Solar ponds:
Source: Research Institute for Sustainable Energy.
Solar ponds are shallow salt-water lakes, in which high water temperatures can be achieved. Solar ponds are usually lined with black plastic, which acts as an efficient absorber of solar radiation. The fresh water is maintained at the surface, with an increasing salt content towards the bottom of the pond. The combination of dense salt water and solar heat build-up can create temperatures up to 85-90°C, which are sufficient to produce an organic vapour to drive a turbine and a generator.
This method of extracting energy from the sun is interesting but is not yet developed to a stage where it can be considered as a means of generating electricity as cheaply as a coal-fired power station. However, it could possibly compete with a diesel-fired power station in a remote area.
While there have been many experiments in solar pond projects, a number of challenges exist including:
- Wind-induced waves affecting the salinity and temperature gradient;
- Contamination (dust and algae);
- Evaporation;
- Salt water from the pond getting into fresh water underground;
- A long settling-down period (up to 11 months) if the pond is disturbed.
For more information,
go to:
 www.greenhouse.gov.au/renewable/recp/solar/three.html
 Next Section >> Solar farms.
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