You guys do realize that you don't have to wait for more energy, right? If you have an iPhone just have both the game and the settings app opened at the same time. When you run out of energy, go into the setting apps, change the date to 24 hours ahead, then go back into the game and you'll have full energy. Then go back to the settings app, press "set automatically" and your phone will go back to the correct date, and you'll still have full energy in the game. Just keep repeating that every time you run out of energy.