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