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Geothermal Energy Development Operations and Maintenance: Resource Requirements and Impact Sources

Minimal land-disturbing activities are anticipated during the operations and maintenance phase.

The operations and maintenance phase involves the operation and maintenance of the geothermal field(s) and the generation of electricity. The types of operations and maintenance activities depend on the size and temperature of the geothermal reservoir.

The following factors could contribute to adverse environmental impacts during the operations and maintenance phase of project development.

Operations and Maintenance Phase - Requirements and Impact Sources

  • Acreage Requirements — The operations and maintenance phase would involve from 50 to 350 acres, depending on the geometry of the geothermal system and the anticipated size of the power development. Of this acreage, the power plant itself would account for 15 to 25 acres; the well field development and equipment (including the pipeline system) would account for 5 to 70 acres. The transmission lines would require from 25 to 240 acres, ranging in length from 5 to 50 miles with a corridor width of about 40 feet.
  • Emissions — Emissions would include dust and exhaust from combustion engines (associated with worker and maintenance vehicle traffic). Geothermal power plant electricity generation would result in emissions of carbon dioxide (though much lower than for fossil fuels). Criteria and greenhouse gases could also result from use of heating, ventilation, and air conditioning systems. Particulate emissions would be released from cooling tower drift if wet cooling is used. Fires and accidents could also be a source of air emissions. Well blowouts could be a source of emissions of hydrogen sulfide, carbon dioxide, mercury, arsenic, and boron (if present in the geothermal resource).
  • Waste Generation — Cooling water would be discharged to a permitted evaporation pond. Sanitary waste would be generated by the on-site workforce.
  • Water Needs — Water would be needed for cooling power plants and for reinjection to replenish the geothermal reservoir. Water would likely be brought to the site by a pipeline or obtained from an on-site well.
  • Workforce — During normal operations, full-time operational and maintenance crews would be required at the project site. The number of workers required for the routine operation of a power plant is typically 3 per shift; however, additional workers (as many as 12, depending on the plant size) may be on-site during the day to perform maintenance and management activities.
  • Time — The operations and maintenance phase would last from 10 to 50 years.
  • Utility Requirements — Electrical power needs would be met by the on-site geothermal power plant.