Energy - What Is It?
Energy causes things to happen around us. Look out the window.
During the day, the sun gives out light and heat energy. At night, street lamps use electrical energy to light our way.
When a car drives by, it is being powered by gasoline, a type of stored energy. The food we eat contains energy. We use that energy to work and play. We learned the definition of energy in the introduction:
"Energy Is the Ability to Do Work."
Energy can be found in a number of different forms. It can be chemical energy, electrical energy, heat (thermal energy), light (radiant energy), mechanical energy, and nuclear energy.
What Is Electricity?
Electricity figures everywhere in our lives. Electricity lights up our homes, cooks our food, powers our computers, television sets, and other electronic devices. Electricity from batteries keeps our cars running and makes our flashlights shine in the dark.
Here's something you can do to see the importance of electricity. Take a walk through your school, house or apartment and write down all the different appliances, devices and machines that use electricity. You'll be amazed at how many things we use each and every day that depend on electricity.
But what is electricity? Where does it come from? How does it work? Before we understand all that, we need to know a little bit about atoms and their structure.
All matter is made up of atoms, and atoms are made up of smaller particles. The three main particles making up an atom are the proton, the neutron and the electron. Electrons spin around the center, or nucleus, of atoms, in the same way the moon spins around the earth. The nucleus is made up of neutrons and protons.
Electrons contain a negative charge, protons a positive charge. Neutrons are neutral – they have neither a positive nor a negative charge.
There are many different kinds of atoms, one for each type of element. An atom is a single part that makes up an element. There are 118 different known elements that make up every thing! Some elements like oxygen we breathe are essential to life.
Each atom has a specific number of electrons, protons
and neutrons. But no matter how many particles an atom has, the number of electrons usually needs to be the same as the number of protons. If the numbers are the same, the atom is called balanced, and it is very stable.
So, if an atom had six protons, it should also have six electrons. The element with six protons and six electrons is called carbon. Carbon is found in abundance in the sun, stars, comets, atmospheres of most planets, and the food we eat. Coal is made of carbon; so are diamonds.
Some kinds of atoms have loosely attached electrons. An atom that loses electrons has more protons than electrons and is positively charged. An atom that gains electrons has more negative particles and is negatively charge. A "charged" atom is called an "ion."
This chain is similar to the fire fighter's bucket brigades in olden times. But instead of passing one bucket from the start of the line of people to the other end, each person would have a bucket of water to pour from one bucket to another. The result was a lot of spilled water and not enough water to douse the fire. It is a situation that's very similar to electricity passing along a wire and a circuit. The charge is passed from atom to atom when electricity is "passed."
Scientists and engineers have learned many ways to move electrons off of atoms. That means that when you add up the electrons and protons, you would wind up with one more proton instead of being balanced.
Since all atoms want to be balanced, the atom that has been "unbalanced" will look for a free electron to fill the place of the missing one. We say that this unbalanced atom has a "positive charge" (+) because it has too many protons.
Since it got kicked off, the free electron moves around waiting for an unbalanced atom to give it a home. The free electron charge is negative, and has no proton to balance it out, so we say that it has a "negative charge" (-).
So what do positive and negative charges have to do with electricity?
Scientists and engineers have found several ways to create large numbers of positive atoms and free negative electrons. Since positive atoms want negative electrons so they can be balanced, they have a strong attraction for the electrons. The electrons also want to be part of a balanced atom, so they have a strong attraction to the positive atoms. So, the positive attracts the negative to balance out.
The more positive atoms or negative electrons you have, the stronger the attraction for the other. Since we have both positive and negative charged groups attracted to each other, we call the total attraction "charge."
Energy also can be measured in joules. Joules sounds exactly like the word jewels, as in diamonds and emeralds. A thousand joules is equal to a British thermal unit.
When electrons move among the atoms of matter, a current of electricity is created. This is what happens in a piece of wire. The electrons are passed from atom to atom, creating an electrical current from one end to other, just like in the picture.
Electricity is conducted through some things better than others do. Its resistance measures how well something conducts electricity. Some things hold their electrons very tightly. Electrons do not move through them very well. These things are called insulators. Rubber, plastic, cloth, glass and dry air are good insulators and have very high resistance.
Other materials have some loosely held electrons, which move through them very easily. These are called conductors. Most metals – like copper, aluminum or steel – are good conductors.
Resistance and Static Electricity
As we have learned, some kinds of atoms contain loosely attached electrons. Electrons can be made to move easily from one atom to another. When those electrons move among the atoms of matter, a current of electricity is created.
Take a piece of wire. The electrons are passed from atom to atom, creating an electrical current from one end to the other. Electrons are very, very small. A single copper penny contains more than
10,000,000,000,000,000,000,000 (1x1022) electrons.
Electricity "flows" or moves through some things better than others do. The measurement of how well something conducts electricity is called its resistance.
Copper is used in many wires because it has a lower resistance than many other metals. The wires in your walls, inside your lamps and elsewhere are usually copper.
A piece of metal can be made to act like a heater. When an electrical current occurs, the resistance causes friction and the friction causes heat. The higher the resistance, the hotter it can get. So, a coiled wire high in resistance, like the wire in a hair dryer, can be very hot.
Some things conduct electricity very poorly. These are called insulators. Rubber is a good insulator, and that's why rubber is used to cover wires in an electric cord. Glass is another good insulator. If you look at the end of a power line, you'll see that it is attached to some bumpy looking things. These are glass insulators. They keep the metal of the wires from touching the metal of the towers.
Circuits
Electrons with a negative charge, can't "jump" through the air to a positively charged atom. They have to wait until there is a link or bridge between the negative area and the positive area. We usually call this bridge a "circuit."
When a bridge is created, the electrons begin moving quickly. Depending on the resistance of the material making up the bridge, they try to get across as fast as they can. If you're not careful, too many electrons can go across at one time and destroy the "bridge" or the circuit, in the process.
In Chapter 3, we learned about electrons and the attraction between positive and negative charges. We also learned that we can create a bridge called a "circuit" between the charges.
We can limit the number of electrons crossing over the "circuit," by letting only a certain number through at a time. And we can make electricity do something for us while they are on their way. For example, we can "make" the electrons "heat" a filament in a bulb, causing it to glow and give off light.
When we limit the number of electrons that can cross over our circuit, we say we are giving it "resistance". We "resist" letting all the electrons through. This works something like a tollbooth on a freeway bridge. Copper wire is just one type of bridge we use in circuits. Before electrons can move far, however, they can collide with one of the atoms along the way. This slows them down or even reverses their direction. As a result, they lose energy to the atoms. This energy appears as heat, and the scattering is a resistance to the current. Think of the bridge as a garden hose. The current of
electricity is the water flowing in the hose and the water pressure is the voltage of a circuit. The diameter of the hose is the determining factor for the resistance.
Current refers to the movement of charges. In an electrical circuit – electrons move from the negative pole to the positive. If you connected the positive pole of an electrical source to the negative pole, you create a circuit. This charge changes into electrical energy when the poles are connected in a circuit – similar to connecting the two poles on opposite ends of a battery.
Along the circuit you can have a light bulb and an on-off switch. The light bulb changes the electrical energy into light and heat energy.
Stored Energy and Batteries
If you look at a battery, it will have two ends &emdash; a positive terminal and a negative terminal. If you connect the two terminals with wire, a circuit is formed. Electrons will flow through the wire and a current of electricity is produced.
Inside the battery, a reaction between the chemicals takes place. But reaction takes place only if there is a flow of electrons. Batteries can be stored for a long time and still work because the chemical process doesn't start until the electrons flow from the negative to the positive terminals through a circuit.
How the Chemical Reaction Takes Place in a Battery
A very simple modern battery is the zinc-carbon battery, called the carbon battery for short.
This battery contains acidic material within and a rod of zinc down the center. Here's where knowing a little bit of chemistry helps.
When zinc is inserted into an acid, the acid begins to eat away at the zinc, releasing hydrogen gas and heat energy. The acid molecules break up into its components: usually hydrogen and other atoms. The process releases electrons from the Zinc atoms that combine with hydrogen ions in the acid to create the hydrogen gas. If a rod of carbon is inserted into the acid, the acid does nothing to it.
But if you connect the carbon rod to the zinc rod with a wire, creating a circuit, electrons will begin to flow through the wire and combine with hydrogen on the carbon rod. This still releases a little bit of hydrogen gas but it makes less heat. Some of that heat energy is the energy that is flowing through the circuit.
The energy in that circuit can now light a light bulb in a flashlight or turn a small motor. Depending on the size of the battery, it can even start an automobile.
Eventually, the zinc rod is completely dissolved by the acid in the battery, and the battery can no longer be used. For a "great" on-line page about batteries, visit the Energizer Learning Center.
Turbines, Generators and Power Plants
As we learned in Chapter 2, electricity flows through wires to light our lamps, run TVs, computers and all other electrical appliances. But where does the electricity come from?
In this chapter, we'll learn how electricity is generated in a power plant. In the next few chapters, we'll learn about the various resources that are used to make the heat to produce electricity. InChapter 7, we'll learn how the electricity gets from the power plant to homes, school and businesses.
Thermal power plants have big boilers that burn a fuel to make heat. A boiler is like a teapot on a stove. When the water boils, the steam comes through a tiny hole on the top of the spout. The moving steam makes a whistle that tells you the water has boiled. In a power plant, the water is brought to a boil inside the boiler, and the steam is then piped to the turbine through very thick pipes. In most boilers, wood, coal, oil or natural gas is burned in a firebox to make heat. Running through the fire box and above that hot fire are a series of pipes with water running through them. The heat energy is conducted into the metal pipes, heating the water in the pipes until it boils into steam. Water boils into steam at 212 degrees Fahrenheit or 100 degrees Celsius.
In the second picture to the left, you'll see the turbine and generator at MSU's power plant. The big pipe on the left side is the steam inlet. On the right side of the turbine is where the steam comes out. The steam is fed under high pressure to the turbine. The turbine spins and its shaft is connected to a turbogenerator that changes the mechanical spinning energy into electricity.
The third picture on the right is of the turbine fan before it is placed inside the turbine housing. You can see a close-up of the turbine blades on the fourth picture. The turbine has many hundreds of blades that are turned at an angle like the blades of a fan. When the steam hits the blades they spin the turbine's shaft that is attached to the bottom of the blades.
After the steam goes through the turbine, it usually goes to a cooling tower outside the where the steam cools off. It cools off and becomes
water again. When the hot pipes come into contact with cool air, some water vapor in the air is heated and steam is given off above the cooling towers. That's why you see huge white clouds sometimes being given off by the cooling towers. It's not smoke, but
is water vapor or steam. This is not the same steam that is used inside the turbine.
The cooled water then goes back into the boiler where it is heated again and the process repeats over and over.
Most power plants in California use cleaner-burning natural gas to produce electricity. Others use oil or coal to heat the water. Nuclear power plants use nuclear energy to heat water to make electricity. Still others, called
geothermal power plants, use steam or hot water found naturally below the earth's surface without burning a fuel. We'll learn about those energy sources in the next few chapters.
Electricity Transmission System
After electricity is produced at power plants it has to get to the customers that use the electricity. Our cities, towns, states and the entire country are criss-crossed with power lines that "carry" the electricity.
As large generators spin, they produce electricity with a voltage of about 25,000 volts. A volt is a measurement of electromotive force in electricity. This is the electric force that "pushes" electrons around a circuit. "Volt" is named after Alessandro Volta, an Italian physicist who invented the first battery.
The electricity first goes to a transformer at the power plant that boosts the voltage up to 400,000 volts. When electricity travels long distances it is better to have it at higher voltages. Another way of saying this is that electricity can be transferred more efficiently at high voltages.
it gets. So, some of the electrical energy is lost because it is changed into heat energy. High voltage transmission lines carry electricity long distances to a substation.
The power lines go into substations near businesses, factories and homes. Here transformers change the very high voltage electricity back into lower voltage electricity. From these substations (like in the photo to the right), electricity in different power levels is used to run factories, streetcars and mass transit, light street lights and stop lights, and is sent to your neighborhood.
In your neighborhood, another small transformer mounted on pole (see picture) or in a utility box converts the power to even lower levels to be used in your house. The voltage is eventually reduced to 220 volts for larger appliances, like stoves and clothes dryers, and 110 volts for lights, TVs and other smaller appliances.
Rather than over-head lines, some new distribution lines are underground. The power lines are protected from the weather, which can cause line to break. Have you ever seen what happens after an ice storm?
The picture on the right shows high voltage towers that crumpled from the weight of ice during a 1998 ice storm that hit Canada and parts of the United States. More than 1,000 high voltage towers and 30,000 wooden utility poles were destroyed in Canada by the storm.
Close to 1.4 million people in Quebec and 230,000 in Ontario were without electricity. In many places, power not fully restored for up to a week. Weather people called it the most destructive storm in Canadian history.
When electricity enters your home, it must pass through a meter. A utility company worker reads the meter so the company will know how much electricity you used and can bill you for the cost. After being metered, the electricity goes through a fuse box into your home. The fuse box protects the house in case of problems. When a fuse (or a circuit breaker) "blows" or "trips" something is wrong with an appliance or something was short- circuited.
Fossil Fuels - Coal, Oil and Natural Gas
Where Fossil Fuels Come From
There are three major forms of fossil fuels: coal, oil and natural gas. All three were formed many hundreds of millions of years ago before the time of the dinosaurs – hence the name fossil fuels. The age they were formed is called the Carboniferous Period. It was part of the Paleozoic Era. "Carboniferous" gets its name from carbon, the basic element in coal and other fossil fuels.
The Carboniferous Period occurred from about 360 to 286 million years ago. At the time, the land was covered with swamps filled with huge trees, ferns and other large leafy plants, similar to the picture above. The water and seas were filled with algae – the green stuff that forms on a stagnant pool of water. Algae is actually millions of very small plants.
Some deposits of coal can be found during the time of the
dinosaurs. For example, thin carbon layers can be found during the late Cretaceous Period (65 million years ago) – the time of
the Carboniferous Period. For more about the various geologic eras, go to www.ucmp.berkeley.edu/help/timeform.html
As the trees and plants died, they sank to the bottom of the swamps of oceans. They formed layers of a spongy material called peat. Over many hundreds of years, the peat was covered by sand and clay and other minerals, which turned into a type of rock called sedimentary.
More and more rock piled on top of more rock, and it weighed more and more. It began to press down on the peat. The peat was squeezed and squeezed until the water came out of it and it eventually, over millions of years, it turned into coal, oil or petroleum, and natural gas.
Natural Gas Distribution System
We learned in Chapter 8 that natural gas is a fossil fuel. It is a gaseous molecule that's made up of two atoms – one carbon atom combined with four hydrogen atom. It's chemical formula is CH4. The picture on the right is a model of what the molecule could look like.
Don't confuse natural gas with "gasoline," which we call "gas" for short. Like oil, natural gas is found under ground and under the ocean floor. Wells are drilled to tap into natural gas reservoirs just like drilling for oil. Once a drill has hit an area that contains natural gas, it can be brought to the surface through pipes.
The natural gas has to get from the wells to us. To do that, there is a huge network of pipelines that brings natural gas from the gas fields to us. Some of these pipes are two feet wide.
Natural gas is sent in larger pipelines to power plants to make electricity or to factories because they use lots of gas. Bakeries use natural gas to heat ovens to bake bread, pies, pastries and cookies. Other businesses use natural gas for heating their buildings or heating water.
From larger pipelines, the gas goes through smaller and smaller pipes to your neighborhood. In businesses and in your home, the natural gas must first pass through a
meter, which measures the amount of fuel going into the building. A gas company worker reads the meter and the company will charge you for the amount of natural gas you used.
Energy can be found in a number of different forms. It can be chemical energy, electrical energy, heat (thermal energy), light (radiant energy), mechanical energy, and nuclear energy.
In some homes, natural gas is used for cooking, heating water and heating the house in a furnace.
In rural areas, where there are no natural gas pipelines, propane (another form of gas that's often made when oil is refined) or bottled gas is used instead of natural gas. Propane is also called LPG, or liquefied petroleum gas, is made up of methane and a mixture with other gases like butane.
Propane turns to a liquid when it is placed under slight pressure. For regular natural gas to turn into a liquid, it has to be made very, very cold.
Cars and trucks can also use natural gas as a transportation fuel, but they must carry special cylinder-like tanks to hold the fuel.
When natural gas is burned to make heat or burned in a car's engine, it burns very cleanly. When you combine natural gas with oxygen (the process of combustion), you
produce carbon dioxide and water vapor; plus the energy that's released in heat and light.
from natural gas is less than burning a more "complex" fuel like gasoline. Natural gas-powered cars are more than 90 percent cleaner than a gasoline-powered car.
That's why many people feel natural gas would be a good fuel for cars because it burns cleanly. Next chapter is about Biomass Energy.
Biomass Energy
Biomass is matter usually thought of as garbage. Some of it is just stuff lying around -- dead trees, tree
branches, yard clippings, left-over crops, wood chips (like in the picture to the right), and bark and sawdust from lumber mills. It can even include used tires and livestock manure.
Your trash, paper products that can't be recycled into other paper products, and other household waste are normally sent to the dump. Your trash contains some types of biomass that can be reused. Recycling biomass for fuel and other uses cuts down on the need for "landfills" to hold garbage.
This stuff nobody seems to want can be used to produce electricity, heat, compost material or fuels. Composting material is decayed plant or food products mixed together in a compost pile and spread to help plants grow. California produces more than 60 million bone dry tons of biomass each year. Of this total, five million bone dry tons is now burned to make electricity. This is biomass from lumber mill wastes, urban wood waste, forest and agricultural residues and other feed stocks.
If all of it was used, the 60 million tons of biomass in California could make close to 2,000 megawatts of electricity for California's growing population and economy. That's enough energy to make electricity for about two million homes!
How biomass works is very simple. The waste wood, tree branches and other scraps are gathered together in big trucks. The trucks bring the waste from factories and from farms to a biomass power plant. Here the biomass is dumped into huge hoppers. This is then fed into a furnace where it is burned. The heat is used to boil water in the boiler, and the energy in the steam is used to turn turbines and generators (seeChapter 8).
Biomass can also be tapped right at the landfill with burning waster products. When garbage decomposes, it gives off methane gas. You'll remember in chapters 8 and 9 that natural gas is made up of methane. Pipelines are put into the landfills and the methane gas can be collected. It is then used in power plants to make electricity. This type of biomass is called landfill gas.
A similar thing can be done at animal feed lots. In places where lots of animals are raised, the animals - like cattle, cows and even chickens - produce manure. When manure decomposes, it also gives off methane gas similar to garbage. This gas can be burned right at the farm to make energy to run the farm.
Using biomass can help reduce global warming compared to a fossil fuel-powered plant. Plants use and store carbon dioxide (CO2) when they grow. CO2 stored in the plant is released when the plant material is burned or decays. By replanting the crops, the new plants can use the CO2 produced by the burned plants. So using biomass and replanting helps close the carbon dioxide cycle. However, if the crops are not replanted, then biomass can emit carbon dioxide that will contribute toward global warming.
So, the use of biomass can be environmentally friendly because the biomass is reduced, recycled and then reused. It is also a renewable resource because plants to make biomass can be grown over and over. Today, new ways of using biomass are still being discovered. One
Next chapter is about Geothermal Energy.
Geothermal Energy
Geothermal Energy has been around for as long as the Earth has existed. "Geo" means earth, and "thermal" means heat. So, geothermal means earth-heat.
Have you ever cut a boiled egg in half? The egg is similar to how the earth looks like inside. The yellow yolk of the egg is like the core of the earth. The white part is the mantle of the earth. And the thin shell of the egg, that would have surrounded the boiled egg if you didn't peel it off, is like the earth's crust.
Below the crust of the earth, the top layer of the mantle is a hot liquid rock called magma. The crust of the earth floats on this liquid magma mantle. When magma breaks through the surface of the earth in a volcano, it is called lava.
For every 100 meters you go below ground, the temperature of the rock increases about 3 degrees Celsius. Or for every 328 feet below ground, the temperature increases 5.4 degrees Fahrenheit. So, if you went about 10,000 feet below ground, the temperature of the rock would be hot enough to boil water.
Deep under the surface, water sometimes makes its way close to the hot rock and turns into boiling hot water or into steam. The hot water can reach temperatures of more than 300 degrees Fahrenheit (148 degrees Celsius). This is hotter than boiling water (212 degrees F / 100 degrees C). It doesn't turn into steam because it is not in contact with the air.
When this hot water comes up through a crack in the earth, we call it a hot spring, like Emerald Pool at Yellowstone National Park pictured on the left. Or, it sometimes explodes into the air as a geyser, like Old Faithful Geyser pictured on the right.
About 10,000 years ago, Paleo-Indians used hot springs in North American for cooking. Areas around hot springs were neutral zones. Warriors of fighting tribes would bathe together in peace. Every major hot spring in the United States can be associated with Native American tribes. California hot springs, like at the Geysers in the Napa area, were important and sacred areas to tribes from that area.
In other places around the world, people used hot springs for rest and relaxation. The ancient Romans built elaborate buildings to enjoy hot baths, and the Japanese have enjoyed natural hot springs for centuries.
Hydro Power
When it rains in hills and mountains, the water becomes streams and rivers that run down to the ocean. The moving or falling water can be used to do work. Energy, you'll remember is the ability to do work. So moving water, which has kinetic energy, can be used to make electricity.
For hundreds of years, moving water was used to turn wooden wheels that were attached to grinding wheels to grind (or mill) flour or corn. These were called grist mills or water mills.
Water can either go over the top of the wheel like in the photograph on the left, or the wheel can be placed in the moving river. The flow of the river then turns the wheel at the bottom like in the moving graphic on the right. Today, moving water can also be used to make electricity.
Hydro means water. Hydro-electric means making electricity from water power.
Hydroelectric power uses the kinetic energy of moving water to make electricity. Dams can be built to stop the flow of a river. Water behind a dam often forms a reservoir Like the picture of Shasta Dam in Northern California pictured on the right. Dams are also built across larger rivers but no reservoir is made. The river is simply sent through a hydroelectric power plant or powerhouse. You can see this in the picture of The Dalles Dam on the Columbia River along the border of Oregon and Washington State.
Hydro is one of the largest producers of electricity in the United States. Water power supplies about 10 percent of the entire electricity that we use. In states with high mountains and lots of rivers, even more electricity if made by hydro power. In California, for example, about 15 percent of all the electricity comes from hydroelectric.
The state of Washington leads the nation in hydroelectricity. The Grand Coulee, Chief Joseph and John Day dams are three of six major dams on the Columbia River. About 87 percent of the electricity made in Washington state is produced by hydroelectric facilities. Some of that electricity is exported from the state and used in other states.
Nuclear Energy – Fission and Fusion
Another major form of energy is nuclear energy, the energy that is trapped inside each atom. One of the laws of the universe is that matter and energy can't be created nor destroyed. But they can be changed in form.
Matter can be changed into energy. The world's most famous scientist, Albert Einstein, created the mathematical formula that explains this. It is:
This equation says:
E
[energy] equalsm
[mass] timesc
2 [c
stands for the velocity or the speed of light.c
2means
c
timesc
, or thespeed of light raised to the second power — or
c
-squared.] You can listen to Einstein's voice explaining this at:www.aip.org/history/einstein/voice1.htm
Please note that some web browser software may not show an exponent (raising something to a power, a mathematical expression) on the Internet. Normally
c
-squared is shown with a smaller "2
" placed above and to the right of thec
.Scientists used Einstein's famous equation as the key to unlock atomic energy and also create atomic bombs.
The ancient Greeks said the smallest part of nature is an atom. But they did not know 2,000 years ago about nature's even smaller parts.
As we learned in chapter 2, atoms are made up of smaller particles -- a nucleus of protons and neutrons, surrounded by electrons which swirl around the nucleus much like the earth revolves around the sun.
The world's ocean may eventually provide us with energy to power our homes and businesses. Right now, there are very few ocean energy power plants and most are fairly small. But how can we get energy from the ocean? There are three basic ways to tap the ocean for its energy. We can use the ocean's waves, we can use the ocean's high and low tides, or we can use temperature differences in the water. Let's take a look at each.
Wave Energy
Kinetic energy (movement) exists in the moving waves of the ocean. That energy can be used to power a turbine. In this simple example, to the right, the wave rises into a chamber. The rising water forces the air out of the chamber. The moving air spins a turbine which can turn a generator.
When the wave goes down, air flows through the turbine and back into the chamber through doors that are normally closed.
This is only one type of wave-energy system. Others actually use the up and down motion of the wave to power a piston that moves up and down inside a cylinder. That piston can also turn a generator.
Most wave-energy systems are very small. But, they can be used to power a warning buoy or a small light house.
Solar Energy
Mithraism, Roman religion, Hinduism, Buddhism, the Druids of England, the Aztecs of Mexico, the Incas of Peru, and many Native American tribes.
We know today, that the sun is simply our nearest star. Without it, life would not exist on our planet. We use the sun's energy every day in many different ways.
When we hang laundry outside to dry in the sun, we are using the sun's heat to do work – drying our clothes. Plants use the sun's light to make food. Animals eat plants for food. And as we learned in Chapter 5, decaying plants hundreds of millions of years ago produced the coal, oil and natural gas that we use today. So, fossil fuels is actually sunlight stored millions and millions of years ago.
Indirectly, the sun or other stars are responsible for ALL our energy. Even nuclear energy comes from a star because the uranium atoms used in nuclear energy were created in the fury of a nova – a star exploding. Let's look at ways in which we can use the sun's energy.
Wind Energy
Wind can be used to do work. The kinetic energy of the wind can be changed into other forms of energy, either mechanical energy or electrical energy.
When a boat lifts a sail, it is using wind energy to push it through the water. This is one form of work.
Farmers have been using wind energy for many years to pump water from wells using windmills like the one on the right.
In Holland, windmills have been used for centuries to pump water from low-lying areas.
Wind is also used to turn large grinding stones to grind wheat or corn, just like a water wheel is turned by water power.
Today, the wind is also used to make electricity.
The blades of the turbine are attached to a hub that is mounted on a turning shaft. The shaft goes through a gear transmission box where the turning speed is increased. The transmission is attached to a high speed shaft which turns a generator that makes electricity.
If the wind gets too high, the turbine has a brake that will keep the blades from turning too fast and being damaged.
You can use a single smaller wind turbine to power a home or a school. A small turbine makes enough energy for a house. In the picture on the left, the children at this Iowa school are playing beneath a wind turbine that makes enough electricity to power their entire school.
We have many windy areas in California. And wind is blowing in many places all over the earth. The only problem with wind is that it is not windy all the time. In California, it is usually windier during the summer months when wind rushes inland from cooler areas, like the ocean to replace hot rising air in California's warm central valleys and deserts.
In order for a wind turbine to work efficiently, wind speeds usually must be above 12 to 14 miles per hour. Wind has to be this speed to turn the turbines fast enough to generate electricity. The turbines usually produce about 50 to 300 kilowatts of electricity each. A kilowatt is 1,000 watts (kilo means 1,000). You can light ten 100 watt light bulbs with 1,000 watts. So, a 300 kilowatt (300,000 watts) wind turbine could light up 3,000 light bulbs that use 100 watts!
As of 1999, there were 11,368 wind turbines in California. These turbines are grouped together in what are called wind "farms," like those in Palm Springs in the picture on the right. These wind farms are located mostly in the three windiest areas of the state:
Altamont Pass, east of San Francisco
San Gorgonio Pass, near Palm Springs
Tehachapi, south of BakersfieldTogether these three places in California make enough electricity to supply an entire city the size of San Francisco! About 11 percent of the entire world's wind-generated electricity is found in California. Other countries that use a lot of wind energy are Denmark and Germany.
Once electricity is made by the turbine, the electricity from the entire wind farm is collected together and sent through a
transformer. There the voltage is increase to send it long distances over high power lines..
Renewable Energy vs. Fossil Fuels
we discussed the world's supply of fossil fuels — oil, coal and natural gas and how it is being depleted slowly because of constant use. Fossil fuels are not renewable, they can't be made again. Once they are gone, they're gone.
We also learned that there's no shortage of renewable energy from the sun, wind and water and even stuff usually thought of as garbage — dead trees, tree branches, yard clippings, left-over crops, sawdust, even livestock manure, can produce electricity and fuels — resources collectively called "biomass."
In contrast, emissions from cars fueled by gasoline and factories and other facilities that burn oil affect the atmosphere. Foul air results in so-called greenhouse gases. About -81% of all U.S. greenhouse gases are carbon dioxide emissions from energy-related sources.
Renewable energy resource development will result in new jobs for people and less oil we have to buy from foreign countries. According to the federal government, America spent $109 billion to import oil in 2000. If we fully develop self-renewing resources, we will keep the money at home to help the economy.
Continued research has made renewable energy more affordable today than 25 years ago. The cost of wind energy has declined from 40 cents per kilowatt-hour to less than 5 cents. The cost of electricity from the sun, through photovoltaics (literally meaning "light-electricity") has dropped from more than $1/kilowatt-hour in 1980 to nearly 20cents/kilowatt-hour today. And ethanol fuel costs have plummeted from $4 per gallon in the early 1980s to $1.20 today.
But there are also drawbacks to renewable energy development.
For example, solar thermal energy involving the collection of solar rays through collectors (often times huge mirrors) need large tracts of land as a collection site. This impacts the natural habitat, meaning the plants and animals that live there. The environment is also impacted when the buildings, roads, transmission lines and transformers are built. The fluid most often used with solar thermal electric generation is very toxic and spills can happen.
Solar or PV cells use the same technologies as the production of silicon chips for computers. The manufacturing process uses toxic chemicals. Toxic chemicals are also used in making batteries to store solar electricity through the night and on cloudy days.. Manufacturing this equipment has environmental impacts.
Also, even if we wanted to switch to solar energy right away, we still have a big problem. All the solar production facilities in the entire world only make enough solar cells to produce about 350 megawatts, about enough for a city of 300,000 people. that's a drop in the bucket compared to our needs. California alone needs about 55,000 megawatts of electricity on a sunny, hot summer day. And the cost of producing that much electricity would be about four times more expensive than a regular natural gas-fired power plant.
So, even though the renewable power plant doesn't release air pollution or use precious fossil fuels, it still has an impact on the environment.
Wind power development too, has its downside, mostly involving land use. The average wind farm requires 17 acres of land to produce one megawatt of electricity, about enough electricity for 750 to 1,000 homes. However, farms and cattle grazing can use the same land under the wind turbines.
Wind farms could cause erosion in desert areas. Most often, winds farms affect the natural view because they tend to be located on or just below ridgelines. Bird deaths also occur due to collisions with wind turbines and associated wires. This issue is the subject of on-going research.
Producing geothermal electricity from the earth's crust tends to be localized. That means facilities have to be built where geothermal energy is abundant. There are several geothermal resource locations in California. The Geysers area north of San Francisco is an example. In the course of geothermal production, steam coming from the ground becomes very caustic at times, causing pipes to corrode and fall apart. Geothermal power plants sometimes cost a little bit more than a gas-fired power plant because they have to include the cost to drill. Environmental concerns are associated with dams to produce hydroelectric power. People are displaced and prime farmland and forests are lost in the flooded areas above dams. Downstream, dams change the chemical, physical and biological characteristics of the river and land.
Unlike fossil fuels, which dirties the atmosphere, renewable energy has less impact on the environment
Renewable energy production has some drawbacks, mainly associated with the use of large of tracts of land that affects animal habitats and outdoor scenery. Renewable energy development will result in jobs and less oil imported from foreign countries.
In California, about one-half of ALL the energy we use goes into transportation – cars, planes, trucks, motorcycles, trains, buses. And of all the oil we use in the state about three-quarters of all it goes into making gasoline and diesel fuel for vehicles.
As we learned in Chapter 8, oil goes through a refinery where it is made into many different products. Some of them are used for transportation: aviation fuel, gasoline and diesel fuel. From the refinery and larger storage tank farms, transportation fuels are usually trucked to service stations in tanker trucks. These trucks can hold 10,000 gallons in each tank. The tanker trucks deliver the gasoline to the services stations.
At service stations, the two grades of gasoline, regular and premium, are kept in separate underground storage tanks. When you pump the gasoline into your car, you are pumping it from those tanks below ground. Mid-grade gasoline is a combination of the two types. Other vehicles, such as trucks and some cars use diesel fuel, which is also made from oil. It is brought to service stations the same way.
California has more than 26 million vehicles on its roads. All the vehicles in the state used 14.4 billion gallons of gasoline in 2001. That's more gasoline that all other countries except for the United States and the former Soviet Union. This makes California the third-largest user of gasoline in the world!
Fourteen billion gallons of gasoline is enough to fill a line of 10,000 gallon tanker trucks stretched bumper to bumper from San Francisco to San Diego, back to San Francisco, and then part of the way to Sacramento!
Burning gasoline, however, creates air pollution. That's why oil companies are creating newer types of gasoline that are cleaner than the kind we use today. Beginning in 1996, all the gasoline sold in California will be this newer, cleaner type called "reformulated gasoline." The main ingredient in that gas, however, MTBE was
found to hurt water supplies if it leaked. So, that additive is being removed by 2005.
Another concern about using oil for transportation is that a lot of oil used comes form the Middle East. This makes the U.S. very vulnerable if there is political unrest. During the 1970s, Americans saw long lines at the gas pumps because oil from the Middle East was turned off by the Oil Producing Exposting Countries - OPEC. And we're in in worse shape in 2002 because we're importing more and more oil form the Middle East than ever before.
Because of concerns about air pollution and petroleum-dependence, new clean-burning fuels made from fuels other than oil are being introduced. These fuels include methanol, ethanol, natural gas, propane and even electricity. The car on the right uses methanol, the same fuel used in Indianapolis Speedway race cars.
All these fuels are called alternative fuels because they are an alternative to gasoline and diesel. Cars and trucks that use them are called Alternative Fuel Vehicles or AFVs.
Right now, there are only a small number of cars and trucks that are running on fuels other than gasoline and diesel. Energy officials
hope, however, that one-quarter of all the vehicles will run on alternative fuels by the year 2025.
For more on alternative fuel vehicles, we have a whole section on Energy Quest. Go to our Transportation
Saving Energy and Energy Conservation
Some of the energy we can use is called renewable energy. These include solar, wind, geothermal and hydro. These types of energy are constantly being renewed or restored.
And there are finite or limited amounts of these non-renewable energy sources. That means they cannot be renewed or replenished. Once they are gone they cannot be used again. So, we must all do our part in saving as much energy as we can.
In your home, you can save energy by turning off appliances, TVs and radios that are not being used, watched or listened to.
You can turn off lights when no one is in the room.
By putting insulation in walls and attics, we can reduce the amount of energy it takes to heat or cool our homes.
Insulating a home is like putting on a sweater or jacket when we're cold... instead of turning up the heat.
The outer layers trap the heat inside, keeping it nice and warm.
New space-age materials are being developed that insulate even better. This person's fingers are protected by Aerogel Insulation Material created by the Lawrence Berkeley National Laboratory. The person cannot even feel the flame!
Hydrogen and Future Energy Sources
We learned in Chapter 8 that fossil fuels were formed before and during the time of the dinosaurs – when plants and animals died. Their decomposed remains gradually changed over the years to form coal, oil and natural gas. Fossil fuels took millions of years to make. We are using up the fuels formed more than 65 million years ago. They can't be renewed; they can't be made again. We can save fossil fuels by conserving and finding ways to harness energy from seemingly "endless sources," like the sun and the wind.
We can't use fossil fuels forever as they are a non-renewable and finite resource. Some people suggest that we should start using hydrogen.
Hydrogen is a colorless, odorless gas that accounts for 75 percent of the entire universe's mass. Hydrogen is found on Earth only in combination with other elements such as oxygen, carbon and nitrogen. To use hydrogen, it must be separated from these other elements.
Today, hydrogen is used primarily in ammonia manufacturing, petroleum refining and synthesis of methanol. It's also used in NASA's space program as fuel for the space shuttles, and in fuel cells that provide heat, electricity and drinking water for astronauts. Fuel cells are devices that directly convert hydrogen into electricity. In the future, hydrogen could be used to fuel vehicles (such as the DaimlerChrysler NeCar 4shown in the picture to the right) and aircraft, and provide power for our homes and offices.
Hydrogen can be made from molecules called hydrocarbons by applying heat, a process known as "reforming" hydrogen. This process makes hydrogen from natural gas. An electrical current can also be used to separate water into its components of oxygen and hydrogen in a process called electrolysis. Some algae and bacteria, using sunlight as their energy source, give off hydrogen under certain conditions.
Hydrogen as a fuel is high in energy, yet a machine that burns pure hydrogen produces almost zero pollution. NASA has used liquid hydrogen since the 1970s to propel rockets and now the space shuttle into orbit. Hydrogen fuel cells power the shuttle's electrical systems, producing a clean by-product – pure water, which the crew drinks.
You can think of a fuel cell as a battery that is constantly replenished by adding fuel to it – it never loses its charge.