The recipe for Wood Gas Solid Fuel is kind of pointless when compared to the default recipe
Wood Gas: 20 Wood Gas + 20 Heavy oil = 1 Solid Fuel in 2 seconds
Default: 20 Heavy Oil = 1 Solid Fuel in 2 seconds
There is no benefit from using wood gas vs. the default recipe especially when it adds a byproduct of coal for making the wood gas. Maybe change Heavy oil for Fish oil if you're worried about a balance issue?

Huh... Yeah, you're right. It's been a while since I made this so I forget what the logic was at the time, but this does indeed make no sense. I'll have to re-run the energy gain numbers again and see if I can find something more reasonable.

OK, I have some time. Let's crunch the energy density numbers. I'm going to disregard Heavy Oil entirely since it's in both recipes in the same amount. The only difference is Wood Gas and how much energy density that adds. Wood Gas costs 217KW at 5s, so 1.085MJ + 10 Wood at 2MJ each for a total of 11.085MJ in total. It produces 7 Coal at 4MJ each for a total 14MJ + 100 Wood Gas. So technically, that's 100 Wood Gas and 2.915MJ gain of energy, or 29.15MJ per unit of Wood Gas.

Wood Gas Solid Fuel costs an additional 20 Wood Gas relative to Solid Fuel from just Heavy Oil. Again, we're disregarding the Heavy Oil and looking at just the added energy cost. Said added energy cost would be 20 Wood Gas at 29.15KJ each, for a total extra of 583KJ. For the Wood Gas Solid Fuel recipe to be worth bothering for, it needs to account for that extra energy cost, as well as some overhead to cover the extra cost of transportation and the increased complexity. Here, we have three options.

I could increase the yield. However, with a base yield of 1, the minimum increase I can do is to double it to 2, which would be massive. Solid Fuel is worth 12MJ per unit, so doubling the input would drastically overpower the recipe. Lowering the cost of Wood Gas wouldn't make a difference since Solid Fuel from Heavy Oil would always be better. I could lower the cost in Heavy Oil, which... would require me to also account for the cost of Heavy Oil, which I'd currently like to avoid doing. I could alternately reduce crafting time. Going to 1 second would make this recipe a faster alternative, as all other recipes are 2 seconds per unit crafting time. That would also lower the cost of the recipe by 217KW in Chemical Plant run costs. However, that reduction would be diminished with energy cost reduction Modules or Beacons.

Alternately, I can refactor the entire recipe, increasing costs, yield and time by a factor of 10. So 200 Wood Gas, 200 Heavy Oil and 20 seconds in return for 10 Solid Fuel. I think I'm going to have to account for the Heavy Oil in this one, though. Basically, by making all the values larger, I can increase yield by a smaller amount - say 12 Solid Fuel up from 10, or a 20% increase in yield.

Let me know if you like any of these proposals and I can work them back into the mod. Might have to do something similar with Bioplastic, as well. I THINK that one's already optimal, but I like consistency.

Well, this fell through the cracks and I just forgot about it. I'm doing an unrelated fix, so might as well give this another crack.

The reason I didn't want to consider Heavy Oil energy capacity before was due to how complex oil processing is. However from what I can tell, it's more efficient to produce Solid Fuel Heavy Oil Cracking -> Solid Fuel than from Heavy Oil -> Solid Fuel directly. The latter is 20 Heavy Oil -> 1 Solid Fuel, or 40 Heavy Oil -> 2 Solid Fuel, at a cost of 840KJ and a gain of 24MJ. That's a gain of 579KJ per unit of Heavy Oil. The former is 40 Heavy Oil -> 30 Light Oil -> 3 Petroleum at a cost of 1.68MJ and a gain of 36MJ. That's a gain of 858KJ per unit of Heavy Oil. There's no gain in volume from Light Oil Cracking -> Solid Fuel, so that's the cost we're trying to beat.

Just for the sake of completeness since we'll need it, though: 20 Petroleum -> 1 Solid Fuel costs 420KJ and gains 12MJ. That's a gain of 579KJ per unit of Petroleum. 10 Light Oil -> 1 Solid Fuel costs 420KJ and gains 12MJ. That's a gain of 1.158MJ per unit of Light Oil. That should give us enough data to calculate with.

Let's use Advanced Oil Processing for Solid Fuel. It gives us 25 Heavy Oil, 45 Light Oil, 55 Petroleum. So that's 25 Heavy Oil + 52.11MJ's worth of Light Oil and another 31.845MJ's worth of Petroleum, for a total of 81.855MJ when Refinery cost is accounted for. Without Biodome Industries, the Heavy Oil would be worth an additional 21.45MJ's worth of Solid Fuel. So Biodome Industries needs to be competitive with that.

OK, so what's the cost of Wood Gas? If we go from scratch, then that's a 10 craft in the Biodome which consumes 93KW and produces 10 wood worth a total of 20MJ. That costs 930KJ, which gives us 1.907MJ per piece of Wood obtained that way. Wood Gassification produces 7 Coal and 100 Wood Gas over 5 seconds. That's a crafting cost of 1.05MJ and a gain of 28MJ's worth of energy in coal. In other words, each unit of Wood Gas already nets us a gain of 269.5KJ. It's important to note that this energy gain is theoretical due to side products, not an intrinsic value of the Wood Gas itself. Currently, it's a waste product the player needs to get rid of, because Solid Fuel from Wood Gas is only slightly less bad than Heavy Oil -> Wood Gas, while it needs to compete with Heavy Oil Cracking -> Wood Gas.

So... Heavy Oil -> Solid Fuel is a gain of 579KJ per unit of Heavy Oil. Heavy Oil Cracking -> Solid Fuel is a gain of 858KJ per unit of Heavy Oil. Currently, Solid Fuel from Wood Gas is a 2s craft time at a cost of 20 Wood Gas and 20 Heavy Oil. I'm reticent to consider the energy gained from including Wood Gas because it makes no sense to me intuitively. If Wood Gassification didn't produce Wood Gas at all, then nothing about Solid Fuel production would change, so I don't accept that incorporating a "waste product" somehow increases the productivity of a recipe. Players might as well get themselves a Flare Stack mod and vent the Wood Gas, then just go with the Light Oil Cracking they're already doing at their refineries anyway.

With that said, we'll consider Wood Gas to be "free" - neither a net negative nor a net positive. It's a thing we're getting from an energy-positive process of making charcoal. As such, we need the Solid Fuel from Wood Gas recipe to exceed the efficiency of Heavy Oil Cracking -> Solid fuel. Let's say we up the Wood Gas cost quite a bit, to say 40, but drop the Heavy Oil cost down to 10. 10 Heavy Oil per 1 Solid Fuel costs 420KJ to make, gives us 12MJ back, or a total of 1.158MJ per unit of Heavy Oil. That's a significant increase over the energy gain of 858KJ per unit of Heavy Oil from Heavy Oil Cracking -> Solid Fuel. It might be a bit too significant, but I think I'm happy with it, honestly.

Long story short, expect the Solid Fuel from Wood Gas recipe to change into "40 Wood Gas + 10 Heavy Oil" in this coming patch.