Pyrolysis oil are affected by temperature, reaction time, algae species, algae concentration, reaction atmosphere, and catalysts, in subcritical water reaction conditions. Bio-oil typically requires significant additional treatment to render it suitable as a refinery feedstock to replace crude oil derived from petroleum, coal-oil, or coal-tar. Tar is a black mixture of hydrocarbons and free carbon obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. Wood-tar creosote is a colourless to yellowish greasy liquid with a smoky odor, produces a sooty flame when burned, and has a burned taste. It is
Tar Heel History of a Southern State" (3rd edition, 1973) that North Carolina led the world in production of naval stores from about 1720 to 1870. At the time, tar was created by piling up pine logs and burning them until hot oil seeped out from a spout. The vast production of tar from North Carolina led many, including Walt Whitman, to give the derisive nickname of "Tarboilers" to the residents of North Carolina. North Carolina was nicknamed the "Tar and Turpentine State" because of this industry. Somehow, these terms evolved until the nickname Tar Heel was used to refer to residents