Solar Home Electricity using Natural Convection - proposal for a mini solar chimney with venturi to multiply air flow velocity and to generate electricity from solar energy with high efficiency



Photovoltaics have made possible the massive increase in solar electricity during the last decade with their application to individual homes and community schemes.  Convection is one of the vital processes of nature playing a dominant role in the atmosphere, the oceans and in the sun.  Is it possible to devise a small solar convection engine that could be used in residential gardens and in rural villages to provide electricity for individual homes and community schemes?  Such a model is proposed based on a mini solar chimney and venturi.

A mini solar chimney of height 2 metres and cross-sectional area 4 m2 receives warm air from a solar collector of area 8 m2.  The air flow is required to pass through a venturi where it acquires high velocity.  The extra kinetic energy of the air flow comes from the internal energy of the warm air.  A turbine sited in the throat of the venturi generates electricity.  It is calculated that to achieve an efficiency of 50% the venturi should be of diameter 0.2 metres, accelerating the air flow to up to 50 ms-1 giving an electrical output of up to 3 kw in bright sunshine.  This small model should generate 24 kwh/day in a sunny climate.  Larger models are also considered.

The author asks research workers in renewable energy laboratories to build, test and develop such a model.  If successful at an economic price, the recommended model could find an enormous market for individual residential gardens in advanced countries.  Equally it could provide solar home electricity on a massive scale in individual homes and community schemes in developing countries.  Natural convection could provide solar home electricity on the same scale and using parallel consumer mechanisms to those pioneered by photovoltaics.

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