Applied Sciences (Nov 2019)
Evaluation of the Coupling of a Hybrid Power Plant with a Water Generation System
Abstract
This paper presents the design and analysis of an energy/water system that combines a 20 MW hybrid concentrated solar/biomass power plant with an advanced wastewater treatment facility. Designed to be installed in one of the most demanding areas of the Iberian Peninsula, the Spanish region of Andalusia, this plant seeks to provide the area with potable water and electricity. The solar block works with a mixture of molten salts, while the biomass backup system of the power plant uses olive pomace. The implementation of a direct potable reuse facility further enhances the sustainability of the project. Urban sewage from the region is collected and passed through a series of purification procedures in order to generate potable water ready to be directly blended into the water distribution system. A sensitivity analysis is conducted to determine the feasibility of the co-generation of electricity and water in the area. With a capacity factor of 85% and an annual operation of 7,446 hours, the hybrid solar/biomass power plant generates 148.92 GWh. Exergetic analyses have been realized for two extreme cases: exclusive use of the solar block and exclusive use of the biomass system. An overall plant exergetic efficiency of 15% is found when the solar block is used and an efficiency of 34% is calculated when the biomass support system is used. Following an economic analysis, a total investment of 211,526,000 € is required for the full implementation of the system with a resulting levelized cost of energy of 0.25 €/kWh. We find that the selling price of the generated potable water which makes the plant operation economically viable is found to be 14.61 €/m3. At present, this price seems relatively high in view of current conditions; yet it is expected to become more realistic under future heightened water scarcity conditions, especially in arid regions.
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