Evaluation and optimization of a new energy cycle based on geothermal wells, liquefied natural gas and solar thermal energy.

Today, due to the increase in environmental crises and the challenges facing fossil energies, it seems necessary to exploit and use renewables. Solar and geothermal energies can be integrated as a clean and promising energy production system to produce different forms of useful energy. The existing geothermal wells in Sabalan power plant provide different thermodynamic characteristics. In this regard, this paper develops the thermodynamic-conceptual design and optimization of a new energy cycle based on Sabalan geothermal wells. The considered energy process is based on two flash cycles (FCs), and two bottoming cycles (a Kalina cycle (KC) and a CO 2 -based Transcritical Rankine cycle (CTRC)). KC and CTRC can increase the level of power generation. Besides that, in the planned energy process, heat exchangers are employed in order to reduce energetic and exergetic losses to transfer thermal energy to a liquefied natural gas cycle (LNGC). LNGC can improve the electrical energy production level. Further, it can supply natural gas (NG) to consumers in the suburbs of the power plant. Additionally, a solar energy system based on parabolic trough solar collectors (PTSCs) has been embedded in order to produce a part of the thermal energy of the energy process. In order to achieve optimal results, the genetic algorithm has been applied to optimize the energetic and exergetic performance of the considered energy process. Based on the research outcomes, the total electricity output of the designed energy process is approximately equal to 26.1 MW. Energy efficiency of almost 24.9% and exergy efficiency of nearly 53.4% are calculated for the energy cycle. Furthermore, the total exergy destroyed through the energy process is approximately 29.5 MW. Under the optimization results, the rates of energy efficiency improvement and exergy destruction reduction for mode A (with NG production) are 17.9% and 3.53%, respectively. Besides, for mode B (without NG production) the rates of energy efficiency reduction and exergy efficiency improvement are 31.7% and 22.1%, respectively. Finally, it was found that, on average, almost 112 collectors are required to supply heat based on the assumption of using solar energy. [ABSTRACT FROM AUTHOR]