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.

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.

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.

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.

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).

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.

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.

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 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.