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).

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

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.

The national average is around 1.5 million gallons per well , according to the EPA.

The national average is around 1.5 million gallons per well , according to the EPA.

The national average is around 1.5 million gallons per well , according to the EPA.

U.S. energy consumption is projected to rise 9% by 2040, or 0.3% per year, while global consumption will increase about 50% over the same period

U.S. energy consumption is projected to rise 9% by 2040, or 0.3% per year, while global consumption will increase about 50% over the same period

U.S. energy consumption is projected to rise 9% by 2040, or 0.3% per year, while global consumption will increase about 50% over the same period

Increasing market share of compact fluorescents was primarily responsible for the increased lighting efficiency between 2001 and 2010.

Increasing market share of compact fluorescents was primarily responsible for the increased lighting efficiency between 2001 and 2010.

Increasing market share of compact fluorescents was primarily responsible for the increased lighting efficiency between 2001 and 2010.

In 2014, the industrial sector represented 32% of U.S. energy use, while transportation was 28%. Residential and commercial were 22% and 19% respectively.

In 2014, the industrial sector represented 32% of U.S. energy use, while transportation was 28%. Residential and commercial were 22% and 19% respectively.

In 2014, the industrial sector represented 32% of U.S. energy use, while transportation was 28%. Residential and commercial were 22% and 19% respectively.

The most recent federal efficiency standards, finalized by the U.S. National Highway Traffic Safety Administration (NHTSA) and the Environmental Protection Agency (EPA) in 2012, are projected to increase fuel economy to the equivalent of 54.5 mpg for cars and light-duty trucks by model year 2025, while also reducing CO2 emissions. 

The most recent federal efficiency standards, finalized by the U.S. National Highway Traffic Safety Administration (NHTSA) and the Environmental Protection Agency (EPA) in 2012, are projected to increase fuel economy to the equivalent of 54.5 mpg for cars and light-duty trucks by model year 2025, while also reducing CO2 emissions. 

The most recent federal efficiency standards, finalized by the U.S. National Highway Traffic Safety Administration (NHTSA) and the Environmental Protection Agency (EPA) in 2012, are projected to increase fuel economy to the equivalent of 54.5 mpg for cars and light-duty trucks by model year 2025, while also reducing CO2 emissions. 

The most recent federal efficiency standards, finalized by the U.S. National Highway Traffic Safety Administration (NHTSA) and the Environmental Protection Agency (EPA) in 2012, are projected to increase fuel economy to the equivalent of 54.5 mpg for cars and light-duty trucks by model year 2025, while also reducing CO2 emissions. 

Fossil fuels represent the largest source of stored solar energy, resulting from the transformation of biomass over millions of years into oil, natural gas and coal. 

Fossil fuels represent the largest source of stored solar energy, resulting from the transformation of biomass over millions of years into oil, natural gas and coal.