The limited supplies of fossil fuels, the damage which can be done to the environment by their extraction from the earth’s crust and the pollution which their burning can cause are all reasons why other, alternative sources of energy are being explored. Try to find out some information about these alternative sources of energy.
When we hang laundry outside to dry in the sun, we are using the sun's heat to do work -- drying our clothes.
The sun has always been an energy source.
Plants use the sun's light to make food. Animals eat plants for food.
And as we found out earlier, decaying plants and animals millions of years ago produced the coal, oil and natural gas that we use today.
So, fossil fuels actually got their start as sunlight many millions of years ago.
The sun can also be used to heat water for hot water in our homes and businesses.
Solar Hot Water
In the 1890s solar water heaters were first used in California. They proved to be a big improvement over wood and coal-burning stoves. Artificial gas made from coal was available too to heat water. But it cost 10 times the price we pay for natural gas today. And electricity was even more expensive!
Many homes used solar water heaters. In 1897, 30 percent of the homes in Pasadena, just east of Los Angeles, were equipped with solar water heaters. As mechanical improvements were made, solar systems were used in Arizona, Florida and many other sunny parts of the United States.
By 1920, thousands of solar water heaters had been sold. But by then, large deposits of oil and natural gas were discovered in the western United States. As these low cost fuels became available, solar systems began to be replaced with heaters using fossil fuels.
Today, solar water heaters are making a come back. There are more than half a million of them in California alone! They heat water for use inside homes and businesses. They also heat swimming pools like in the picture.
Panels on the roof of a building, like this one on the right, contain water pipes. When the sun hits the panels and the pipes, the sunlight warms them.
That warmed water can then be used in a swimming pool.
Solar Thermal Electricity
Solar can also be used to make electricity.
Some solar power plants, like the one in the picture to the right in California's Mojave Desert, use a highly curved mirror called a parabolic trough to focus the sunlight on a pipe running down a central point above the curve of the mirror. The mirror focuses the sunlight to strike the pipe, and it gets so hot that it can boil water into steam. That steam can then be used to turn a turbine to make electricity.
In California's Mojave desert, there are huge rows solar mirrors arranged in what's called "solar thermal power plants" that use this idea to make electricity for more than 350,000 homes. The problem with solar energy is that it works only when the sun is shining. So, on cloudy days and at night, the power plants can't create energy. Some solar plants, are a hybrid technology. During the daytime they use the sun. At night they use natural gas to boil the water so they can continue to make electricity.
Another form of solar power plants to make electricity is called a Central Tower Power Plant, like the one to the right.
Sunlight is reflected off 1,800 mirrors circling the tall tower. The mirrors are called heliostats and turn to face the sun all day long.
The light is reflected back to the top of the tower in the center of the circle where a fluid is turned very hot by the sun's rays. That fluid can be used to boil water to make steam to turn a turbine and a generator.
This experimental power plant is called Solar II. It is being re-built in California's desert using newer technologies than when it was first built in the early 1980s. Solar II will use the sunlight to change heat into mechanical energy in the turbine.
The power plant will make enough electricity to power about 10,000 homes. Scientists say larger central tower power plants will be able to make electricity for 100,000 to 200,000 homes.
Solar Cells or Photovoltaic Energy
We can also change the sunlight directly to electricity using solar cells.
Solar cells are also called photovoltaic cells -- or PV cells for short -- and can be found on many small appliances, like calculators, and even on spacecraft. They were first developed in the 1950s for use on U.S. space satellites. They are made of silicon, a special type of melted sand.
When sunlight strikes the solar cell, electrons (red circles) are knocked loose. They move toward the treated front surface (dark blue colour). An electron imbalance is created between the front and back. When the two surfaces are joined by a connector, like a wire, a current of electricity occurs between the negative and positive sides.
These individual solar cells are arranged together in a PV module. Some of the modules are set on special tracking devices to follow sunlight all day long.
The electrical energy from solar cells can then be used directly. It can be used in a home for lights and appliances. It can be used in a business. Solar energy can be stored in batteries to light a roadside billboard at night. Or the energy can be stored in a battery for an emergency roadside cellular telephone when no telephone wires are around.
Some experimental cars also use PV cells. They convert sunlight directly into energy to power electric motors on the car.
Here's what we Learned
- Sunlight has always been a source of energy for plants, animals and humans. We use sunlight and heat from the sun to dry clothes outside.
- The sun's heat can be used to warm water flowing through pipes on a roof. More than 500,000 solar water-heating systems are used in California.
- Sunlight can also be focussed in a solar thermal system to heat water or other fluids to make steam. The steam can be used to turn turbines to make electricity.
- Sunlight can be used directly in solar cells or PV cells to make electricity.
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 waterpower.
Today, the wind is also used to make electricity.
Blowing wind spins the blades on a wind turbine -- just like a large toy pinwheel. The blades 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 and being damaged.
We have many windy areas in California. The only problem with wind is that it is not windy all year long. 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.
And wind speeds must be above 12 to 14 miles per hour 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 1995, there were 13,437 wind turbines in California. These turbines are grouped together in what are called wind "farms." Theses wind farms are located mostly in the three windiest areas of the state:
- Altamonte Pass east of San Francisco
- San Gorgonio Pass near Palm Springs
- Tehachapi south of Bakersfield
Together these three places make enough electricity to supply an entire city the size of San Francisco with power! About 30 percent of the world's wind-generated electricity are found in California. Other countries that use a lot of wind energy are Denmark and Germany.
But once electricity is made, it has to get from the wind turbines to our homes, factories and schools. The electricity transmission system is discussed in our next chapter.
Here's what we Learned
- Wind energy can be used to do work.
- Wind has been used for many years to drive boats and in windmills to grind grains or pump water.
- Wind turbines are being used today to make electricity.
- Wind spins the large blades which turn generators inside the turbine to make electricity
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 as a source of energy.
For hundreds of years, moving water was used to turn wooden wheels that were attached to grinding wheels to grind flour or corn. Today, moving water can also be used to make electricity.
Hydro means water. Hydroelectric 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. Dams are also built across larger rivers but no reservoir is made. The river is simply sent through a hydroelectric power plant.
The water flows through a pipe called a penstock and pushes against blades in a turbine, causing them to turn. The turbine is similar to the kind used in a power plant that we learned about in But instead of using steam to turn the turbine, water is used.
The turbine spins a generator to produce electricity. The electricity can then go to your home, to your school, to factories and businesses.
Hydropower today can be found in the mountainous areas of California where there are reservoirs and along major rivers.
Here's what we Learned
- Hydropower uses the kinetic energy of moving water.
- The moving water can be used to turn wheels to grind grains or in a hydroelectric power plant to make electricity.
- Moving water goes through a turbine spinning the shaft, which turns a generator to make electricity.
- California's hydroelectric power plants are found along dams on rivers and in the mountains.
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 famous scientist Albert Einstein created the mathematical formula that explains this. It is:
E = mc2
This equation says:
E [energy] equals m [mass] times c2 [c stands for the speed of light. c2 means c times c, or the speed of light raised to the second power -- or c-squared.]
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 the c.
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 , 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.
Nuclear Fission
An atom's nucleus can be split apart. When this is done, a tremendous amount of energy is released. The energy is both heat and light energy. This energy, when let out slowly, can be harnessed to generate electricity. When it is let out all at once, it makes a tremendous explosion in an atomic bomb. The word fission means to split apart.
A nuclear power plant (like Diablo Canyon Nuclear Plant shown on the right) uses uranium as a "fuel." Uranium is an element that is dug out of the ground many places around the world. It is processed into tiny pellets that are loaded into very long rods that are put into the power plant's reactor.
Inside the reactor of an atomic power plant, uranium atoms are split apart in a controlled chain reaction.
In a chain reaction, particles released by the splitting of the atom go off and strike other uranium atoms splitting those. Those particles given off split still other atoms in a chain reaction. In nuclear power plants, control rods are used to keep the splitting regulated so it doesn't go too fast.
If the reaction is not controlled, you could have an atomic bomb. But in atomic bombs, almost pure pieces of the element Uranium-235 or Plutonium, of a precise mass and shape, must be brought together and held together, with great force. These conditions are not present in a nuclear reactor.
The reaction also creates radioactive material. This material could hurt people if released, so it is kept in a solid form. The very strong concrete dome in the picture is designed to keep this material inside if an accident happens.
This chain reaction gives off heat energy. This heat energy is used to boil water in the core of the reactor. So, instead of burning a fuel, nuclear power plants use the chain reaction of atoms splitting to change the energy of atoms into heat energy.
This water from around the nuclear core is sent to another section of the power plant. Here it heats another set of pipes filled with water to make steam. The steam in this second set of pipes powers a turbine to generate electricity.
Learn more about nuclear fission by visiting other web sites:
Nuclear Fusion
Another form of nuclear energy is called fusion. Fusion means joining smaller nuclei (the plural of nucleus) to make a larger nucleus. The sun uses nuclear fusion of hydrogen atoms into helium atoms. This gives off heat and light and other radiation.
In the picture to the right, two types of hydrogen atoms, deuterium and tritium, combine to make a helium atom and an extra particle called a neutron.
Also given off in this fusion reaction is energy! Thanks to the University of California, Berkeley for the picture.
Scientists have been working on controlling nuclear fusion for a long time, trying to make a fusion reactor to produce electricity. But they have been having trouble learning how to control the reaction in a contained space.
What's better about nuclear fusion is that it creates less radioactive material than fission, and its supply of fuel can last longer than the sun.
You can learn more about nuclear fusion by visiting other locations on the Internet. The locations are:
Here's what we Learned
- Nuclear fission means splitting an atom apart.
- Splitting an atom releases heat and light energy.
- In a nuclear power plant, an atomic chain reaction is controlled to produce heat to boil water. That water boils water in pipes to make steam to turn a turbine and a generator to make electricity.
- Nuclear fusion means combines atomic nuclei to make a larger nucleus.
- The sun uses nuclear fusion of hydrogen into helium to make light and heat energy.
- Scientists are trying to create nuclear fusion to make a cleaner source of power.
The world's ocean may eventually provide us with energy to power our homes and businesses. Right now, most ocean energy power plants are only experimental and 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 lighthouse.
Tidal Energy
Another form of ocean energy is called tidal energy. When tides comes into the shore, they can be trapped in reservoirs behind dams. Then when the tide drops, the water behind the dam can be let out just like in a regular hydroelectric power plant.
In order for this to work well, you need large increases in tides. An increase of at least 16 feet between low tide to high tide is needed. There are only a few places where this tide change occurs around the earth. Some power plants are already operating using this idea. One plant in France makes enough energy from tides to power 240,000 homes.
Ocean Thermal Energy
The final ocean energy idea uses temperature differences in the ocean. If you ever went swimming in the ocean and dove deep below the surface, you would have noticed that the water gets colder the deeper you go. It's warmer on the surface because sunlight warms the water. But below the surface, the ocean gets very cold. That's why scuba divers wear wet suits when they dive down deep. Their wet suits trapped their body heat to keep them warm.
Power plants can be built that use this difference in temperature to make energy. A difference of at least 38 degrees Fahrenheit is needed between the warmer surface water and the colder deep ocean water.
Using this type of energy source is called Ocean Thermal Energy Conversion or OTEC. It is being used in both Japan and in Hawaii in some demonstration projects.
Here's what we Learned
- The ocean's energy can be used three basic ways.
- Wave energy systems use the up and down motion of waves to turn a turbine and/or generator.
- Tide energy systems traps high tides in a reservoir. When the tide drops, the water behind the reservoir can flow through a power plant, just like a regular hydroelectric plant.
- Ocean thermal energy conversion uses the difference in temperature between warm surface water and cold Deep Ocean water to make electricity.
Related web site:
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.
But many of the other forms of energy we use in our homes and cars are not being replenished. Fossil fuels took millions of years to create. They cannot be made over night.
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.
To make all of our newspapers, aluminium cans, plastic bottles and other goods takes lots of energy.
Recycling these items -- grinding them up and reusing the material again -- uses less energy than it takes to make them from brand new, raw material.
So, we must all recycle as much as we can.
We can also save energy in our cars and trucks.
Make sure the tires are properly inflated.
A car that is tuned up, has clean air and oil filters, and is running right will use less gasoline.
Don't over-load a car. For every extra 100 pounds, you cut your mileage by one mile per gallon.
When your parents buy a new car, tell them to compare the fuel efficiency of different models and buy a car that gets higher miles per gallon.
You can also save energy in your school.
Each week you can choose an energy monitor who will make sure energy is being used properly.
The energy monitor will turn off the lights during recess and after class.
You can make "Turn It Off" signs for hanging above the light switches to remind yourself.
You can start an in your school. Click the words Energy Patrol to go to another location in our Internet site that tells you how to set one up in your school.
You can make sure your classmates recycle all aluminium cans and plastic bottles, and make sure the library is recycling the newspapers and the school is recycling its paper.
Conclusion
To make sure we have plenty of energy in the future, it's up to all of us to use energy wisely.
We must all conserve energy and use it efficiently. It also ups to those of you who will want to create the new energy technologies of the future.
One of you might be another Albert Einstein and find a new source of energy. It's up to all of us. The future is ours but we need energy to get there.
Related web sites:
Fossil Fuels and the Environment
- Although fossil fuels have several advantages:
- they are accessible,
- they are a mature technology,
- they are transportable,
- there are also several important disadvantages:
- they produce acid rain
- they add to pollution levels
- they contribute to global warming
End Use / Future Energy Sources...
As a country we depend greatly on the use of oil and gas as sources of energy. (). Because it is a finite resource (and we are well aware of this in Louisiana), the use of alternative sources of energy must be explored.
My class is extremely involved in environmental issues throughout the year. One of the units we do relates to alternative energy sources. The objective is for the students to determine what types of energy sources can be used in our location and under what conditions. During this time, the class builds water wheels designed to make something move and experiments with wind power as well as designing and building machines that work using solar power.
As an introduction to the unit we brainstorm the various types of energy sources and discuss all the positive and negative effects of their use. Then, based on this list, the children determine the type of alternative energy source they believe would be best suited for use in our area. The choice is invariably solar power because of the heat in Louisiana. After this unit the children usually revise their choice because it becomes apparent to them that heat is not the necessary ingredient for solar power, it is the rays of the sun that we often do not get because of the cloud coverage.
Summary
Parabolic Solar Collectors collect the light rays of the sun. The light rays reflect off the side’s equal to the angle they came in at (the angle of reflection). Because the shape of the collector is parabolic, the light rays come together at a point above the collector. This point is called the hot spot. The location of the hot spot varies based on the location of the sun, but it can be located by moving your hand around the perimeter and across the inside of the solar cooker until you find the hottest area and then raise your hand slowly until you reach the hot spot. This is usually quite hot.
Materials
Parabolic Solar Collectors (4-5 students can use one simultaneously)-an old umbrella lined with silver mylar works quite well.
Kraft flavored marshmallows (these come in different colours and are important in the assessment of knowledge).
Uncooked spaghetti noodles (as thick as possible) These are used as skewers. The kids eat them after they roast their marshmallows (no trash).
Procedures
A clear, sunny day is a necessity for this activity. (It need not be a hot day but it must be sunny).
Around 11 a.m, place the cookers in an area where no shadows will be cast on them This will allow the cookers to heat up prior to use.
Review the angle of reflection concept with the students.
Explain the method of determining the hot spot on the cookers.
Place your hand about six inches above the rim of the cooker. With your eyes closed, slowly rotate your hand around the perimeter of the cooker. When you find the spot that is hottest, slowly raise your hand until the heat comes to a localized point. The hot spot is where you want to hold your marshmallow. (This also can be determined by using a piece of paper. Place the paper over the hottest area until the light comes to a point on the paper. I prefer having the children feel the heat however.)
Have the children choose the marshmallow they would like to roast and allow them to skewer them using the spaghetti noodles.
Time to Cook
Carefully listen to the children's observations related to the various cooking time of the different colours. Allow plenty of time to discover why some get finished before others. (White will never roast. Chocolate gets finished fastest, and the others vary based on how light the colour is.)
Hold a classroom discussion based on the results. If you wanted to design a solar collector what colour would you want it to be? Why?
At this point the children design different types of collectors that will hold water. These are placed outside in the sun (on a clear day) and tested at 15-minute intervals to determine which heat the fastest.
Roxson Welch: Roxson Welch is a third grade teacher at Baker Heights Elementary. She is the 1993 Presidential Award for Elementary Science Teaching recipient as well as winner of the 1994 Exemplary Elementary Science Teacher for the Council of Elementary Science International and the 1994 Conservationist Teacher of the Year for the Southeastern United States.
Willem (Aug 24) has asked, "...how does one internalise the irreplaceable losses of life and nature?"
Obviously these losses can't be calculated in economic terms. But if it were agreed, that
excessive consumption of fossil fules results in too massive losses of this kind (and there might be other good reasons too), steps could be taken to reduce this consumption by encouraging energy saving and increased energy efficiency.
One way of doing this is to increase the taxation on the use of fossil fules (reducing tax on labour income correspondingly). This can be considered as internalizing costs, which so far have been external only. It is impossible to say whether the costs in question will have been internalised completely or only partly this way. But fuel consumption will be reduced, decreasing the externalities resulting from it and thus the losses mentioned.
As I have written several times to this list, per capita energy consumption in Europe is only about half that of the US. This is not due to more concern with consumers and producers neither about the loss of species and nature values nor about global warming, nor is the living standard in Europe very different from that in the US. It is simply reacting rationally to heavily taxed energy prices - saving energy. Energy prices in Europe are about twice as high as in the US due to taxation.
Admittedly most of these taxes have been imposed years back for fiscal reasons, long before the environment became of major concern (and thus they were not balanced by the reduction of other taxes). But they are for the benefit of the environment today. Just imagine how much the environment would benefit if the present US energy consumption
were reduced to half. A good part of those irreplaceable losses could be avoided. And the end of oil would be farther away - making the transition away from oil more likely to succeed in time.
If we decide through some democratic process what level of protection we
want to give to 'life and nature', then we can charge fees on disturbance
of life and nature, whether paving, monoculture, pollution, taking of
living things for food or other use, or whatever, and the prices we see
in the marketplace will reflect those expressed wishes for preservation
of life and nature. (Prices will be higher for those things which,
according to our own expressions, we ought to consume less of.)
Jay Hanson wrote:
> Economists who assume away political realities are skipping the hard part.
> In the politics-by-money world that economists worked so hard to create,
>
Real demons, these economists, first they labour to create an ugly
political reality, then they pointedly ignore it. How and why did this
change happen?
> It
> is politically impossible to "internalize the costs"
>
So, the fact that environmental costs have been internalized in so many
cases is merely a mirage, is it?
> Booth sees old
> technologies replaced by new technologies which bring new environmental
> problems and new "vested political interests" who are opposed
> environmental
> regulation.
>
And what about new technologies created by environmental regulation,
aimed at fixing environmental problems? (Hint: such constitute a multi-
billion-dollar business in countries such as Germany.) Presumably,
these would be interested in environmental regulation, being self-interested
capitalists.
George Antony
The Carbon Cycle
The carbon cycle is one of the most vital of all the atmospheric cycles. During the carbon cycle, carbon moves from vast reserviors -the ocean and atmosphere- on through organisms and ecosystems. Carbon is entering the atmosphere every second. It does this by cells engaging in aerboic respiration, as fossil fules burn, and as volcanos erupt. The world's oceans hold most of the carbon in a dissolved form. The soild and the plant biomass of the atmosphere are the next largest carbon holders. Most of the atmospheric carbon is in the form of carbon dioxide. The average time that an ecosystem holds any one carbon atom varies greatly. In the Chesapeake Bay ecosystem, decomposers cannot break down organic compounds to smaller bits, so carbon slowly accumulates into peat. From the consumption of fossil fules, and air pollution carbon is not being recycled properly. The result is the green house effect which contributes to global warming.