A new breed of solar tower may soon be sprouting up in Namibia, providing the nation with a carbon-free source of electricity and food during the day and night. At one and a half kilometers tall and 280 meters wide, these massive solar updraft towers could potentially produce 400MW of energy each - enough to power Windhoek, the nation’s capital. Proposed by intellectual property company Hahn & Hahn, the towers generate energy by forcing heated air through a shaft lined with wind turbines. Additionally, the base of each tower will function as a 37 square km greenhouse where crops can be grown.
Solar updraft towers are an oft-overlooked source of alternative energy, although they do require a great expanse of space and copious amounts of sunlight. Theo von Backström from the Department of Mechanical Engineering at South Africa’s Stellenbosch University states: “One of the main reasons why commercial solar chimney power plants have not been built that they have to be very large to be economically viable”. Fortunately Namibia’s arid desert region provides plenty of space for such a generator, and the country sees around 300 days of sunshine per year.
Solar updraft towers generate energy by using sunlight to heat the air within a vast transparent greenhouse situated at the base of the chimney. As the hot air rises, it is funneled into the reinforced concrete chimney, driving a series of wind turbines which in turn generate energy.
The structure’s greenhouse base provides the perfect environment for growing crops, which actually allow the plant to produce energy after the sun has set. The water used for crops is heated during the day and transfers this energy to the tower at night. Once the towers are constructed they require very little maintenance, and Namibia has agreed to finance half of the costs of the $780,000 pre-feasibility report.