I agree about the direct solid fuel production from coal mechanic: it's too efficient, especially since the process also produced creosote, which can make even more creosote. Even wood to coal is a bit too efficient: I can understand 2 wood for one coal, but creosote is produced as well.
If creosote as a useful byproduct is to be kept as a mechanic, I feel like the wood-to-coal and coal-to-solid fuel material requirements should be about doubled. Otherwise, with the current numbers along with production modules, solid fuel production from coal is much too efficient. I think simply condensing energy products shouldn't give you free extra energy without production module use (like Solid Fuel to Rocket Fuel). It would be different if another/more resources were needed to produce another energy product (like Rocket Fuel to Nuclear Fuel).
