Solar-Geothermal Hybrid Cycle Analysis for Low Enthalpy Solar and Geothermal Resources

Abstract

Innovative solar-geothermal hybrid energy conversion systems were developed for low enthalpy solar and geothermal resources that take advantage of the potential synergies of solar thermal and geothermal power cycles. A range of power cycle configurations and working fluids were evaluated in terms of both thermodynamic and economic metrics. Accurate pure component property data and equation of state models were utilized using the Aspen Plus platform for mass and energy balance calculations. A parametric steady-state study was completed to examine the performance over the range of conditions resulting from diurnal and seasonal variations as well as geothermal reservoir depletion. The results of the diurnal and seasonal parametric studies were used to estimate the annualized electricity generation. A dynamic model was created for the selected hybrid system and used to examine the transient performance for a typical January day and a typical July day. The study was focused on determining the hybrid configuration that yielded the highest annualized electricity generation. The levelized cost of electricity (LCE) was estimated using equipment costing rules of thumb developed from Aspen HTFS and Aspen ICARUS software and from other sources.