The steam from geysers in California, Nevada and Utah is being tapped for power generation but not for greenhouse heating. The heated water that comes from the ground is distributed through fin radiation or root zone heating. There are dozens of greenhouse operations in the Rocky Mountain and West Coast states that are heated by medium temperature geothermal energy. Thermal wells and springs in some parts of the world can provide hot water that can be used directly for heat. Heat pumps are available as air to air, air to water, water to water or water to air systems. This low grade soil heated air or can be used directly, or, for heating the greenhouse to a higher temperature, a heat pump can be used. For the greenhouse production of perennials, herbs, nursery stock and some vegetables.

There is also a lag time of about 8 weeks between the maximum surface temperature and the maximum soil temperature at this level which is helpful in winter heating and summer cooling. At the 5 to 6 foot depth, the temperature is more uniform, averaging about 50РІВРЏ with a variation that depends on soil characterisitcs and the environmental conditions above ground level. The soil temperature at the surface varies considerably over the year and closely follows the air temperature. Geothermal heat resources can be classified into three categories: low, medium, and high temperature. Geothermal heating systems recover this energy and convert it to heat that can be utilized in greenhouses and other buildings. Soil and water below ground contain a vast reservoir of thermal energy.

Geothermal energy for homes