The primary sources of energy, or primary fuels, need to be processed or transformed into energy sources that are more convenient to run our cars, heat and light our homes, run our music players, and charge our batteries. The energy types, which we use every day, are known as secondary energy sources, or energy carriers. This is because they are made from the primary energy sources – they are not found in nature.
The key carrier energy types - the energy that we use every day are fuels for the home - electricity, natural gas, heating oil, and propane - and the fuels that get us around - gasoline, diesel, and aviation fuels. Hundreds of technologies have been developed to capture, manipulate, and harness large amounts of these energies for useful purposes, thereby improving the quality of our lives.
Fuels for the Home
The fuels we typically use at home are electricity and natural gas. Heating oil and propane are used, primarily in the Northeastern U.S. and rural areas, for heating during the cold winter months. But where do these fuels come from, and how are they made for our use? Why do we use these fuels? The diagram below shows how these carrier fuels are generated and brought to your home.
Please click on each energy source for more information.
Electricity: is a type of energy characterized by the movement of electrons. Electricity is very convenient for use in the home, powering our appliances, TV sets, our air conditioners, and computers – virtually everything in the home. Can you imagine life without this versatile and vital energy carrier?
As illustrated in the Fuels for the Home diagram, it takes a lot of effort to get electricity to our homes. Several primary energy sources – coal, natural gas, oil, nuclear, wind, solar, geothermal, and water power - are all used to make electricity at power plants.
Despite these various energy sources, most power plants generate electricity in similar ways. Click on each type of electric power generation plant on the Fuels for the Home diagram to see how electricity is made.
The electricity also has to be moved from where it is conveniently generated to our homes – often over very large distances. We see these power lines every day and they are a key part of getting electricity to our homes. Learn more about electricity transmission by clicking on the Fuels for the Home diagram.
Coal is the most common primary energy source used to generate electricity, followed by natural gas and nuclear power (uranium fuel). Costs, ease of obtaining and transporting fuels, and the ability to meet the constant demand for electricity are the main reasons for their popularity. As you can see from the Fuels for the Home diagram, these primary fuels must be extracted from the earth, processed, and moved to the power generation plants before electricity can be made. Learn more about how oil, natural gas, coal, and nuclear energy are extracted and processed to make fuels for electric generation by clicking on the Fuels for the Home diagram.
U.S. Electricity Production (2007)
4,064,702
Thousand Megawatt-hours
Share of Net Generation by Source
Coal
49%
Natural Gas
20%
Nuclear
19%
Hydro
7%
Oil
2%
Others
3%
Source: Dept of Energy - Energy Information Administration
Electricity Generation
Costs per kilowatt-hour
Plant Efficiency
Nuclear
2-9 cents
30-48%
Hydroelectric
2-12 cents
60-90%
Oil, Coal, Natural Gas
2-10cents
26-60%
Geothermal
2-10 cents
6-13%
Wind
3-10 cents
30-60%
Solar Thermal
4-20 cents
3-20%
Solar Cells
5-40 cents
10-15%
Average cost to U.S consumers for electricity is 10 cents per kilowatt-hour
Costs Sources:
Efficiency Sources:
United Nations Development Program
California Energy Commission
Nuclear Energy Institute
Dept of Energy
U.S. Department of Energy
U.S. Department of the Interior
University of Massachusetts
Institute of Physics
International Energy Agency
Wisconsin Valley Improvement Co.
Zero Emission Cars
Electricity can also be used to power electric cars – often termed zero emission vehicles. Although the cars themselves do not emit emissions, the power plants that generate the electricity often do. Building the cars and batteries that run them takes energy, usually from the fossil fuels. The metals in the cars and batteries must also be mined and processed, taking more energy. The plastics in the cars and batteries come from oil. Thus there are emissions, environmental issues, and energy consumption of fossil fuels to make and run these cars. To see if there is a net positive benefit to electric cars, scientists and engineers use Life Cycle Analysis, which takes in to account all of these energy and material inputs, environmental effects, and waste streams.
Some questions we may ask ourselves concerning zero emission vehicles are: If we switched from gasoline to electric cars, how much additional electricity would the U.S. need? Does the U.S. have the electrical generating capacity? How quickly and conveniently can you charge the car’s batteries? How does the cost per mile compare with gasoline? Is there a net positive effect on the environment?
You must think about the entire energy picture before you can make wise energy choices.
Natural gas: is a form of chemical energy. Natural gas is commonly used to heat our homes and to cook our meals. Natural gas is extracted from the earth using wells and processed to remove water, carbon dioxide, and other unwanted gases. It is then compressed to provide the energy to move the natural gas via underground pipelines to your home. Since the natural gas fields and processing/compression facilities are often located far from your home, and because it is transported by underground pipeline, most of this infrastructure is invisible to us.
Number of Homes heated by:
Natural Gas
55%
Electricity
39%
Heating Oil
7%
Propane
4%
Source: Department of Energy
Click on the natural gas processing portion of the Fuels for the Home diagram to learn more about how natural gas is extracted and processed.
Heating oil and Propane: are also forms of chemical energy. Heating oil and propane are used to heat homes, especially in the Northeastern U.S and rural areas where natural gas is not available. Heating oil and propane are made from oil, which must be extracted from oil fields using wells, and then sent to a refinery where oil is processed to make not only heating oil and propane, but our transportation fuels, the material that can be turned into plastics, and even asphalt for our roads. Heating oil and propane are then moved to regional storage centers, usually by pipeline, barge, train, or truck, where it is loaded into tanker trucks and sent to our homes.
Click on the oil processing portion of the fuels for the home diagram to see how oil is extracted and processed. You will learn about our transportation fuels in the next section.
Our way of life depends on mobility. Transportation fuels allow us to get to school, to work, to shopping and to get out and have fun – fast and conveniently. All the things we need – like food and clothing – rely on transportation fuels to get to stores in our neighborhoods.
Please click on each energy source for more information.
The fuels we typically use to get around are gasoline, diesel, and when we fly, aviation fuels - all made from oil. According to the Department of Energy, 28 percent of U.S. energy use goes towards moving people and goods around. We drive our cars, trucks, buses, and motorcycles 3 trillion miles a year!
Currently only a small portion of our transportation fuels are made from biomass. Ethanol, commonly made from corn, is blended to varying amounts with gasoline. Biodiesel, made from recycled vegetable oil or made directly from biomass such as soybeans or palm oil plants, can be used as a stand alone transportation fuel, or more commonly, blended with diesel made from petroleum.
U.S. Transportation Fuels Use in 2005 (Billions of Gallons)
Gasoline
138
Diesel
43
Ethanol
4
Biodiesel
0.1
Source: Dept of Energy - Energy Information Administration
Natural gas is sometimes used for transportation, primarily in fleets like buses and government vehicles. But like biodiesel, natural gas is not a common transportation fuel today. A fuel being researched for use in the future is hydrogen.
And very little electricity, less than 0.1 percent according to the Department of Energy, is used as a transportation fuel in the U.S. The most common use is to run electric trains for mass transportation in large cities.
U.S. Transportation Fuel Consumption by Type
Gasoline
62%
Diesel
24%
Aviation Fuel
8%
Natural Gas
2%
Others (biofuels, propane, electricity, etc)
4%
Source: Debt of Energy
But where do these fuels come from, and how are they transformed for our use? The diagram below shows how these carrier fuels are generated and made available for our use. Click on each part of the Fuels for Getting Around diagram to learn more about how the fuels are made and brought to us.
Gasoline, Diesel, and Aviation Fuels: These fuels are a type of chemical energy and are the fuels we use every day to get around. They are made from oil, which must be extracted from oil fields using wells, and then sent to a refinery where oil is processed to make not only gasoline, diesel, and aviation fuels, but fuels to heat our homes, material that can be turned into plastics, and even asphalt for our roads. These fuels are stored in regional distribution centers near population centers before they are moved to your local gasoline station.
These fuels run our cars, trucks, buses, airplanes, locomotives, boats, and cargo ships. What would our lives be like without these vital fuels? Click on the oil refining facility on the Fuels for Getting Around diagram to see how these fuels are made and other interesting facts.
Biofuels: These fuels are a type of chemical energy. They consist of ethanol – an alcohol and biodiesel, which is essentially vegetable oil. They are made from various crops, and are typically blended into gasoline or diesel. Click on the biofuels processing plant in the Fuels for Getting Around diagram to see how these fuels are made and other interesting facts.
Natural Gas: This fuel is also a type of chemical energy. Natural gas must be extracted from natural gas fields, processed to remove impurities, and compressed before it can be used. It is used primarily to run company and government car, bus and truck fleets. Natural gas must be compressed for use in transportation, and most fueling stations don’t have that capability. Click on the natural gas processing plant on the Fuels for Getting Around diagram to see how these fuels are made and other interesting facts.
Hydrogen: This is also a type of chemical fuel. It is currently used to fuel our rockets and the space shuttle. It is being researched as a fuel for future use in transportation here on earth. Hydrogen does not exist in its elemental form on the earth. It needs to be made from molecules which contain hydrogen as a component, such as natural gas or water.
Hydrogen can be used directly as a fuel to be burned – as it is in our space rockets. Hydrogen can also be used to power fuel cells – essentially batteries that run on hydrogen fuel – that could power our vehicles. Click on the hydrogen processing plant on the Fuels for Getting Around diagram to see how this fuel is made and interesting facts.
The primary sources of energy, or primary fuels, need to be processed or transformed into energy sources that are more convenient to run our cars, heat and light our homes, run our music players, and charge our batteries. The energy types, which we use every day, are known as secondary energy sources, or energy carriers. This is because they are made from the primary energy sources – they are not found in nature.
The key carrier energy types - the energy that we use every day are fuels for the home - electricity, natural gas, heating oil, and propane - and the fuels that get us around - gasoline, diesel, and aviation fuels. Hundreds of technologies have been developed to capture, manipulate, and harness large amounts of these energies for useful purposes, thereby improving the quality of our lives.