Yes, we appreciate the value of Steam Bots being able to self fuel. The next version will only go up to a certain point on our tech tree and subsequent versions will extent this. It just happens that the next version doesn't reach the Steam Age and so your bot tech is limited. The Mk3 bot will most likely be very similar to the original Steam Bot and future versions might include even more advanced bots like charged batteries or solar powered that don't require fuel.