We are also discussing about how complex/simple the actual icon should be. Might also try some form of playing with letters "E" and "C". Along the lines of
https://logotournament.com/contests/gamedb winning entry.
I admit we do not have a nice and defined idea we would like implemented but we would like to have one developed as we go. Perhaps a combination of a graphical element (such as a leaf, although i have to say it might be too straightforwardly pointing into "green" direction ) and a stylized trick with letters.