Saturday, 19 December 2009

Process of Salinity Gradient Thermal Energy

In the twenty-first century the solar pond's design is based on the naturally occurring phenomenon of the salinity-gradient-thermal-energy process which was first observed in Transylvania in the early 1900s. Solar ponds are human-made structures lined with a dark material filled with three layers of different densities of salt to harness the solar power. The green energy that is available is 6,000 times higher than all the global fossil fuel consumption in the last century in 1990. (1) The resulting solar thermal energy is stored within the bottom storage layer of the solar pond. Therefore the hot saline water can be transferred through pipes to be reheated to produce steam. This steam can drive a steam turbine and generator which will provide electricity for the water pumps to ensure the desalination of saltwater from the ocean and drinking water affected by salt in the outback. One of the main advantages of a solar pond application when combined with a desalination plant is that the design can be modified either to suit the densely populated urban or sparsely populated rural areas of Australia. To fully understand the process of the salinity-gradient-thermal-energy, please be so kind as to refer to the data below.

  • The first layer consists of brackish water, which technically can range from 0.5 to 30 grams of salt per litre of water. Brackish water on the whole cannot be defined as a precise example of saline content as this can vary depending on the application of whether it is natural or human-made.
  • The water in the second layer cannot rise because the water in the first layer has less salt content and is therefore lighter in density. The water cannot fall because the water in the third layer has a higher salt content and is heavier in density. The middle layer keeps the top and bottom layers separate acting as a transparent insulator trapping the heat of the sunlight in the third layer.
  • Large quantities of salt are dissolved in the third layer making it too dense for the water and air to rise to the surface. The temperature of the bottom layer of the hot water can range from 70 -100 Celsius, which has a very high salt content. The bottom layer traps the heat in a similar way to a solar storage battery.

Process of Salinity Gradient Thermal Energy
copyright © Marjorie Savill Linthwaite 2004 / 2005 / 2009 - 2010
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Reference List

Solar Pond - courtesy of SpotFilms

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