Investigation of three integrated energy systems with desalination, heat storage, thermochemical cycles and heat upgrade

Abstract

This thesis study proposes three different novel renewable energy-based multigeneration integrated systems with molten salt heat storage and desalination options where copper-chlorine (Cu-Cl) and magnesium-chlorine (Mg-Cl) thermochemical water-splitting cycles for hydrogen production are used. System 1 integrates the wind, solar and geothermal energies with high temperature electrolysis, methanol synthesis and multi-effect desalination. Systems 2 and 3 have two variants such that the first variant considers integration of solar and geothermal-energies with multi-effect desalination and thermochemical hydrogen production through Cu-Cl and Mg-Cl cycles respectively. The second variant of systems 2 and 3 replaces the solar thermal energy with mercury-based heat pump system to provide the required heat for the respective thermochemical cycles. Systems are presented and analyzed thermodynamically through energy and exergy approaches to be compared with each other in terms of their energy and exergy efficiencies. A series of parametric studies have been conducted for all the systems in order to see the effects of different operating conditions on energy and exergy efficiencies and system outputs. Five case studies have been performed by considering Vancouver, Canada to produce five useful outputs to meet the needs of a community. These commodities are electricity, freshwater, space heating, hot water, hydrogen and methanol (only for the first system). According to thermodynamic analysis, the second variant of system 3 is capable of achieving an overall energy efficiency of 49.58% and an overall exergy efficiency of 59.23% for the system which uses heat upgrading options from geothermal energy to meet the high-temperature requirement of the thermochemical Mg-Cl cycle chosen as a hydrogen production method at 25 °C ambient temperature and 101 kPa ambient pressure. At the same time, the second variant of system 3 has 47012 kW exergy destruction rate which is the lowest one when compared to other evaluated systems.