Joined Cases C-566/11, C-567/11, C-580/11, C-591/11, C-620/11 and C-640/11: Judgment of the Court (Fifth Chamber) of 17 October 2013 (requests for a preliminary ruling from the Tribunal Supremo — Spain) — Iberdrola SA, Gas Natural SDG SA (C-566/11), Gas Natural SDG SA (C-567/11), Tarragona Power SL (C-580/11), Gas Natural SDG SA, Bizcaia Energía SL (C-591/11), Bahía de Bizcaia Electricidad SL (C-620/11), E.ON Generación SL and Others (C-640/11) (Request for a preliminary ruling — Protection of the ozone layer — Scheme for greenhouse gas emission allowance trading within the Community — Method of allocating allowances — Allocation of allowances free of charge)