Natural Gas
Natural gas is the number one energy source for home use, and it is the primary heating fuel for homes in the United States. The biggest reason for the popularity of Natural gas is price. The US Energy Information Adminstration released the following prices for 2007 as stated in equivalent MM of BTUs.

Natural gas is a fossil fuel that is primarily methane, but also includes significant quantities of ethane, propane, butane and pentane. These other materials are removed prior to being delivered to your home. Natural gas is formed by the decomposition of organic matter in the absence of oxygen (anaerobic decay). It is found in oil fields, natural gas fields and coal beds. Less pure forms of natural gas (Biogas) are found in swamps and landfills.

Natural gas is used in homes for central heating, hot water heating, cooking and clothes drying. According to the U.S. Census Bureau in their report Characteristics of New Housing, 2003, 70 percent of single family homes completed in 2003 use natural gas heating, followed by 27 percent that use electric heat, and 2 percent that use heating oil. This is compared with 47 percent of new homes using natural gas in 1986. Approximately 52% of all U.S. homes today are heated and/or cooled with natural gas.

Despite this massive increase in the proportion of homes using natural gas the actual volume of natural gas consumed has not increased to the same degree due to increased efficiency of natural gas appliances. Modern top of the line gas furnaces can achieve efficiencies of over 90 percent (meaning that only 10 percent of the energy contained in the natural gas is lost as waste heat). Even low-end natural gas furnaces achieve high efficiencies, around 78 percent.

Natural gas is also used indirectly in homes as it provides about 20% of the electricity produced.

Natural gas burns cleaner than other oil and coal, and produces less carbon dioxide per unit energy released. For an equivalent amount of heat, burning natural gas produces about 30% less carbon dioxide than burning oil and about 45% less than burning coal.