The energy we capture for use on Earth comes largely from the Sun or from nuclear forces local to our own planet.

The energy we capture for use on Earth comes largely from the Sun or from nuclear forces local to our own planet.

Fossil fuels (petroleum, natural gas, and coal) account for 84% of the energy used in the United States.

Fossil fuels (petroleum, natural gas, and coal) account for 84% of the energy used in the United States.

Gasoline, diesel fuel, and natural gas all release CO2 when burned.

Gasoline, diesel fuel, and natural gas all release CO2 when burned.

Gasoline, diesel fuel, and natural gas all release CO2 when burned.

Electricity is a secondary energy source because it can only be produced from the use of primary energy sources such as coal, natural gas, or nuclear reactions.

Electricity is a secondary energy source because it can only be produced from the use of primary energy sources such as coal, natural gas, or nuclear reactions.

Electricity is a secondary energy source because it can only be produced from the use of primary energy sources such as coal, natural gas, or nuclear reactions.

Electricity is a secondary energy source because it can only be produced from the use of primary energy sources such as coal, natural gas, or nuclear reactions.

In 2008, wind accounted for 0.5% of America’s energy portfolio.

In 2008, wind accounted for 0.5% of America’s energy portfolio.

Renewable energy accounted for 7% of the total U.S. energy supply in 2008, less than any other type of energy source.

Renewable energy accounted for 7% of the total U.S. energy supply in 2008, less than any other type of energy source.

Nuclear power accounted for 9% of the U.S. energy supply in 2008.

Nuclear power accounted for 9% of the U.S. energy supply in 2008.

Out of all the renewable energy sources, biomass contributed the most to U.S. energy consumption in 2008.

Out of all the renewable energy sources, biomass contributed the most to U.S. energy consumption in 2008.

Out of all the renewable energy sources, biomass contributed the most to U.S. energy consumption in 2008.

In 2008, the United States depended most on coal to generate electricity. Coal provided approximately 49% of the electricity generated by the United States that year.

In 2008, the United States depended most on coal to generate electricity. Coal provided approximately 49% of the electricity generated by the United States that year.

In 2008, the United States depended most on coal to generate electricity. Coal provided approximately 49% of the electricity generated by the United States that year.

Oil, biofuels, natural gas, and coal are all used to generate electricity in the United States.

Oil, biofuels, natural gas, and coal are all used to generate electricity in the United States.

Oil, biofuels, natural gas, and coal are all used to generate electricity in the United States.

Oil, biofuels, natural gas, and coal are all used to generate electricity in the United States.

Nearly 80% of France’s electricity is produced by nuclear power plants.

Nearly 80% of France’s electricity is produced by nuclear power plants.

Less than 2% of the U.S. supply of natural gas is imported from outside North America.

Less than 2% of the U.S. supply of natural gas is imported from outside North America.

More than a quarter of the world’s coal reserves are located in the United States.

More than a quarter of the world’s coal reserves are located in the United States.

In 2005, a million Btu of energy from coal cost approximately $2, versus $5 for natural gas and $10 for oil. However, prices can fluctuate due to changes in the economy and new government policies.

In 2005, a million Btu of energy from coal cost approximately $2, versus $5 for natural gas and $10 for oil. However, prices can fluctuate due to changes in the economy and new government policies.

Almost 1% of U.S. electricity was generated by wind in 2008.

Almost 1% of U.S. electricity was generated by wind in 2008.

Tidal energy is gravitational in origin. Solar energy comes from nuclear reactions in the Sun.

Tidal energy is gravitational in origin. Geothermal energy comes from radioactive decay inside the earth.

Tidal energy is gravitational in origin. Solar energy comes from nuclear reactions in the Sun, and geothermal energy comes from radioactive decay inside the earth.

The ampere, or amp, is the most commonly used measurement for electric current.

The ampere, or amp, is the most commonly used measurement for electric current.

The ampere, or amp, is the most commonly used measurement for electric current.

There is no silver bullet. Tomorrow’s energy, like today’s, will likely come from a variety of sources.

There is no silver bullet. Tomorrow’s energy, like today’s, will likely come from a variety of sources.

There is no silver bullet. Tomorrow’s energy, like today’s, will likely come from a variety of sources.

Consuming the largest amount of energy, space heating accounts for 31% of all residential energy used. Space cooling accounts for an additional 12% of energy usage.

Consuming the largest amount of energy, space heating accounts for 31% of all residential energy used. Space cooling accounts for an additional 12% of energy usage.

Consuming the largest amount of energy, space heating accounts for 31% of all residential energy used. Space cooling accounts for an additional 12% of energy usage.

U.S. consumption of energy sources is projected to rise by 13% between now and 2030.

U.S. consumption of energy sources is projected to rise by 13% between now and 2030.

Worldwide consumption of energy sources is projected to rise by nearly 50% between 2006 and 2030.

Worldwide consumption of energy sources is projected to rise by nearly 50% between 2006 and 2030.

The United States and Canada are both developed countries. China and India are projected to have the greatest growth in energy consumption between 2006 and 2030.

Pakistan and Turkey are developing countries, but it is China and India that are projected to have the greatest growth in energy consumption between 2006 and 2030.

In 2008, 37% of the United States’ total energy consumption came from oil, more than any other energy source.

In 2008, 37% of the United States’ total energy consumption came from oil, more than any other energy source.

With less than 5% of the world’s population, the United States is home to one-third of the world’s automobiles.

With less than 5% of the world’s population, the United States is home to one-third of the world’s automobiles.

In 2008, the United States used approximately 99.2 quads. One quad is about as much total energy as the city of Chicago requires in one year.

In 2008, the United States used approximately 99.2 quads. One quad is about as much total energy as the city of Chicago requires in one year.

90% of the coal mined in the United States was used to generate electricity in 2006.

90% of the coal mined in the United States was used to generate electricity in 2006.

With 5% of the planet’s population, the United States uses 20% of the world’s total energy.

With 5% of the planet’s population, the United States uses 20% of the world’s total energy.

Roughly 21% of the electricity used in residential and commercial buildings goes to lighting.

Roughly 21% of the electricity used in residential and commercial buildings goes to lighting.

Roughly 21% of the electricity used in residential and commercial buildings goes to lighting.

In 2008, industry used 31% of the total energy used; next was transportation at 28%, then residential at 22%, and commercial at 19%.

In 2008, industry used 31% of the total energy used; next was transportation at 28%, then residential at 22%, and commercial at 19%.

In 2008, industry used 31% of the total energy used; next was transportation at 28%, then residential at 22%, and commercial at 19%.

The average U.S. household consumes an average of 10,000 kilowatt-hours each year.

The average U.S. household consumes an average of 10,000 kilowatt-hours each year.

In 2008, the U.S. imported about 66% of its oil supply. This percentage is expected to grow even higher over the next two decades.

In 2008, the U.S. imported about 66% of its oil supply. This percentage is expected to grow even higher over the next two decades.

The British Thermal Unit, or Btu, is frequently used as a measure for energy content of fuels. One gallon of gasoline contains about 124,000 Btu.

The British Thermal Unit, or Btu, is frequently used as a measure for energy content of fuels. One gallon of gasoline contains about 124,000 Btu.

The British Thermal Unit, or Btu, is frequently used as a measure for energy content of fuels. One gallon of gasoline contains about 124,000 Btu.

While wind energy has many benefits, all of the above are considered drawbacks to wind energy.

While wind energy has many benefits, all of the above are considered drawbacks to wind energy.

While wind energy has many benefits, all of the above are considered drawbacks to wind energy.

Biofuels contain carbon and although they may burn “cleaner” than oil-derived fuels, they do not avoid generating carbon dioxide emissions.

In the United States, the transportation sector releases the most CO2. In 2006, the transportation sector released nearly 2 billion metric tons of carbon dioxide, nearly all of which was from oil.

In the United States, the transportation sector releases the most CO2. In 2006, the transportation sector released nearly 2 billion metric tons of carbon dioxide, nearly all of which was from oil.

In the United States, the transportation sector releases the most CO2. In 2006, the transportation sector released nearly 2 billion metric tons of carbon dioxide, nearly all of which was from oil.

Almost 20% of the world’s CO2 is released by the United States.

Almost 20% of the world’s CO2 is released by the United States.

The average U.S. car gets 21.4 mpg. About 19 pounds of carbon dioxide are emitted for every gallon burned, or 0.9 lb/mile.

The average U.S. car gets 21.4 mpg. About 19 pounds of carbon dioxide are emitted for every gallon burned, or 0.9 lb/mile.

Coal-fired power plants are likely to emit 30% less CO2 in 2030.

Coal-fired power plants are likely to emit 30% less CO2 in 2030.

All of the above are emitted from coal-fired power plants and can be harmful to our health and the environment.

All of the above are emitted from coal-fired power plants and can be harmful to our health and the environment.

All of the above are emitted from coal-fired power plants and can be harmful to our health and the environment.

All of the above are emitted from coal-fired power plants and can be harmful to our health and the environment.

Mining coal disturbs the land and modifies the chemistry of rainwater runoff, which in turn affects stream and river water quality.

U.S. domestic production of crude oil peaked around 1970 at about 9.5 million barrels per day and declined to about 5.1 million barrels per day by 2006.

All of the above are emitted by vehicles running on gasoline and diesel fuel.

All of the above are emitted by vehicles running on gasoline and diesel fuel.

All of the above are emitted by vehicles running on gasoline and diesel fuel.

All of the above are emitted by vehicles running on gasoline and diesel fuel.

Based upon the 2007 CAFE standards, the new average mpg required by 2020 is 35 mpg.

Based upon the 2007 CAFE standards, the new average mpg required by 2020 is 35 mpg.

In 2009, there were no commercial coal-fired plants utilizing carbon capture and sequestration.

In 2009, there were no commercial coal-fired plants utilizing carbon capture and sequestration.

All of the reasons mentioned are considered obstacles to producing cars that run on hydrogen fuel cells.

All of the reasons mentioned are considered obstacles to producing cars that run on hydrogen fuel cells.

All of the reasons mentioned are considered obstacles to producing cars that run on hydrogen fuel cells.

A gallon of gasoline contains about the same energy as 1 kg of hydrogen. Although fuel cells are expected to be twice as efficient as gasoline vehicles, hydrogen is very diffuse and storing an ample supply on board represents an engineering challenge.

A gallon of gasoline contains about the same energy as a kg of hydrogen. Although fuel cells are expected to be twice as efficient as gasoline vehicles, hydrogen is very diffuse and storing an ample supply on board represents an engineering challenge. Take the full quiz to learn your energy IQ.

Energy intensity is a measure of a nation’s energy efficiency represented through energy use per unit of GDP (Gross Domestic Product).

Energy intensity is a measure of a nation’s energy efficiency represented through energy use per unit of GDP (Gross Domestic Product).

Reducing demand through the improved efficiency of devices and procedures is another way to improve our energy situation.

Lighting accounts for 18% of the electricity used in the United States. A 12% decrease in overall electricity use in buildings could be realized if incandescent bulbs were replaced with CFL or LED bulbs.