So the demons, much like ghosts in real life, gather their energy through electricity, but it isn't local in Hell, so a company called Voxtech-- I MEAN Falstricity inc. developed an artificial energy made from harnessing the power of hellfire. It shines bright blue instead of yellow, and is used to power all rings of hell and is used in food and drink to provide energy to the demons so they don't, ya know, die. A demon, depending on what age and what type, can go for a certain amount of time without energy. Hellborne can make it about a couple of weeks, demons about a month, deadly sins for 6 months, Lucifer's right hands for a few years, and Lucifer forever. One of the main reasons demons and hellborne travel to Earth is to get a taste of real energy. Real electricity, not Falstricity. It's like a drug to them, and it's easy to get addicted (basically what it does to them is what it would do to humans if you put alcohol in an energy drink). It's sold illegally in hell, since nowadays it's illegal to travel to Earth because of the Great Exorcisms (I'll get into that later).