Gas dryers use the combustion of natural gas to create heat, which a fans blows onto wet clothes that are being tumbled in the machine. Electricity is used to power the fan and tumble the contents.
Gas dryers require a gas line connection to function. Natural gas pulled into the unit is then combusted, creating heat that is transferred to a metal heating element. A fan blows air through small holes in the heating element, heating it up as it enters the main chamber and comes into contact with the clothing. This heat causes the water in the clothing to evaporate.
Most dryers use a single motor to power both the fan and the tumbler with a pulley system. While gas dryers use a significant amount of electricity, they use much less than electrical dryers, which must warm the heating element using electrical resistance.
Since the price of heating using natural gas is significantly lower than heating with electricity as of 2015, gas dryers are more economical to run even though they cost a bit more to purchase and may require expert help to install. In addition, gas dryers typically operate at a higher temperature than their electrical counterparts, leading to further savings over time.