maybe they could genarate as a workshop with a giant hole in the side where one Machine went funny or generate as a city that had a nuclear meltdown 
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Edit:
If they contain any machines, they should be uncraftable, overpowered and rusted (meaning they are unreliable)
This is my energy producer using Buildcraft, Zeldo's Additional Pipes, and Equivalent Exchange
The Collector turns glowstone dust into glowstone blocks which is then pumped out and is turned into four glowstone dust. Then it's pumped through a chest (to separate them out) then into a Distribution Pipe
which sends one back to the Collector, the other three become One and a Half Alchemical Coal (which mean every two cycles three Alchemical Coals are produced). Then the Alchemical Coal is pumped into three to five genarators (not sure how many are nedded but one can't keep up).
EDIT: Three Genarators are enought
