The present invention is a process and apparatus for forming various bio-products from cellulosic plant material. The plant material is subjected to a pulping step in which lignin is extracted from the material by an aqueous lignin solvent to form a lignin-solvent mixture and purified cellulose. The lignin-solvent mixture can be separated from the water to form a high energy density fuel that can be used independently or combined with biodiesel. The purified cellulose can be used in conventional processes, e.g., paper making, or can be converted to fermentable sugars with a cellulase enzyme to produce other bio-products depending on the operating conditions of the fermenter. The bio-products produced by the fermenter can include the solvent that may be recycled for use in extracting the lignin.