Electronic Submersible Pump (ESP) Technology and Limitations with Respect to Geothermal Systems (Fact Sheet)

The current state of geothermal technology has limitations that hinder the expansion of utility scale power. One limitation that has been discussed by the current industry is the limitation of Electric Submersible Pump (ESP) technology. With the exception of a few geothermal fields artificial lift technology is dominated by line shaft pump (LSP) technology. LSP's utilize a pump near or belowreservoir depth, which is attached to a power shaft that is attached to a motor above ground. The primary difference between an LSP and an ESP is that an ESP motor is attached directly to the pump which eliminates the power shaft. This configuration requires that the motor is submersed in the geothermal resource. ESP technology is widely used in oil production. However, the operating conditionsin an oil field vary significantly from a geothermal system. One of the most notable differences when discussing artificial lift is that geothermal systems operate at significantly higher flow rates and with the potential addition of Enhanced Geothermal Systems (EGS) even greater depths. The depths and flow rates associated with geothermal systems require extreme horsepower ratings. Geothermalsystems also operate in a variety of conditions including but not limited to; high temperature, high salinity, high concentrations of total dissolved solids (TDS), and non-condensable gases.