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Seawater desalination plays an important role when fighting the freshwater scarcity that many places around the world are currently facing. The increasing need for desalinated water is followed by a high energy demand. It is therefore essential that an expansion of desalination capacity is accompanied by a parallel use of renewable energy sources in this process. This thesis presents a techno-economic study on a reverse osmosis (RO) desalination plant, with a nominal power consumption of 15 MW, that is powered by a concentrated solar power (CSP) plant combined with a photovoltaic (PV) power plant, in Kuwait. The main aim of this thesis was to find which system designs would give the lowest global warming potential and levelized cost of the desalinated water. In addition, it has been investigated how electricity price and emission allowance cost could make a solar power plant competitive to the grid. For this purpose, some components in the whole system were simulated using System Advisor Model and Engineering Equation Solver. With the results obtained from the simulations, a dynamic model of the whole system was developed in MATLAB, Simulink where simulations were done for a typical meteorological year in Shagaya, Kuwait. Both on-grid and off-grid systems were considered. In the on-grid case, the lowest cost of water was obtained with only PV (ca 0.65 USD/m3) and this could reduce carbon emissions by 30 % compared to only using the grid. Combining CSP and PV could reduce the carbon emissions by 85 % but with a 35 % increase in water cost. It was found that an electricity price of 0.1 USD/kWh or an emission allowance cost of 70 USD/tCO2-eq would make a CSP + PV plant competitive to the grid. These results indicate that the choice of which system is best for powering an on-grid RO plant depends on how the environmental and economic factors are prioritised. In the case of the off-grid system, both the lowest cost of water (ca 0.9 USD/m3) and the highest capacity factor were obtained with a CSP + PV plant with 16 h of storage, a solar multiple of 3 and a PV capacity of 28 MW. |
