Greenhouse heating is one of the popular applications of geothermal energy because using this renewable resource in the greenhouse industry is both an economical and efficient way to heat. Geothermal heating systems can be designed to utilize low-temperature ( > 100°F) geothermal resources, which makes the greenhouse an attractive application. These resources are widespread throughout the western states providing a significant potential for expansion of the geothermal greenhouse industry. The evaluation of a greenhouse project for the utilization of geothermal energy is covered in an accompanying article, "Geothermal Greenhouse Heating" by Kevin Rafferty