Renewable Energy Projects
The Solar Chimney

Botswana is heavily reliant on coal and imported electricity to meet its electrical power demand. Energy production from coal and other conventional method is damaging to the environment and non-renewable. However, the country is endowed with a huge supply of renewable energy resources, especially solar energy.

The country receives over 3200 hrs of sunshine hours per year and an average insolation on a horizontal surface of 21MJ/M 2 . To exploit this resource BOTEC carries out a number of Research and Development work on Solar Technologies.

Solar Chimney

The Solar Chimney project was started in 2002, the technology is simple, environmentally friendly and does not need cooling water, a resource that is scarce in Botswana.

The Solar Chimney technology uses three simple traditional techniques (i.e. the glass roof , the chimney and the wind turbine) that are used in our everyday life situations to produce electricity. The glass roof collects heat from the sun to produce hot air, which is then drawnup the chimney. The hot air drives the turbine, which is installed, at the base of the chimney.

The only practical prototype was constructed around 1981/82 in Manzanares, Spain and was very tall (195m). Such tall chimney are expensive to construct and will provide a major structural engineering challenges.

The BOTEC prototype solar Chimney is shorter and stands at 22m. While acknowledging the fact that short chimneys can only deliver air velocity too low to start a wind turbine, we envisage that with modifications to the design a short solar chimney can run a wind turbine and generate electricity. The objective of this project is therefore to prove or disapprove the concept of a short solar chimney with a ducted turbine.

Research work is currently on going and the ultimate aim is to have a working short solar chimney. Should the concept prove to work a short chimney will be constructed using mainly local material resources and installed it in a remote village in Botswana at least by 2016.

Solar Thermal Test Facility

 Motshegaletau