Geothermal Results – Life Cycle Assessment Review
To better understand geothermal power systems, NREL completed a comprehensive review and analysis of life cycle assessments on flash steam and enhanced geothermal systems (EGS) published between 1980 and 2010.
The figure below shows the results of the review and analysis of published life cycle assessments on geothermal electricity generation passing screens for quality and relevance. Life cycle assessments estimate that full life cycle CO2-equivalent emissions for geothermal energy technologies are less than 50 g CO2eq/kWhe for flash steam geothermal power plants and less than 80 g CO2eq/kWhe for projected EGS power plants.
Although few geothermal studies are available for review, these findings suggest that greenhouse gas emissions for geothermal technology are small relative to those of coal-fired electricity generation. Additional geothermal life cycle assessments are needed to better understand sources of variability and to corroborate the results published to date.