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.

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.

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.

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.

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.

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.

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

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.

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.