The two main routes are biochemical (typically fermentation) and thermochemical (involving gasification). In either case, access to suitable feedstocks is critical to keep production costs in-line. Typical bio-based feedstocks are corn, sugarcane, and beets. The biochemical route is being commercialized by the Brazilian chemical company Braskem who is the leader in the manufacturing of bio-polyethylene. Braskem has access to large sugarcane crops in Brazil. Enzymes are used in the fermentation process to convert sugars into ethanol and butene. Metathesis of ethylene and butene produces propylene monomer. The Braskem process can be summarized (2):