How wine-surplus bioethanol is produced
At the Alcázar de San Juan plant the production process starts with the cleaning and dehydration of the raw alcohol purchased in tenders that the Spanish Agricultural Guarantee Fund calls every quarter. The purity of the alcohol is raised from 92% to 99.9% and, after denaturalization, it is marketed as bioethanol.
There are four phases in the production process:
- Desulphurization: Eliminates the sulphur dioxide (SO2) present in the raw alcohol.
- Dehydration: Reduces the water content through screening with zeolites (substances that capture water molecules).
- Demethylation: The methanol content is separated in dehydrated alcohol (99.9%). While methanol is corrosive for vehicles, it can be marketed as a chemical or fuel product for other uses.
- Storage in tanks: The product is piped to a tanker truck; along the way, a substance is added that denaturalizes the bioethanol to avoid its use for human consumption.