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.

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.

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

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

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

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

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.

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.

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).

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.