CSP and THE desalination of sea water
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| Click the picture for a larger image showing
how waste heat from CSP can be used for the desalination of sea water. The
diagram also shows how melted salt may be used to store solar heat so that
electricity generation may continue through the night. |
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One of the most interesting aspects of CSP is that the waste heat from the turbines may be used for the desalination of sea water. This is shown schematically in the diagram on the right.
The basic idea is that spent steam from the turbines is used to raise the temperature of sea water (via a heat exchanger) causing it evaporate. The water vapour that comes off is then condensed as fresh water. This is normally done in a succession of stages ("multi-effect distillation") to improve overall efficiency. A vacuum is applied at all stages to promote evaporation.
A neat feature of this process is that it also has the effect of cooling the spent steam, something that is in any case needed in all thermal power stations. Without the cooling effect of the desalination process, the spent steam would normally be cooled by means of a cooling tower that sheds the waste heat into the atmosphere—a scandalous waste of energy that has been a feature of traditional power stations for many years, and is still widespread.
A team of researchers at the German Aerospace Center has produced a study called 'AQUA-CSP' about using waste heat from CSP plants for the desalination of sea water. A copy may be downloaded from the Reports page.
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Last updated: 2009-01-05
(ISO 8601)
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