Trophic Interactions Within Aquatic Ecosystems

Ahmad Hemami

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781000010565
• Edition: 1
• Topic: Politics & International Relations
• Subtopic: Politics
• Index: Politics & International Relations

Electricity and Electronics for Renewable Energy Technology: An Introduction provides a foundational understanding of electricity and the methods and devices specific to electricity from renewable sources.

The book begins with a brief explanation of the necessary mathematics and then:

• Addresses the basics of electricity and relationships, motors and generators, transformers, and networks and distribution
• Tackles the key concepts associated with electronics, diodes and transistors, switching devices, and power converters
• Covers digital electronics from number systems and logic circuits to encoders and decoders
• Explores advanced subjects such as reactive power and the operation of a transistor

• 
  
  

A lab manual andPowerPoint presentation are available with qualifying course adoption.

Featuring extensive review questions and practice problems at the end of each chapter, Electricity and Electronics for Renewable Energy Technology: An Introduction instills an essential knowledge of electricity and electronics required for work with renewable energy.

1
Energy and Electricity

OBJECTIVES: After studying this chapter, you will be able to

• Explain why concern about energy is so important
• Understand the energy need in the world
• Define the sources of energy
• Define the sources of renewable energy
• Understand the importance of electrical energy
• Evaluate your knowledge of electricity and electronics
• Recognize the importance of renewable energy
• Learn some terms in electricity
• Understand the importance of safety at work and some basic safety rules
• Explain some examples of static electricity
• Understand a number of applications of static electricity

New terms: Breaker, fuse, safety rules, safety standards, static electricity

1.1 Introduction

Electricity is a type of energy. Although it is not a type of energy stored in fossil and nuclear fuels, it can be obtained from conversion of the chemical energy contained in fossil fuel or nuclear energy contained in certain metals. It can also be obtained by converting mechanical energy in the form of wind and hydro to electrical energy. In fact, electric generators only convert mechanical energy to electricity, while the mechanical energy itself can be the result of converting some other types of energy. This is because energy cannot be generated; it can only be converted from one type to the other.

In gas, oil, and coal power plants the chemical energy of fossil fuel is first converted to mechanical energy and then mechanical energy is converted to electrical energy. Similarly, in nuclear power plants, atomic energy is first converted to heat then to mechanical energy through steam turbines and finally to electrical energy.

In hydraulic turbines the mechanical energy from the flowing water, and in wind turbines the mechanical energy from wind is converted to electrical energy. A direct conversion of heat/light from sun to electrical energy takes place in solar cells. Solar panels are a large number of solar cells put together. Solar heat can be gathered also by solar collectors, which contain a number of tubes that absorb heat from sunshine and warm up water (or another liquid, in general). At a larger scale an array of reflective mirrors receive the sun’s heat and concentrate it at a common collector to boil water and generate steam. Geothermal energy is also another source of available energy without greenhouse effect and nuclear waste.

As you know, both fossil fuel and nuclear power plants have residual, which is not environmentally friendly. In other words, it is a contaminant for the environment. Water, wind, sun, and some other (very limited in quantity at the present time) renewable sources of energy are those without any harmful residual or contamination.

Two main reasons are behind the emphasis for renewable energy. One is contamination and global warming, and the other is the fact that the fossil fuels eventually dry up, and there will be no more oil, gas, and coal. The same thing can be said about nuclear energy because the reserves of nuclear fuels are not unlimited.

We and the future generations of mankind need to understand that humanity can only survive if we live in harmony with nature. We should eliminate any waste, and all our energy must ultimately be provided by renewable sources.

1.2 Need for Energy

Electricity is only one part of the energy that mankind needs. We cannot imagine living without electricity. Equally, we cannot imagine living without transportation, buildings, and so forth; all of these consume energy. The need for energy cannot be overemphasized. It is an everlasting fact. This is partly due to the increase in the population of the world and partly because of conversion to modern living by many nations. If the world population stayed constant, we could imagine that one day all the people could have a moderate modern life, if we would act wisely. The unfortunate fact is the population increases, and the unwise actions by many, from small scale at an individual level to large scale of nations and countries.

According to a 2011 report by British Petroleum “World primary energy consumption grew by 5.6% in 2010, the largest increase in percentage terms since 1973.” This percentage is for the entire energy consumption, which implies transportation, heating (and cooling), electricity, and so forth.

Electrical energy, by itself, has a faster pace of growth. “Electricity demand is increasing twice as fast as overall energy use, and is likely to rise 76% by 2030 (from 2010).”^*

Figure 1.1 depicts the growth rate of electricity during 2000 to 2012 period. Table 1.1 illustrates the rate of growth of electric energy for some countries and regions.

Despite the remarkable growth of renewable energy (mainly the number of installed wind turbines and solar panels) in many industrialized countries, the renewable energy covers only a small fraction of the total electrical energy demand (less than 2 percent in the world, 2.3 percent in the United States). Since 2011, China ranks first in terms of installed wind turbines per year, followed by the United States. Nevertheless, many regions have the potential and the capacity for much more wind and solar energy. China, for instance, has an estimated capacity of between 700 and 1200 gigawatts (GW). (Gigawatt is a measure of electric power. Giga stands for one billion. If you look at any electric device, even a simple one like a light bulb, the amount of its power is stamped on it [e.g., 100 W and 60 W].)

Figure 1.1 World electricity consumption (billion kWh). (From International Energy Agency.)

Table 1.1 Population and Energy Growth 1990–2008

1.3 Renewable Energy

If we set aside the energy reserves of the Earth in the form of fossil fuel and metals that are used as nuclear reactor fuels, one can say that almost all other energy on the Earth comes either from the sun or from the heat stored under the Earth’s crust. This is because except for tidal energy, which is attributed to the moon, the energy in the wind, waterfalls, and ocean waves all stem from the effect of sun on the Earth’s atmosphere. The source of wind is the heat from the sun, and ocean waves are caused by the wind. Also, if biofuels are considered, the growth of plants is due to the sun’s light and heat. Solar energy, as the name implies, involves direct energy from the sun.

Inside the Earth there exists a tremendous amount of thermal energy. This heat, called geothermal energy, can be used for heating buildings on a small scale, but it can also be used for generating steam and running steam turbines for generating electricity, as in power plants.

All the aforementioned categories of energy are called renewable because they do not create pollutants or dangerous residuals, which are harmful for the environment and all the living creatures on Earth. Also, they are regenerated, and, in general, they are abundant.

Presently, of the above-mentioned renewable energies, only wind and solar energy have gained momentum, because, in general, renewable energy is a low-grade energy (except hydro energy), meaning that although it is plentiful, it is not concentrated (the amount of energy per volume is low) or it is expensive to extract.

Despite all the advantages associated with renewable energy, a primary criterion is the cost. Compared to coal, oil, and gas, which determine the unit price for energy, renewable energy is still expensive. In particular, the initial cost for installations is high. Nevertheless, because the supply of all the fossil and similar fuels is limited, it is not too hard to understand that one day mankind must count only on those renewable sources of energy and nothing else.

Out of various renewable energy sources, the one that has been used frequently and for a long time is hydro energy. One reason for this is the large-sized hydraulic turbines. There is a significant difference between hydro energy and other renewable sources, which are of low grade. In the last 20 years the progress made in wind turbine technology and solar cells has made use of these devices more efficient and more cost effective, making them viable for large-scale and commercial use. However, tidal and sea wave energy are not yet candidates for commercially accepted production.

In general, we can say that renewable energy can be directly used, as appropriate to the usage, or it can be converted to electricity. For example, wind turbines in the past have been used for mechanical work, such as in grinding wheat and for pumping water from wells for irrigation. Although still this can be done, almost all wind turbines today change the wind energy into electricity. The obvious reason is that electrical energy can be relatively easily transmitted from the point of production to the point of consumption. Similarly, solar and geothermal energy can be directly used for heating or can be converted to electricity.

Renewable energy can be defined as energy from the sources without pollutants of the environment, such as CO₂, radioactive waste, and harmful chemicals.

Converting wind energy or solar energy to electricity at the commercial level is performed in wind farms and solar farms with many turbines or solar panels. Their power output can be comparable to conventional power plants. For example, instead of one steam turbine with 500 MW, we may have 250 wind turbines of 2 MW. Nevertheless, the technology used for wind turbines and solar power plants is not the same as used in the conventional power generation, although both generate electricity.

This book is not intended to be about wind turbines or solar panels and how they work, though Chapter 21 has a short description of the main components and their specifications. The principal point is to describe how electricity is generated in these nonconventional power plants. This by itself is necessary knowledge for people in the field.

1.4 Electricity

The important and most significant feature of electrical energy is its transportability (see Figure 1.2). Compared to thermal and mechanical energy, one can say that electricity is relatively cheap to transport but rather expensive to store. For both transportation and storage the scale under consideration is very large. We are not referring to an ordinary pen size battery or a car battery. We are talking about transporting/storing electricity for a city.

As you progress through this book, step by step you will learn about electricity and many relevant topics. There is always more to learn, and you may go into more depth on many topics, but time and other factors do not allow one to grasp everyth...

Table of contents

• Cover
• Half Title
• Title
• Copyright
• Dedication
• Contents
• Preface
• Acknowledgments
• Author
• 1 Energy and Electricity
• 2 Basic Mathematics and Systems of Measurement Units
• 3 Atomic Structure of Materials
• 4 DC and AC Electricity
• 5 Voltage, Current, and Power
• 6 DC Circuits Relationships
• 7 DC Motors and Generators
• 8 AC Circuits Relationships
• 9 Three-Phase Systems
• 10 Transformers
• 11 AC Motors and Generators
• 12 Electric Power Transmission and Distribution
• 13 Electronic Components, Functions, and Devices
• 14 Diode
• 15 Regulating Diodes and Applications
• 16 Diode Rectifiers and Filters
• 17 Transistor
• 18 Transistor Circuits
• 19 Switchable Diodes and Gated Transistors
• 20 Power Converters
• 21 Electronic Power Converters in Wind Turbines and Solar Photovoltaic Systems
• 22 Digital Electronics
• 23 Logic Circuits and Applications
• 24 Encoders and Decoders
• Glossary
• Appendix A: Internal Resistance of Batteries and Battery Aging
• Appendix B: Switches
• Appendix C: Special Transformers
• Appendix D: Mil and Circular Mil
• Appendix E: Standard Resistors
• Appendix F: Quality Factor of RLC Circuits
• Appendix G: Structure of Logic Gates
• Index