Development of a Hybrid Powerplant for Kuwait: The Simultaneous Production of Power, Fresh Water and Cooling

The harsh summer months of Kuwait combined with massive urbanisation projects, population growth and generous subsidies resulted in a rapid increase in electricity and freshwater consumption over the past 30 years. This led the government to invest heavily in large and capital intensive cogeneration powerplants that generate electricity via steam turbines and produce desalinated seawater through the utilisation of the multi-stage flash (MSF) desalination process. Air-conditioning (A/C) load accounts for about 70% of electric peak-load during summer. As a result, Kuwait consumes annually millions of barrels of oil and tons of natural gas that can be otherwise exported or saved for the future as a strategic commodity. The main objective of this research is to develop, model and recommend an optimum hybrid powerplant configuration and operation strategy for Kuwait that can simultaneously satisfy the demand for electricity, freshwater and cooling based on minimum fuel consumption. This is achieved by modelling and simulation of steam Rankine cycle, MSF water desalination and absorption refrigeration systems (ARSs) in Matlab to estimate their steam consumption. Reverse osmosis (RO) desalination and vapour-compression A/C are linked to the hybrid simulation program via their electricity consumption. Simulations show that during the hybrid configuration power-RO-AR is the most viable for Kuwait. During the winter months of January, February and December the optimum operation strategy with minimum fuel cost is the power-RO. On the other hand, operating the powerplant in the power-RO-AR hybrid mode during summer results in minimum fuel cost. The total annual fuel cost savings resulting from modifying the Doha West (DW) powerplant configuration and operation strategy are estimated to be about $363 million. This amounts to savings of about 8 million barrels of oil and 114 million m3 of natural gas per year. Furthermore, the payback period of hybridising the DW powerplant by adding RO desalination and AR system is one year with net savings of $127 million in the second year of operation.