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.

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 everything the first time.

Most likely, you have some basic knowledge of certain facts about electricity because you use it at home and in your cell phone and other consumer electrical/electronic equipment, even though you may be hearing about direct current, alternating current, and many other terms for the first time. You should not worry about it, as things become clearer in a timely manner and at a gradual pace.

Initially, electricity is divided into two categories: electricity and static electricity. There are similarities and differences between the two. This book is mainly about the first category, the type that we can use and our life nowadays much depends on it. That is to say that we are so used to it that we probably cannot live without it.

Figure 1.2 One important aspect of electricity is its transportability.

The next section describes what static electricity is. The proportion of the size of this paragraph to the size of the book is more or less the same as the ratio between the applications and the importance of static electricity to electricity.

1.5 Static Electricity

Although there are a few applications of static electricity, compared to those we call electric devices (because they need electricity to work), the number is so much smaller. At the large scale, lightning is an example of static electricity, which is accompanied by thunder. It is a large instantaneous flash of light, called the lightning bolt, which occurs as a result of a sudden discharge of stored electrical energy. There is tremendous amount of energy released this way, but the unfortunate fact is that we cannot use this energy for useful application. There is no way of using this energy, which is released in a fraction of a second. It is too much energy in too little time.

At the smaller scale, most of us have experienced a small spark accompanied by a shock sometimes when we open the door of a car or a room. Experiencing this phenomenon depends on the material of the sole of the shoe we are wearing and the carpet or ground we walk on, as well as the amount of humidity in the air. Usually, this happens in dry air, and if we have rubber soles. The phenomenon is as a result of accumulation of electrons (electrons are one of the fundamental particles of all the material around us). This shock is exactly a small-scale representation of what happens with lightning in clouds.

Accumulation of electrons takes place when certain materials rub together, for example rubber and some plastics. In the case of lightning it is the clouds (air with water vapor) that move relative to each other. If the electrons find a path to move through, then the discharge occurs. But, if they do not find a path, the effect will appear in a different form. For example, things stick together because there is some attraction force created between the materials. For instance, you have often seen that the thin plastic wraps stick together and that it is not easy to separate them. Also, some surfaces collect dust more than others. This is due to static electricity, again created by rubbing two dissimilar materials together.

This latter phenomenon is used for certain purposes in industry. One good example is the photocopier machine, in which the very small particles of toner (the dry ink, which is black carbon powder) stick to the parts of paper that have been charged through the process. A hot cylinder then melts them to penetrate into the paper in the form of ink. A similar usage is in the manufacturing of sand paper.

A very common application is used for painting large pieces such as automobile body parts. In order to have a uniform layer of paint all over a part to be painted, the process is automated. In passing through a chamber the charged tiny paint droplets stick to the body of the moving piece that is to be painted. Similarly, in industrial stacks, to prevent dust and smoke from going up and polluting the atmosphere, they are absorbed by a body that has received static electricity and attracts the small pieces of carbon and dust when passing nearby.

All the above examples, including stack cleaning and air filtering are among the industrial application of static electricity.

1.6 Safety at Work and Safety Rules

We work for our living. Therefore work must not endanger our lives nor must it harm the workers, but accidents always happen. As a professional individual when working with electricity, we must avoid any unsafe conditions by following the safety rules. Something that one must always care for is “safety.” Every year all over the world in manufacturing sectors and service industries, a noticeable number of both fatal and nonfatal injuries happen for various reasons. Examples of these include falling, burning, getting crushed, and suffocating. The reason can be equipment failure, operator error, and negligence. Table 1.2 indicates the numbers of fatal electricity related injuries in all United States in 2010.

In all professions and in all industrial sites, there are many chances for something to go wrong, e.g. a machine breaks or some accident happens. But, a large percentage of accidents are due to lack of respect for safety rules and/or the lack of knowledge about what to do in case of an accident. It is everybody’s responsibility to minimize the risk of anything that can be harmful to oneself or others. For all this, safety rules are set by the authorities in each country. To minimize the risks of something harmful or dangerous, one must always follow the safety rules.

At this time we will not mention those safety rules that require technical terms, which we have not yet introduced. Nevertheless, safety rules are often commonsense rules. In other words, in many cases one knows the rule by recognizing what way is safe to carry out a task and what way is not. The important thing to have always in mind is to put safety first.

Electricity, despite all its advantages, comes with certain dangers, and in working with electricity, one has the risk of facing the contained, but invisible, danger in it. Learning about electricity will make you aware of these dangers. You will know about the risks and dangers, in the same way that you can visually judge the danger in a car coming toward you or a large rock that could start rolling down the hill.

As a first, common rule for safety, we can mention: if there is a potential for a hazard or failure of equipment, never take a risk. Working with faulty equipment is an example of taking a risk. One must always be sure about the reliability of the equipment. If we can put it as the next safety rule, if you are not sure, or if you do not know, ask; do not assume.

Live wires, or hot wires, can be dangerous. They can burn and kill. They may be quiet and what is inside them be invisible, but they can be lethal. Use precautions when working with electricity. Do not work on live wires unless you must and only if you are equipped with the knowledge and the proper equipment to do so.

In the United States, safety standards are set and monitored by Occupational Safety and Health Administration (OSHA). In Canada a branch of Canadian Standards Association (CSA) takes care of occupational health and safety (OHS) matters. Both OSHA and CSA develop occupational health and safety guidelines and procedures. These are well documented and can be purchased in printed or electronic forms.

Safety standards by OSHA, CSA, and their equivalent organizations in other countries, describe the detailed property of the equipment to use, the steps and/or procedures for testing equipment, and so on.

Because we have not yet discussed much about electricity and its terms, we continue the discussion here with only a few items:

1. Almost all electrical equipment is protected by a safety device that disconnects electricity. In the simplest form, this safety device is a fuse, which is a piece of wire that can melt upon getting very hot. A fuse is for the safety of equipment or apparatus. When something goes wrong, the wire in the fuse burns, or melts, and the device is no longer connected to electricity and in danger of being damaged. The piece of wire in a fuse is supposed to melt. A fuse can also protect an operator because if it does not disconnect a device from electricity, the danger of something going wrong is still there, no matter if the device is already damaged or not.

   Fuse: Protective device for an electric device or circuit consisting of a piece of wire that melts and disconnects the circuit if current surpasses a specific value.

   Understand the importance of a fuse, or a breaker, which does the same thing in a different way. A breaker has a mechanism that disconnects electricity, without melting a junction wire. It can be put back to work by pressing a button after the cause of the problem is removed. One must always use a fuse or breaker of the correct size. This is not the physical size; it is the rating of the fuse or breaker that must be considered. It is normally written on it.

   Breaker: Normally physical device that breaks an electric current and disconnects a device from electricity in order to protect it from damage.

2. For any job you may need the proper tools and the proper clothing. Do not try to do a job without being prepared, which implies having the proper tools and the clothing. Ornamental attachments to clothes, particularly metallic ones, and pieces hanging from them can cause problems; they can get in the way or get caught in a machine. Long hair is not an exception. Jewelry such as rings and sometimes even a watch should be taken off if they can cause a hazard.

   If you are carrying tools, again, you must carry them correctly and properly. For example, if you are climbing a ladder, you should not have everything you need in your hands but rather in a secure bag, so that your hands are free and the tools do not slip or pop out of your pocket or bag.

3. If there is a danger of falling (you or others), or any other type of danger, you need to put sufficient signs to alert people of the danger. If you are working inside a hole, you must make sure that people do not knowingly or unknowingly drop something on top of you. If working on a machine, make sure that you put adequate signs so that others can know what is going on so that nobody turns on the machine.

1.7 Chapter Summary

• Mankind needs energy for living, in the form of heating and cooling, cooking, and making things.
• Essential energy comes from fossil fuel (coal, oil, and gas), atomic power, hydro, wind, sun, and a few other renewable sources.
• Fossil fuel and atomic energy come from mining coal, oil, and the radioactive metals from the ground, but, one day these reserves will come to an end. The only remaining sources of energy then will be the ones that are cyclically renewed in nature.
• The origin of all renewable energy (except geothermal energy) can be considered to be the sun and to some extent the moon.
• Consumption of energy by humans is increasing every day.
• Electricity is a type of energy. It is relatively easy to transfer from one place to another.
• Wind turbines convert mechanical energy from wind to electrical energy.
• Solar cells convert the sun’s heat and light to electricity.
• Static electricity is a sort of electrical energy that cannot be stored and gradually consumed.
• Lightning is an example of static electricity.
• Static electricity can be put to useful applications in manufacturing sand paper, photocopy machines, filtering air, and industrial painting.
• Compared with other types of energy, electricity can be easily transported from one point to another.
• For any technical worker it is very important to understand the safety rules of his/her profession and follow those rules at work.
• A large number of accidents can be prevented if the safety rules are followed and if no risk is taken.

Review Questions

1. Why should we be concerned about energy?
2. Is electric energy the only type of energy we need?
3. If we have only electric energy (suppose sometime in the future), is it responsive to all our needs? Explain.
4. Presently, what are the sources of energy?
5. What is the advantage of electrical energy over other types?
6. How can we store electrical energy?
7. How can we store mechanical energy?
8. Why is safety so important?
9. Give a few examples of static electricity.
10. What are the main causes of accidents?
11. What is the difference between electricity and static electricity?
12. Is electricity dangerous? If so, in what ways?
13. Can static electricity be dangerous? Explain.
14. What does OSHA stand for?
15. What is OSHA?