How is thermal energy used?

Thermal energy has everything to do with heat. Therefore, solar thermal energy, which involves the capture of heat from the sun, provides our most common uses for thermal energy. Second to solar thermal energy, and growing by leaps and bounds, is geothermal energy, which involves the capture of heat encased within the earth's crust.

There are several different systems for harnessing solar thermal energy, but all involve harnessing solar heat to perform a task:

• Solar thermal power plants use large mirrors to boil a liquid, which creates steam. That steam then turns an electric turbine. 
• Solar hot water systems use solar radiation to heat the domestic water supply. 
• Solar thermal heating collects solar heat to warm the living space.
• Solar pool heating cycles pool water through solar thermal collectors. 

Solar thermal energy is at work every day. It is the force that kicks on at sunrise, warming us on the walk to school or work, and making those summer trips to the lake the pleasant experiences that they are. Any greenhouse, sun room, skylight, window or concrete floor harnesses solar thermal energy in a passive way (without the use of fans, pumps or moving parts of any kind).

Geothermal energy captures heat trapped within the earth. In homes, geothermal energy is used for both heating and cooling. Because the upper layer of the earth's crust remains at a constant temperature year-round, indoor air can be cycled through this layer of earth and either preheated or cooled, depending on the season. In geothermal power plants, deep holes are drilled into the earth to access superheated rock layers and water heated by the earth's molten core. This water is pumped to the surface, where it creates steam and turns an electric turbine.