Methods, process, apparatus, equipment, and systems are disclosed for converting biomass into bio-oil fractions for chemicals, materials, feedstocks and fuels using a low-cost, integrated fast pyrolysis system. The system improves upon prior art by creating stable, bio-oil fractions which have unique properties that make them individually superior to conventional bio-oil. The invention enables water and low-molecular weight compounds to be separated into a final value-added fraction suitable for upgrading or extracting into value-added chemicals, fuels and water. Initial bio-oil fractions from the process are chemically distinct, have low-water content and acidity which reduces processing costs normally associated with conventional bio-oil post-production upgrading since fewer separation steps, milder processing conditions and lower auxiliary inputs are required. Biochar is stabilized so that it can be handled safely. The integrated fast pyrolysis process includes biomass storage, preparation, pretreatment, and conversion, product recovery and processing to create and store stable biochar and bio-oil fractions.