Advanced Power Plants for Use with Hot Dry Rock (HDR) and Enhanced Geothermal Technology

Abstract

The future commercialization of the Hot Dry Rock (HDR) or Enhanced Geothermal System (EGS) technologies will be dependent on solving both technical and economic issues. The major identified barriers to commercialization of these technologies are the costs of drilling the wells, the supply of water and the pumping of the HDR produced brine. Drilling costs are related to the geological formations and well depth, and thus power plants, which effectively utilize lower temperature fluids from shallower wells can reduce power production costs. Power plants which do not consume any water in the conversion process regardless of fluid temperatures, and are insensitive to water chemistry, can optimize HDR/EGS commercial power projects. Organic Rankine Cycle (ORC) binary based power conversion technology effectively utilizes air cooled condensers with no consumption of geothermal fluid. Such closed loop power plants generate electricity with EGS produced fluid with temperatures from 95oC to 315oC without loss of water in the power plant, and with no corrosion or scaling of the plant components. In addition, modular power units may be used to increase power plant capacity as more EGS fluid production is developed. This presentation describes advanced geothermal power conversion systems and along with case histories of operating power plants employing these conversion systems.