Infinite Firestorm Wall
If you have a firestorm wall and it is fully charged, you can 
make it last forever without having to turn it off to charge. 
First charge your wall fully, then turn it on. Before it turns 
off or runs out of power sell or turn off your power plants 
until the words "On Hold" appear in the firestorm Icon. Your 
wall will stay on forever and will not run out of power until 
you build or turn on your power plants.