Electrical Engineering: Economy Through Air Power

Yugoslav Geologist Bozidar Djordjevitch had an ingenious idea. Every spring, he said, water from melting snow pours into Yugoslavia's Karst caves, compressing air that whistles out through vents in the earth's surface. Why not seal the caves and funnel the escaping air to gas turbines, which could convert it into useful energy? Djordjevitch soon had an answer: the caves are vented in too many places; they are almost impossible to seal off.

To Professor Hans-Joachim Martini, director of West Germany's Federal Geological Survey, the basic idea still seemed sound, so he cleverly worked out a new version of Djordjevitch's plan. For...