motivation - principle - technology - [energy production costs]

With the support of construction companies, the glass industry and turbine manufacturers a rather exact cost estimate for a 200 MW solar updraft tower could be compiled. We asked the utility "Energie Baden Württemberg" to determine the energy production costs compared to coal- and combined cycle power plants based on equal and common methods (Fig.7). Purely under commercial aspects with a gross interest rate of about 11% and a construction period of 4 years during which the investment costs increase already by 30% (!) electricity from solar updraft towers is merely 20% more expensive than that from coal. In case of the solar updraft tower the interest on the fix investment governs the price of electricity, whereas in the case of fossil fuel power plants the variable fuel costs are the deciding factor.

By just reducing the interest rate to 8%, electricity from solar updraft towers would become competitive today (Fig. 8). In low-wage-countries the costs will reduce further especially those of the glass roof collector which alone amounts to 50% of the overall costs.

Fig. 7: Comparison between the energy production costs of two x 200 MW solar updraft towers and 400 MW coal and combined cycle power plants according to the present business managerial calculations.

Fig. 8: Energy production costs from solar updraft towers, coal and combined cycle

power plants depending on the interest rate.

On the other hand there are a number of advantages: No ecological harm and no consumption of resources, not even for the construction. Solar updraft towers predominantly consist of concrete and glass which are made from sand and stone plus self-generated energy. Consequently in desert areas - with inexhaustible sand and stone solar updraft towers can reproduce themselves (Fig.9). A truely sustainable source of energy! The (high) investment costs are almost exclusively due to labour costs. This creates indigenous jobs, and a high net product for the country with increased tax income and reduced social costs (=human dignity, social harmony), and in addition no costly imports of coal, oil, gas which is especially beneficial for the developing countries releasing means for their development.Therefore, now it is absolutely essential to build and test a large solar updraft tower.

Fig.9: solar updraft tower feeding glass- and cement-factories with energy for the construction of a further solar updraft tower.