ˆ Introductionˆ The Solar Chimney a. Parts of the Solar Chimney i. Collector ii. Turbines iii. Chimney b. Working Principles of Solar Chimney c. Technology 9. The Energy Storage In the Collector 10. Cost 11. The Mildura Solar Chimney 1 Advantages 1 Disadvantages 1 Conclusion 1 References
The end of oil is coming; The energy demand will be doubled in the next 30 years Insecurity in energy supplies International tensions However a major threat is more urgent to be encountered ClimateChangeThe overall electrification rate in India is 64.5% while 35.5% of thepopulation still live without access to electricity.Total Installed Capacity in India (as on 30-06-2011) is 1,76,990.40 MW
Today, there is a growing awareness that some alternative energy sourcescould have an important role to play in the production of electricity. However, only the solar energy represents totally nonpollutinginexhaustible energy resource35,000 km² area of the Thar Desert has been set aside for solar power projects,sufficient to generate 700 to 2,100 GW.In 2010, total worldwide energy consumption was 1,32,000 TWh (377lack MW). The potential for renewable energy is: solar energy 4,44,000 TWh, wind power 1,67,000 TWh, geothermal energy 1,39,000 TWh, biomass 70,000 TWh, Hydropower 14,000 TWh and ocean energy 280 TWh. For India, because of location, solar energy is best suited.
There are lots of methods of using the solarenergy , and the Solar Chimney is one of them, whichcan be seen below, in figure 1. Fig. 1 The Prototype Manzanares Solar Chimney.
In 1978, it was suggested by Professor Schlaich of Stuttgartuniversity that power could be produced by a hybrid solar system.The solar chimney system consists of three parts; The collector, Turbines. The chimney.
2.a.i. The Collector Collector is the part, which isused to produce hot air bygreen-house effect. It is usually 5-6meters high and covers a very largearea about thousands of m² as seen infıgure 2. Fig. 2 The Collector.
Fig. 3 The glazed collector roof of Solar Chimney.
There is no limitation for the surface area.The larger the area, the more energy generated fromthe chimney. There should be slightly increasing height towards tothe chimney in order to obtain minimum friction loss. Covering materials may be different, such as; glass,plastic film or glazed collector. The most efficient oneis glazed collector.It can convert up to 70% of irratiated solar energyinto heat a typical annual average is 50%.
2.a.ii. Turbines Turbines, seen in figure 4, are used to convert air current to the mechanical energy. Turbines are placed horizontally in chimney, vertically in the collector. To do this, one big turbine or a few small turbines should be used in chimney, as can be seen from the figure 5. and figure 6. Fig. 6 Small turbines  Fig. 5 Turbine with largeFig. 4 Turbine for Solar Chimney diameter .Power Station.
2.a.iii. The chimneyThe most important part of theplant is the chimney,seen in fıgure7.It acts likes a pressure tube. Fig. 7 The chimney. Longer the chimneys height, the more the energy produced from thechimney. The efficiency of the chimney is not depend on the amount of thetemperature rising, but depends on the outside temperature.• Thus, efficiency directly proportional to the ratio between the heightof the chimney and the outside temperature.
Transparent roof, which is seen infıgure 8, admits the short wave solarradiation component and retains long-waveradiation from the heated ground. Thus, when solar radiation passthrough the transparent roof it is absorbedby the ground elements and it converts intoheat energy. Fig. 8 Transparent roof.
So, Why use a pipe or air channel to enclosethe turbines? Why not have a large "windfarm ," with turbines mounted on towers inthe open air?
Answer: First, the wind turbines enclosed in a pipe can produce 8 times as much power for a given wind speed than a turbinein the open air. Second, the wind farm concept would require a muchlarger numbers of turbines. Also, the wind speed in the open air around thecollector is significantly less than the air velocity through the airchannel.
The Floating Solar Chimney is made by a set of successive tubular balloons, can beconstructed with an existing polyester fabric giving lowinvestment cost(as shown in the figure beside). These tubes are lighter thanair due to internal lighter thanair gas (He or NH4)
This accordion type folding end isunfolding partly when the structureis bending, securing that the warmair does not escape from its Direction ofbottom. Wind Main Chimney made of parts Heavy Mobile Chimne Base y Seat Folding Lower Part
Supporting RingInner fabric wall Inflated or Aluminum tubeStrong fabric ofthe heavy base Lifting Tube Filled with lifting Gas Lower ring of the heavy base Upper Ring of the heavy base Accordion type folding lower Seat of the part floating solar chimney
The body with the heavy base of theFloating Solar Chimney is incliningdue to external winds. Wind direction
w eibull c ons tant k = 2; dec line 50 % for v= 10 m /s ec Due to the titling property of 8the FSC, its operational height 7is decreasing under externalwinds 6 5 dec reas e in F S C H eight % 4 3 2 1 0 1 1.5 2 2.5 3 3.5 4 Á verage annual w ind s peed in m /s ec
Since collectors produce hot air by greenhouse effect, to produce electric during thenight, tight water-filled tubes are placedunder the roof, as seen in fıgure 12. The water heats up during the daytime Fig. 12 Principle of heat storage underneath the roofand emits its heat at night. using water-filled black tubes . These tubes are filled only once, nofurther water is needed, because the tubesremain closed after filling process.
The 1000m Solar Chimney inMildura, Australia, will be the highestman-made structure on Earth, and canproduce 200MW of electricity,providing power to 200,000homes.Schematic seen of aconstruction of a chimney is in figure14. Fig. 14 Construction of a chimney
Details of the solar chimney are as follows:Location: Mildura, AustraliaType: Solar Tower power plant with steel-reinforced concrete tower andsteel/glass solar air collector (alternatively with polymer glazing)Features: The base of the tower will be between 170 to 200 metres. Thechimney is basically a very simple tube with wall thickness of 25cm,diameter of 150m and a height of 1000m. The collector roof will be 5000min diameter.Power: Up to 500 Gigawatt hours per yearCompany: Enviromission LtdConstruction time: About 18-24 monthsExpected completion date: 2005 .
• Thus a glass roof SAEPP, generating 20 GWh/year and ratingpower ~4.5 MW, of area ~1.0 square Km, and with an FSC ofH~800m and d=40m, should cost ~63.20 Crore RUPEES
It provides electricity 24 hour a day from solar energy alone. No fuel and no cooling water is required. By FSC of 1000m, up to 1.2% of horizontal solar radiation can be convertedinto electricity.It is a low investment cost electricity generating technology, thus the directcost of the produced KWh is low (less than 6 cents/KWh) The materials concrete, glass and steel necessary for the building of solarchimney power stations are everywhere in sufficient quantities. No ecological harm and no consumption of resources. The collector itself functions as a greenhouse and could be used forgrowing cash crops.It is shown that FSC Technology Power Plants is 5 to 6 times cheaper thanCFC Technology Power Plants.
Some estimates say that the cost of generating electricity from asolar chimney is 5x more than from a gas turbine. Although fuel isnot required, solar chimneys have a very high capital cost. The structure itself is massive and requires a lot of engineeringexpertise and materials to construct .
Solar chimney power stations could make important contributions to theenergy supplies in Africa, Asia and Australia, because there is plentyof space and sunlight available there. By little improvement in Efficiency and cost reduction, it can bebest alternative Future electricity demand could reach the 45000 T Wh. Thenecessary land for the 30 years FSC power plants is 1.000.000 Km2(1000 Km X 1000 Km)
“Thermal engineering” by R.K.Rajput 6th edition ch.13 Draught A brief history of solar chimney.Retrieved 02.07.2009 from; http://www.visionengineer.com/env/solar_flue.shtml Solar Chimney-Technology.Retrieved from; http://www.sbp.de./de/html/projects/solar/aufwind/pages_auf/techno.htm. ‘Solar chimney cost estimation’ from www.solartower.org.uk/floating-papageorgiou.php Solar Chimney-Energy cost.Retrieved 10.11.2004 from; http://www.sbp.de/de/html/projects/solar/aufwind/pages_auf/enprocos.htm www.floatingsolarchimney.gr/.../EEESD_Modular_solar_collector. Efficiency of FSPs from Retrieved 10.11.2004 http://www.solar- tower.org.uk/floating-papageorgiou.php Solar collector material; Retrieved 07.11.2008 from www.sciencedirect.com/science/article/pii/