Unfortunately, flaring is by no means uncommon at the Cepsa refinery. Flaring can occur as the result of a safety response mechanism to release pressure during unplanned over-pressuring of plant equipment (much like a spout on a tea-kettle), but refineries also use flaring simply as a means for burning flammable "waste" gases or by-products that are not economical to retain. (C&P http://en.wikipedia.org/wiki/Gas_flare in your browser for further info)