Closed Cycle Convergent Solar Chimney
Summary
A new configuration is described for conversion of solar energy into electricity using natural convection in a closed cycle. It is based on the solar chimney but with a venturi multiplication of up to 100 times the vertical flow velocity. The air flow is accelerated inside a conical glass vessel with a turbine fitted near the top of the cone. Exit air then falls under gravity via an outer channel to complete the cycle. The key feature is that the work done in lifting air to the level of the turbine is simultaneously exactly compensated by the potential energy gained by air falling in the outer return channel. There is no nett loss to gravity. The closed cycle has a theoretical efficiency of up to 100%. Calculations are presented for an experimental model of height 3 m, absorber diameter 4 m and turbine diameter of 0.4 m. At insolation 750 wm-2 this could generate up to 9.42 kwh and could be the basis of solar home electricity systems. A Table is presented of calculations for larger models of height 3, 5, 10, 20, 50 and 100 m and ever larger output. The author asks readers to build an experimental model to verify and develop the proposal.