Glycerol from biodiesel production: Technological paths for sustainability

Abstract Increases in biodiesel production have led to a surplus of crude glycerol, which represents a major bottleneck in the biodiesel production chain and has created new challenges to its sustainable use. Although there is a wide range of potential uses for crude glycerol, they are limited by its degree of purity, which affects its physical, chemical and biological properties. This paper presents a review and analysis of patents related to the use of glycerol in the period from 1993 to 2015, showing the quantity and diversity of work related to the search for alternatives to add value to glycerol. It was found that 85.7% of the filed patents fell into four categories of applications: 1) manufacture of chemical products; 2) production of polymer compounds; 3) production of biofuels and biogas; and 4) purification and use of glycerol. In this regard, the development of new technologies for the use of glycerol, without the need for traditional purification steps, are fundamental. This paper portrays the efforts that have been made in this direction and the obstacles that still have to be overcome.