Click https://www.youtube.com/watch?v=YKT59QybrTM&feature=player_detailpage for 45 minute documentary on how Tesla came up with the concept of atmosphere-based electricity and how the financial powers withdrew investment with Tesla (who had his copyrights copied by Marconi) before he could succeed with his plan of "free energy for everyone."

Click https://www.youtube.com/watch?v=MFohadroheM&feature=player_detailpage for an explanation of the Tesla circuit that "captures" electrons in the atmosphere and then utilizes it to power the transformer (that in turn creates the electricity).  The moderator provides a link with a pdf file for further explanation.

Click http://www.instructables.com/id/How-To-Make-A-Tesla-Turbine-Greenest-Turbine/ for extended information on the materials needed to build the Tesla Turbine, which is about as "green" as you can get in terms of producing electricity.  It is unfortunate with my search of websites related to this fascinating concept; I surfed other sites and every site visited has a "cost" of some kind, so this is the best I can do.