Just out of wanting to understand you, here, why do you think that oil-fired boilers should be more efficient than solid fuel boilers?
I think in terms of the gameplay choices, solid fuel is more of just a "stand in" for using fluid as fuel directly due to a number of issues related to the fluid dynamics that we've tried to avoid over the years. Nowadays, you certainly can use the fluid as fuel directly in a number of mods (including mine), but in those cases, I'm not sure why the fluid fuel would be more efficient. One thing one of my mods does -- truly, I'm not trying to plug my mods, it's just that I've been playing with the energy production methods and efficiencies for a long time, now -- is enforce different efficiencies between burning petroleum fuels (whether solid or fluid) and nuclear fuels, or making heat from fossil fuels rather that nuclear, and between whether you burn the petroleum fuel in a boiler vs. burning it directly in a generator. I get why the efficiencies would be different between these things. What is your thinking about why the efficiencies would be different for a petroleum fuel relative to whether it is solid or fluid? Either way I want to know your thinking, but if you have a good reason I haven't considered, I might implement it.