THE SOLAR UPDRAFT TOWER.
The Solar Updraft Tower (SUT) is a natural draft device which uses solar radiation to provide upward momentum to the in-flowing air, thereby converting the thermal energy into kinetic energy. It uses a combination of three established technologies: the greenhouse, the chimney, and the wind turbine.
- This greenhouse is also called the collector and is essential for the realization of the greenhouse effect. The surface beneath the transparent collector becomes is heated because of solar radiation and on its turn warm up the air. Warm air wants to rise but is trapped and can only escape via the chimney.
- The updraft chimney is located in the centre of the greenhouse.
- The airflow in the chimney drives a wind turbine that produces electricity.
The relatively low-tech approach could allow local resources and labour to be used for construction and maintenance. The maintenance and operation of a tower is very cheap and simple. The turbine is the only moving component and therefore as a system very reliable. This makes the SUT very suitable for remote areas.
1982 MANZANARES
An experimental test tower was built in Manzanares, Spain in 1982 by Schlaich Bergermann & partners. The power plant operated for approximately eight years and was decommissioned in 1989.
The chimney had a height of 195 metres (640 ft) and a diameter of 10 metres (33 ft) with a collection area (greenhouse) of 46 hectares (110 acres) and a diameter of 244 metres (801 ft), obtaining a maximum power output of about 50 kW. Various materials were used for testing, such as single or double glazing or plastic (which turned out not to be durable enough). One section was used as an actual greenhouse.
POTENTIALS IN SEMI-ARID REGION OF NIGERIA
Details of SUT technology were reviewed including the experimental and theoretical studies, nowadays status, and economical feasibility. Estimations were based on an average sunshine houres and solar radiation of respectively 9 hours, and 7kW/m2/day.
The importance of SUT technology being a most suitable solution for power generation in semi-arid region of Nigeria cannot be overemphasized.
