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Producing bioethanol, the phases


Produce bioethanol: as seen in the articleDIY bioethanol, the production of thebioetnaolit is by no means an easy task.

In the United States, thebioethanolit is produced above all from substances rich in starch such as corn and potatoes. Therebioethanol production, as well as that of other biofuels, has triggered the phenomenon ofland-grabbing, literally "land grabbing ": the multinationals have bought vast areas of land in the southern hemisphere and used them for the cultivation of corn destined tobiofuels. Putting ethical issues aside, let's see which stages are suitable forproduce bioethanol.

The production process of thebioethanolcan be divided into three phases:

  1. The preparation of molasses, or sugary solutions to be fermented.
  2. The fermentation section.
  3. Distillation phase ofethanolwith waste water treatment.

These three phases can take place with different techniques, just as the preparation of the molasses can be carried out starting from different substrates (sugars, starches, cellulose…).

The production ofbioethanolfirst generation
For first generation biofuelswe mean all biofuels obtained from substrates obtained from specific crops.

One of the most used treatments in America forproduce bioethanolsees the use of specially grown corn-based substances.

For produce bioethanol it starts from the process of dry-grinding (dry grinding): the corn grain is ground dry to obtain a coarse flour to which water will be added. The mixture is placed at high temperatures and prepares for the fermentation phase. The fermentation of molasses takes place thanks to enzymes capable of producing liqueurs containing high percentages ofethanol. The ethanol produced by fermentation is not pure at all but mixed with water and other liquids. To obtainbioethanolpure it proceeds with the distillation which must take place at controlled pressure and temperature. At the end of the ethanol distillation section, the residual water must be treated.

Second generation bioethanol production
Large multinationals are starting toproduce bioethanolstarting from wood waste and cellulose-based substrates. This process is more complex because to get bioethanol second generation sugars must be extracted from the cells present in the wood waste (these plant cells are protected by a layer of lignin, more difficult to "break"). Wood products have a much lower purchase cost thancorn (essential in the food sector) but the presence of lignin inhibits the hydrolysis process and hinders the extraction of sugars. In this scenario, multinationals carry out more complex chemical-physical processes. The challenge is to find a production process that can be beneficial, at the same time, for companies and the environment with a positive energy balance.

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Video: Bioethanol production process (October 2020).