CAL started producing steel towers forturbines in 1991 after the company was taken over by HW Urban Management of Berlin. Before reunification of Germany, CAL was an industrial combine producing pipes for oil refining and gas pumping, mainly for export to former Soviet countries. After its privatisation, CAL switched products to wind turbine towers and radio masts and is now concentrating increasingly on the wind market. The company's growth has been startling. In 1993 it made 84 towers and expects to treble this to around 240 by the end of 1994. The market is bound to expand, according to CAL, as wind turbine manufacturers move away from concrete towers to steel for a number of reasons: greater stability, longer life (at least 20 years) optimal corrosion protection, simpler installation, environmental compatibility and the pleasing aesthetics of steel towers, says CAL managing director Klaus-Joachim Lehmann.
CAL is currently researching the characteristics required of steel towers for 1 MW machines. It is also looking at the practical limit to the size of such a tower, with the key dimension the diameter of the base. Road transport is possible up to a diameter of around 4.8 metres, it says. The company is looking into new designs to allow towers to be constructed in components which fit into containers to facilitate transport.