Thermal energy is used to cook food, heat buildings and generate electricity. The joule, named after James Prescott Joule, is the unit by which thermal energy is measured.
It is easy to confuse thermal energy and heat, or even think that the terms can be used interchangeably. However, the two terms are quite different. Thermal energy is the energy that comes from heat. When thermal energy is transferred, it is called heat. Heat is a temperature and is measured in degrees of Fahrenheit or Celsius. An object can contain thermal energy, but it cannot contain heat.
Thermal energy most commonly comes from fossil fuels such as coal or gas. In addition, thermal energy can be generated by resources such as biomass, solar and geothermal.
- Biomass - this is a fuel generated from organic materials. Some examples are scrap lumber, manure and forest debris
- Solar - in addition to being used for producing electricity, sunlight can also be used to generate heat. Solar water heaters are one example of using the sun as a resource for thermal energy
- Geothermal - geothermal energy is heat from the earth. Some examples of sources for geothermal energy are hot springs, hot steam from vents in the earth and using the stable temperature of the earth in conjunction with underground heat pumps