NOVELTY - Producing renewable fuel involves (a1) providing at least one bio-oil selected from high-stability bio-oil, intermediate-stability bio-oil, and low-stability bio-oil; and (b1) processing at least one of the bio-oils in petroleum refinery according to at least one of the following methods (i) through (vi): e.g. (i) combining at least a portion of the high-stability bio-oil with first petroleum-derived stream of the petroleum refinery to form first combined stream, hydrotreating the first combined stream to produce first hydrotreated stream, and fractionating the first hydrotreated stream.    USE - As process and system for producing renewable fuels (claimed).    ADVANTAGE - The process produces commercial quantities and with enhanced efficiency by integrating bio-oil production system with conventional petroleum refinery.    DETAILED DESCRIPTION - Producing a renewable fuel involves (a1) providing at least one bio-oil selected from high-stability bio-oil, intermediate-stability bio-oil, and low-stability bio-oil, where the high-stability bio-oil has stability parameter of less than 30 centipoise per hour (cp/h), the intermediate-stability bio-oil has a stability parameter of 30-75 cp/h, and the low-stability bio-oil has stability parameter greater than 75 cp/h; and (b1) processing at least one of the bio-oils in petroleum refinery according to at least one of the following methods (i) through (vi): (i) combining at least a portion of the high-stability bio-oil with first petroleum-derived stream of the petroleum refinery to form first combined stream, hydrotreating the first combined stream to produce first hydrotreated stream, and fractionating the first hydrotreated stream; (ii) combining at least a portion of the high-stability bio-oil with second petroleum-derived stream of the petroleum refinery to form second combined stream, catalytically cracking the second combined stream to produce second cracked stream, and fractionating the second cracked stream; (iii) combining at least a portion of the intermediate-stability bio-oil with third petroleum-derived stream of the petroleum refinery to form third combined stream, hydrotreating the third combined stream to produce third hydrotreated stream, catalytically cracking at least a portion of the third hydrotreated stream to produce third cracked, stream, and fractionating the third cracked stream; (iv) combining at least a portion of the intermediate-stability bio-oil with fourth petroleum-derived stream of the petroleum refinery to form fourth combined stream, hydrotreating the fourth combined stream to produce fourth hydrotreated stream, thermally cracking at least a portion of the fourth hydrotreated stream to produce fourth cracked, stream, and fractionating the fourth cracked stream; (v) combining at least a portion of the low-stability bio-oil with fifth petroleum-derived stream of the petroleum refinery to thereby form fifth combined stream, thermally cracking at least a portion of the fifth combined stream to produce fifth cracked stream, and fractionating the fifth cracked stream; and/or (vi) combining at least a portion of the low-stability bio-oil with sixth petroleum-derived stream of the petroleum refinery to form sixth combined stream, fractionating at least a portion of the sixth combined, stream into at least a sixth heavy bio-fraction and sixth light bio-fraction, hydrotreating at least a portion of the sixth light bio-fraction to produce sixth hydro treated bio-fraction, and thermally cracking at feast a portion of the sixth heavy bio-fraction to produce sixth thermally cracked bio-fraction. An INDEPENDENT CLAIM is included for system (S1) for producing renewable fuels, comprising bio-oil production facility containing biomass conversion reactor for converting biomass into bio-oil; a petroleum refinery for refining petroleum products; and an integration system for combining at least a portion of the bio-oil from the bio-oil production facility with at least one petroleum-derived streams in the petroleum refinery for co-processing with it, where the integration system comprises at least one of first, second, third, fourth, fifth, and/or sixth integration mechanism for combining at least a portion of the bio-oil with at least one of the petroleum-derived streams, where the refinery comprises at least one of the following refining systems (i) through (vi): (i) first hydrotreating unit and first fractionator, where the first hydrotreating unit is located downstream of the first integration mechanism and the first fractionator is located, downstream of the first hydrotreating unit; (ii) second catalytic cracking unit and second fractionator, where the second catalytic cracking unit is located downstream of the second integration mechanism and the second fractionator is located, downstream of the second catalytic cracking unit; (iii) third hydrotreating unit, third catalytic cracking unit, and third fractionator, where the third hydrotreating unit is located downstream of the third integration mechanism, where the third catalytic cracking unit is located downstream of the third hydrotreating unit, where the third fractionator is located downstream of the third catalytic cracking unit; (iv) fourth hydrotreating unit, fourth hydrocracking unit, and fourth fractionator, where the, fourth hydrotreating unit is located downstream of the fourth integration mechanism, where the fourth hydrocracking unit is located, downstream of the fourth hydrotreating unit, where the fourth fractionator is located downstream of the fourth hydrocracking unit; (v) fifth thermal cracking unit and fifth fractionator, where the fifth thermal cracking unit is located downstream of the fifth integration mechanism and the fifth fractionator is located downstream of the, fifth thermal cracking unit; and/or (vi) sixth fractionator, sixth thermal cracking unit, and sixth hydrotreating unit, where the sixth fractionator is located downstream of the sixth integration mechanism, where the sixth thermal cracking unit is located downstream of the sixth fractionator, where the sixth hydrotreating unit is located downstream of the sixth fractionator.