Solar Driven Wind Turbines - an alternative configuration for the solar chimney of modest height and high efficiency


The solar chimney has a cylindrical chimney about 1000 m height at the centre of a solar collector of area up to 20 km2.  Turbines at the base of the chimney harness the kinetic energy of air flow.  The overall efficiency is 2-3%.

An alternative configuration is proposed with an annular (ring-shaped) chimney of modest height forming the outer circumference of the solar collector.  This provides the chimney with a very large cross-sectional area.  Turbines are symmetrically sited around the inner circumference of the solar collector to harness the kinetic energy of incoming air flow.  The total area of cross-section of the turbines is severely restricted.  In this way air flow velocity through the turbines is a considerable multiple of its velocity through the chimney.  Efficiency is multiplied by the square of this multiple.

Calculations have been carried out for a range of dimensions from height 200 m down to height 3 m with maximum output ranging from 174 MW down to 3 KW.  An experimental model is suggested of chimney height 10 m and outer diameter 25 m.  This gives maximum output 127 KW with an efficiency of over 40%.

The author asks experts on the solar chimney to carry out a theoretical assessment of the proposals and to build, study and improve on the experimental model suggested.  The configuration described could provide electricity from solar energy on a large scale with 40-50% efficiency.

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