Claus Michelsen Halle Institute for Economic Research   P.O. Box 11 03 61 Halle, 06017 Germany   cmn@iwh-halle.de   http://www.iwh-halle.de/d/abteil/REGO/cmn/pers.htm           JEL Areas: R3 : Production Analysis and Firm Location: General Q4 : Energy: General