the wide range of results is in many cases largely accounted for by the effects of luc and iluc but there is currently no consensus on a recognized methodology of quantifying those effects in particular for iluc which is not even considered in most studies this is for instance the case if residual biomass can be used for animal feed or fertilizer and the emissions related to the replaced feed or fertilizer are then subtracted from the fuel emissions many of the processes also produce significant excess heat andor byproducts suited for heat and electricity generation which similarly have associated substitution effects