Andrej Pustisek teaches energy economics at the University of Applied Science, Stuttgart, Germany and at the University of Karlsruhe (KIT), Germany, owns a consulting companys providing services to international natural gas and energy companies, inter alia, in arbitration proceedings, and lectures international courses on natural gas. In 2017 his latest book ‘Natural gas: a commercial perspective’ has been published. He studied Geophysics and Economy in Vienna, Cologne and Munster. He holds a Ph.D. in Geophysics and a Ph.D. in Economy. In 1990, he started in international natural gas purchasing of Wintershall, Kassel, Germany. As of 1993 he headed different departments of WINGAS, Kassel, Germany (a Gazprom and BASF joint venture). From 2002 to 2012, he worked for E.ON Ruhrgas, Essen, Germany; first as Senior Vice President International Natural Gas Sales and from 2008 as Senior Vice President Portfolio Management.