We told you something last week about Siemens Gamesa and its attempt to break into the Electrothermal Energy Storage or ETES market, and talked this week to Hasan Özdem, Head of Technology Management and Projects at the company, to dig a little deeper. Our big concern in our coverage last week was that the two conversion rates – one where the system retains most of the heat (98%) from heating industrial stones, and the other which is that once converted back into electricity it only outputs 45% of the original source energy. The electricity creates hot air, blown over stones to heat them to 800 degrees and uses a stream turbine to turn the heat back into electricity. Özdem attacked…