I think he was saying about the nitro coalfuel, although this one has lesser heat (18k) than biofuel (from biomass) so it's not really.. useful.. I suggested to up this a bit.. hopefully it gets implemented
The nitro-diesel can't be used in liquid fueled box (I think this is a bug because Greg said he had added heat value for this).
The hydrogen.. haven't tried it since the nerf of GT hydrogen (it's now 2k heat) (which is pretty reasonable from real life point of view)
There's one more.. methane (only 3k heat).. and requires 25k eu if you get it from foods....
Ref: biofuel provides 32k heat; lava provides 1k heat..
In conclusion, just use the biofuel lol..