive features of the pv system is that its power output matches very well with the peak load demand. It produces more power on a sunny summer day when the air-conditioning load strains the grid lines Figure 3-10 . The use of pv installations in buildings has risen from a mere 3 MW in 1984 to 16 MW in 1994, at a rate of 18...

Speed and Power Relations

The kinetic energy in air of mass m moving with speed V is given by the following in SI units The power in moving air is the flow rate of kinetic energy per second. Therefore Kinetic Energy m V joules. Power mass flow rate per second y2 If we let P mechanical power in the moving air p air density, kg m3 A area swept by the rotor blades, m2 V velocity of the air, m s Horizontal axis wind turbine showing major components. Courtesy Energy Technology Support Unit, DTI, U.K With permission....

Opti Slip

Wind speed, pitch angle, generator speed, and power output under fluctuating wind speed in 1650 kW turbine. Source Vestas Wind Systems, Denmark. With permission. Generator output power variation with wind speed in the blade pitch-regulated and stallregulated turbines. important, as it determines all major components and their ratings. The alternative strategies and the corresponding speed control methods fall in the following categories. The fixed-speed operation of the generator naturally fits...

Photovoltaic Power

Solarex With Fuel Cell

The photovoltaic pv power technology uses semiconductor cells wafers , generally several square centimeters in size. From the solid-state physics point of view, the cell is basically a large area p-n diode with the junction positioned close to the top surface. The cell converts the sunlight into direct current electricity. Numerous cells are assembled in a module to generate required power Figure 3-1 . Unlike the dynamic wind turbine, the pv installation is static, does not need strong tall...

Acknowledment Of Power System

The book of this nature on emerging technologies, such as the wind and photovoltaic power systems, cannot possibly be written without the help from many sources. I have been extremely fortunate to receive full support from many organizations and individuals in the field. They not only encouraged me to write the book on this timely subject, but also provided valuable suggestions and comments during the development of the book. Dr. Nazmi Shehadeh, head of the Electrical and Computer Engineering...

Wind Power

The first use of wind power was to sail ships in the Nile some 5000 years ago. The Europeans used it to grind grains and pump water in the 1700s and 1800s. The first windmill to generate electricity in the rural U.S.A. was installed in 1890. Today, large wind-power plants are competing with electric utilities in supplying economical clean power in many parts of the world. The average turbine size of the wind installations has been 300 kW until the recent past. The newer machines of 500 to 1,000...

Generator Drives

Wind Turbine Characteristics Figure

The turbine speed is generally much lower than the desired speed for the electrical generator. For this reason, the turbine speed in most wind systems is stepped up using a drive system. The system can be fixed-speed or variable-speed as described in this chapter. The wind-power equation as derived in Chapter 3 is as follows As seen earlier, the value of Cp varies with the ratio of the rotor tip-speed to the wind speed, termed as the tip-speed-ratio TSR. Figure 7-1 depicts a typical...

Efficiency and Cooling

Self Excited Braking Using Capacitor

The values of R1 and R2 in the equivalent circuit represent electrical losses in the stator and the rotor, respectively. As will be seen later, for a well-designed machine, the magnetic core loss must equal the conductor loss. Therefore, with R1 and R2 expressed in perunit of the base impedance, the induction machine efficiency is approximately equal to the following For example, a machine with R1 and R2 each 2 percent, we write R1 R2 0.02 perunit. The efficiency is then simply 1-2 0.02 0.02...

Solar Thermal System

Molten Salt Power Tower System Schematic

The solar thermal power system collects the thermal energy in solar radiation and uses at high or low temperature. The low temperature applications include water and space heating for commercial and residential buildings.1 Producing electricity using the steam-turbine-driven electrical generator is a high temperature application discussed in this chapter. The technology of generating electrical power using the solar thermal energy has been demonstrated at commercial scale. The research and...

Weibull Probability Distribution

Rayleigh Wind Speed Distribution

The variation in wind speed are best described by the Weibull probability distribution function 'h' with two parameters, the shape parameter 'k', and the scale parameter 'c'. The probability of wind speed being v during any time interval is given by the following h v Cj e c J for 0 lt v lt 4-19 In the probability distribution chart, h is plotted against v over a chosen time period, where h fraction of time wind speed is between v and v Av 4 20 By definition of the probability function,...

Preface

The total electricity demand in 1997 in the United States of America was three trillion kWh, with the market value of 210 billion. The worldwide demand was 12 trillion kWh in 1997, and is projected to reach 19 trillion kWh in 2015. This constitutes the worldwide average annual growth of 2.6 percent. The growth rate in the developing countries is projected to be approximately 5 percent, almost twice the world average. Most of the present demand in the world is met by fossil and nuclear power...

Electrical Generator

Solar Generator Design Drawings

6.1 Electromechanical Energy Conversion The conversion of the mechanical power of the wind turbine into the electrical power can be accomplished by any one of the following types of the electrical machines the direct current DC machine. These machines work on the principles of the electromagnetic actions and reactions. The resulting electromechanical energy conversion is reversible. The same machine can be used as the motor for converting the electrical power into mechanical power, or as the...

Wind Power System

Met Matrix For Wind Turbine

The wind power system is fully covered in this and the following two chapters. This chapter covers the overall system level performance, design considerations and trades. The electrical generator is covered in the next chapter and the speed control in Chapter 7. The wind power system is comprised of one or more units, operating electrically in parallel, having the following components the wind turbine with two or three blades. the yaw mechanism such as the tail vane. the speed sensors and...

Mode Mean and rmc Speeds Compared

The important difference between the mode, mean, and the rmc speeds is illustrated in Table 4-2. The values of the three speeds are compiled for four shape parameters k l.5, 2.0, 2.5, and 3.0 and three scale parameters c 10, 15, and 20 mph . The wind power densities are calculated using the respective speeds in the wind power equation P 1 2 p V3 watts m2 using the air mass density of 1.225 kg m3. We observe the following from the c 15 rows 1. For k 1.5, the power density using the mode speed is...

Variable Speed Operation

Tip Speed Ratio

At a given site, the wind speed can vary from zero to high gust. As discussed in Chapter 4, the Rayleigh statistical distribution is found to be the best approximation to represent the wind speed at most sites. It varies over a wide range. Earlier in Chapter 4, we defined the tip-speed ratio as follows Tsr _ Linear speed of the blade outer most tip _cc R where R and c are the rotor radius and the angular speed, respectively. For a given wind speed, the rotor efficiency Cp varies with TSR as...

Wind in the World

The wind energy stands out to be one of the most promising new sources of electrical power in the near term. Many countries promote the wind-power Flexible, Lightweight Blades Made of New Materials Innovative Hub Attachment Optimized Power Train Enhanced Micrositing Smart Controls Power Electronics Modern wind turbine for utility scale power generation. Declining cost of wind-generated electricity. Source AWEA DOE IEA. technology by national programs and market incentives. The International...

Polycrystalline and Semicrystalline

Area Primary Lens Active Cell Area

This is relatively a fast and low cost process to manufacture thick crystalline cells. Instead of drawing single crystals using seeds, the molten silicon is cast into ingots. In the process, it forms multiple crystals. The conversion efficiency is lower, but the cost is much lower, giving a net reduction in cost per watt of power. Single-crystal ingot-making by Czochralski process. Source Cook, G., Photovoltaic Fundamental, DOE NREL Report DE91015001, February 1995. Single-crystal ingot-making...

Energy Distribution

Solar Research Centre Delhi

If we define the energy distribution function e _ kWh contribution in the year by the wind between v and v Av Then, it would look like that in Figure 4-12, which is for the Rayleigh speed distribution. The wind speed curve has the mode at 5.5 m s and the mean at 6.35 m s. However, because of the cubic relation with the speed, the maximum energy contribution comes from the wind speed at 9.45 m s. Above this speed, although V3 continues to increase in cubic manner, the number of hours at those...

Sun Intensity

Golf Condition Sun Intensity Sensor

The magnitude of the photocurrent is maximum under full bright sun 1.0 sun . On a partially sunny day, the photocurrent diminishes in direct proportion to the sun intensity. The i-v characteristic shifts downward at a lower sun i-v characteristic of 22 watts pv module at full and half sun intensities. Source United Solar Systems Corporation, San Diego, California. With permission. i-v characteristic of 22 watts pv module at full and half sun intensities. Source United Solar Systems Corporation,...