A Department of Energy funded study of advanced cycles and high-potential working fluids for Organic Rankine Cycles (ORC) for use in Enhanced Geothermal Systems (EGS) and their impact on cost of electricity has been conducted. The work completed to date, in coordination with AltaRock Energy, Inc., characterized the performance of advanced cycles and high-potential working fluids for EGS resource temperatures. A cash flow model to estimate the levelized cost of electricity (LCOE) is being developed. This model includes high resolution cost models for the EGS reservoir in combination with the power plant. The impact of power cycle, working fluid, and geothermal well specifications on LCOE and optimized plant configurations are evaluated. From an available list of more than 17,000 pure components, 35 working fluids were identified as high-potential. In addition to the numerous fluids that were screened from commonly available sources, additional fluids were screened from vendors that are less common or even not on the market yet. An additional 3 working fluids were included for comparison to the current state-of-the-art. The performance of the working fluids was evaluated in a subcritical ORC, supercritical ORC, and trilateral flash cycle and compared to the performance in baseline subcritical ORCs. The primary advantage of the supercritical cycle or trilateral flash cycle over the subcritical cycle is a better match between resource cooling curve and working fluid heating curve. The lack of constant temperature evaporation allows the heat source to be cooled to a lower temperature despite a similar pinch point as in a comparable subcritical cycle leading to greater utilization of the geothermal resource. The supercritical cycle offers significant improvement in net power output compared to a baseline subcritical cycle. The topics that will be presented include the modeling efforts for the supercritical, subcritical and trilateral flash cycles, the cost & economic modeling of EGS plants and results of the comparison with baseline subcritical cycles resulting in a 30-50% increase in net power output and optimized LCOE calculations. Disclaimer “This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability of responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, or process, or serviceable by trade name, trademark, manufacture, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state of reflect those of the U.S. Government or any agency thereof.”

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