Eviro Seminar

Solar energy scenario in India • 200 clear sunny days. • Annual reception :- 5000 trillion kWh • Potential of 35 MW per square km. • Average solar energy incident:- 4-7 kWh/m2 • Solar energy produced is only 0.5 % of other energy sources.

What is a Solar Updraft Tower? • Sometime also called as ‘solar chimney’ or just ‘solar tower’. • It is a solar thermal power plant. • Combination of solar air collector and central updraft tube to generate a solar induced convective flow.

Three essential elements • Solar air collector • Chimney/Tower • Wind turbines

Working of Solar Updraft Tower • Air is heated by solar radiation under a low circular transparent or translucent roof open at the periphery • Thus, the roof and the natural ground below it form a solar air collector. • In the middle of the roof is a vertical tower with large air inlets at its base.

Contd…. • The joint between the roof and the tower base is airtight. • As hot air is lighter than cold air it rises up the tower. • Suction from the tower then draws in more hot air from the collector, and cold air comes in from the outer perimeter

Properties of Collector • Hot air for the solar tower is produced by the greenhouse effect. • It consist of a glass or plastic glazing stretched horizontally several meters above the ground. • The height of the glazing increases adjacent to the tower base. • This glazing admits the solar radiation component and retains long-wave re-radiation from the heated ground.

Working of solar updraft tower

Storage

Design of Solar Updraft Tower • Output of solar tower:P = Qsolar . ŋcoll . ŋtower . ŋturbine • Input of solar tower:Qsolar = Gh . Acoll • Efficiency of Tower:ŋtower = Ptot /Q

How draft is caused? • The tower converts the heat-flow into kinetic energy and potential energy. • Density difference of the air caused by the temperature rise in the collector works as a driving force. • The lighter column of air in the tower is connected with the surrounding atmosphere at the base and at the top of the tower, and thus acquires lift.

Advantages of Solar tower • There’s no fuel (no exploration, transport, disposal, smog, or landscaping costs) • The primary cost is in the initial development as operating costs are minimal • No pollution or planet-warming gases. • As compared to wind farms, the sun is more consistent (in the right locations). • Freely available source of energy.

Disadvantages of Solar Tower • Conversion of solar to electrical energy is only 0.5 % (5 W/m2 of 1 kW/m2) • Initial cost is very high. • Design is complicated. • More area is required for the construction of solar tower.

(Burronga Station, Riverland area of New South Wales, Australia)

Specifications of Enviro Mission Tower • • • • • •

Electricity generation :- 200 MW. Chimney height :- 1000 metre (3281 feet). Collector :- 7 km diameter. Wind speed :- 70 km/hr (49 ft/sec). Consist of 32 wind turbines. 35 degrees Celsius on the edges of the greenhouse to around 70 degrees Celsius once it reaches the middle. • Cost of electricity will be 7 euro cents per kWh.

Features of Enviro Mission Solar Tower • Cost of project is about one billion australian dollars. • Will provide enough electricity for around 2,00,000 households. • It will abate over 9,00,000 tons of greenhouse gases from entering the environment.

Prototyping • Located in Manzares, Spain. • 50 kW prototype plant. • Operated for seven years and conclusively proved this technology. • It was a base for construction of the 200 MW project.

Comparison of enviro mission tower with other tall buildings