Integrating desalination with concentrating solar power: large scale cogeneration of water and electricity.

[摘要] ENGLISH ABSTRACT: The demand for fresh water is a growing concern that is shared globally. Finite fresh water resources, accompanied by an exponential population growth will demand the need for additional installed desalination plants worldwide. However, desalination is extremely energy intensive with the costs thereof depending on the availability of local energy resources (coal, oil, gas, etc.). Fortunately, most arid regions generally also have high solar energy resources that could be utilized instead of conventional fossil fuel resources. Concentrating solar power (CSP) is steadily gaining more market acceptance as the cost of electricity from CSP power plants progressively declines. Cogeneration is an attractive prospect for future CSP developments as the simultaneous production of power and potable water can have positive economic implications towards increasing the feasibility of CSP plant developments. This is a theoretical case study, within the context of Namibia, in Southern Africa, investigating the possible benefits and concerns of integrating a multiple-effect desalination (MED) plant with a 100MWe concentrating solar power (CSP) tower plant for the large scale cogeneration of electricity and potable water (CSP+D). The focus of this study is set on the analytical modelling of a MED plant which captures the sensitivities of the parameters required for cogeneration analysis. A simplified CSP and Rankine cycle is modelled in terms of the optical-to-thermal conversion of energy. The high capital costs of thermal desalination heat exchangers as well as the pumping of seawater far inland is the most significant barrier in making this approach competitive against more conventional desalination methods such as reverse osmosis. The compromise between the lowest levelized cost of electricity and potable water depends on the sizing and the top brine temperature of the desalination plant. Additionally, the feasibility and final sizing of a CSP+MED plant would ultimately depend on the Namibian CSP tariffs and structures as well as the tariff for desalination.

[发布机构] Stellenbosch University