Session: 30-14 Waste Heat Recovery & Geothermal

Paper Number: 129331

129331 - Comparison of Geothermal Power Systems in Texas 

The state of Texas has the highest renewable energy production in the United States with 33% of their total power generation from wind and solar resources. This study explores the ability to utilize geothermal energy as an underutilized resource in the state. Different cycle architectures and fluids have been compared given the specific geological conditions in the state. The cycle architectures include a supercritical carbon dioxide (sCO­2­) thermosiphon, a natural-convection-driven system utilizing the temperature gradient between the geological reservoir and the surface level power generation system, a direct heated sCO2 simple cycle, and water-brine binary simple cycle for both sCO2 and ORC systems, and a recuperated cycle. Four different fluids were assessed for the different architectures: sCO2, R-134a, R-600, R-717 (ammonia). The cycles were compared through the total power output for the cycles, the cooling duty required, the thermal efficiency and the exergetic efficiency for geothermal reservoir source temperatures between 100-250°C. The pressures and the flow rates were varied to maximize the variables of interest. The results show that all the architectures are viable for power production, but the sCO2 thermosiphon is least attractive due to the low flow rate achieved from natural convection alone. The ORC systems performed the best for low temperature reservoirs while the directly heated sCO₂ system performed the best for the higher temperature reservoirs.

Presenting Author: Owen Pryor Southwest Research Institute

Presenting Author Biography: Dr. Owen Pryor is a Research Engineer at Southwest Research Institute. At SwRI, Dr. Pryor has developed conceptual systems with a focus on the energy infrastructure and decarbonization. He is currently working on several projects related to the optimization of novel cycles for sCO2 and related fluids. He graduated from the University of Central Florida with his Ph.D. in 2018. At UCF, he focused on combustion characteristics and novel diagnostic systems for carbon dioxide diluted methane mixtures. Dr. Pryor has published over 40 publications on turbomachinery and combustion and has 3 patents pending for various novel cycles.

Authors:

Owen Pryor Southwest Research Institute
Cole Replogle Southwest Research Institute
Reese Roddy Southwest Research Institute