TKM COLLEGE OF ENGINEERING

SEMINAR ON SOLAR UPDRAFT

TOWER

Guided By, Presented By, Dr. Reby Roy M Sajid M7-A, 7329

Contents Abstract Introduction What is Solar Updraft Tower The technology (The Collector, The Chimney, Turbines) The energy storage Solar Updraft Tower in various area Typical dimensions and electrical output Advantages Disadvantages Conclusion References

ABSTRACT

A solar updraft tower power plant – sometimes also called 'solar chimney' or just ‘solar tower’ – is a solar thermal power plant utilizing a combination of solar air collector and central updraft tube to generate a solar induced convective flow of air which drives pressure staged turbines to generate electricity

INTRODUCTION

In many parts of the world there is a growing awareness that some alternative energy sources could have an important role to play in the production of electricity.

However, solar energy represents totally non polluting energy resource that can be utilized economically to supply man’s energy needs for all time.

WHAT IS A SOLAR UPDRAFT TOWER

The Solar Updraft tower is a renewable type power plant. Solar updraft towers are like an inverted funnel, with wide skirt to collect air to then turn a turbine in the tower. (A solar updraft

tower in Australia)

HOW DOES A SOLAR UPDRAFT TOWER WORKS?

Incident solar radiation heats the air under a large transparent collector roof.

The temperature difference causes a pressure drop over the height of chimney resulting in an upwind which is converted into mechanical energy by the turbines and then into electricity via conventional generators.

( Principle of solar updraft tower)

Thus the solar updraft tower combines 3 well-known technologies in a novel way

the glass roof hot air collector

the chimney

wind turbines with generator

Principle of the solar updraft The collector

THE COLLECTOR:Hot air is produced by the greenhouse effect.

The collector consisting of plastic film or glass plastic film. The roof material is stretched horizontally 2 or 6 m above the ground.

The height of the roof increases adjacent to the chimney base, so that the air is diverted to the chimney base with minimum friction loss.

THE TECHNOLOGY

THE CHIMNEY: The chimney itself is

the plant's actual thermal engine. It is a pressure tube with low friction loss because of its optimal surface-volume ratio.

In a large solar chimney the collector raises the temperature of the air by about 40°C.

This produces an up draught velocity in the chimney of about 15m/s. It is thus possible to enter into an operating solar chimney plant for maintenance without difficulty .

Solar Chimney Prototype at Manzanares (Spain)

Several factors contribute to the physical design of the chimney.

The chimney should be designed to minimize the frictional losses

to maximize the pressure difference in the tower.

The pressure difference in the tower is proportional to its height, so maximizing the height of the tower is critical to improving the efficiency of the tower.

TURBINES

Turbines are used to convert kinetic energy of air into the mechanical energy and then to electrical energy.

The air warmed in the collector rises up towards the chimney and runs the turbine.

This results in rotational energy in the turbine.

This rotational energy is converted into electrical energy.

Continued………

Turbine with large diameter

In order to obtain maximum energy from the warmed air, turbine blades should cover all the cross-sectional area of the chimney. To do this one big turbine or a few small turbine s should be used in the chimney

THE ENERGY STORAGE

Water filled black tubes are laid down side by side on the black sheeted or sprayed soil under the glass roof collector.

They are filled with water once and remain closed thereafter, so that no evaporation can take place.

The volume of water in the tubes is selected to correspond to a water layer with a depth of 5 to 20 cm depending on the desired power output.

The water inside the tubes stores a part of the solar

heat and releases it during the night, when the air in the collector cools down .

Principle of heat storage underneath the roof using water-filled black tubes

SOLAR UPDRAFT TOWERS IN VARIOUS AREA

In Spain (Manzanares): The chimney had a height of 195 metres and a diameter of 10 metres with a collection area (greenhouse) of 46,000 m² (about 11 acres (45,000 m2), or 244 m diameter) obtaining a maximum power output of about 50 kW.

Jinshawan Updraft Tower: In December 2010, a solar updraft tower in Jinshawan in Inner Mongolia, China started operation, producing 200-kilowatts of electric power. The 1.38 billion project was started in May 2009 and its aim is to build a facility covering 277 hectares and producing 27.5 MW by 2013. The greenhouses will also improve the climate by covering moving sand, restraining sandstorms

In Namibia: The Namibian government started operation for a 400 MW solar updraft tower called the 'Green tower'. The tower is to be 1.5 km tall and 280 m in diameter, and the base will consist of a 37 km2 greenhouse in which cash crops can be grown.

In Arizona: In October 2010, EnviroMission announced further plans to build two 200 MW Solar Updraft Towers in Western Arizona with the help of Southern California Public Power Authority (SCPPA).

Capacity MW 5 30 100 200

Tower height

Typical Dimensions And Electricity Output

m 550 750 1000 1000

Tower Diameter

m 45 70 110 150

Collector Diameter

m 1250 2900 4300 7000

Electricity Output

GWh/a 14 99 320 680

ADVANTAGES

Due to the heat storage system the solar chimney will operate 24h on pure solar energy.

Solar chimneys are particularly reliable and not liable to break down, in comparison with other solar generating plants.

Unlike conventional power stations, solar chimneys do not need cooling water.

Cultivation of crops. Solar towers built in deserts instigates plant

growth.

DISADVANTAGES High construction cost ◦ Requires a large amount of initial capital Efficiency & Production Cost ◦ Cost/kWh is higher than traditional forms of

natural gas energy production

Requires large amount of land ◦ Not suitable for areas with high cost/acre

CONCLUSION Current energy production from coal and oil is

damaging the environment and are non-renewable. Solar energy is the answer

Sensible technology for the use of solar power must:

-Be simple and reliable,

-Be accessible to the technologically less developed countries that are sunny and often have limited raw materials resources,

-Not need cooling water or produce waste heat,

-Be based on environmentally sound production from renewable materials.

SOLAR UPDRAFT TOWER MEETS THESE

CONDITIONS!!!

REFERENCES www.wikipedia.org

www.sciencedirect.com

www.solarserver.de/lexikon/aufwindkraftwerk.jpg

Non-Conventional Energy Sources by GD Rai

THANK YOU