National Teacher Enhancement Project

Middle School Home Energy Audit


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What is energy production?


Electricity is the force of moving electrons. Electrons are the tiny charged negative particles of a atom that move around the nucleus of an atom. The nucleus is composed of protons (positive charged) and neutrons (neutral charge). Electrons are held in their shell by an electrical force between the electron and the proton. The number and charge of the electrons are equal to the number and charge of the protons when the atom is balanced. The neutrons can vary in number. The electrons closest to the nucleus have a strong attraction or force to the protons in the nucleus. The electrons in the outer shells sometimes do not have a strong attraction and can be forced out of their shell or orbit. Electron can move from one atom to another by applying a force. Electricity is moving electrons.
Have you every crossed a room and felt a shock when you touched an object? This is called static electricity. It is the streaming electrons from you to another object. Lightning is the movement of electrons from cloud to cloud or cloud to ground. The electrons push against each other and move because like forces repel each other, opposite the force between electron and proton that attracted each other.

Magnets use in Electricity

All of the forces are in balances in most objects with half of the electrons distributed evenly and orbiting in one direction or force, and the other half distributed evenly in another direction or force. An object that does not have even scattering or distribution of electrons is the magnet. Most of the electron are on opposite ends of the magnet and orbiting in opposite directions. Imbalance forces are created between the ends or one pole the North (N) and the other end or pole the South (S). The electrons flow from the North Pole to the South Pole making a magnetic field. Magnets also repel like or the same charged particles(proton to proton), (electron to electron) if you put the same charged Pole together ( North to North), (South to South). Magnets also attract if you put the opposite Pole (North to South) together. The same as the opposite charge particles proton and electron attract each other.

This magnetic property can be used to produce electricity by using the push and pull of the magnetic fields. Electrons in some metals (Aluminum ,Copper) are easily pushed from their orbits by magnets. Power plants make electricity by using hugeturbines. A variety of nonrenewable or renewable fuels may be used to super heat water into stream that turns the turbines. The turbines are attached to a generator shaft. Coils of metal and magnets are inside the generator with electrons being pushed or pulled from one metallic atom to another by the magnetic field that is moving. From the wire electricity goes to a transformer that steps up the voltage.
Transmission lines are where the electrons from the transformer flow at a higher voltage for more efficiency. Electricity travels very quickly to our homes. Before it goes into our home it goes through step-down transformers at substations and step-down transformers outside our homes. In the United States the electricity is 120 volts and the usage is measured by a meter from the Utility Company.


The cost of electricity depends on the cost of the fuel to generate electricity; the cost of the building where it is generated, and the efficiency of the power plant to change the type of energy into electricity. Electricity is neither a renewable or nonrenewable energy source but a secondary source that we have to use nonrenewable or renewable energy to make it.





Coal makes over 50 % of the electricity in the United States because it is cheap and abundant. Coal, natural gas and oil are considered fossil fuels because they are chemical remains of old sea animals and plants. Coal is nonrenewable resource (cannot be made in a short amount of time) that developed from the remains of plants that lived in large swamps millions of years ago. Through pressure and heat the plant material chemically and physically changes to a product that has less oxygen and a higher concentration of hydrocarbon.

Underground and surface mining are the the ways coal is mined for usage. Coal goes from mining to a preparation plant for cleaning and then it is usually shipped by train to the power plants. Most coal in the U. S. is burned to heat water into steam. The power plants where the fossil fuel is burned are called thermal because they use heat energy. Coal burning produces emissions of carbon dioxide and sulfur. Power plants try to remove the sulfur by using low-sulfur coal (anthracite) and machines (scrubbers) to remove sulfur from the emissions. Sulfur can react with oxygen to produce sulfur dioxide, a chemical that can harm trees and water when it combines with water to make acid rain.


Nonrenewable-Natural Gas

About 13 % of electricity in the United States is a result of the chemical conversion of natural gas to heat energy for electricity. Natural gas, like coal is another fossil fuel. It is the result of pressure and heat changing ancient plants and tiny sea animals.

Natural gas usually has to be drilled since it is trapped in deep underground pockets of porous rocks. It can be found by itself or in petroleum deposits or coal beds. After it is drilled or comes out of the earth it has to be cleaned and separated into parts. The major chemical in natural gas is methane but there are smaller parts of butane and propane that are separated out after processing. In the drilled form, natural gas is a nonrenewable resource but landfill natural gas is a renewable resource since it can be made from rotting garbage. It is transported by pipelines from the source to its final destination. The major use for natural gas is not electricity but industry.



About 3% of electricity in the United States is a result of the chemical conversion of petroleum to heat energy for electricity. Petroleum, like coal and natural gas is a fossil fuel. It is the result of pressure and heat changing ancient plants and tiny sea animals. Petroleum like natural gas has to be drilled since it is trapped in deep underground pockets of porous rocks. Crude oil or oil are other names for petroleum. and when it comes out of the ground it can be as thick as tar or as thin as gasoline. It is also a nonrewable source since we cannot make new petroleum. After the oil is drilled, it has to be pumped up the surface and moved through pipelines to an oil refinery. At the oil refinery, the oil is processed into many types of fuels like diesel, heating and jet or thousands of products. Most petroleum products are transported through pipelines after the refinery.

The environment may be harmed with oil exploration, oil drilling, and pipeline, so the petroleum industry is working hard to protect the environment.



Propane is rarely used to convert to electricity in the United States. It is another fossil fuel like coal, natural gas and petroleum. Since it is a fossil fuel it is a nonrenewable resource. It is the result of pressure and heat changing ancient plants and tiny sea animals. Propane is mixed usually with petroleum and natural gas in underground deposits.

When natural gas is processed one of the gases that separates out is propane with methane being 90 per cent. When petroleum is refined gasoline is the major product and propane is another. After the refining propane is piped to distribution centers and then to bulk plants. Propane is stored under pressure as a liquid in tanks for easier storage. Propane is mainly used in rural United States in homes and farms that are not easily accessed by natural gas pipelines. Propane is a clean-burning fuel that leaves engines clean and almost pollutant free.


Greenhouse Effect

The atmosphere is composed of nitrogen , oxygen and greenhouses gases. Less than one percent of the atmosphere are greenhouse gases ,which composed water vapor, carbon dioxide, methane, CFC's, ozone and nitrous oxide. Carbon dioxide is produced when we burn fossil fuels and wood. Methane is produced when animals and plants decay.

The greenhouse effect is the trapping or absorbing of heat energy in the atmosphere by the greenhouse gases and bouncing it back to earth. This level of greenhouse gases has increased in the last few years and the average temperature on earth has risen. This effect is called global warming. Some scientist think this will cause major problems for earth and that we should lower the amount of fossil fuels we burn. The U. S. is responsible for a third of world's carbon dioxide emissions or 25 tons of carbon dioxide per person each year. Generating electricity accounts for much of the carbon dioxide emissions. Generating electricity by most renewable sources does not produce carbon dioxide because no fuel is being burned.



Nuclear energy can be broken down into two areas; nuclear fusion and nuclear fission. Nuclear fusion is where the energy is released when the nucleus of the atoms are combined or fused together to form a large atom. This type of energy production is part of the future because of the cost of hydrogen power plants. The sun produces this type of energy.
Nuclear fission is the splitting of atoms to form smaller atoms, releasing energy. Nuclear power plants use this type of nonrewable energy to produce energy by splitting atoms that are easily split like uranium. During nuclear fission a small atomic particle called a neutron hits the nucleus of the atoms (usually uranium) and breaks it into lighter elements and energy. The energy is the energy released from the bonding of the protons and electrons together to make the element. In this process more neutrons are released which go on to hit other nucleus of atoms in a repeated process called chain reaction. This process is used in nuclear power plant reactors with the core of the reactor containing the uranium fuel. Ceramic pellets about 1 centimeter contain uranium fuel that give off energy equal to 120 gallons of petroleum. Fission generates heat that boils water. The steam turns huge generators like the coal plant but the steam has to changed back into cooled water in a structure called the cooling tower. This process is repeated over and over to produce energy. The waste is radioactive and causes environmental problems if not handled properly.

Renewable- Biomass

Biomass can pollute the air when it is burned like a fossil fuel but sulfur and acid rain are not produced. Biomass is a renewable energy because it is and energy source that we can grow more in a short amount of time since it is any organic matter that can be used as an energy source. It is the oldest energy source.( wood burning) Plants get their energy from the sun in a process called photosynthesis.

To release the energy you do not only have to burn the biomass, you can release it by bacterial decay, fermentation or conversion from gas to liquid. Bacterial decay is the way garbage in landfill changes to methane. Wells are drilled to capture the methane. Methane is then purified and used as an energy source to produce heat (thermal energy) or electricity. Fermentation is adding bacteria to biomass and produce ethanol (an alcohol). We can use 10 percent ethanol made from corn and added to gasoline to run our cars. The engines in our cars do not need to be changed plus it is a less polluting fuel. Adding heat and chemicals to biomass can convert it into liquid fuels and gas. The gas and liquid fuels can be converted into thermal energy or electricity. India used cow manure to produce methane gas in this way for heat and lights.


Renewable- Geothermal

Geothermal or the earth's heat is a renewable resource. It is generated in the earth's core and we can dig well and pump the heated underground water to the surface. Most of the geothermal activity is found along the crustal plate boundaries where volcanoes and earthquakes occur.

One of the types of geothermal is hydrothermal energy which has water and heat. In the United States, low temperature (50-300 degrees Fahrenheit) hydrothermal is used for heating buildings and agriculture. High temperature (300-700 degrees Fahrenheit is used to make electricity. The resources are harvested by drilling wells and piping the hot water (steam) to the surface. The dry steam power plant has the geothermal resource piped from the well to a turbine generator to make electricity. When the steam cools the water is piped back into the earth. Geothermal only produces .4% of our electricity in the United States. Geothermal power plants produce almost no emissions and don't have to transport or burn fuel to produce electricity.



The energy from the sun is produced by nuclear fusion in the suns core and travels at the speed of light to earth (186,000 miles/ second). Solar energy is a renewable source since there will be solar energy as long as the sun exists.
Solar electricity and be produced by photovoltaic cells (PV cells or solar cells) or solar thermal systems. Solar cells are made up of silicon (sand) and can supply energy to batteries or electrical power. When sunlight strikes the solar cell, electrons move around causing an electric current. This conversion requires no machinery but it is very expensive. It is 25 cents a kilowatt-hour compared of 8.9 cents on the average. Photovoltaic systems are mainly used in undeveloped areas. Solar thermal systems use solar energy to produce electricity by concentrating the energy. This is done by a solar collector with a mirrored surface to focus sunlight onto a receiver that heats a liquid. The super heated liquid makes steam to produce electricity.

Renewable- Wind

Wind is the result of the uneven heating of the earth surface causing air to be in motion. Wind is a renewable resource because as long as there is a sun there will be wind.
Wind machines or mills have been used for centuries in harnessing the wind's kinetic energy. There are two types of wind machines; horizontal, and vertical. Horizontal-axis wind machines have blades that are parallel to the ground and vertical-axis wind machines go at a 45 degree angle to the ground. Wind plants or farms have to be carefully designed and located for maximum wind harvesting. The disadvantage to wind machines is that the wind does not always blow at 14 mph or more to make kinetic energy that can be converted to electricity. This type of wind happens only 25% of the time. The advantage is that it does not pollute and there will always be wind.


Hydro means water in Greek. The moving water is kinetic energy. Hydropower is a renewable energy source because as long as it rains. Hydropower has been around for centuries.

Hydro power plants are usually built on a river or an artificial dam to allow for storing water for potential energy. The hydro plant is usually made up :

  • a dam that allows for water to be controlled
  • a lake or reservoir where water can be stored
  • a plant where the power or electricity is produce
The dam opens up to allow water to flow through the gate into a large tube (penstock) onto a turbine blade. The fast moving water spins the turbine blade that is attached to a generator to produce electricity. The electricity is then transported to the utility company by transmission lines. Hydropower produces eight to 11 percent in the United States. World wide hydropower is 25% of the electricity production total.


Electricity can be produced by a chemical reaction between two metals and a chemical solution in a battery. Different ends of the battery are attached to different metals and the chemicals free more electrons on one level than the other. The end that frees more electrons is the positive charged (more protons) and the other end develops a negative charge because it have more electrons. When a wire is attached from the positive to the negative end a flow of electrons passes through the wire to balance the forces. A device that does work is a load. A light bulb or object can be placed in between the flow and electricity can do work (see the previous Energy page). Batteries can be used to store energy for future use. One example of that is the use of batteries to store excess electrical energy in photovoltaic systems. The energy stored in batteries after generation by the solar cells can then be used when the sun does not shine.


Students: Click on the button at the left to connect to the Power Worksheet.

Created for the NTEP II Fermilab LInC program sponsored by Fermi National Accelerator Laboratory Education Office and Friends of Fermilab, and funded by United States Department of Energy, Illinois State Board of Education, North Central Regional Technology in Education Consortium which is operated by North Central Regional Educational Laboratory (NCREL), and the National Science Foundation.


Authors: Sue Emmons, Powell Middle School, Littleton, CO; Kevin Lindauer, John F. Kennedy High School, Denver, CO; Linda Lung, National Renewable Energy Laboratory, Golden, CO; John Sepich, Scott Carpenter Middle School, Westminster, CO; ; Janet Stellema, Monarch K-8, Louisville, CO.
Created: September 9, 1998 - Updated: October 3, 2001.