Dr. Antonio Pfliiger, former head of the IEA Energy Technology Collaboration Division as well as Dr. Paolo Frankl, head of the Renewable Energy Division, and Dr. Mike Enskat, Senior Programme Manager for Energy at GTZ, provided guidance and input. Several IEA colleagues also provided useful data and comments on the draft, in particular Ralph Sims, Lew Fulton, Michael Waldron, Pierpaolo Cazzola, Francois Cuenot, Timur Gul, Ghislaine Kieffer and Yasmina Abdeliah. Raya Kiihne, Thomas Breuer and Thorben Kruse coordinated the GTZ contribution.