Investigation of an auxiliary option to meet local energy demand via an innovative small-scale geothermal-driven system; a seasonal analysis

Abstract

Regarding the decrease in energy supply in urban areas at the peak periods of seasonal consumption, this study is steered towards working on an auxiliary option supporting the required energy load of the urban sector. Since the fluctuations in local energy demand should be addressed via local capabilities, this study focuses on geothermal energy as the renewable energy-based option to design a novel seasonal multigeneration system. The designed small-scale system consists of a flash-binary geothermal cycle (producing electricity) whereby its waste heat is recovered by a regenerative organic Rankine cycle (producing electricity), a desalination unit based on thermal processes (producing freshwater) together with a single-effect absorption chiller and a heating production unit for addressing the warm and cold weather conditions, respectively. The system is comprehensively analyzed from the 3E concept (energy, exergy, and economic) and optimized using a genetic algorithm both thermodynamically and economically. Also, a net present value (NPV) method is used to predict the revenue and payback period of the system. Based on the outcomes, the sensitivity of the performance criteria undergoes a principal variation with the geothermal water inlet temperature. Also, the genetic algorithm estimated that the highest energy and exergy efficiencies and lowest total unit cost of products are respectively 56.04%, 67.25, and 9.37 $/GJ in summer and 57.57%, 68.42%, and 8.73 $/GJ in winter.