This paper presents an optimization approach for the production of syngas from biogas via tri-reforming. The optimization, formulated as a NLP problem, is performed for three syngas ratios according to the desired product: methanol, ethanol or Fischer-Tropsch (FT) fuels. As a result, the optimal operating conditions and biogas composition are defined. For the production of ethanol, a biogas composed by a CH4:CO2 ratio of 0.52:0.48 is desired, requiring 0.035 mol of O-2 per mol of Biogas in the reformer. For the production of methanol and FT, biogas with the largest content of methane is suggested to be reformed with 0.275 mol O-2/mol biogas. The largest H-2:CO ratio required for methanol is achieved by feeding steam in a WGS reactor after the reformer. The syngas optimization study is completed by evaluating tri-reforming for the production of FT fuels from biogas via high and low temperature FT synthesis. The production cost for a plant fed with 12 MMm(3)/y of biogas results in $3/gal for biodiesel via HTFT and $1.7/gal via LTFT.