Geothermal Direct-Use — Meeting Clean Air Standards
Someday, geothermally heated greenhouses, like this one in Idaho, may be able to use the carbon dioxide found in geothermal fluids as a growth stimulant.
Geothermal direct-use applications—such as greenhouses, district and space heating, and aquaculture—can easily meet local and federal clean air standards, which help protect our environment.
Geothermal fluids vary from resource to resource. The low- to mid-temperature geothermal fluids used for direct-use typically contain lower levels of gases than the higher temperature fluids used for power production. And today, most geothermal direct-use applications circulate these fluids through closed-loop, emissions-free systems.
The carbon dioxide found in geothermal fluids could prove beneficial to direct-use greenhouse applications. Carbon dioxide is a very effective growth stimulant for plants. Studies have shown that an increase in carbon dioxide from a normal level of 300 part per million (ppm) to approximately 1,000 ppm can raise crop yields up to 15 percent. Therefore, some researchers suggest that geothermal heating systems could utilize the carbon dioxide present in the fluids if they find a way to remove any hydrogen sulfide, which can damage plants. Most geothermal fluids usually contain low, non-hazardous levels of hydrogen sulfide.