Optimization of Geothermal Energy-Powered Seawater Desalination Systems

PIETRASANTA, ARIANA; MUSSATI, SERGIO F.; MOROSUK, TATIANA; AGUIRRE, PIO A.; MUSSATI, MIGUEL C.

Warsaw

Conferencia; 15TH CONFERENCE ON RESEARCH AND DEVELOPMENT IN POWER ENGINEERING (RDPE); 2021

Institute of Heat Engineering (Warsaw University of Technology) and the Institute of Applied Research (WUT) in collaboration with the Committees on Energy, Thermodynamics and Combustion, Polish Academy of Sciences.

The world´s demands of freshwater and electricity are rising fast. Much research is being conducted at addressing the challenges of using renewable energy for electricity generation and meeting the energy requirements of seawater desalination plants. The coupling of renewable energy sources such as wind, solar, and geothermal with desalination systems holds great promise for increasing water supplies in water-scarce regions. The effective integration of these technologies would allow countries to address water shortage problems with a domestic energy source that does not produce air pollution or contribute to the climate change problem. In this paper, the optimization of a process that integrates a double-flash geothermal power cycle with reverse osmosis (RO) and multi-effect distillation (MED) desalination systems is addressed. To this end, a nonlinear optimization mathematical model of the integrated process is developed and implemented in GAMS – a high-level, general purpose algebraic modeling system for mathematical programming and optimization – and simultaneously solved using the solver CONOPT – a code based on the generalized reduced gradient (GRG) algorithm –. The total annual cost of the integrated system is the proposed objective function to be minimized. The main design specifications are the electricity and freshwater demands, which are considered as model parameters. Also, the number of effects in the MED unit and the seawater specifications (temperature and salinity) are considered as model parameters. The influence of these parameters on the optimal solutions is investigated. Several process alternatives based on an existing geothermal power station are studied.