Wind turbines are the most successful source of renewable energy but wind is unpredictable. Solar energy is predictable and thoroughly reliable. If solar energy could be used to provide the air flow for a wind turbine using natural convection, then wind turbines could have the availability of solar energy.
Using the principles of the solar air collector, the solar chimney and the venturi, a configuration has been devised and customised to provide air flow to a 100 m diameter wind turbine at its rated velocity 15 ms-1 at maximum insolation. It requires a chimney of 50 m height and 300 m diameter surrounded by a solar collector of diameter 560 m. The air flow generated passes through a convergent-divergent nozzle at the base of the chimney to multiply air flow velocity; the horizontal rotation turbine is sited in the throat of the nozzle. It is calculated that at insolation 750 wm-2 the solar driven wind turbine generates 15.6 MW with an efficiency of 11.6%.
The efficiency of conversion of air flow in a ducted turbine to electricity is much higher than for a turbine in open air. This and the higher availability of solar energy mean that a 100 m diameter turbine used in this configuration will generate 5-10 times the output of its equivalent conventional turbine. If built in repeat patterns on desert or low value agricultural land, the solar driven wind turbine could generate an average 14 MW km-2 in tropical climates.
The author asks experts in solar and wind energy to consider, test and develop the proposal.