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Technoeconomic and exergy analysis of a solar geothermal hybrid electric power plant using a novel combined cycle

2018-01-15
Bonyadi, Nima
Johnson, Evan
Baker, Derek Keıth
A novel Solar Geothermal Hybrid Electric Power Plant (SGHEPP) based on the hybridization of an existing binary Geothermal Electric Power Plant by adding a solar-powered steam-Rankine topping cycle is proposed. The proposed SGHEPP has several benefits. First, the hybridization scheme does not require the binary bottoming cycle to be physically modified or operated outside its design conditions. Second, the proposed SGHEPP has a higher turbine inlet temperature, which results in higher solar-to-electricity conversion efficiencies. Third, the daily energy production for the SGHEPP peaks on sunny summer days when electricity prices are generally highest. And fourth, the design reduces the consumption of geothermal resources, which can extend the useful life of declining and marginal geothermal fields. Annual simulations are run for a representative plant in southwestern Turkey and used to assess the plant's energetic, exergetic, and economic performance. The performance of four designs are compared that differ with respect to how the geothermal resources are managed and the size of the solar field. A representative design has an incremental solar efficiency of 12.2% and consumes up to 17% less brine than a similar stand-alone geothermal plant. The calculated solar based LCOE for each design is in the range of 163-172 USD MWh(-1).