What is the fuel in Cirus?

Could you elaborate on the concept of "fuel" in the context of Cirus, and what specific role does it play within the system? I'm curious to understand if it's akin to traditional currencies serving as the lifeblood of economies, or if it holds a more unique function within the blockchain or cryptocurrency ecosystem. Furthermore, how is this fuel generated, acquired, and utilized within Cirus? Lastly, are there any unique challenges or advantages associated with this particular fuel that sets it apart from other systems?