This presentation gives details about "Solar ponds" This is good topic in non-conventional energy sources category.

1. SOLAR PONDS AND
ITS APPLICATIONS
PREPARED BY-
KUNAL S. MAHAJAN
BE ELECTRICAL, GCOE, JALGAON.

2. INDEX
 INTRODUCTION
 SOLAR POND
 WORKING PRINCIPLE
 ADVANTAGES
 DISADVANTAGES
 APPLICATIONS
 REFRENCES

3. INTRODUCTION
 As we know SOLAR energy is widely freely available, and is said to be
future energy as it is renewable energy.
 Solar energy is free ,but the devices and methods of storing solar thermal
energy are very expensive.
 Had you ever thought of storing the solar thermal power without any
expensive solar storage devices?
 SOLAR POND, is a one of method for trapping and storing solar energy
and using it later as the input for thermal power generation plant.

4. What is a solar pond?
A pool of saltwater which acts as a
large-scale solar thermal
energy collector
It includes an integral heat storage
for supplying thermal energy

5. Solar pond
 A solar pond is a body of water that collects and stores solar
energy.
 Solar energy will warm a body of water (that is exposed to the
sun), but the water loses its heat unless some method is used
to trap it.
 Water warmed by the sun expands and rises as it becomes
less dense. Once it reaches the surface, the water loses its heat
to the air through convection, or evaporates, taking heat with
it.
 The colder water, which is heavier, moves down to replace the
warm water, creating a natural convective circulation that
mixes the water and dissipates the heat.

6. Construction
 We know that fluids such as water and air rise up when heated.
 Solar ponds stops this process when large quantity of salt are
dissolved in hot bottom layer of the pond, making it too dense
to rise to surface and cool down.
 Solar pond consists of three main layers. The top layer is cold
and has little salt content. The bottom layer is hot,70-80°C , and
very salty.
 Separating these two layers is important gradient zone. In this
salt content increases with increase in depth. Water in gradient
zone can’t rise, because water above it has less salt content and
is therefore lighter.
 Similarly, water can’t fall because water below it has a higher salt
content and is heavier.
 Thus the stable gradient zone act as a transparent insulator,
permitting sunlight to be trapped in the hot bottom layer, from
which useful heat is withdrawn.

7. Working
 When solar radiation strikes the pond, most of it is absorbed by the
layer at the bottom of the pond.
 The temperature of the dense salt layer therefore increases.
 If the pond contained no salt, the bottom layer would be less dense
than the top layer as the heated water expands. The less dense layer
would then rise up and the layers would mix.
 But the salt density difference keeps the ‘layers’ of the solar pond
separate.
 The denser salt water at the bottom prevents the heat being
transferred to the top layer of fresh water by natural convection,
due to which the temperature of the lower layer may rise to as
much as 95°C.

8. Heat Extraction
 For application purpose heat is to be extracted from
bottom layer of the pond.
 Pumping the brine i.e. saturated hot salt water
through an external heat exchanger or an evaporator
removes the heat from the bottom layer.
 In an heat exchanger there is inlet of cold water and
outlet for hot water.
 This hot water is then used for various applications,
such as thermal power plant, dairy plants,etc.

9. Solar Pond In Electric Circuit

10. Energy-Cost Comparison

11. Advantages
 Environment friendly energy – no pollution!
 Reliable energy source.
 Stores heat, so it can be used 24*7*365.
 Can be constructed according to requirements.
 Low maintenance costs.

12. Disadvantages
 Low efficiency
 Space availability
 Salt and water supply needed
 Low efficiency due to:
 Heat losses
 Bottom losses
 Top losses
 Radiation losses

13. Solar Ponds In India

14. APPLICATIONS
 Salt production (for enhanced evaporation or purification of salt, that is
production of ‘vacuum quality’ salt)
 Aquaculture, using saline or fresh water (to grow, for example, fish or brine
shrimp)
 Dairy industry (for example, to preheat feed water to boilers)
 Fruit and vegetable canning industry
 Fruit and vegetable drying
 Grain industry (for grain drying)
 Water supply (for desalination) .

15. References
 G.D.Rai,Khanna Publication, 'Energy Sources’.
 Enersalt website (2011) Solar pond. Available at:
http://www.enersalt.com.au/Local%20Publish/html/more_info.html
(Accessed: Mar. 2011)
 http://www.ece.utep.edu/research/Energy/Pond/pond.html
 http://journals.tubitak.gov.tr/physics/issues/fiz-98-22-6/fiz-22-6-6-
97061.pdf
 http://www.teriin.org/case/solar.htm

16. For more info contact
kunalmahajan03@gmail.com