Module Two: The Impact of Science on Society PDF

Module Two THE IMPACT OF SCIENCE ON SOCIETY FD12A 107 108 FD12A  Module 2 THE IMPACT OF SCIENCE ON SOCIETY INTRODUCTION In this module, we examine some of the...

Module Two THE IMPACT OF SCIENCE ON SOCIETY FD12A 107 108 FD12A  Module 2 THE IMPACT OF SCIENCE ON SOCIETY INTRODUCTION In this module, we examine some of the ways in which science impacts on today’s society – energy production and use, health and disease, information technology, and some aspects of biological and biotechnological research. You can probably think of few of your activities that do not depend on access to some form of energy, either directly or indirectly. In fact most of our daily activities at the individual and societal level involve energy in one form or another. All the important industries in the Caribbean require the use of considerable amounts of energy for their survival. At all levels of productivity reliable sources of energy are important. We therefore need to consider the implica- tions of high energy costs for the economic status of the region. The impact of these energy-based activities on the physical environment is also an area of concern. It is also true to say that an ability to feed its citizens and keep them in good health are basic requirements for the productivity and well-being of any society. To this end, research is pushing back the frontiers of knowledge of life itself, its conditions, and management. As we seek to understand and deal with the consequences of explor- ing the nature of life, ethical issues arise and must be considered carefully. FD12A 109  Information technology has influenced significantly the ways in which society organizes itself and communicates. The Caribbean is no exception. Each day we are brought into closer contact with the rest of the world via the Internet, cell phones and cable television. We cannot remain ignorant of the principles underlying information technology and its influence on how we conduct our lives. We hope that after considering these aspects of science, medicine, and technology, you will become more aware of how they affect our society, and seek answers to new and deeper questions than you have asked up to now. STRUCTURE The module is divided into six units: UNIT 1 Basic scientific concepts UNIT 2 Energy production and use UNIT 3 Health and disease in the Caribbean UNIT 4 Biotechnology and society UNIT 5 Information technology and society UNIT 6 Some ethical and gender issues Each unit is divided into sessions that cover different topics. A number of questions/concern/issues are raised, usually at the end of a session. These are intended to provide leads for private reflec- tion or for discussions in tutorials. Caribbean contributions are interwoven throughout the text. “Society” is to be interpreted to mean society in general, but Caribbean society in particular. OBJECTIVES On completion of this module, you should be able to: 1. Examine critically, through the use of selected examples, the contribution of energy availability and use, health and nutrition status, and biotechnological advances to the development of today’s society 110 FD12A  2. Evaluate the impact of information and communication technologies on today’s society 3. Discuss from an informed scientific and Caribbean perspective some of the major, current controversial issues in science, medicine, and technology 4. Comment knowledgeably on the Caribbean contribution to the fields of science, medicine, and technology 5. Comment on the impact of gender-related issues on science, medicine, and technology 6. Examine some of the ethical issues involved in present day scientific and biotechnological activity FD12A 111 112 FD12A  Unit 1 Basic Scientific Concepts: A very brief introduction Atomic structure and the structure of matter The way matter behaves, for example, the way one chemical reacts with another chemical suggests that all matter is made up of very small particles. The particles may be atoms, combinations of atoms called molecules, or electrically charged particles called ions. These particles are too small to be seen yet scientists have been able to deduce their structure, create models of how they are arranged in different substances, and predict how they will react, indicating that the models are fairly accurate. The fundamental particle of all matter is the atom. It is defined as the smallest part of an element that can exist and still have the properties of the elements. Examples of elements are carbon, hydro- gen, oxygen, iron, copper, sulphur, aluminum and so on. Atoms are made up of electrons (with one negative charge), protons (positively charged) and neutrons (no charge), sometimes called sub- atomic particles. The protons and the neutrons are found in the nucleus of the atom and the electrons are outside the nucleus and move around it. The atom was originally compared to the solar system with the nucleus as the sun and the electrons orbiting around it as the planets move around the sun. The number of elec- trons and their arrangement vary from one element to another. FD12A 113  Figure 1.1 The helium atom The oxygen atom Key: p – protons, n – neutrons, x – electrons Note that the number of protons (and neutrons) in the nucleus is always the same as the number of electrons in the outer ring so they are balanced (negative and positive charges cancel). Sometimes elec- trons escape from the outer ring or an additional electron enters the atom. The result is a positively or negatively charged particle called an ion. Atoms use their outer shells to form bonds. These bonds are of different kinds. What is important is that they hold different atoms together to form combinations of atoms which are referred to as molecules. For example, sodium atoms and chloride atoms are bonded together in sodium chloride, which is common salt. The way in which bonds are formed, the number of atoms, and how they are arranged contribute to the properties of different compounds. Like atoms, these bonds cannot be seen. Scientists use models to show how they imagine the atoms and bonds are arranged in molecules. Figure 1.2 The sulphur molecule 114 FD12A  Small molecules can combine to form much larger molecules. Many of the molecules found in living organisms are giant molecules (e.g. proteins) that are built up from smaller units (e.g. amino acids) into which they can be broken down again. Appropriate enzymes (specialised protein molecules) control the building up and breaking down processes. (More on enzymes later.) Figure 1.3 A model of a large protein molecule Nuclear energy The nucleus of an atom is held together by a lot of energy. For its tiny size a nucleus contains so much energy that it forms a notice- able percentage of the mass of the nucleus as a whole. Some elements have more energy in their nuclei than others. When a very large nucleus, held together by a large quantity of energy, splits into smaller fragments, some mass is lost and a corresponding amount of energy is released. A chain reaction is set off causing more and more nuclei to split. The energy appears as the kinetic energy of the frag- ments and when these rapidly moving fragments collide, thermal energy is produced. Early atom bombs depended on this type of chain reaction to release energy from all the nuclei at once. Nuclear power stations do not explode because controls are placed on the chain reaction so that fission (the splitting of the atoms) takes place much more slowly in an orderly fashion. FD12A 115  Electricity Electricity is a form of energy resulting from the existence of charged particles e.g. electrons, protons etc. An electric current is a flow of charge. The rate of flow of the electric charge is measured in amperes. Household appliances such as electric kettles run on a few amperes. Batteries in appliances such as a flashlight work by allowing a flow of current through the bulb and back to the battery. When the light is switched off the flow of charge stops. A volt is the force that causes the current to flow at a particular rate (it can be compared to the way a pump forces water to flow along a pipe). The battery pumps the charge around the flashlight; different batteries have different voltages. The batteries used in some pocket radios and small flashlights have a pumping force of 1.5 volts. A car battery supplies 12 volts of pumping force to get a car started. The size of the current that a battery will pump round a circuit depends on the voltage of the battery and the conductor along which the charge must flow. All metals will conduct electricity. Some metals are better conduc- tors than others. Some substances, e.g. rubber and wood, do not conduct electricity at all. Semi-conductors are substances that have conducting properties somewhere between conductors and non- conductors i.e. they are fairly good conductors under certain condi- tions. A generator is a machine that can convert mechanical energy into electrical energy. In the generator, an electric current is created when wires are moved through a magnetic field. A turbine is an engine that drives the generator. Turbines can be driven by wind, steam, water or diesel power. Nuclear power is used to produce the steam in some power stations. 116 FD12A  Figure 1.4: Energy conversions in a power station Source: Lambert and Mohammed, Chemistry for CXC Microscopes and cells Cells are the basic structural and functional units of living things. They are the building blocks of which the tissues and organs of most organisms are made. Bacteria, protozoa, and yeasts are single- celled organisms; most other organisms are multi-cellular i.e. made up of many cells. Cells become differentiated to perform different functions. These specialised cells vary in structure to suit their func- tions so there is really no such thing as a typical cell. However all cells share certain characteristics. Cells also vary considerably in size but the size of an “average” cell could be about one fiftieth of a millimetre (or 20 microns). Individual cells were first seen in 1655 by Robert Hooke, who was not only a biologist but an excellent technician, when he built the first microscope. As lenses improved so did the early microscopes and in 1849 the notion that all living things were made up of cells was put forward as the cell theory. The simple light microscopes used in schools magnify objects up to 400 times their normal size. A good light microscope can magnify objects effectively about 1500 times. “Typical” plant and animal cells are shown below as they appear under a light microscope. FD12A 117  Figure 1.5 Diagram of an animal cell Diagram of a plant cell For many years, cell biology was limited by what could be seen using light microscopes and what was seen was assumed to be all there was to the structure of cells. With the invention of the elec- tron microscope in the 1950s the cell was revealed to contain much more than was visible before. This had a great impact not only on knowledge of cell structure but on how cells functioned. Electron microscopes revolutionised cell biology. They can magnify objects 500,000 times. (An object the size of the full-stop at the end of this sentence would be enlarged to a diameter of over 1 kilometre!) One limitation of using an electron microscope is that specimens must be mounted in a vacuum and are therefore dead. Other treat- ments to prepare the specimen may create distortions called arte- facts that may not be present in the living specimen. Some of these problems have now been overcome by using improved types of elec- tron microscopy. Figure 1.6 Diagram of an animal cell as seen under an electron microscope 118 FD12A  Enzymes Enzymes are biological catalysts. They control the rate at which reactions take place in living cells. Enzymes control the functioning of cells and therefore the functioning of whole organisms. Enzymes are protein molecules that, until very recently, are made only by living organisms. There are many different kinds of enzymes with different functions. Some are responsible for releasing energy from the food we eat after it goes to the cells, others break down the food in our mouth, stomach, and intestines so that it can be absorbed by our bodies. Some enzymes can convert the waste products from the activities of cells into useful products and it is enzymes that destroy cells when they are old and worn out so they can be replaced by new cells. One of the remarkable properties of enzymes is their specificity. Each type of enzyme will only work on one particular reaction or type of reaction. They are also specific in that different enzymes work under different conditions. For example, the enzymes that work in the stomach work in very acid conditions while those that work in the mouth work best in nearly neutral conditions. Lower in the intestines there are enzymes that will work only in very alkaline conditions. All the enzymes in the human body work best at temperatures close to our normal body temperature but the enzymes in an arctic fish can function at much lower temperatures. Very high fevers are dangerous because they destroy the body’s enzymes and stop the functions they control. Genes control the production of enzymes and by so doing, control what cells make and how they function. It is now possible to use genetic engineering techniques to create microorganisms that produce enzymes they do not normally make. In some cases more than one gene is inserted into the same organism so that it produces a variety of enzymes. For example, the microorganisms that secrete the enzymes found in washing powder carry genes for making the enzymes that break down various proteins as well as fats. In this way they can get rid of a wide range of stains. Enzyme technology, as this branch of biotechnology is called is now very important commercially. FD12A 119  REFERENCES Avison, John H. Physics for CXC. Surrey: Thomas Nelson and Sons, 1998. Jackson, Barry and Whiteley, Peter. CXC Physics. Harlow: Addison, Wesley, Longman, 1996. Lambert, Norman and Mohammed, Marine. Chemistry for CXC. Oxford: Heinemann, 1993. Thompson, Della (ed.). The Concise Oxford Dictionary. Oxford: Clarendon Press, 1995. 120 FD12A  Unit 2 Energy Production and Use INTRODUCTION We use the words “work” and “energy” very often in our everyday conversations. When scientists talk about work or energy they may not mean the same things that you understand these terms to mean. When you push a book along a table, for a scientist you would have done work. In the everyday usage of the word, such an activity would hardly be counted as real work! In science, these words have meanings that are more specific than their everyday meanings. For example, we say that we do work when we exert a force and also move a distance while exerting that force. To do “work”, no matter how light, you need energy; everything we do in our domestic lives and in our industrial pursuits requires energy. Without energy, there would be no life, no work, and no industrial activity. Humans and all other living things produce energy in their bodies during the process of tissue respiration when food (fuel) is oxidized (“burnt”) in each cell. The energy needed for many machines to do work is produced when fuel is burned in the engine. Energy then is the ability to do work. When you think about it carefully, this definition is perhaps not so far removed from the common usage. FD12A 121  In this unit, we focus on the various forms and sources of energy and we explore the production and use of energy, with particular emphasis on industrial activity in the Caribbean. OVERVIEW This unit has three sessions. The first session – What is energy? – explores the concept of energy and looks at the forms and sources of energy. In the second session – Energy production – we examine in depth how energy is made available from fossil fuels, our traditional source of energy. We also consider the worldwide demand for energy and we discuss newer energy technologies that are developing. In the final session – Industries in the Caribbean – we look at the production and/or use of energy in the petroleum/petro-chemical industry, the sugar industry, the mining of bauxite, and tourism. Throughout the unit, we consider the economic and environmental implications of energy-based activity and the need for conservation of energy. LEARNING OBJECTIVES After completing this unit you should be able to: 1. Explain the concept of energy 2. Explain the difference between renewable and non-renewable sources of energy 3. Discuss the critical role of energy in human activity 4. Describe traditional and “alternative” sources of energy 5. Discuss the advantages and disadvantages of using different sources of energy in the context of modern demands for energy 6. Describe some major Caribbean industrial activities and their energy requirements 7. Discuss the impact of energy-based activity on the environment 8. Explain why conserving energy is of particular importance for Caribbean people 122 FD12A  FOR THE STUDENT While it is important for you to understand what the various indus- trial processes entail, you need not memorize the details of these processes. READINGS l The Pros and Cons of Nuclear Energy. http://members.tripod.com/funk_phenomenon/nuclear/procon.htm l Pros and Cons of Nuclear Generation. http://ess.geology.ufl.edu/ess/Labs/TermPapersFall99-00/Cavanaugh/Pr l Sources of energy and electricity: Cleaner and greener. A program of Leonardo Acacemy Inc. http://www.cleanerandgreener.org/schools/energysources.htm l Buarque de Hollanda, Jayme and Alan Douglas Poole. Sugar cane as an energy source in Brazil Instituto Nacional de Efficiena Energetica. http://www.inee.org.br [email protected] l Learning about renewable energy. Consumer energy information. EREC Fact Sheets US Department of Energy. htpp://www.eren.doe.gov/erec/factsheets/rnwebergy.html l Environmental initiatives in the hotels industry: A case study of the Park Royal on St Kilda Road. l EnviroNET Australia. http://www.environment.gov.au/net/environet.html l Gerston, Jan. Hotels strive for water use efficiency. Texas Water Resources Institute. http://twri.tamu.edu/twripubs/WtrSavrs/v3nl/article- 4.html l Information on oil spills. Oil spills in history. http://response.restoration.noaa.gov/faqs/history.html l Largest oil spills. http://library.thinkquest.org/26026/Statistics/largest_oil_spills.html l An introduction to some basic scientific concepts. FD12A 123 124 FD12A  Session 2.1 What is Energy? Forms of energy Work is done when a force causes a stationary body to move, or a moving body to come to a stop. As we said earlier, energy is needed to do work. The amount of work required is determined by the magnitude of the force and the distance moved, but is independent of the speed of movement. Thus, to lift a 1 kg brick 1 meter high a given amount of work has to be done. This amount is equal to the product of the weight and distance moved. Energy is needed to do this work. Energy exists in many different forms. One method of classifying energy lists the following forms: l Kinetic energy l Potential energy l Thermal energy l Nuclear energy Kinetic energy This is the energy of a body due to its mass and speed of movement. The faster a body moves, the more kinetic energy it possesses. When water is heated and it turns into steam, the steam particles possess a lot of kinetic energy because they move rapidly. As the particles of steam are moving rapidly they occupy more space, that is, there is a large change in volume. Steam does not stay in a kettle because it cannot be contained inside it. What would happen if the kettle had no way for the steam to escape? In a closed container, the pressure will build up enormously. The energy of the steam can be used to move things. In other words, steam can be used to do work. For example, steam can provide the energy to do work in turbines. FD12A 125  Potential energy On the everyday, macroscopic scale potential energy is that which a body possesses because of its mass and its position relative to the centre of the earth (actually the centre of gravity of the earth). When the 1 kg brick in the example above is lifted 1 meter, the work done to raise the brick increases the potential energy of the brick. The larger the brick and/or the higher it is, the greater its potential energy. If the brick falls, its potential energy is converted into kinetic energy as it moves and this is manifested by its speed of movement. ACTIVITY (a) Which brick has the greater potential energy? (b) Which brick will show the greater kinetic energy as it falls? Common sense will tell you which brick will fall faster or do the most damage or hit you with the greatest force. Only the terms are new. Water cascading down a waterfall possesses potential energy due to its position and kinetic energy due to its movement as it falls. This is the source of energy used in hydroelectric power stations. Chemical substances also possess stored potential energy. This is referred to as chemical energy. During the combustion of fuels, the 126 FD12A  chemical bonds in the molecules of the fuels are broken, a reaction takes place, and new products are formed. Heat energy is released in the process and this heat energy can be used to do work. n Find out more We can see from the discussion above that work and energy, meas- about atoms, ured in joules, are interconvertible and can exist in different forms. molecules and chemical bonds, if For a long time an important physical law was that energy can you do not know neither be created nor destroyed (but it could be converted from one about them already. form to another). This is called the law of conservation of energy. Thermal energy Everyone in the Caribbean is very familiar with the heating effect of the sun. Heat is the result of the transfer of thermal energy from one object to another. Solar thermal energy (often referred to simply as “solar energy”) is heat energy obtained by exposing a collecting device to the rays of the sun. The process of harnessing the sun’s thermal energy will be explored in detail later in the unit. There is also geothermal energy. This refers to energy emanating from the hot interior of the earth. This is particularly noticeable in areas of high volcanic activity such as the sulphur springs in St Lucia, Dominica, and Montserrat. At these sites, the geothermal energy converts underground water into steam which is emitted from vents in the earth’s surface, along with sulphur, oxides of sulphur, and other materials. In Guadeloupe, steam generated with geothermal energy is made to turn turbines to produce electricity. Nuclear energy Another form of energy that you have probably heard a lot about is nuclear energy. This refers to energy associated with the nuclei of atoms. Atomic nuclei are made up of positively charged particles (protons) and neutrons pressed together into an extremely small space. If you have ever tried to push the like poles of two magnets together, you will have noted that they repel each other more strongly as they get closer. It takes vast amounts of work to push the protons and neutrons together, consequently the energy required to hold these nuclear components together is also enor- mous. The greater the energy required to hold the constituents of the nucleus together, the smaller the mass becomes. This what is shown in Einstein’s famous equation: E = mc2 FD12A 127 n Light travels at In moving the brick up against gravity, the work was stored as ~3x10 to the 8th m/s potential energy, which could be released when the brick fell. (186,000 miles per second). In view of Similarly, a vast amount of energy is released when nuclei of certain the very large value elements such as uranium are split. One kilogram of uranium of c, (the speed of light in a vacuum), releases more energy than the burning of 3 million kilograms of coal. even a minute The energy is emitted in the form of heat and light. The process is amount of mass (m) is equivalent to called nuclear fission. Energy from nuclear fission can be harnessed enormous amounts to produce electricity. If the nuclear fission process is uncontrolled, of energy (E). So much then for the an atomic bomb results and there is an enormous and powerful law mentioned above explosion. – energy can be created from matter and vice versa. We At the start of the section, it was noted that work depended only on must therefore the distance through which a force moved, and not the speed of the reformulate the law in terms of the movement. However, to lift the brick rapidly clearly demands more conservation of than to lift it slowly. This aspect of activity – the rate of doing work mass-energy. or of expending energy, is referred to as power. Since work (or energy) is measured in joules, power is measured in joules per second or watts (W). A kilowatt (kW) is simply 1,000 watts. Most of our devices today use energy in the form of electrical energy. This is a form of potential energy. Bulk sources of energy (rivers, petroleum or coal burners or nuclear reactors) are converted into electrical energy for general distribution. In our automobiles, the energy source comes from burning gasoline. Some of the energy is converted into mechanical energy (turning the crankshaft) and some into electrical energy (through the spinning of the dynamo or n Find out what the term voltage means. alternator) to run the lights and other devices, directly or after stor- age in the battery. Sources of Energy The human species consumes energy at an alarming rate. Our pres- ent, and no doubt future, lifestyles demand energy for all our activi- ties. Where is all this energy to come from? Is there enough to satisfy the needs of a hungry world? What are the sources of energy on which we can call when necessary? Energy sources can be classified into two main groups – non- renewable sources and renewable sources. As the name suggests, once non-renewable sources have been used, they cannot be 128 FD12A  replaced. Examples of non-renewable sources of energy are crude oil, natural gas (crude oil and natural gas are collectively referred to as petroleum), and coal. They are reservoirs of fuel slowly produced over millennia by the action of heat and pressure on organic matter in low-oxygen environments. This is no longer taking place because present conditions are not appropriate. In any event, this process takes so long (millions of years), that it could not keep up with our present demand for energy. (We will go into this in more detail in the next session). Renewable sources of energy are always available to us. The sun, the wind (which to a great extent depends upon the heating effects of the sun) and the ocean are examples of renewable resources that are sources of energy. The sun’s energy can be used without fear of depleting the source. The sun will come up tomorrow (at least within the normal human horizon of thinking). If we use the wind to drive windmills, to grind sugar cane, this will not (we think) cause us to run out of wind. Ocean tides, (caused by the gravita- tional influences of the moon and sun) and temperature differences (caused by the differential heating by the sun), can also serve as energy sources which appear not to be readily depleted, hence renew- able. The issues of dwindling supplies of non-renewable energy and our ability to harness renewable sources of energy in useable quantities are of great concern. CRITICAL THINKING ACTIVITY Wood is a renewable source of energy that has been used by humans since they discovered how to make fire. Plant material can be said to store the energy of sunlight. 1. What are the implications of relying on wood as our only source of energy? 2. Do you think the controlled use of plant material should be considered as a source of energy for the future? FD12A 129  QUICK REVIEW n Forms of energy: kinetic, potential, thermal, nuclear n Sources of energy: crude oil, natural gas, coal, sun, wind, ocean tides DO YOU REMEMBER? n Write down the meanings of the following terms then go back and check to see how many you got right. Energy Kinetic energy Potential energy Nuclear energy Chemical energy Geothermal energy Power Joules Watts Non-renewable energy source Renewable energy source 130 FD12A Session 2.2 Energy Production Harnessing fossil fuels Petroleum is called a fossil fuel. It is formed from decomposed plant and animal matter, trapped by rocks and buried deep under the earth’s surface. Over very long periods of time, this decomposed organic material may be converted into crude oil (hereafter referred to as “oil”) and natural gas because of the intense pressure and heat present in the rock formations within the earth. The oil and gas move through the rocks towards the earth’s surface. However, more often than not, they do not reach the surface itself and are trapped between layers of rocks. Drilling must be done to reach the trapped oil and gas which is then pumped to the surface. Oil is a complex mixture of several substances that are called hydro- carbons because their molecules contain carbon and hydrogen only. This complex mixture is separated into a set of simpler mixtures in oil refineries in a process called fractional distillation. Figure 2.1: Diagram of a fractionating column Fractionating columns used in oil distilleries consist of steel towers that may be up to 60m in height. At intervals along the height, are trays with holes. As the columns are hot at the base but cooler near the top, each tray is cooler than the one below it. Crude oil is heated in a furnace and then passed into the lower part of the column. When the raw material enters the column, most of the fractions of the oil are already in the form of a gas. The mixture of gases rises rapidly up the column. When each gas reaches a tray where the temperature is slightly below its own boiling point, it condenses to a liquid on the tray. The fractions are drawn off their respective trays by pipes and piped to separate storage containers. The most volatile gases i.e. those with the lowest boiling point, come off at the top e.g. methane, the least volatile fall to the bottom. FD12A 131  Table 2.1 shows some of the uses to which these hydrocarbon frac- tions are put. Table 2.1 Petroleum fractions and their uses* Fraction Boiling Point Molecular Typical uses (oC) size Gas –164 to 30 C1 – C4 Heating, Cooking Gasoline 30 to 200 C5 – C12 Motor fuel Kerosene 175 to 275 C12 – C16 Fuel for stoves, diesel & jet engines Heating oil Up to 375 C15 – C18 Furnace oil (for heating homes) Lubricating oils 350 and up C16 – C20 Lubrication, mineral oil Greases Semi-solid C18 – Up Lubrication, petroleum jelly Paraffin wax Melts at 52 – 57 C20 – Up Candles, toiletries Pitch & tar Residue in boiler High Roofing, asphalt paving *Molecular size is indicated by the number of carbon atoms in the molecules found in each fraction. Adapted from Seager, S.L. and M.R. Slabaugh. Chemistry for Today. Brooks/Cole Publishing Co., USA, 1997. Commercially distributed natural gas consists mainly of the gas methane, which is the simplest hydrocarbon. However, natural gas obtained in the fields may contain other hydrocarbons, moisture and other contaminants. It must, therefore, be processed before being distributed. Because of its gaseous state, natural gas is not as easily distributed as oil. It can be pumped to users along pipelines. When it is cooled below –164oC it changes state and becomes a liquid that is called Liquid Natural Gas (LNG). This is stored in large, double-walled, insulated tanks. Compressed Natural Gas (CNG) is natural gas that has been pressurized and stored in tanks. Harnessing and transporting natural gas can be expensive. Sometimes, it is cheaper for the natural gas produced in oil fields to be “flared” instead of being harnessed. The gases are simply allowed to burn off in the open air. This practice is rarely seen again, the 132 FD12A  value of natural gas having increased considerably as oil supplies decrease and oil prices go up. Flaring can contribute to the green- house effect as it releases large quantities of carbon dioxide into the atmosphere (see Module 1 Unit 1). Coal is also a fossil fuel but it consists mainly of carbon. It is formed out of plant material that accumulated at the bottom of swamps many, many years ago. Over time, the organic material at the bottom of swamps was compacted by the weight of sand, clay and other debris on top of it and was transformed into coal. Supplies of coal are found at considerable depths below the surface of the earth. It is still mined mainly by human effort. This is a tedious and often dangerous venture as coal is sometimes found along with pockets of combustible gases such as methane that can cause explosions. In times past, coal was a more important source of energy. It was used as a fuel mainly for heating and cooking, and in steamships and trains. In many industrialised countries it has been replaced for these purposes by oil and natural gas. However, coal continues to be used in large quantities for generating electricity in a number of industrialised countries such as Canada and the USA. It is estimated that more than 55% of all electricity generated in the USA is still generated in coal-fired power plants (American Coal Foundation). Now that oil reserves are decreasing, there is renewed interest in coal as a fuel. Releasing energy from fossil fuels It is quite clear that for the time being we will remain largely dependent on fossil fuels as our main source of energy. Until alterna- tive sources are widely available generating energy from what is now available is an important concern because of economic and environmental implications. We now turn to how the energy trapped in fossil fuels is released in useable forms and used to gener- ate energy. Both oil and natural gas consist of hydrocarbons. When these hydro- carbons burn (the reaction is called a combustion reaction), poten- FD12A 133  tial energy stored in these chemical compounds is transformed into heat energy which is released and can be used to do various kinds of work. The reaction can be represented as follows: HYDROCARBON + OXYGEN à CARBON DIOXIDE + STEAM + HEAT ENERGY The reaction above represents what happens when there is complete combustion of the hydrocarbon. If the combustion is incomplete, some carbon monoxide is formed, as well as particles of carbon. Carbon monoxide is a poisonous gas, carbon dioxide is known to contribute to the greenhouse effect and particles of carbon in the air can contribute to respiratory ailments. In addition, because these fuels usually contain some impurities such as sulphur, other prod- ucts (such as the oxides of sulphur) are also formed during the reac- tion contributing to acid rain. In the case of gasoline, which is used in motor vehicles, a compound of lead is sometimes added to improve the engine’s performance (see Module 1, Unit 1). The downside of this is that when the gasoline burns in the engine, lead compounds, which are converted to lead oxide, are released into the atmosphere. This is dangerous when inhaled. Natural gas is considered to be a cleaner fuel than gasoline because it produces less carbon monoxide and carbon when it burns. For this and other reasons, CNG is now being marketed as a fuel to replace gasoline in motor vehicles. However, methane (of which natural gas is mainly composed), is considered to be a more detrimental green- house gas than carbon dioxide so natural gas leaks can have serious negative effects on the environment. When coal burns, carbon dioxide is the main product and heat is released. The reaction is as follows: CARBON + OXYGEN à CARBON DIOXIDE + HEAT ENERGY However, because of incomplete combustion and impurities in the coal, carbon monoxide, oxides of sulphur, oxides of nitrogen, and other materials are also released into the atmosphere. As indicated earlier, all of these products contribute to the pollution of the envi- ronment. It is estimated that the burning of coal is responsible for 30–40 % of the world’s carbon dioxide emission. 134 FD12A  In the Caribbean, what we refer to as “coal” is really charcoal. Charcoal is still produced in some of the rural areas by burning wood under low oxygen conditions. This is the source of most of the coal used in the Caribbean. The process consists of laying branches and tree trunks in specified n In addition to burning charcoal, ways in a shallow pit dug in the earth. The wood is covered with there is much leaves and then soil. Holes are created in the mound to allow for the burning of vegetation in clearing land in the flow of a limited supply of air. The mound is then lit and incom- Caribbean. plete combustion of the wood occurs, producing charcoal. Charcoal Are there feasible alternatives to these is still used as a fuel for domestic purposes in some areas. It has practices, which polluting effects similar to those described for coal. Furthermore, the release carbon dioxide into the practice of cutting down trees for fuel without replanting can lead atmosphere? to deforestation and consequent negative impacts on the environ- ment. The demand for energy – matters of concern How much do we need? The demand for energy has been increasing rapidly worldwide. It has been estimated that the demand has increased by 32% between 1980 and 1998. What is striking about this is that, whereas the increase in demand in industrialised countries such as the USA seems to be slowing down somewhat, the demand is increasing in some developing countries with increasing opportunities for indus- trial activity and high population growth rates (hence, increasing consumer consumption rates). Figure 2.2 r as Increase in Energy Demand by Region 1980–1998 ange ne e Figure 2.2 illustrates the increase in demand rates on a global level. Far East Africa There are some complicating factors Middle East associated with the increased energy Eastern Europe demand at the global level. One factor is Western Europe that much of the world’s energy supply Central & South America is provided by fossil fuels. In 1999, 39.4% North America of the world’s energy was derived from -20% 0 20% 40% 60% 80% 100% 120% oil, 23.0% from dry natural gas and Change in Energy Use 22.3% from coal. In the Caribbean, oil is For further information see: the main fuel used. In 1999, 90% of all www.whole-systems.org/oil.html FD12A 135  energy needs in the region were met by the use of oil, and most of it was imported. Only Barbados, Trinidad and Tobago, and Cuba have crude oil and natural gas reserves. Is there enough? The problem is that fossil fuels are a non-renewable source of energy. Early estimates predicted that during the period 1965 – 2025, we would have used up 80% of the world’s supply of oil. It had also been projected that it was unlikely that very large oil reserves would be discovered in the future. In short, the message is that the world’s supply of oil is running out; of course it always is, but not as soon as predicted at that time. In 2001 the British Ministry of Defence said, “Reserves of fossil fuels are not expected to be nearing exhaustion by 2030, or for some time thereafter…” The discovery of new and unexpected sources of oil has allayed fears somewhat. More oil is now available than could have been expected twenty years ago. It seems that prospecting efforts intensify whenever the threat of depletion looms large. In addition, energy security is crucial for countries like America, which is at present desperate to secure a safe and continuing supply. Although they use the largest proportion of the world’s oil and gas, comparatively little of it is to be found in their own country. The Department of Energy estimates are as follows: Production of crude oil 7.8 million barrels per day (MMbd) Imports of crude oil and refined products 9.6 MMbd Consumption 19.4 MMbd (26% world total in 1998) Dependence on foreign oil 50% Share from OPEC 43% American companies do have major interests in a large proportion of the oil fields of the world but these may not always remain accessi- ble to them at prices they can afford. This has acted as an incentive to find new sources of oil and gas. Clearly the ability to find new sources varies with need but there is no doubt that those of us who survive until the middle of the 2000s 136 FD12A  will be dependent on energy sources other than oil and gas. Oil giants, such as Shell and BP, are already positioning themselves to become less oil-bound, and to become instead energy giants. By developing more efficient alternative sources of energy such as hydrogen fuel cells and photovoltaics they expect to reduce their oil dependency. When such environmentally friendly fuel sources become more cost effective as fuels for automobiles, oil usage should plummet, and the threat or impact of “running out” will be reduced. The whole scenario is very complex and interesting. Concerned students can find more information in the following article: “The end of cheap oil” by Colin J. Campbell and Jean H. Laherrere, Scientific American, March 1998. Can we afford fossil fuels? A second factor has to do with the cost of oil and its impact on developing countries. Oil prices have been rising steadily for the last 10 years. Like most developing countries we are net importers of fossil fuels and related products. The relatively high cost of these commodities puts a very heavy strain on national budgets and drains our very limited foreign exchange reserves. Even in an oil-producing country such as Trinidad where petrol used to be very cheap, fuel costs have risen considerably over the last ten years. (Oil was previously subsidised by the government who can no longer afford to do that. Consumers now pay the market price.) In addition to what is listed as the going price of oil, most other countries have to pay the additional cost of transport. The problem we face in the Caribbean and other developing countries is how to push development without using more and more energy. The more we spend on energy the less there is to spend on other important developmental aspects of the economy. We will consider some alter- natives later. Environmental concerns Yet another important factor is the effect of on the environment using fossil fuels. The two main problems are oil spills and air pollu- tion. In countries that produce and/or refine oil, there is the poten- tial for oil spills and leaking gas lines. The October 2001 oil spill in the Point Fortin community in South Trinidad, resulting from the blow-up of an oil well, is an example of the negative environmental FD12A 137 WORST OIL SPILLS impact that such activity can have. There was widespread damage (millions of gallons) to crops and animals, and dislocation of nearby communities. Oil 1980 Mexico 428 spills that take place at sea are an even greater threat to the environ- 1983 Per. Gulf 185 ment. 1983 S. Africa 80 1978 France 76 1979 Tobago 50 In addition, as described above, the products of the combustion of 1981 Libya 42 fuels such as gasoline (i.e. sulphur dioxide, oxides of nitrogen, 1979 Barbados 41 carbon dioxide) contribute significantly to the production of acid Source: rain, and increase the likelihood of significant global warming with Coping with an Oiled Sea. U.S. Congress, all their negative consequences. Office of Technology Assessment (1990) In highly industrialised countries, there are environmental laws and policies that are designed to minimise the incidence of environmen- tal degradation from these sources. Despite this they remain the greatest contributors to air pollution. In the Caribbean, the threat to the environment persists for different reasons. Some environmental protection laws are on the books but are not policed. In others, these laws and policies are only now being operationalised. (See Module 1, Unit 1 for a discussion of the Kyoto protocol.) Because of these and other factors, there has been a concerted effort worldwide towards the reduction of the dependence on fossil fuels and the development of alternative sources of energy. ? ? CRITICAL THINKING ACTIVITY What are the major factors of concern that have led to the search for alternative sources of energy? Of the following, which one do you consider the most influen- tial factor: increased demand for fossil fuels, decreasing supplies of fossil fuels, increasing cost of fossil fuels, environ- mental concerns? Give reasons for your opinion. 138 FD12A  Session 2.3 Meeting Our Energy Needs: Alternative Sources Reducing dependence on fossil fuels Did you know that it is possible to make clean energy from manure? Scientists are exploring the possibilities latent in all sorts of materials. Petroleum can be produced from some garbage and they are investigating the feasibility of converting old car tires back into oil and of using oils from various plants. The truth is any material that can burn is a potential source of energy, similarly, anything that moves can become a source of energy. The trick is to produce energy from them in sufficient quantities at a commercially reason- able cost. Much of the thrust in developing new energy technologies is centred on the use of renewable sources of energy. We will now explore three possibilities of particular interest to the Caribbean, solar energy, wind energy, and ocean thermal energy. Solar energy Solar energy technology makes use of energy from the sun. This is, perhaps, the alternative energy technology that has been most researched in the Caribbean. The late Professor Oliver Headley of the Cave Hill campus of The University of the West Indies pioneered research and development in this area. One of the major attractions of solar energy technology for us in the Caribbean is that we have no shortage of sunlight. It has been calculated that the solar energy received on one of our islands on a bright, sunny day is more than a year’s petroleum imports! Another attraction of solar energy technology is that it does not impact negatively on the envi- ronment (at least not directly – problems with batteries, their production and disposal, come later). In addition, once the initial installation costs are met solar energy is relatively cheap; some might call it free. We shall explore three applications of this technol- ogy – solar water heating, solar drying, and photovoltaic power. FD12A 139  In most common solar water heaters, the sun’s rays fall on a collecting device called a flat plate collector. Water pipes are attached to this collector plate. The whole unit is contained in an insulated box covered with glass. As the collector plate becomes heated, the water flowing through the pipes also becomes heated and this hot water is made to flow into the same type of insulated storage tanks that come with elec- tric heaters. These tanks hold more than enough hot water to serve a household even when the sun is not shining. Some Figure 2.3 tanks also have a back-up electrical system but in our part of the A standard 4 square meter, 300 world this is hardly necessary. litre domestic, flat- plate solar water The solar water heater industry in Barbados was started in the heater in Jamaica. 1970s by two private companies (Headley, 1995). The government Solar Dynamics is of Barbados has encouraged the expansion of the industry by the largest Caribbean solar providing income tax incentives for citizens who invest in solar water heater water heaters. By 1995, about 30% of households in Barbados had manufacturer. solar water heaters installed. It has also proved a boon for the hotel (Courtesy of O. industry; most hotels and guest-houses use solar powered water Headley) heaters. Though the initial cost of installation may be considered high, it is reported that the savings generated in the long-term are substantial. The technology is not as widespread in other Caribbean countries. The use of the sun’s energy for solar drying is not new to the Caribbean or, indeed, to many parts of the world. Over the years, solar drying has been used in rural areas of the Caribbean with agri- cultural products such as cocoa, meat, fish, and pimento (allspice) berries and other plant materials. The scientific process in all types of dryers is the removal of moisture in the materials by vaporisa- tion. The procedure is simple – the material to be dried is simply laid out on sheets in the sun. Sometimes, sheets of galvanised iron are used. This material heats up very quickly in the sun, as anyone who has had to fix a galvanised roof knows only too well! The purpose of removing moisture is to preserve produce and prevent spoilage. Micro-organisms, for example, bacteria and fungi which cause spoilage, tend to grow rapidly in a moist medium. Drying produce when it is in abundance preserves it for long peri- ods, reducing gluts and shortages. One drawback of the old method 140 FD12A  was the risk of rain wetting the produce as some crops took weeks to dry. Within recent times, the technology has been refined and solar dryers have been constructed and used for drying plant and animal material, including those identified above. Much research on solar dryers has been carried out by scientists at the University of the West Indies, beginning in 1972 at the St Augustine campus. Dryers are now used with crops such as sorrel, bananas, papaya, yam, sweet potato, ginger, nutmeg, herbs, and timber. The drying temper- ature in these dryers ranges from 40oC to 65oC and the drying times are much reduced, ranging from 15–25 hours. The simplest form of solar dryer is a wire basket. The basket is made of a wooden frame with the sides and bottom made of wire. The top is covered with plastic. Air flows freely through the basket and this aids in the drying process. These are affordable even for small or subsistence farmers. More complex dryers are available in the form of cabinets. A somewhat different use of solar energy is in the production of electricity from sunlight using photovoltaic cells (photo = light; voltaic = electricity). These cells convert sunlight directly into electricity. Unlike the case with other systems for producing electricity (described in more detail later in the Unit) photovoltaic cells do not involve Figure 2.4 moving parts such as turbines. This means that the maintenance This 11,100 watt costs are likely to be lower. solar photovoltaic panel on the roof of the Skeete's Bay A photovoltaic module (or “panel” as they are commonly called) is Fishing Complex, made up of many cells that are typically made of the element sili- Barbados, con, which is a semi-conductor. A semi-conductor is a material powering a 1- that is neither a very good conductor of electricity nor a very bad tonne-per-day icemaker for the conductor. It has the useful property that its ability to conduct can fisherfolk, has been be altered and controlled by adding small amounts of other operating since substances to it. Simply put, when sunlight hits these cells, some of April 2001. the energy is absorbed and transferred to the semi-conductor. This (Courtesy of Prof. Oliver Headley.) energy causes some of the electrons in the semi-conductor to be FD12A 141  “freed” from their atoms. The cell is constructed so that these elec- trons flow in a particular direction and constitute an electric current. Several cells are connected in series (that is, one after the other) so that the current flows along a single path to provide the required output. Photovoltaic cells are not yet very efficient. A simple cell absorbs only 15% – 25% of the incident sunlight. This is because sunlight is radiation that is made up of a range of different wavelengths, only a portion of which have the right amount of energy to activate the semi-conductor material. Because of this and other constraints, several acres of large solar panels would be needed to produce enough electricity for industrial use. Photovoltaic cells are used to power the electrical systems of satel- lites. (Why do you think this is possible?) You may be more familiar with the use of these cells in calculators. Within the Caribbean photovoltaic cells have been used to supply electricity in a rural school in Trinidad, and to power a radio station in Curacao. The cells are used to charge storage batteries, and additional devices convert the available “direct current” from the battery into the “alternating current” used for powering most domestic and indus- trial appliances. Wind energy The kinetic energy of the wind can be used to do work. We are all familiar with the use of wind power in sailing and even kite flying! Windmills are the devices used to harness wind energy for other types of work. Holland is probably best known for its windmills. They are a very familiar sight on the landscape and have been used for centuries to pump water from low-lying areas. In some Caribbean islands such as Tobago, Barbados, and Jamaica, one can still see the towers of windmills that were used to grind sugarcane. In order for wind energy technology to be effective, the wind must be blowing at a reasonable speed. (Holland is a very windy coun- try!) It has been estimated that wind speeds of at least 6.5 meters per second (m/s), that is about 10 miles per hour, are needed for this purpose. The Windward Islands are thought to have good prospects for wind energy. The problem with wind energy technology is that 142 FD12A  Figure 2.5 Kilronan wind farm uses state-of-the-art technology to produce clean, renewable electricity. Each of the wind machines has a hub height of about 40 metres and a rotor diameter of the same dimensions. The turbine is constructed from three aerodynamically shaped blades linked by a shaft to what is known as the nacelle, which houses the gearbox and generator. The rotating blades drive the shaft, which in turn drives the generator, and electricity is produced. The electricity then travels down cables inside the tower and passes through a transformer into the local electricity network. Source: http://www.kilronanwindfarm.com/tech.html suitable winds are not usually available all year round in any given location. Electricity generating windmills are basically wind-powered turbines. Each turbine consists of two or three angled blades mounted on a shaft that is connected to a gear transmission box. The wind causes the blades of the turbine to move and the kinetic energy of the wind is converted into kinetic energy in the spinning blades. The spinning speed is magnified by the gear transmission and this in turn causes a generator to rotate, producing electricity. Turbines are usually mounted on towers since wind speeds normally increase with height. On the island of Curaçao there is a modern wind farm, consisting of twelve 20 kW turbines. Similar efforts in Antigua, Barbados, Barbuda, and Monsterrat were not found to be feasible, unfortu- nately only after construction. In 1995 a wind turbine was constructed at the high school, Munro College Jamaica. This turbine not only supplies the school with its electrical energy needs, but it also generates income of approximately US$30,000 per year from the sale of electricity to surrounding areas. Wind energy is relatively clean. There are no hazards from the emis- sion of polluting gases into the atmosphere. Noise pollution may, however, pose a problem on wind farms. FD12A 143  Ocean thermal energy conversion Traditionally, the method for harnessing energy from water has involved the use of turbines to convert the kinetic energy of falling water (for example, from waterfalls) into electricity. Ocean thermal energy conversion (OTEC) is a relatively new technology that also harnesses energy from water. It utilises the difference in the temper- ature of the water at the surface of the ocean and the water about 1000 metres deep. Such differences in ocean waters can be found in the tropics. The process uses the warm ocean waters to cause a substance with a low boiling point, such as ammonia, to evaporate. The vapour is then fed into a turbine to produce electricity. Cold water from the bottom of the ocean is used to condense the ammonia vapour back to the liquid form. The cycle is then repeated. There are some spin-offs to the operation. The cold water needed to condense the vapours must be pumped up from the bottom of the sea. Seawater from such depths is usually rich in nutrients and, thus, the water that is pumped up can be used to feed fish in a marine fish farm. The original demonstration project was in Cuba but no serious efforts at utilising OTEC have occurred in the Caribbean to date. The enterprise is a costly one. Clearly there are several limitations to adopting alternative sources n What would you consider to be critical of energy as a primary source of energy for a country. However, components of an while research is proceeding to make these alternatives more effi- energy policy for small island states cient and cost effective we can consider their use for supplementing such as the present sources thus reducing the amount of imported energy we Caribbean islands? require. Alternative sources of energy are also ideal for small rural Caribbean communities and isolated homes that have no electricity supply at present. 144 FD12A  QUICK REVIEW n Three ways of using solar energy: Providing hot water, drying crops, making electricity. n Three reasons for using solar energy in the Caribbean: Reasonable cost (after installation), non-polluting, sunshine available all year. n Three steps in producing electricity by a wind turbine: Wind turns the blades, gears increase spinning speed, and a generator rotates. n What is OTEC? Ocean Thermal Energy Conversion: Using warm surface sea water to vaporise a gas that turns a turbine; using cold bottom water to condense the gas for recycling. n Make sure you know what these words mean: Solar water heater Solar dryer Micro-organism Electron Photovoltaic cell Semi-conductor Turbine n Question: Why have photovoltaic cells not been used on a large scale? FD12A 145 146 FD12A  Session 2.4 Industries in the Caribbean In this session, we will look at three industries and how they produce or use energy. The steps in some of the processes are described briefly. Note carefully the points at which energy use is or can be minimized, or deleterious environmental effects prevented, particularly by recycling. The petroleum/petrochemical industry There are only three Caribbean countries that have oil and natural gas reserves – Trinidad & Tobago, Barbados, and Cuba. Of these, Trinidad and Tobago is the largest producer and revenue from oil is their largest foreign exchange earner. However, oil production is declining and it is projected that the country’s oil reserves will last for only the next 10–15 years. Oil was discovered in Trinidad and Tobago in 1866 and the first oil wells were dug in 1907. The production of crude oil began the year after the first oil wells were dug and refining of oil started in 1912. The oil refinery at Point-Pierre in southern Trinidad was once the largest in the western hemisphere and was very important during the Second World War. Other refineries were constructed but refining is now done only at the Pointe-a-Pierre facility. This refinery uses both local and foreign crude oils for its operations. Among its products are gasoline, diesel oil, and jet fuel. It currently has a refining capacity of about 160,000 barrels/day. However, the Hovensa refinery in St Croix, US Virgin Islands, with a refining capacity of 525,000 barrels/day, is now the largest in the western hemisphere. Trinidad and Tobago export both crude oil and petroleum products to the USA and petroleum products to CARICOM and other countries. International companies exploring for oil in Trinidad during the 1960s, found natural gas. These finds were not exploited then as gas FD12A 147  earned very little compared to oil. It was not until 1977 that Amoco started using its offshore natural gas reserves. Between 2000 and 2001, significant gas discoveries were made and the government has since been encouraging further exploration for natural gas. The increase in exploration for natural gas at the end of the twentieth century has been phenomenal. Natural gas is becoming more impor- tant to the Trinidad and Tobago economy than oil. Exploration is an expensive and a financially risky business. Consequently there is a large foreign input in the exploration for natural gas in Trinidad and Tobago although a few private local companies are also involved. The government holds major shares in one company, The National Gas Company (NGC), which purchases most of the natural gas used in Trinidad and Tobago. The gas is then transported and resold to consumers. Natural gas is sold as LNG and CNG. It is also pumped directly to a few homes in Trinidad for domestic usage. In Barbados, natural gas was pumped from bulk storage facilities to homes, as it was in Jamaica many years ago. A few gas stations in Trinidad sell CNG to the relatively small number of motorists who have converted their vehicles to use CNG instead of gasoline. The Point Lisas Industrial Estate in central Trinidad was developed in the 1970s using natural gas as its main source of energy. Natural gas was used to generate cheap electricity for several large industries that developed on the estate and the surrounding districts. Natural gas is used in the production of ammonia, methanol, urea, iron and steel, and in other smaller manufacturing processes. During an economic downturn in the 1990s the government of Trinidad and Tobago sold off most of its interests in gas-based companies, leaving foreign investors to drive activity in this sector. Trinidad and Tobago is one of the world’s leading exporters of methanol and ammonia. The expansion of these energy-based industries continues. Natural gas is also used in Trinidad and Tobago in the production of electricity at plants other than Point Lisas. The cost of electricity in Trinidad and Tobago is therefore relatively cheap compared with costs in other Caribbean territories. Oil that is mined in Barbados is shipped to Trinidad for refining and returned for domestic consumption. In Jamaica, although there has 148 FD12A  been some drilling activity, no significant oil and gas deposits have yet been found. Some refining is done at the Petrojam facility, which is a 36,000 barrel-per-day operation in the capital, Kingston. Crude oil is imported mainly from Mexico and Venezuela. Although there are no drilling and refining operations in St Lucia, the island has a significant storage facility owned by Hess. Trinidad and Tobago, with its vibrant energy sector, does not have control over the amount of revenue gained from oil as oil prices fluc- tuate depending on the world market. The price of oil is controlled largely by the Organisation of Petroleum Exporting Countries (OPEC), which is a group of 11 developing countries that supply 40% of the world’s oil output. OPEC adjusts its oil output to help ensure a balance between supply and demand. This impacts signifi- cantly on the world price of oil. Trinidad and Tobago is not a member of OPEC; its output of oil is probably not significant enough compared to the OPEC countries. Most CARICOM countries face the daunting task of importing petroleum products at significant costs. This puts a severe strain on national budgets; it also has serious implications for the cost of living in these countries since fuel is needed for practically all domestic and industrial pursuits. There are also hidden costs that are energy-related. Among these are health costs due to the impact of environmental pollution on the population. CRITICAL THINKING ACTIVITY There is an economic cost to ensuring that operations in the oil industry do not pollute the environment. Such costs are passed on to the consumer. Should the focus be on making oil cleaner or cheaper? (Consider short-term and long-term benefits and drawbacks). FD12A 149  The sugar industry For over 300 years sugar formed the basis of most Caribbean economies. The world consumption of sugar has increased steadily over the last several hundred years, yet Caribbean sugar is in decline. Why is this so? Basically the need for Caribbean sugar has fallen significantly. Beetroots have been bred that produce sugar in satis- factory amounts to support the demands of the countries in which they are grown; new technologies have been developed that lead to the production of sugar from crops such as corn. The bottom line is that sugar is now produced less expensively in many other coun- tries. (See Unit 3 for more on developing substitutes.) Considerations of food security have led most Caribbean countries to maintain some production of sugar although the world price of sugar is low, well below the production cost of sugar in the Caribbean. The industry is only viable because of special marketing arrangements with the European Union and the USA. These prefer- ential trade arrangements are under threat, and are likely to be phased out over the next 5–6 years. The sugar cane plant is one of the most efficient energy converters found in nature. Efficiency here means the ratio of output (as meas- ured by the calorific value of the product) to input (as measured by the total amount of energy received from the sun). For sugar cane, this is about 2%. This translates into about 10 tons of sugar per hectare per year. This quantity varies depending on the variety of cane, the soil and weather conditions. Cane is still harvested manually and is a significant source of labour in some territories. In Trinidad and Tobago, during the crop season, it employs more workers than the oil industry. It is also harvested using mechanical harvesters and loaders. These machines operate with fossil fuels. The production of sugar from cane involves three main stages – extraction, evaporation, and storage. l The first stage of processing is the extraction of the cane juice. The cane is crushed in a series of large roller mills and the cane 150 FD12A  fibre, called bagasse, is carried away for use as fuel or used as mulch. Bagasse is burnt in furnaces to produce steam in boilers. This steam is used for heating the juice in the further stages of production. This means that a cane factory can be more self- sufficient from an energy perspective. l Next the cane juice is treated with a chemical called milk of lime which settles out a lot of the impurities which can then be sent back to the fields as fertiliser. The juice is then heated under a vacuum causing water to evaporate. The vacuum allows the evaporation to take place at a lower temperature than normal, and it also prevents darkening of the product. Evaporation causes the juice to thicken into syrup. Sometimes, the syrup is treated with lime again but, more often than not, it just goes on to the crystal-making step, with further evaporation taking place under a vacuum. l Evaporation is done in a series of steps and the steam generated in one step is used to heat the vessels for the next stage of evaporation. l The final product, raw sugar, may be used in that state or else sent to be refined. Refining factories exist in Jamaica and Trinidad. SELF-CHECK 1. Draw a simple flow diagram to show the steps involved in making sugar. 2. List the points at which fossil fuels are used in the industry. 3. Which steps reduce the amount of fossil energy used? ACTIVITY 1. Find out what is “gasahol”. 2. Outline the production and use of “‘gasahol” in Brazil. 3. What possibilities does it offer for reviving the sugar cane industry in your country and reducing energy imports? FD12A 151  Mining bauxite Large deposits of bauxite are found in Jamaica and Guyana. Bauxite is an ore of the metal aluminium. It occurs as hydrated oxide of aluminium (this means that aluminium is chemically combined with oxygen to form the oxide and there are also some water mole- cules attached). Aluminium is a good conductor of heat and electric- ity. Thus, it is used extensively for domestic and commercial purposes. The mining of bauxite for use in making aluminium is, therefore, an important economic activity. When the bauxite is dug out of the ground it contains a number of impurities in addition to the hydrated aluminium oxide. The first step after mining the bauxite involves removing these impurities. The ore is first ground into small particles. The particles are then heated with concentrated sodium hydroxide solution. The oxide of aluminium reacts with the sodium hydroxide to form a solution. Most of the impurities present do not react and can readily be filtered off. The solution is cooled and diluted with water. Some hydrated aluminium oxide is added to this diluted solution. These act as “seeds”, causing more of the hydrated oxide to be precipitated. The precipitate is washed and heated to give the pure aluminium oxide, which is called alumina. One method of obtaining aluminium from alumina is a process called electrolysis. The alumina is first heated to a very high tempera- ture until it melts. An electric current is passed through the molten alumina via graphite rods. Molten aluminium forms at one of the rods and is run off from the bottom of the container in which the electrolysis takes place. This process requires a great deal of electrical energy. In both Guyana and Jamaica, the ore is mined (and sometimes refined) and exported, but there is no production of aluminium from the ore, partly because of the high cost of the electrical energy required. Furthermore, the production of the metal would only be profitable if there was a large market for it. Although Jamaica was the second largest exporter of alumina in the world in the 1970s, that position has since changed due to the expansion of the industry in places such as Australia and the West African country of Guinea. 152 FD12A  Other world economic conditions have reduced availability of markets for Caribbean bauxite. There are some environmental problems associated with the mining of bauxite. The main problem is the disposal of the impurities precipitated with the sodium hydroxide (known as “red mud”) after reclamation of as much of the sodium hydroxide as is possible. There are also hazards due to dust and noise. When the bauxite exists close to the surface as it does in Jamaica another problem is possible, that is, the removal of the topsoil and the resulting defor- estation. It is noteworthy that in Jamaica, efforts are made to conserve the environment by the reclamation and rehabilitation of mined-out bauxite lands. Profitable agricultural enterprises have also been undertaken using this reclaimed land. New processes for the disposal of the red mud have curtailed the growth of the toxic red mud lakes, some of which already occupy whole valleys. Tourism Tourism is the largest foreign exchange earner in several of the smaller Caribbean islands. There has been a rapid increase in the rate of construction of guesthouses and hotels in the islands over the recent past. Energy is required for the successful operation of many aspects of this industry and, in most territories, oil is the source of this energy. Most Caribbean islands have to import oil and its many products so a considerable amount of the money earned from tourism is spent on these imports. Many hotels and guesthouses already practice environmental conservation, including energy conservation. Lighting, water heat- ing, and air-conditioning are three areas of the hotel industry that consume large amounts of energy. Some energy conservation in each of these areas is effected by the following methods: l Installing photoelectric switches or timing devices that turn lights off when they are not needed. l Using fluorescent light bulbs instead of incandescent ones since the former are far more efficient. FD12A 153  l Installing solar water heaters or using the waste heat from air- conditioning units to heat water. l Improving the efficiency of their boilers by eliminating leaks and ensuring proper insulation of pipes. Hot condensate can also be recycled to boilers, thereby using less cold water (and less energy) in the system. l Putting in devices in the frames of doors that trip off air- conditioning units in hotel rooms when the door is opened. CRITICAL THINKING ACTIVITY 1. What might be some useful strategies to alert Caribbean peoples to the need to conserve energy in all spheres of human activity? 2. What are the important messages to be conveyed? QUICK REVIEW Twenty questions – find the answers in the unit. 1. Which countries in the Caribbean produce oil or gas? 2. In which countries are refineries to be found? 3. Where is Point Lisas Industrial Estate and what happens there? 4. Who controls the world price of oil? 5. What are the costs of using petroleum products as a source of energy? (Consider economic and environmental costs) 6. Why is the Caribbean sugar industry in decline? 7. How is cane juice turned into sugar? 8. At what points in the production of sugar are fossil fuels used? 9. At what points in manufacturing sugar is energy saved? 10. In what other way can waste from making sugar be used? 11. In which Caribbean countries is Bauxite found? 154 FD12A FD12A  12. How is alumina made from bauxite? 13. Why is aluminium important? 14. What is the main reason why aluminium is not made in the Caribbean? 15. What are the main environmental problems caused by baux- ite mining and refining? 16. What efforts have been made to offset the negative effects of bauxite mining and refining? 17. What three areas of the hotel industry consume the most energy? 18. What conservation practices can hotels use to save energy? 19. How do these four industries compare in terms of energy use and energy savings? 20. What are the overall implications for the future development of the Caribbean, of not having our own energy sources? SUMMARY In this unit we looked at energy, its production and its use in four Caribbean industries. Important points that emerged were the high cost of importing energy, the implications of this for development, the environmental effects of using petroleum products, and efforts at energy conservation. In session 2.1 we defined energy as the ability to do work and described four forms of energy. These were the kinetic energy of moving bodies, potential energy due to the position and mass of an object, thermal or heat energy, and nuclear energy from breaking chemical bonds in the nuclei of atoms. We also introduced the concepts of renewable and non-renewable sources of energy. Energy production was the focus of Session 2.2. When carbon-based compounds such as fossil fuels are burnt, they release useable energy but also air pollutants such as carbon dioxide. This was an important FD12A 155  concern. We saw that a number of familiar products such as fuels for cooking, motors, and jet planes, petroleum jelly, toiletries, and asphalt are products of crude oil. Coal, another fossil fuel still used to generate electricity in some countries, was also discussed. Other areas of concern are the increasing demand for energy, the depletion of fossil fuels, and its rising cost. We noted that these factors have led to a search for alternative sources of energy so we considered the use of energy from the sun, solar energy, the use of windmills, and thermal energy from sea water, and the possibilities they offer for the Caribbean. In the final session, we examined four Caribbean industries that produce or use large amounts of energy. Attention was paid to those areas of production and use where energy savings can be made. The environmental side effects of these productive activities were also discussed. The industries described were petroleum, bauxite, sugar, and tourism. In all cases we saw the constraints on development imposed by our present dependence on foreign sources of energy. Importing energy is expensive but development activities need energy. We face the dilemma of how to fuel development at a reasonable cost. 156 FD12A  REFERENCES Caribbean fact sheet. http://www.eia.doe.gov/emeu/cabs/carib.html Energy production and consumption. http://www.whole-systems.org/oil.html Headley, O. Solar and alternative energy in the Caribbean: Prospect and retrospect. In L. Moseley and O. Headley (Eds.), Sustainable Alternatives for Small Island States. Bridgetown: UWI Centre for Environment and Development, 1994. Headley, O. Solar thermal systems for use in the Caribbean. In R. Wilson (ed.), Proceedings of the high-level workshop on renewable energy technologies. Port of Spain: UNESCO, 1995. Reay, J., and J. Steward. Science applied in the Caribbean. London: Macmillan, 1988. St Aimee, D. Overview of renewable energy considerations for the Caribbean. In L. Moseley and O. Headley (eds.), Sustainable Alternatives for Small Island